Download 8th International Workshop on Planetary, Solar and Heliospheric

8th International Workshop on
Planetary, Solar and Heliospheric
Radio Emissions (PRE 8)
October 25-27, 2016
Seggauberg near Leibnitz/Graz, Austria
Cover design and PRE 8 logo design by Manuel Scherf
Webpage http://pre8.oeaw.ac.at/
Local Organizing Committee (LOC)
Georg Fischer ([email protected])
Claudia Grill ([email protected])
Doris Hradecky ([email protected])
Maxim Khodachenko ([email protected])
Mykhaylo Panchenko ([email protected])
Manuel Scherf ([email protected])
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Welcome Address
Dear participants,
the Scientific Organizing Committee (SOC) is pleased to welcome you to our 8th International
Workshop on Planetary, Solar and Heliospheric Radio Emissions, commonly known as “PRE 8”.
Previous PRE meetings all took place in Graz in the years 1984, 1987, 1991, 1996, 2001, 2005 and
2010. This is the first PRE meeting outside of Graz, but the centre of the capital of the province of
Styria is just 35 km north from “Schloss Seggau”, our meeting place of the 2016 PRE workshop.
Besides the slight change in location, there is also a change in the organization of the workshop, in
which a newly formed Scientific Organizing Committee chaired by a new main organizer has taken up
the torch. As most of you know, Prof. Helmut Rucker was the main organizer of all previous PRE
meetings in Graz. The SOC is most grateful to Helmut for doing a fantastic job in organizing 7 PRE
meetings over almost 3 decades. This effort has really been an invaluable service to our scientific
community. The SOC is also grateful to our sponsors, namely the Austrian Ministry for Transport,
Innovation and Technology, the Province of Styria, Europlanet, URSI and the Space Research Institute
of the Austrian Academy of Sciences.
As organizers we are setting the stage. We hope that you are going to like our new stage in this
historical castle next to the city of Leibnitz, and also surrounded by gentle hills where the grapes for
excellent wines are growing. Now it is up to you, our dear participants, to make the performance by
presenting your newest findings about planetary radio emissions and by engaging in interesting
scientific discussions. We wish you all a scientifically productive meeting and a pleasant stay.
Welcome to PRE 8 at Schloss Seggau!
Scientific Organizing Committee (SOC)
Georg Fischer (chair)
Gottfried Mann
Philippe Zarka
Maxim Khodachenko
Mykhaylo Panchenko
Alain Lecacheux
Joseph Lazio
Manuela Temmer
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Meeting Agenda
Key topics of our workshop are the recent developments in the study of non-thermal radio emissions
from the Sun, the five radio planets, the heliosphere, and potential radio emissions from exoplanets.
Special emphasis is put on current missions like Cassini and Juno, but also new findings from data of
older missions like Stereo, Voyager, Galileo, Wind or Ulysses are welcome. Studies of terrestrial radio
emission data from missions like MMS, Themis, Van Allen Probes, Cluster or Demeter can be another
important topic. In addition to space-based observations, new developments in ground-based radio
telescopes will be matters of discussion that should lead to a better coordination of ground- and
space-based observations. Presentations should focus on physical properties of radio emissions like
rotational modulation, fine structures in dynamic spectra, polarization as well as source direction,
and theoretical modelling and simulation of plasma and magnetic processes leading to their
generation. Key question for future missions like Solar Orbiter or JUICE can also be addressed.
Sponsors
Austrian Ministry for Transport, Innovation
and Technology (Bundesministerium für
Verkehr, Innovation und Technologie)
The Province of Styria
Europlanet
NA1 – Innovation through Science Networking
Task 5 – Coordination of ground based
observation
Space Research Institute (IWF, Institut für
Weltraumforschung)
Austrian Academy of Sciences (Österreichische
Akademie der Wissenschaften)
International Union of Radio Science
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General information
Location of the workshop
PRE 8 takes place in the conference hotel “Schloss Seggau” in Seggauberg 1, A-8430 Leibnitz, in
Austria. It is located on a hill next to the small town of Leibnitz with about 12,000 inhabitants. The
map shows you the location of the castle with the town on its eastern side and a lake (Sulmsee) and
gentle hills on the western side. Leibnitz is located about 35 km south of Graz, and about 30 km
south of the airport Graz-Thalerhof.
The foundations for the historic castle Seggau were already laid in the 12th century, and after several
reconstructions the castle was completed in its present form in the second half of the 17 th century.
Schloss Seggau was the residence of the Styrian bishops until 1786, after which it remained their
summer residence until the mid-20th century. Today Schloss Seggau is a conference hotel in which
modern architecture was carefully integrated within the historical buildings.
Transportation
Leibnitz and Schloss Seggau can be reached from the airport Graz-Thalerhof in about 20-30 minutes
by car or taxi. The price for the taxi ride should be around 50-60 €. There is also public transport
(trains) from the airport Graz to the city of Leibnitz which typically go every half hour (price around 7
€). For the exact train schedule check out the website http://fahrplan.oebb.at/bin/query.exe/en?.
Schloss Seggau is located about 3 km from the train station in Leibnitz, which is a 5 minute taxi ride.
We do not recommend walking to the castle, since it is on a hill with partly no boardwalk along the
street. There should be taxis at the train station and if not call one of the local taxi companies (Taxi
Werber: +43 3452 2217; Taxi Sackl: +43 3452 2218).
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Social events: Wine tasting and excursion
On the evening of the first workshop day, Tuesday October 25, we will have a wine tasting event
starting at 8 PM as a kind of icebreaker party. The region of southern Styria is well-known for its
excellent white wines, for example, wines from Erich and Walter Polz were served at the wedding
dinner of Princess Madeleine of Sweden in 2013. The wines of “Schloss Seggau” are also produced by
Erich and Walter Polz, and we will taste 5 different wines in the wine cellar of the castle. We
recommend that you take your jacket/coat with you since there is no heating in the wine cellar. This
event is sponsored by the Space Research Institute of the Austrian Academy of Sciences.
Our second social event is a visit to the chocolate factory “Zotter” in Bergl close to Riegersburg. We
will leave from the parking place of Schloss Seggau on Wednesday, October 26, at 1:30 PM, and a 1hour bus ride will take us there. Zotter (http://www.zotter.at/en/homepage.html) is a company that
produces its chocolates from bean to bar, and we will wander around the transparent chocolate
factory to see the transformation of the cocoa bean into chocolate. And there are numerous places
in the factory where you can taste the chocolate and eat as much of it as you want. This tour typically
takes about 1 hour, but you can also stay longer if you wish. At the end of the tour there is a shop
where you can choose among at least 100 different sorts of chocolate. There you can buy some
chocolate bars, which might be a nice gift for your family at home. There is also a park and small zoo
behind the factory which can be visited at no additional costs, until we reconvene at the bus around
5 PM to leave at 5:15 PM sharp. We should be back at Schloss Seggau around 6:15-06:30 PM, just in
time for dinner at 6:30 PM. The costs for this trip (organized bus transportation, entrance fee at
Zotter) are covered by your registration fee.
Weather and dress
The average high temperature for the south of Styria (Graz, Leibnitz) in October is 16°C (61°F), and
the average low temperature is 5°C (41°F). The average precipitation for October is 75 mm, and the
sun is shining for 4.5 hours on average per day. Conditions at the end of October can be quite
variable, it could be nice and sunny with temperatures around 20°C, but it is also possible to have
rainy weather with temperatures slightly above freezing level. In rare occasions there can be even
snow, which usually melts away quite quickly. In recent years it used to be quite nice weather on
October 26, which is a national holiday in Austria.
Restaurants, bars, shops, banks
Since coffee breaks, lunches and dinners are included in your registration fee, it will not be necessary
to go to other restaurants. Furthermore, Schloss Seggau has its own castle tavern. There are
restaurants, bars, shops and banks with ATMs in the city centre of Leibnitz (orange marked streets in
the map on page 6). There is no ATM at the castle. The city centre of Leibnitz can be reached by
car/taxi (see transportation) or in a 20-minute walk by foot. But note that castle Seggau is located on
a hill and you might walk on trails through the woods downhill and uphill since at some parts there is
no boardwalk along the street to the castle. Please also note the Wednesday, October 26, is a
national holiday in Austria, and so shops and banks will be closed.
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Proceedings
We ask all participants (regardless of presentation type) to provide us a written article about their
presentation for the proceedings. The conference contributions will be collected and reviewed. They
are going to be published in a proceedings book by the Austrian Academy of Sciences Press, which
should be released in autumn 2017. We plan to keep up our tradition and publish the “Planetary
Radio Emissions VIII” proceedings book in the same layout and format as the books of the previous
seven workshops, so that it will add neatly to the “silver series” PRE books. Additionally we plan to
produce a memory stick with all papers from PRE 1-8. Book and memory stick will be sent to each
conference participant at no additional costs. For your contribution please take notice of the
following page limits:
Contributed papers (talks & posters): 8 pages; Invited papers: 12 pages
Note that your whole manuscript including figures and references has to be within this page limit.
We ask you to deliver your contribution as Latex file, and style files and templates will be available
for download on our webpage (http://pre8.oeaw.ac.at/proceedings.php):
1. The Latex style file pro12.cls
2. a file called mypre8paper.tex where you can easily fill in your text in any text editor
3. the file references.tex where many references will be listed alphabetically for you to select
them for copy and paste into your manuscript
4. an example file example.tex which can be compiled but has no figures
There is no limit on the usage of colour figures. Please convert your figures to ps or eps format for
usage within Latex, but also provide your figures in the original graphic format. Keep in mind that the
jpg format is only appropriate for photos, but not really for scientific diagrams. Please send your
contribution via email to the main organizer of the workshop ([email protected]).
The deadline for the submission is Wednesday, February 1st, 2017!
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Registration fee
For your registration fee of 360 € (students, young scientists below 35 years of age, and amateurs
only pay 180 €) you will receive the following things: Abstract booklet, name badge, coffee breaks,
lunches and dinners (except for beverages consumed at lunch or dinner), wine tasting event,
excursion to chocolate factory with bus ride and entrance fee, proceedings book with memory stick.
So note that even if you are not staying in the conference hotel, all meals and coffee breaks (except
breakfast) are included. Note that also the dinner on the arrival day (Monday, October 24) is covered
by your registration fee.
Workshop time table
MONDAY
OCT. 24
Arrival day
with registration
(registration
starting at 2 PM)
18:30-20:00
Dinner
Free time
TUESDAY
OCT. 25
9:00-10:30
Opening and
Oral Session 1
10:30-11:00
Coffee break
11:00-12:30
Oral Session 2
12:30-14:00
Lunch
14:00-15:30
Oral Session 3
15:30-16:00
Coffee break
16:00-17:30
Oral Session 4
18:30-20:00
Dinner
20:00-21:00
Wine tasting
WEDNESDAY
OCT. 26
THURSDAY
OCT. 27
9:00-10:30
Oral Session 5
9:00-10:30
Oral Session 7
10:30-11:00
Coffee break
11:00-12:00
Oral Session 6
12:00-13:30
Lunch
13:30-18:30
Excursion to Zotter
chocolate factory
(bus travel of ~1 h
one way)
10:30-11:00
Coffee break
11:00-12:30
Oral Session 8
12:30-14:00
Lunch
14:00-15:45
Oral Session 9
15:45-16:15
Coffee break
16:15-18:00
Poster Session
18:30-20:00
Dinner
Free time
18:30-20:00
Dinner
Free time
FRIDAY
OCT. 28
Departure day
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Program Overview
Invited talks are 25+5 minutes, contributed talks should be 12+3 minutes discussion time.
Tuesday, October 25, 2016
Session 1: Opening and results from Juno
Chair: Georg Fischer
09:00-09:30
Welcome Addresses and presentation of local arrangements
09:30-10:00
W.S. Kurth et al.: First observations near Jupiter by the Juno Waves investigation
(invited)
10:00-10:15
G. Hospodarsky et al.: Quasi-Periodic (QP) emissions as observed by Juno Waves.
10:15-10:30
M. Imai et al.: Analysis of Jovian low-frequency radio emissions based on the Juno
Waves data and stereoscopic observations with Juno and Earth-based radio
telescopes
10:30-11:00
Coffee break
Session 2: Jupiter radio emissions
Chair: Philippe Zarka
11:00-11:30
T. Clarke et al.: Jovian decametric emission with the Long Wavelength Array Station 1
(invited)
11:30-11:45
Ch. Higgins et al.: Spectral characteristics of Jupiter’s Io-D decametric radio source
from the Long Wavelength Array Station 1
11:45-12:00
K. Imai et al.: Io-C and Io-B source morphology of Jupiter's decametric emissions from
LWA1 modulation lane data analysis
12:00-12:15
B. Cecconi et al.: Juno-ground-radio observation support
12:15-12:30
T. Kimura et al.: Continuous monitoring of Jupiter’s aurora and Io plasma torus with
the Hisaki satellite: Recent results and future coordination with Juno
12:30-14:00
Lunch break
Session 3: Jupiter radio emissions
Chair: William Kurth
14:00-14:15
M.S. Marques et al.: Statistical analysis of 26 years of observations of decametric
radio emissions from Jupiter
14:15-14:30
P. Zarka et al.: Radio emission from satellite-Jupiter interactions
14:30-14:45
C. Louis et al.: Space-based identification of Ganymede and Europa induced radio
emissions
14:45-15:00
M. Panchenko et al.: Zebra-like fine spectral structures in Jovian decametric radio
emission
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15:00-15:15
A. Kumamoto et al.: Statistical analysis of periodicity of Jovian S-burst
15:15-15:30
Y.-Q. Lou: Polar magnetospheric activities of Jupiter and its inner radiation belt
15:30-16:00
Coffee break
Session 4: Saturn radio emissions
Chair: Georg Fischer
16:00-16:30
S. Badman: Auroral signatures of Saturn’s magnetospheric dynamics (invited)
16:30-16:45
C. Jackman et al.: How do Saturn’s radio emissions respond to magnetospheric
compressions and tail reconnection: an analysis of SKR bursts and Low Frequency
Extensions (LFEs)
16:45-17:15
L. Lamy: Saturnian Kilometric Radiation: current view and pending questions before
the Cassini ‘Grand Finale’ (invited)
17:15-17:30
S.-Y. Ye et al.: Rotational modulation of Saturn kilometric radiation, narrowband
emission and auroral hiss
18:30-20:00
Dinner
20:00-21:00
Wine tasting at wine cellar
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Wednesday, October 26, 2016
Session 5: Earth radio and theory
Chair: Georg Fischer
09:00-09:30
O. Santolik et al.: Whistler-mode chorus and hiss in the inner magnetosphere of
Earth: consequences for JUICE project (invited, talk given by I. Kolmasova)
09:30-09:45
U. Taubenschuss et al.: Interpretation of whistler mode chorus observations with the
Backward Wave Oscillator model
09:45-10:00
J. LaBelle: High electron cyclotron harmonic emissions from aurora
10:00-10:15
T. Burinskaya and M. Shevelev: Generation of auroral kilometric radiation in 3-D
plasma cavity in a dipole magnetic field
10:15-10:30
V. Gubchenko: On the efficiency of the source of electromagnetic emission during
formation of magnetic structures by excitation of inductive field in hot collisionless
astrophysical and laser plasmas
10:30-11:00
Coffee break
Session 6: Instrumentation
Chair: Mykhaylo Panchenko
11:00-11:30
A. Konovalenko et al.: Multi-antenna observations in the low-frequency radio
astronomy for the solar system objects and related topics studies (invited)
11:30-11:45
M. Knapp et al.: HeRO: A space-based low frequency interferometric observatory for
heliophysics enabled by novel vector sensor technology
11:45-12:00
I. Kolmasova et al.: Anticipated plasma wave measurement onboard Exomars 2020
surface platform
12:00-13:30
Lunch break
13:30-18:30
Excursion to Zotter chocolate factory
18:30-20:00
Dinner
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Thursday, October 27, 2016
Session 7: Solar radio emissions
Chair: Gottfried Mann
09:00-09:30
D. Morosan et al.: LOFAR tied-array imaging and spectroscopy of solar radio bursts
(invited)
09:30-09:45
V. Dorovskyy et al.: Properties of groups of solar S-bursts at the decameter band
09:45-10:00
T. Zaqarashvili et al.: Oscillation of solar radio emission at coronal acoustic cut-off
frequency
10:00-10:15
A. Stanislavsky et al.: Progress in the heliographic study using the UTR-2 radio
telescope at decameter wavelengths
10:15-10:30
V. Melnik et al.: Radio manifestation of CME observed on April 7, 2011 in the
frequency band 8-32 MHz
10:30-11:00
Coffee break
Session 8: Solar radio emissions
Chair: Maxim Khodachenko
11:00-11:30
G. Mann et al.: Observations of the Sun with the radio telescope LOFAR
11:30-11:45
C. Lonsdale et al.: Solar imaging using low frequency radio arrays
11:45-12:00
S. Mulay et al.: Multiwavelength study of twenty jets emanating from the periphery
of active regions
12:00-12:15
V. Krupar et al.: Interplanetary type III bursts and density fluctuations in the solar
wind
12:15-12:30
M. Kalinichenko et al.: The investigations of the solar wind beyond Earth’s orbit by
IPS observations at decameter wavelengths: Present state and perspectives
12:30-14:00
Lunch break
Session 9: Exoplanetary radio emissions
Chair: Philippe Zarka
14:00-14:30
J.-M. Grießmeier: The search for radio emission from giant exoplanets (invited)
14:30-14:45
M. Khodachenko et al.: Magnetospheres of hot Jupiters: on the physical phenomena
potentially observable in radio
14:45-15:00
Ch. Weber et al.: On the Cyclotron Maser Instability in ionospheres of hot Jupiters
15:00-15:15
J. E. Enriquez et al.: Searching for brown dwarfs at low radio frequencies
15:15-15:30
Ch. Helling et al.: New insight in atmospheres of extrasolar planets through plasma
processes
15:30-15:45
G. Hodosan et al.: Radio emission of lightning on exoplanets and brown dwarfs: the
case study of HAT-P-11b
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15:45-16:15
Coffee break
Session 10:
Chair: Georg Fischer
16:15-18:00
Poster session with snacks
18:30-20:00
Dinner
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Overview of poster presentations
P01
Ch. Higgins, J. Thieman, S. Fung, F. Reyes, D. Typinski, W. Greenman, R. Flagg, J. Brown, T.
Ashcraft, N. Towne, J. Sky, L. Garcia, and B. Cecconi: The Radio Jove Project: Citizen science
for radio astronomy
P02
F. Tsuchiya, H. Misawa, and H. Kita: Total flux measurement of Jupiter’s synchrotron
radiation during the HISAKI and JUNO campaign periods
P03
H. Misawa, F. Tsuchiya, T. Kimura, Y. Kasaba, and A. Kumamoto: Variation characteristics of
Jupiter’s hectomectric radiation during the Iogenic plasma enhancement period
P04
A. Kumamoto, Y. Kasaba, F. Tsuchiya, H. Misawa, W. Puccio, J.-E. Wahlund, and J. Bergman:
Feasibility of the exploration of the subsurface structures of Jupiter’s icy moons by Jovian
hectometric radiation
P05
L. Lamy: Search for Io, Ganymede and Europe induced radio emissions from Cassini/RPWS
integrated power time series
P06
L. Lamy, L. Denis, P. Zarka, B. Cecconi, and S. Masson: 1977-2017: 40 years of observations of
Jupiter and the Sun with the Nanҫay Decameter Array
P07
S. Hess, L. Lamy, and B. Bonfond: ISaAC, a Jupiter magnetic field model constrained by the
auroral footprints of the Galilean satellites
P08
V. Shaposhnikov, G. Litvinenko, H.O. Rucker, V. Zaitsev, and A. Konovalenko: Io’s ultraviolet
spot emission as a probe of the Jovian magnetic field model
P09
G. Litvinenko, A. Konovalenko, V. Zakharenko, I. Vasilieva, P. Zarka, A. Lecacheux, V.
Shaposhnikov, H.O. Rucker, M. Panchenko, and O. Ulyanov: Analysis of the observational
characteristics of shadow-effects in the Jovian DAM emission
P10
A. Lecacheux, M. Imai, T. Clarke, C. Higgins, M. Panchenko, A. Konovalenko, and A.
Brazhenko: Jovian DAM linear polarization study from coordinated, distant, ground-based
radio telescopes
P11
J. Schiemel, M. Panchenko, H.O. Rucker, A.I. Brazhenko, and A.A. Konovalenko: Jupiter radio
fine structures observed in decametric frequency range by URAN-2 radio telescope
P12
B. Cecconi, A. Pruvot, L. Lamy, P. Zarka, C. Louis, S.L.G. Hess, D.R. Evans, and D. Boucon: Reprocessing and re-analysis of Planetary Radio Astronomy (PRA) of Voyager 1 & 2
P13
Y. Kasaba, T. Kimura, C.M. Jackman, B. Cecconi, L. Lamy, D. Maruno, and A. Morioka:
Characteristics of Saturn’s short-term kilometric radio bursts in 2005-2006 when Cassini
stayed close to the equatorial plane
P14
A. Sasaki, Y. Kasaba, T. Kimura, C. Tao, L. Lamy, and B. Cecconi: The seasonal variation of
Saturn’s auroral radio emissions in 2004-2015: The correlation with solar wind activity and
solar EUV flux
P15
C. Tao, L. Lamy, R. Prangé, N. André, and S. Badman: A diagnosis for the auroral field-aligned
acceleration processes at Saturn using the brightness ratio of H Lyman-α/H2 bands in FUV
auroral emission
P16
K. Mylostna, V.V. Zakharenko, and G. Fischer: Study of SED’s emission parameters
16
P17
G. Fischer, B. Cecconi, J. Bergman, J. Girard, G. Quinsac, and J.-E. Wahlund: Short antennas on
a large spacecraft
P18
Y. Katoh, H. Kojima, K. Asamura, Y. Kasaba, F. Tsuchiya, Y. Kasahara, T. Imachi, H. Misawa, A.
Kumamoto, S. Yagitani, K. Ishisaka, T. Kimura, Y. Miyoshi, M. Shoji, M. Kitahara, O. Santolik,
and J.-E. Wahlund: Science objectives and implementation of Software-type Wave-Particle
Interaction Analyzer (SWPIA) by RPWI for JUICE
P19
W. Majid: Radio emissions from electrical activity in Martian dust storms
P20
S. Hatch, J.W. LaBelle, and C.C. Chaston: The role of small-scale Alfvén waves in the
magnetosphere-ionosphere transition region: Recent developments
P21
R. Treumann, and W. Baumjohann: The ECMI in turbulent reconnecting current layers in
strong guide fields
P22
M. Marek, and R. Schreiber: AKR Cyclotron Maser Instability as self-organized criticality
system
P23
B.P. Dabrowski, A. Krankowski, L. Blaszkiewicz, K. Kotulak, and A. Fron: Low frequency solar
scrutiny with the Polish LOFAR stations
P24
F. Tsuchiya, H. Misawa, K. Iwai, K. Kaneda, S. Matsumoto, A. Kumamoto, M. Yagi, and B.
Cecconi: Database of solar radio bursts observed by solar radio spectro-polarimeter
AMATERAS
P25
Y. Volvach, A. Stanislavsky, and A. Koval: Brightness temperature of decameter solar burst
with high-frequency cut-off
P26
M. Knapp, D. Winterhalter, and T. Bastian: Getting to know the nearest stars: intermittent
radio emission from Ross 614
P27
J. Turner, J.-M. Grießmeier, P. Zarka, and I. Vasylieva: The search for radio emission from the
55 Cnc exoplanetary system using LOFAR
17
18
Abstracts
Oral presentations
19
20
Session 1: Tuesday, Oct. 25, 09:30-10:00, invited talk
First observations near Jupiter by the Juno Waves investigation
W.S. Kurth (1), M. Imai (1), G. B. Hospodarsky (1), D. A. Gurnett (1), S. J. Bolton (2), J.E.P. Connerney
(3), and S. M. Levin (4)
(1) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
<[email protected]>
(2) Southwest Research Institute, San Antonio, TX, USA
(3) Goddard Spaceflight Center, Greenbelt, MD, USA
(4) Jet Propulsion Laboratory, Caltech, Pasadena, CA, USA
The Juno spacecraft successfully entered Jupiter orbit on 5 July 2016. One of Juno’s primary
objectives is to explore Jupiter’s polar magnetosphere for the first time. An obvious major aspect of
this exploration includes remote and in situ observations of Jupiter’s auroras and the processes
responsible for them. To this end, Juno carries a suite of particle, field, and remote sensing
instruments. One of these instruments is a radio and plasma wave instrument called Waves,
designed to detect one electric field component of waves in the frequency range of 50 Hz to 40 MHz
and one magnetic field component of waves in the range of 50 Hz to 20 kHz. Waves made
observations of upstream plasma waves such as electron plasma oscillations and ion acoustic waves
in Jupiter’s foreshock beginning nearly 1 AU from Jupiter. The instrument recorded a very clear
signature of the one bow shock crossing encountered by Juno on its approach. Waves also clearly
identified a number of entries into Jupiter’s outer magnetospheric cavity through the detection of
trapped continuum radiation. At higher frequencies, kilometric, hectometric, and decametric
emissions were observed. The most obvious decametric observations observed on approach were Iorelated emissions. Juno’s first perijove pass with science observations will occur on 27 August 2016
and brings with it the possibility of in situ observations of plasma waves on auroral field lines and the
passage through the source region of the most intense planetary radio emissions in the solar system.
Regular, bi-weekly science observations near perijove are planned starting on 2 November 2016.
21
Session 1: Tuesday, Oct. 25, 10:00-10:15
Quasi-Periodic (QP) emissions as observed by Juno Waves
G. Hospodarsky (1), M. Imai (1), W.S. Kurth (1), D.A. Gurnett (1), and S.J. Bolton (2)
(1) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
<[email protected]>
(2) Southwest Research Institute, San Antonio, TX, USA
A number of quasi-periodic (QP) signatures with periods of <1 minute to tens of minutes have been
detected in the wave and particle observations of the Jovian magnetosphere by a number of
different spacecraft. QP variation with similar periods has also been reported of the brightness of the
Jovian aurora. In radio and plasma wave observations by Voyager, these QP emissions were given the
name Jovian type III radio bursts due to their dispersion spectral shape similar to solar type III radio
bursts, though on much shorter time scales. Ulysses observations found that these emissions were
made up primarily of two periods, 15 and 40 minutes, and renamed the emissions quasi-periodic
emissions because the Jovian type III designation might imply a specific generation mechanism.
Galileo observations found QP enhancements in the Jovian trapped continuum, but with a much less
organized (more random) periodicity. Joint Ulysses, Galileo and Cassini observations showed that the
many of the events were seen simultaneously by multiple spacecraft at very different locations,
suggesting that the emission is beamed in a strobe light or flash bulb like manner. The Juno
spacecraft with its low altitude polar orbit around Jupiter provides a new opportunity to examine
these QP signatures. The Juno spacecraft Waves instrument detected QP emissions during the
approach to Jupiter, prior to the successful orbit insertion on July 5, 2016, and during the initial
perijove orbits, including QP emissions detected in the high latitude polar region at very low
altitudes. The properties of these emissions as detected by Juno will be discussed.
22
Session 1: Tuesday, Oct. 25, 10:15-10:30
Analysis of Jovian low-frequency radio emissions based on the Juno Waves
data and stereoscopic observations with Juno and the Earth-based radio
telescopes
M. Imai (1), W.S. Kurth (1), G.B. Hospodarsky (1), D.A. Gurnett (1), S.J. Bolton (2), J.E.P. Connerney
(3), S.M. Levin (4), P. Zarka (5), B. Cecconi (5), A. Lecacheux (5), and L. Lamy (5)
(1) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
<[email protected]>
(2) Southwest Research Institute, San Antonio, TX, USA
(3) NASA Goddard Space Flight Center, Greenbelt, MD, USA
(4) Jet Propulsion Laboratory, Caltech, Pasadena, CA, USA
(5) LESIA, Observatoire de Paris, Meudon, France
Observations of Jupiter's low-frequency radio emissions were made using the radio and plasma wave
instrument (Waves) onboard the Juno spacecraft, which is now successfully orbiting Jupiter. The
Waves instrument is composed of three on-board receivers that record the electric fields from 50 Hz
to ~40 MHz and the magnetic fields from 50 Hz to 20 kHz. They are connected to one electric dipole
antenna and one magnetic search coil sensor. By means of the null point and the modulated spectral
intensity from the dipole antenna aboard the Juno spinning spacecraft, the Waves instrument
enables us to perform a two-dimensional determination of the direction finding of incoming waves
below 5 MHz based on the short dipole approximation. During Juno's interplanetary cruise prior to
the Jupiter orbit insertion on July 5, 2016, the first Jovian radio observations were made for
kilometric (KOM) radiation in March, and for hectometric (HOM) and decametric (DAM) radiation in
May 2016. Also, the Juno Waves instrument performed the first in-situ measurements of Jovian
auroral radio emission sources on 27 August 2016. Using the Waves data from Juno's approach to the
initial orbit of Jupiter, we show the characteristics of each radio component as viewed from Juno at
higher and lower Jovigraphic latitude. In addition, we present some preliminary results of
stereoscopic observations of Jovian DAM emissions with Juno and ground-based radio telescopes
(e.g., Nançay Decameter Array in France), thereby suggesting the latitudinal beaming structures from
Jupiter's polar regions.
23
Session 2: Tuesday, Oct. 25, 11:00-11:30, invited talk
Jovian decametric emission with the Long Wavelength Array Station 1
T. Clarke (1), Ch.A. Higgins (2), M. Imai (3), and K. Imai (4)
(1) Remote Sensing Division, US Naval Research Laboratory, DC, USA
<[email protected]>
(2) Middle Tennessee State University, Murfreesboro, TN, USA
(3) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
(4) Department of Electrical Engineering and Information Science, Kochi National College of
Technology, Japan
The Long Wavelength Array Station 1 (LWA1) is located in central New Mexico, USA. It consists of 256
pairs of 'droopy-dipole' antennas operating between 10 and 88 MHz. The antennas are distributed in
a pseudo-random layout across a 110 m by 100 m region. The station is able to record in
beamformed mode with 4 independent, dual polarization beams or in transient buffer mode with a
short timescale wideband mode or a continuous narrowband mode. Data can be recorded in raw
data mode or can be passed through the hardware spectrometer before recording to disk.
Observations are scheduled based on peer-reviewed proposals.
LWA1 is an excellent planetary radio emission instrument due to its sensitivity and the low radio
frequency interference environment. We have undertaken several Jovian observing campaigns using
the LWA1. Observations have been primarily recorded in raw data beamforming mode with two
overlapping 16 MHz beams covering 10-40 MHz. We produce spectrograms with frequency
resolution of 5 kHz and temporal resolution of 0.21 milliseconds. In Clarke et al. [2014, JGR 119,
9508-9526] we showed that LWA1 data provide excellent spectral detail in Jovian decametric
emission such as simultaneous left hand circular (LHC) and right hand circular (RHC) polarized Iorelated arcs and source envelopes, modulation lane features, S-bursts structures, narrow band Nevents, and apparent interactions between S-bursts and N-events. The start of the LHC Io-C source
region was traced to earlier longitudes than typically found in the literature. Early LWA1 observations
revealed a wealth of Io-D emission, including detection of rare S-bursts during an Io-D event.
These initial results have led to new programs to explore the spectral characteristics of Io-D events
(PI Higgins), investigate modulation lanes of Io-B/Io-C events (PI K. Imai), examine the beaming
structure of S-bursts combining LWA1, NDA, and URAN2 (PI M. Imai), and the LWA1 is one of the
ground-based support facilities for the JUNO mission.
24
Session 2: Tuesday, Oct. 25, 11:30-11:45
Spectral characteristics of Jupiter’s Io-D decametric radio source
from the Long Wavelength Array Station 1
Ch. Higgins (1), T. Clarke (2), K. Imai (3), M. Imai (4), F. Reyes (5), and J. Thieman (6)
(1) Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro,
TN, USA <[email protected]>
(2) Remote Sensing Division, US Naval Research Laboratory, DC, USA
(3) Department of Electrical Engineering and Information Science, Kochi National College of
Technology, Japan
(4) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
(5) University of Florida, Gainesville, FL, USA
(6) University of Maryland, Baltimore County, MD, USA
Jupiter has four well-known Io-related radio sources in its magnetosphere. Models show that sources
Io-A and Io-B emit from the northern hemisphere with right-hand (RH) circularly polarized signatures,
and Io-C and Io-D emit from the southern hemisphere with left-hand (LH) polarization. The Io-A, Io-B,
and Io-C sources were initially labeled A, B, and C, or “early”, “main”, and “late”, respectively [Carr et
al., 1961, ApJ 134, 105; Dulk, 1965, Science 148, 1585-1589]. Io-D was initially called the “fourth
source” after it was identified in the mid-1960s [Dulk, 1965, Science 148, 1585-1589; Gledhill, 1967,
Nature 214, 155-156]. The Io-D source characteristics are less well-known because its spectral
features overlap with the higher intensity Io-B source, and because the lower frequency extent of IoD is more difficult to measure with ground-based antennas.
Recent high resolution polarization measurements using the Long Wavelength Array Station 1
(LWA1) in Socorro, NM, USA show new spectral structure in the Io-D source. The LWA1 provides full
Stokes parameters and 5 kHz spectral and 0.21 ms temporal resolution of Jupiter’s decametric radio
emissions over the bandwidth of 10-40 MHz. Using LWA1 data from 2012-2016, we show Io-D radio
source spectra with double-envelope structures, narrow-banded features, as well as a higher peak
frequency and a larger Io influence than previously known. Studies of the Io-D source may lead to a
better understanding of the dynamics of Jovian magnetic interactions in the southern hemisphere.
Previous work from Clarke et al. [2014, JGR 119, 9508-9526] showed new details of known features
in Jupiter’s spectrum, such as millisecond S-bursts, narrowband N-events, S-N event interactions, and
modulation lanes. M. Imai et al. [2016, ApJ 826, id. 176] using correlated observations of Jupiter Sbursts from the LWA1, the Nançay Decameter Array (NDA) in France, and the URAN2 telescope in the
Ukraine, were able to improve and constrain the minimum beam cone thickness (2.66”) and provide
statistical profiles of S-bursts. Current work by K. Imai shows both LH and RH polarized emissions
with overlapping modulation lane structures that will allow for a new approach to better understand
the emission beam structure and source locations.
25
Session 2: Tuesday, Oct. 25, 11:45-12:00
Io-C and Io-B source morphology of Jupiter's decametric emissions
from LWA1 modulation lane data analysis
K. Imai (1), Ch. Higgins (2), M. Imai (3), and T. Clarke (4)
(1) Department of Electrical Engineering and Information Science, Kochi National College of
Technology, Japan <[email protected]>
(2) Middle Tennessee State University, Murfreesboro, TN, USA
(3) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
(4) Remote Sensing Division, US Naval Research Laboratory, DC, USA
The modulation lanes in Jupiter's decametric radiation, which were discovered by Riihimaa [1968, AJ
73, 265] are groups of sloping parallel strips of alternately increasing and decreasing intensity in the
dynamic spectra. The frequency-time slopes of the lanes can be either positive or negative,
depending on which of the Jovian sources are being observed. In the Imai et al. [1992, Geophys. Res.
Lett. 19, 953-956; 1997, JGR 102, A4, 7127-7136] model for the production of modulation lanes, the
lanes are assumed to be a manifestation of regularly spaced plasma density variations that exist in
the Io plasma torus. The fringes are produced as a result of the passage of the multi-frequency
radiation through an interference grating. By using our model, Jupiter's radio source locations and
beam parameters can be measured precisely. This remote sensing tool is called the modulation lane
method [Imai et al., 2002, JGR 107, A6, pp. SMP 12-1].
The Long Wavelength Array (LWA) is a low-frequency radio telescope designed to produce highsensitivity, high-resolution spectra in the frequency range of 10-88 MHz. The Long Wavelength Array
Station 1 (LWA1) is the first LWA station completed in April 2011, and it is located near the VLA site
in New Mexico, USA. LWA1 consists of a 256 element array operating as a single-station telescope.
The sensitivity of the LWA1, combined with the low radio frequency interference environment,
allows us to observe the fine structure of Jupiter's decametric modulation lanes. Using newly
available wide band modulation lane data observed by LWA1, we measured source locations and
beam parameters. The results of LWA1 data analysis indicate that the radio emitting sources are
located along a restricted range of Jupiter's System III longitude. We only receive one of the
individual sources at a given time because the source has a very thin beam (probably less than few
degrees). We show the measured locations of Io-related sources based on the modulation lanes
observed by LWA1. In this analysis we identified the existence of two independent radio sources in
the case of Io-C events, one from the northern hemisphere (right hand polarization; we named it as
Io-C', Io-C-prime), and one from the southern hemisphere (left hand polarization, Io-C). Previously we
considered that both of the right and left hand components were coming from the same hemisphere.
However we have investigated four other cases to show that different modulation lane patterns exist
between right and left hand components. Thus the right and left hand components are coming from
different hemispheres.
We also identified the radio source of the early part of Io-B (we named it as Io-B', Io-B-prime). It is
located between 50 to 100 degrees CML of System III longitude and is independent of the main part
of Io-B between 100 to 180 degrees CML. The measured center of the source System III longitude
range is about 110 degrees in the case of Io-B' and about 190 degrees in the case of the main part of
26
Io-B. This 110 degrees source longitude corresponds to the brightness peak of the IFP (Io footprint)
and when Io is close to the Io plasma torus center [Bonfond et al., 2013, PSS 88, 64-75]. The 190
degrees source longitude is close to the center of the longitude range of the active magnetic flux
tube for non-Io-related radio emissions [M. Imai et al., 2011, JGR 116, A12233].
27
Session 2: Tuesday, Oct. 25, 12:00-12:15
Juno-ground-radio observation support
B. Cecconi (1,2,3), P. Zarka (1), R. Savalle (2), P. Le Sidaner (2), A. Coffre (4), L. Denis (4), C. Viou (4), A.
A. Konovalenko (5), A. Skoryk (5), S. Yerin (5), Y. Kasaba (6), A. Kumamoto (6), H. Misawa (6), T.
Tsuchiya (6), Y. Hobara(7), T. Nakajo (8), K. Imai (9), V. Ryabov (10), H. Rothkaehl (11), G. S. Orton
(12), T. Momary (12), J.-M. Griessmeier (13), M. Imai(14), J. N. Girard (15,16), L. Lamy (1), M.
Anderson (17), N. André (3,18), V. Génot (3,18), R. Ebert (19), T. Carozzi (20), T. Kimura (21), W. S.
Kurth (14), C. A. Higgins (22,23), J.L. Mugler (22), D. Typinsky (23), T. Clarke (23,24), J. Sky (23,25), R.
Flagg (23), F. Reyes (23), W. Greenman (23), J. Brown (23), A. Mount (23), T. Ashcraft (23), J. Thieman
(23,26), W. Reeve (23), S. Fung (23,26), N. Towne (23), T. King (27), and S. Bolton (19)
(1) LESIA, Observatoire de Paris/CNRS/PSL, Meudon, France <[email protected]>
(2) PADC, Observatoire de Paris/CNRS/PSL, Paris, France
(3) CDPP, CNES/CNRS/Université Paul Sabatier/Observatoire de Paris, Toulouse, France
(4) USN, Observatoire de Paris/CNRS/PSL/Université d’Orléans, Nançay, France
(5) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
(6) Tohoku University, Sendai, Japan
(7) University of Electro-Communications, Tokyo, Japan
(8) Fukui University of Technology, Fukui, Japan
(9) Kochi National College of Technology, Nankoku, Japan
(10) Future University, Hakodate, Hakodate, Japan
(11) Space Research Center, Polish Academy of Sciences, Warsaw, Poland
(12) NASA Jet Propulsion Laboratory, Caltech, Pasadena, CA, USA
(13) LPC2E, CNRS/Université d’Orléans, Orléans, France
(14) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
(15) Rhodes University, Grahamstown, South Africa
(16) AIM/IRFU/SAp-CEA, Université Paris Diderot, Saclay, France
(17) California Institute of Technology, Pasadena, CA, USA
(18) IRAP, CNRS, Université Paul Sabatier, Toulouse, France
(19) Space Science Department, Southwest Research Institute, San Antonio, TX, USA
(20) Institute of Space and Geophysics, Chalmers, Onsala, Sweden
(21) RIKEN Nishina Center for Accelerator-Based Science, Tokyo, Japan
(22) Middle Tennessee State University, Murfreesboro, TN, USA
(23) RadioJOVE, USA
(24) US Naval Research Laboratory, Washington DC, USA
(25) Radio-Sky Publishing, USA
(26) NASA-Goddard Space Flight Center, Greenbelt, MD, USA
(27) IGPP, UCLA, Los Angeles, CA, USA
The JUNO mission is a NASA flagship mission dedicated to the study of Jupiter. Several instruments
are dedicated to the study of the Jovian internal magnetic field and its inner magnetosphere. In the
frame of the preparation of the NASA/JUNO and ESA/JUICE (Jupiter Icy Moon Explorer) missions on
one hand, and the development of a planetary sciences virtual observatory (VO) on the other hand,
we are proposing new tools directed to data providers and scientists, in order to ease low frequency
radio astronomy data products sharing and discovery. We will focus on ground based planetary radio
28
observations (thus mainly Jupiter radio emissions), trying for instance to enhance the temporal
coverage of jovian decametric emission. The data service we will be using is EPN-TAP, a planetary
science data access protocol developed by Europlanet-H2020-RI/VESPA (Virtual European Solar and
Planetary Access). This protocol is derived from IVOA (International Virtual Observatory Alliance)
standards. Observations of Jovian radio emissions from the Nanҫay Decameter Array (France) and
the Iitate radio observatory (Japan) are already shared on the planetary science VO using this
protocol. Amateur radio data from the RadioJOVE project is also available. We will first introduce the
VO tools and concepts of interest for the planetary radioastronomy community. We will then present
the various data formats now used for such data services, as well as their associated metadata. We
will finally show various prototypical tools that make use of this shared datasets.
29
Session 2: Tuesday, Oct. 25, 12:15-12:30
Continuous monitoring of Jupiter’s aurora and Io plasma torus with the Hisaki
satellite: Recent results and future coordination with Juno
T. Kimura (1), G. Murakami (2), A. Yamazaki (2), F. Tsuchiya (3), K. Yoshioka (4), C. Tao (5), H. Kita (3),
S.V. Badman (6), M. Fujimoto (2), and the Hisaki Science Team
(1) Tamagawa High Energy Astrophysics Laboratory, RIKEN Nishina Center for Accelerator-Based
Science, Tokyo, Japan <[email protected]>
(2) Institute of Space and Astronautical Science (ISAS), JAXA, Sagamihara City, Japan
(3) Tohoku University, Sendai, Japan
(4) University of Tokyo, Tokyo, Japan
(5) National Institute of Information and Communications Technology (NICT), Japan
(6) Lancaster University, Lancaster, UK
The Hisaki satellite is the first space telescope that is dedicated to observations of our solar system
bodies. Hisaki has been continuously monitoring the atmosphere and magnetosphere of the solar
system bodies with the extreme ultraviolet (EUV) spectroscope EXCEED since the launch in
September 2013. Dynamics on timescales from 10 s to minutes to a few years were discovered in the
atmosphere and magnetosphere by the continuous monitoring, especially for Jupiter’s aurora and Io
plasma torus. Large joint observing campaigns for Jupiter by Hisaki in coordination with the Hubble
Space Telescope (HST), Juno spacecraft, and other facilities have been made from 2014 to the
present. The results of the campaigns and future coordination with Juno are presented in this talk.
30
Session 3: Tuesday, Oct. 25, 14:00-14:15
Statistical analysis of 26 years of observations
of decametric radio emissions from Jupiter
M.S. Marques (1,2), P. Zarka (2), E. Echer (1), V.B. Ryabov (3), and M.V. Alves (1)
(1) National Institute for Space Research (INPE), Sao Jose dos Campos, Brazil
<[email protected]>
(2) LESIA & USN Observatoire de Paris/CNRS/PSL, Meudon, France
(3) Complex Systems Department, Future University Hakodate, Hakodate, Japan
Jupiter appears to be a complex radio source in the decameter wavelength range. As a consequence,
statistical studies based on long-term observations are requested in order to understand the various
phenomena observed. We present a statistical analysis of 26 years of observations, in digital format,
recorded by the Nançay Decameter Array, France. The emissions were classified using arc shape (in
the time-frequency plane), maximum event frequency, and dominant polarization, with the aim of
distinguishing several types of emissions (Io or non-Io, northern or southern, dawn or dusk). The
results are generally consistent with previous studies. However, the large time coverage of this new
database, together with the new classification method adopted and the better precision in
identifying emissions contours due to the digital data format, allowed us to identify new types of
emissions (Io-A’’, Io-B’ and non-Io-D), as well as changes on the limits of emission regions in the
CML-Io phase diagram. Another significant result is the new, better defined maximum frequency
envelopes of the emissions, especially Io-C, Io-D (as a function of Io’s longitude) and non-Io-C
emissions. Finally, we will present preliminary results on long-term variations of the emissions.
31
Session 3: Tuesday, Oct. 25, 14:15-14:30
Radio emission from satellite-Jupiter interactions
P. Zarka (1,4), M. Soares-Marques (1,2), C. Louis (1), V.B. Ryabov (3), L. Lamy (1), E. Echer (2) , B.
Cecconi (1), and S. Hess (5)
(1) LESIA, Observatoire de Paris/CNRS/PSL, Meudon, France <[email protected]>
(2) National Institute for Space Research (INPE), Sao José do Campos, Brazil
(3) Complex Systems Department, Future University Hakodate, Hakodate, Japan
(4) USN, Obs. Paris/CNRS, Nançay, France
(5) ONERA/DESP, Toulouse, France
Io-Jupiter radio emission is known since 1964, from ground-based decameter observations. It results
from Alfvénic interaction between Io and the Jovian magnetic field that sweeps past it due to the fast
rotation of Jupiter. Ultraviolet emissions from the magnetic footprints of Io, Ganymede and Europa
on Jupiter's upper atmosphere are known since 2002, from Hubble Space Telescope observations. In
the case of Ganymede, which possesses an intrinsic magnetic field, the interaction is believed to be
due to reconnection with the Jovian magnetic field. The radio emission from the Ganymede-Jupiter
interaction, expected to provide new information on this interaction, has been searched for 2
decades with ambiguous conclusions. We have analysed >20 years of observations from the Nançay
decameter array, and we provide clear detection and characterization of this emission. We have also
searched for radio emissions resulting from the interaction of the Jovian magnetic field with the
other Galilean satellites as well as Amalthea. We have found hints for signatures of Europa-Jupiter
and Amalthea-Jupiter interactions. We discuss their significance and implications.
32
Session 3: Tuesday, Oct. 25, 14:30-14:45
Space-based identification of Ganymede and Europa induced radio emissions
C. Louis (1), L. Lamy (1), P. Zarka (1), B. Cecconi (1), and S. Hess (2)
(1) LESIA, Observatoire de Paris, Meudon, France <[email protected]>
(2) ONERA/DESP, Toulouse, France
The Jovian auroral radio emissions are the most intense of our Solar System, and they extend from a
few kHz to 40 MHz. One part of those emissions is driven by the Galilean moon Io, and we expect
that the other Galilean moons Europa, Ganymede and Callisto drive Jovian radio emissions too.
Indeed UV emissions induced by the three first Galilean moons (Io, Europa and Ganymede) exist, and
a previous study showed the first hints of Ganymede, Europa and Callisto induced radio emissions.
Here, using a code named ExPRES (Exoplanetary and Planetary Radio Emissions Simulator), and the
Cassini and the Voyager data we are now able to give the first individual detections for Europa and
Ganymede induced radio emissions, and the areas in phase (position relative to the observer) versus
CML (Central Meridian Longitude - longitude of the observer) where these emissions occur.
33
Session 3: Tuesday, Oct. 25, 14:45-15:00
Zebra-like fine spectral structures in Jovian decametric radio emission
M. Panchenko (1), S. Rošker (2), H.O. Rucker (2), A. Brazhenko (3), A.A. Konovalenko (4), G. Litvinenko
(4), P. Zarka (5), V. Melnik (4), V.E. Shaposhnikov (6), and A.V. Franzuzenko (3)
(1) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
<[email protected]>
(2) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
(3) Institute of Geophysics, Gravimetric Observatory, Poltava, Ukraine
(4) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
(5) LESIA, Observatoire de Paris, Meudon, France
(6) Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
We report the first observation of zebra-like fine spectral structures in the decametric frequency
range of Jovian radio emission. These zebra patterns are observed in the frequency range from 12 to
30 MHz as a number of quasi-equidistant stripes (from 3 to 9) of enhanced brightness with fast
parallel drift in time. The features have been observed by the ground-based radio telescope URAN-2
(Poltava, Ukraine) operated in a decametric frequency range (8-32 MHz). In total 42 zebra pattern
events have been detected during a period of time from September 2012 to April 2015. The
minimum duration of one single zebra pattern was 20 s, and the maximum one was 4 min 50 s. The
intensity of the zebra stripes is 1 - 2 magnitudes lower than the intensities of Io controlled DAM. The
numbers of stripes in one event may vary in time. Zebra patterns are strongly polarized and have
been observed as right-handed (24 events) and left-handed (18 events) polarized radio emission.
Zebra patterns are mainly detected in two active sectors of Jovian CMLs: 90 deg. to 180 deg. for
Northern sources (right-handed polarized) and 300 deg. to 60 deg. (via 360 deg.) for the Southern
sources (left-handed polarized). No correlation with position of Io has been detected. The frequency
interval (df) between neighbouring stripes is from 0.26 to 1.5 MHz, and in the most cases df is
increasing with frequency. Only in 5 events df was decreasing with frequency. The instantaneous
bandwidth of one stripe in zebra patterns is less than the frequency interval between the stripes. We
discuss the double plasma resonance as a possible source of zebra pattern excitation. The performed
analysis of the observations allow us to conclude that observed zebra patterns are a new type of
narrow band spectral structures in Jovian decametric radio emission.
34
Session 3: Tuesday, Oct. 25, 15:00-15:15
Statistical analysis of periodicity of Jovian S-burst
A. Kumamoto (1), S. Kakimoto (2), Y. Sasaki (3), H. Misawa (1), Y. Katoh (1), F. Tsuchiya (1), and B.
Cecconi (4)
(1)
(2)
(3)
(4)
Tohoku University, Sendai, Japan <[email protected]>
TEPCO, Tokyo, Japan
Komaba High School, Nippon Institute of Technology, Japan
LESIA, Observatoire de Paris, Meudon, France
Statistical analysis of the periodicity of Jovian S-burst has been performed based on the dataset from
high-time-resolution observation of Jovian decametric radiation at observatories of Tohoku
University since 1985. Jovian S-bursts consist of narrow-band emissions with a negative frequency
drift rate. The repetition frequency of the emissions is 2-400 Hz [Carr and Reyes, 1999, JGR 104, A11,
25127-25142], which is suggested to be similar with the eigen-frequency of the Jovian Ionospheric
Alfven resonator (IAR) [Ergun et al., 2006, JGR 111, A06212; Su et al., 2006, JGR 111, A06211]. The
eigen-frequency of IAR depends on the Alfven velocity and the scale height of the ionosphere [Lysak,
1991, JGR 96, 1553-1568]. Therefore, we can expect that the repetition frequency of Jovian S-burst
emissions provides us information of the Jovian ionosphere around the Io footprint.
In the analysis we used spectrograms with a bandwidth of 2 MHz selected from a frequency range
from 20 to 40 MHz and a time resolution of 2 msec (from 1985 to 1992), and all those with a
frequency range from 20 to 40 MHz and a time resolution of 0.8 msec (from 2012), and we derived
the repetition frequency of Jovian S-burst emissions. The analysis shows that the repetition
frequency of Jovian S-burst emissions becomes small as the solar zenith angle (SZA) at the Io
footprint increases. The decrease of eigen-frequency of JIAR suggests that the scale height of the
Jovian nightside ionosphere increases probably due to heating by auroral electrons. Because the size
of the dataset of Jovian S-burst with high time resolution obtained from Tohoku University
observatories is too huge to provide via network, we provide the dataset to researchers on request.
In addition, we are also preparing metadata archive for providing information such as operation time
of high time resolution receiver at Tohoku University observatories in the system of Virtual
Observatory (VO) [Erard et al., 2014, Astron. and Computing 7, 71-80, http://voparis-europlanetdev.obspm.fr/] with support of JSPS Bilateral Program "Coordinated observational and theoretical
researches for Jovian and Kronian auroral radio emissions" (http://c.gp.tohoku.ac.jp/sakura/). The
progress of the development of the metadata archives of Jovian S-burst for VO will also be shown in
the presentation.
35
Session 3: Tuesday, Oct. 25, 15:15-15:30
Polar magnetospheric activities of Jupiter and its inner radiation belt
Y.-Q. Lou (1)
(1) Physics Department, Tsinghua Centre for Astrophysics (THC), Tsinghua-National
Astronomical Observatories of China (NAOC) joint Research Centre for Astrophysics,
Tsinghua University, Beijing, China <[email protected]>
In 1992 the Ulysses spacecraft discovered quasi-periodic 40 minute (QP-40) bursts of relativistic
electrons and of associated low-frequency radio emissions from the south polar direction of Jupiter.
These radio bursts are right-hand circularly polarized and strongly correlate with the arrival of fastspeed solar winds at Jupiter. We proposed [Lou, 2001, ApJ 548, 460-465] that these relativistic
electron bursts originate from the circumpolar leakage of Jupiter’s inner radiation belt (IRB) where
intense synchrotron emissions reveal the presence of trapped relativistic electrons therein and based
on this, we predicted that such QP-40 activities should be global as confirmed by later observations.
In particular, such QP-40 radio bursts from the north polar direction should be left-hand circularly
polarized and also strongly correlate with the arrival of fast-speed solar winds at Jupiter. Inside the
Jovian magnetosphere, one should also detect associated QP-40 bursts of relativistic electrons from
the north polar region. In our scenario, the QP-40 variabilities are associated with QP-40 magnetoinertial global IRB oscillations [Lou, 2001, ApJ 548, 460-465] which are excited and sustained by
intermittent high-speed solar winds [Lou, 1994, JGR 99, 14747-14760; Lou, 1996, Geophys. Res. Lett.
23, 609-612]. Around the end of 2000 during the joint campaign of Cassini fly-by, HST and Chandra,
the high-resolution camera (HRC) of the Chandra X-ray Observatory discovered QP-45 variability of Xray hot spot within the north auroral oval of Jupiter during a 10 hour observation [Gladstone et al.,
2002, Nature 415, 1000-1003]. Using the real-time solar wind data from the spacecraft Advanced
Composition Explorer (ACE), our subsequent analysis indicates a likely coincidence of X-ray hot spot
QP-45 variability with the arrival of high-speed solar wind at Jupiter [Lou and Zheng, 2003, Mon. Not.
Roy. Astron. Soc. Letters 344, L1]. After monitoring of several years, we published 6 cm observations
of Jupiter's IRB flux variations using the Urumqi 25 m radio telescope in XinJiang Province of China
[Lou et al., 2012, Mon. Not. Roy. Astron. Soc. Letters 421, L62]. In reference to extensive observations
of different diagnostics and the ongoing Juno mission, we discuss various aspects of our model
scenario and predictions more specifically. The prospect of recent joint space (X-ray, EUV) and
ground (radio and optical) observational campaigns to monitor global magnetic activities of Jupiter
are also discussed.
36
Session 4: Tuesday, Oct. 25, 16:00-16:30, invited talk
Auroral signatures of Saturn’s magnetospheric dynamics
S. Badman (1)
(1) Lancaster University, Lancaster, UK <[email protected]>
Saturn’s aurorae have been observed at UV, IR, and visible wavelengths by space- and Earth-based
instruments. The aurorae are usually brighter on the dawn side, indicating an influence by the solar
wind via enhanced flow shear at the dawn flank. However, the intensity at all local times is also
modulated independently in the north and south by the so-called planetary period oscillations.
Diffuse features equatorward of Saturn’s main emission have been related to scattering of particles
in quasi-steady (nightside secondary arc) or transient (dayside patches) processes. Signatures of
magnetic reconnection have been identified as arcs and spots on both the dayside and nightside,
with particularly broad and intense nightside features occurring in response to solar wind
compressions. These auroral features and the underlying magnetospheric dynamics will be discussed
in relation to concurrent radio emissions such as low frequency extensions of the Saturn Kilometric
Radiation, and 1 h pulsations in auroral hiss.
37
Session 4: Tuesday, Oct. 25, 16:30-16:45
How do Saturn’s radio emissions respond to magnetospheric compressions
and tail reconnection: an analysis of SKR bursts and Low Frequency
Extensions (LFEs)
C. Jackman (1), J.J. Reed (1), D. Whiter (1), L. Lamy (2), and W.S. Kurth
(1) Department of Physics and Astronomy, University of Southhampton, Southhampton, UK,
<[email protected]>
(2) LESIA, Observatoire de Paris, Meudon, France
(3) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
Saturn Kilometric Radiation has been shown to respond both to solar wind compressions and
magnetotail reconnection events through bursts of the main emission [e.g. Taubenschuss et al.,
2006, Ann. Geophys. 24, 3139-3150; Rucker et al., 2008, Adv. Space Res. 42, 40-47; Badman et al.,
2008, Ann. Geophys. 26, 3641-3651] and extensions of the emission to lower frequencies (LFEs) [e.g.
Jackman et al., 2009, JGR 114, A08211]. The LFEs in particular have been suggested to be associated
with a growth/motion of the SKR source region to higher altitudes, analogous to a feature noted in
the terrestrial AKR literature [e.g. Morioka et al., 2007, JGR 112, A06245; Morioka et al., 2008, JGR
113, A09213].
This presentation will review past work linking LFEs to magnetospheric dynamics and show results
from a new study [Reed et al., 2016, in preparation] which focuses on Cassini RPWS and MAG data
from the tail orbits of 2006. This comprehensive new survey aims to advance our ability to use LFEs
as a remote proxy for dynamic magnetospheric events. An automated method to search for LFEs
based on the statistical characteristics of the radio spectrum has been developed. Properties of LFEs
such as their length and recurrence rate will also be discussed.
Finally the link between planetary periodicities (PPOs) at Saturn (as tracked by the SKR and MAG
phases) and SKR bursts/LFEs will be shown, building on results from Jackman et al. [2016, JGR 121,
2922-2934] who examined the correlation between dynamic events in Saturn’s tail and PPO phases.
38
Session 4: Tuesday, Oct. 25, 16:45-17:15, invited talk
Saturnian Kilometric Radiation: Current view and pending questions
before the Cassini ‘Grand Finale’
L. Lamy (1)
(1) LESIA, Observatorie de Paris, Meudon, France <[email protected]>
The Saturnian Kilometric Radiation (SKR) is the most intense Kronian radio emission. It is radiated
from the auroral regions, above the ionosphere up to a few planetary radii, and directly compares to
auroral kilometric to decametric radiations radiated by the Earth and the other giant planets. Our
knowledge on SKR essentially relied on remote observations of Voyager (flybys in 1980 and 1981)
and Ulysses (distant observations in the 1990s), before Cassini started to orbit Saturn in 2004. Since
then, it has been routinely observed by the Radio and Plasma Wave Science (RPWS) experiment from
a large set of remote locations, but also in situ for the first time at a planet other than Earth. In this
presentation, I will review the average remote properties of this radiation (in terms of spectrum,
emission mode, power, dynamics, beaming, polarization, auroral context etc.) and the first insights
brought by in situ passes within SKR sources (auroral plasma, generation mechanism, free energy
source, wave propagation etc.).
39
Session 4: Tuesday, Oct. 25, 17:15-17:30
Rotational modulation of Saturn kilometric radiation,
narrowband emission and auroral hiss
S.-Y. Ye (1), G. Fischer (2), W.S. Kurth (1), J.D. Menietti (1), and D.A. Gurnett (1)
(1) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
<[email protected]>
(2) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Saturn kilometric radiation (SKR), narrowband emission, and auroral hiss are periodically modulated
due to Saturn’s rotation. Cassini RPWS observations of SKR revealed two different modulation rates,
one associated with each hemisphere of Saturn, and it has been shown that the rotation rates are
subject to seasonal change. We analyze the observations of Saturn’s radio emissions by Cassini RPWS
using the Lomb-Scargle spectral analysis and a phase tracing method. It is shown that the rotational
modulation rates of auroral hiss and the 5 kHz narrowband emissions are consistent with those of
SKR. The northern and southern SKR rotation rates coalesced soon after equinox and stayed phaselocked until mid-2012, after which they separated with northern SKR being faster until autumn 2013.
This was followed by a one year interval of similar north and south rotation rates and phases, before
the southern SKR component finally became faster in autumn 2014. Auroral hiss provides an
unambiguous way of tracking the rotation signals from each hemisphere because the whistler mode
waves cannot cross the equator. The phase difference between SKR and auroral hiss varies with the
local time of observation. There is also a local time dependence of the averaged power of auroral
hiss, which indicates that the field aligned currents associated with the generation of auroral hiss are
intensified at dawn and dusk local time sectors.
40
Session 5: Wednesday, Oct. 26, 09:00-09:30, invited talk
Whistler-mode chorus and hiss in the inner magnetosphere
of the Earth: consequences for the JUICE project
O. Santolik (1,2), J. Soucek (1), I. Kolmasova (1), G.B. Hospodarsky (3), W.S. Kurth (3), C.A. Kletzing (3),
and J.-E. Wahlund (4)
(1) Institute of Atmospheric Physics, Czech Academy of Sciences, Prague, Czechia
<[email protected]>
(2) Charles University, Prague, Czechia
(3) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
(4) Swedish Institute of Space Physics, Uppsala, Sweden
Previous observations have shown the importance of measurements of waves in plasmas around
Jovian moons, especially in the light of recent advances in analysis of whistler-mode waves in the
Earth magnetosphere and their importance for acceleration of radiation belt electrons to relativistic
energies. We analyze whistler-mode chorus and hiss using a database of measurements of the Waves
instruments of the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS)
onboard the Van Allen Probes in the Earth's radiation belts. We estimate the time-frequency
structure, polarization and propagation parameters of these waves. We show that high resolution
multicomponent measurements of the fluctuating magnetic and electric fields are necessary for
proper characterization of hiss and chorus. Proposed measurement modes for the low frequency
receiver subsystem of the Radio & Plasma Waves Investigation (RPWI) experiment, which will be
implemented on the JUICE (JUpiter ICy moon Explorer) spacecraft, include onboard processing
designed to be suitable for a similar analysis of whistler-mode waves in the magnetospheres of
Jupiter and Ganymede.
41
Session 5: Wednesday, Oct. 26, 09:30-09:45
Interpretation of whistler mode chorus observations
with the Backward Wave Oscillator model
U. Taubenschuss (1), A. Demekhov (2,3), and O. Santolik (1)
(1) Institute of Atmospheric Physics, Czech Academy of Sciences, Prague, Czechia
<[email protected]>
(2) Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
(3) Polar Geophysical Institute, Apatity, Russia
We present several examples of whistler mode chorus observations from the equatorial source
region made by the THEMIS (Time History of Events and Macroscale Interactions during Substorms)
spacecraft. Electromagnetic analysis of the Poynting vector reveals two groups of oppositely
propagating chorus elements, along and against the direction of the ambient magnetic field.
Additionally, there is a shift in frequency visible between both groups. We interpret these features in
the frame of the Backward Wave Oscillator (BWO) model as a possible generation mechanism for
chorus emission.
42
Session 5: Wednesday, Oct. 26, 09:45-10:00
High electron cyclotron harmonic emissions from aurora
J. LaBelle (1)
(1) Department of Physics and Astronomy, Dartmouth College, Hanover, NH, USA
<[email protected]>
The aurora is characterized by highly non-equilibrium electron distributions that excite a variety of
plasma waves, some of which result in radio emissions that can be detected at ground-level. In the
frequency range between 50 kHz and 10 MHz, five distinct types have been identified: auroral hiss,
auroral kilometric radiation (AKR), auroral roar (electron cyclotron harmonic emissions), auroral
medium frequency burst (MFB), and recently discovered auroral emissions just above the electron
cyclotron frequency. The last few years have seen significant advances in all of these emissions.
Regarding auroral roar emissions, for example, the exciting recent development has been the
discovery of emissions at relatively high harmonics of the electron cyclotron frequency. In contrast to
the lower harmonic emissions which are always left-polarized, the higher harmonic emissions are
sometimes left, sometimes right polarized, with polarization and frequency distribution related to
whether the emissions occur under daylit or darkness conditions. Studies of the fine structure of
multiple harmonics reveal the emissions to sometimes be harmonically related, sometimes not, again
with a relation to daylit or darkness conditions. These studies suggest that two different mechanisms
act to generate two distinct types of cyclotron harmonic radiation, one involving linear excitation and
mode conversion of upper hybrid waves, and the other involving nonlinear wave-wave interactions.
These results are interesting because they identify a naturally occurring nonlinear process in the
near-Earth environment.
43
Session 5: Wednesday, Oct. 26, 10:00-10:15
Generation of auroral kilometric radiation in 3-D plasma cavity
in a dipole magnetic field
T. Burinskaya (1), and M.M. Shevelev (1)
(1) Space Research Institute, Russian Academy of Sciences, Moscow, Russia
<[email protected]>
The generation of the auroral kilometric radiation (AKR) in a narrow three-dimensional plasma cavity
in which a weakly relativistic electron beam propagates along the magnetic field against the cold
plasma background is investigated. The cavity is extended along the latitude and the magnetic field
over distances that are one order of magnitude longer than the cavity width along the longitude.
Using the approximation of geometrical optics, we have studied the time dynamics of different rays
launched from the center of the cavity at an altitude of the Earth’s radius, where the local electron
gyrofrequency is on the order of 200 kHz. The values of the physical parameters correspond to those
experimentally observed at this altitude in the auroral region. The waves are generated due to
electron-cyclotron maser instability, the source of free energy for its development is the transverse
energy of the weakly relativistic electron beam. It is shown that although the electron energy along
the magnetic field is usually less than the transverse energy, it is important to take it into account
when studying the AKR generation in an inhomogeneous magnetic field. Taking into account the
longitudinal velocity of fast electrons expands the region of parameters in which waves with
frequencies above the local cut-off frequency of the background plasma can be generated, and
produces changes of the dispersion relation, due to which the group velocity of waves with the wave
vector radial component directed from the Earth can be directed earthward; the higher the
longitudinal velocity of the fast electron beam, the higher this group velocity. Analysis of the wave
time history has shown that waves launching with a group velocity directed earthward (thereby,
passing twice—downward and upward—through the cavity due to the global magnetic field
inhomogeneity), and with the optimal relation between the wave vector components determining
the wave frequency, its linear growth rate, and the residence time inside the cavity, where the fast
electron beam propagates and electron-cyclotron maser instability can develop, undergo the largest
amplification. The wave refractive index appreciably varies along the ray trajectory, and finally
approaches to unity after the ray exits from the cavity.
44
Session 5: Wednesday, Oct. 26, 10:15-10:30
On the efficiency of the source of electromagnetic emission during formation
of magnetic structures by excitation of inductive field in hot collisionless
astrophysical and laser plasmas
V. Gubchenko (1)
(1) Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
<[email protected]>
For diagnostic purposes and modelling, it is important to study the similarity between the formation
mechanisms of magnetized astrophysical plasma structures (e.g., planetary magnetospheres,
heliosphere, solar/stellar coronas, etc.), as well as their related electromagnetic (e.m.) emissions and
those by the magnetic structures in high energy and dense laboratory laser plasmas. Such similarity
may be expressed in terms of the relevant dimensionless parameters, whereas the absolute values of
plasma parameters in the considered phenomena (e.m. frequency bands, characteristic times, spatial
scales, bulk flow velocities) might be rather different.
In fact, a beam of accelerated/energetic particles formed in the structures is an agent which transfers
energy from the slow to the fast e.m. process. By this, the slow process is responsible for the
inductive formation of an e.m. structure which is self-consistent with the generation of the
accelerated particles. It appears as a kind of a “dark”, i.e. e.m.-invisible process, which takes place
when the squared plasma refractive index remains negative (a so-called subcritical e.m. regime). The
fast process corresponds to the e.m. emission by a beam of accelerated particles. It is a visible
process, which corresponds to a positive squared plasma refractive index (an overcritical e.m.
regime). In terms of the frequency and spatial scales, both processes are sharply separated by plasma
frequency and by wavelength, and are often considered as independent models.
Here we look for a connection between the fast and slow processes and calculate the energetic
efficiency of the accelerated particles production by an inductive source. We express it via the
impedance of the prescribed dipole and toroid type magnetizations which are connected inductively
in the dynamical environment of hot collisionless plasma, characterized by different types of plasma
particle distribution functions (PDF). The magnetization itself is formed by an independent dynamo
mechanism, which is different for space and laser plasmas.
Acceleration of particles is related with the absorption/dissipation of e.m. energy in plasma. It is
most efficient near plasma resonances where the “cold” refractive index tends to infinity. By this, the
major e.m. resonance is at the line with zero frequency. The most known corresponding
phenomenon is a dissipative large-scale magnetic reconnection process. It is responsible for the
formation of a 3D magnetic diffusion region structure which is self-consistent with the currents of
accelerated and diamagnetic particles. In strongly magnetized plasmas, one has to consider
additionally the ion and electron cyclotron resonances as well as the hybrid resonance with the
plasma frequency. These resonances form the magnetic structures by the “cyclotron resonance
magnetic reconnection effect”. These reconnection processes take place inside the narrow
resonance lines where MHD description is not valid, and we apply Vlasov kinetic approach there for
the calculation of the impedance.
45
Acknowledgement: This work was supported in part by the Russian Foundation for Basic Research
(projects no. 14_02_00133, no. 15_42_02567 r_povolzh’e), and the Ministry of Education and
Science of the Russian Federation (contract no. 14.Z50.31.0007). References: V. M. Gubchenko, 2015,
Geomagnetism and Aeronomy 55, No. 7, 831-845, and No. 8, 1009-1025.
46
Session 6: Wednesday, Oct. 26, 11:00-11:30, invited talk
Multi-antenna observations in the low-frequency radio astronomy
for the Solar System objects and related topics studies
A. Konovalenko, (1), P. Zarka (2), H.O. Rucker (3), V. Zakharenko (1), O. Ulyanov (1), M. Sidorchuk (1),
S. Stepkin (1), V. Melnik (1), N. Kalinichenko (1), A. Stanislavsky (1), P. Tokarsky (1), V. Koliadin (1), V.
Shepelev (1), V. Dorovskyy (1), I. Bubnov (1), S. Yerin (1), A. Reznichenko (1), G. Litvinenko (1), N.
Shevchuk (1), A. Koval (1), I. Vasylieva (1). K. Mylostna (1), A. Skoryk (1), A. Shevtsova (1), Y. Volvach
(1), E. Vasylkovsky (1), V. Ryabov (4), A. Lecacheux (5), L. Denis (6), M. Panchenko (7), G. Fischer (7),
M. Imai (8), J.-M. Grießmeier (9), G. Mann (10), O. Litvinenko (1), A. Brazhenko (11), R. Vashchishin
(11), A. Frantsuzenko (11), V. Koshovy (12), A. Lozinsky, and O. Ivantyshin (12)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) LESIA, Observatoire de Paris, CNRS, PSL/SU/UPMC/UPD/SPC, Meudon, France
(3) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
(4) Future University of Hakodate, Hakodate, Japan
(5) LESIA, Observatoire de Paris, CNRS, PSL/SU/UPMC/UPD/SPC, Meudon, France
(6) 3USN (Unité Scientifique de la Station de Nançay), Nançay, France
(7) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
(8) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
(9) LPC2E - University of Orléans, Orléans, France
(10) Leibniz-Institut für Astrophysik Potsdam, Potsdam, Germany
(11) Poltava Gravimetrical Observatory of Institute of Geophysics, National Academy of Sciences
of Ukraine, Poltava, Ukraine
(12) Karpenko Physiko-Mechanical Institute, National Academy of Sciences of Ukraine, Lviv,
Ukraine
Rapid progress currently takes place in the field of low-frequency radio astronomy of meterdecameter-hectometer range of wavelengths. It is caused by a radical modernization of the existing
radio telescopes, creation of a new generation of instruments, space-borne observations, and by the
development of research of all classes of astrophysical objects, including the Solar System. On the
other hand, a range of difficulties specific to low-frequency radio astronomy is known, which are
caused by technical, methodological, and physical limitations. An effective strategy for overcoming
these difficulties is based on synchronous observations using several radio telescopes separated by
distances from a few to several thousand kilometers. This provides an opportunity to reduce and
identify radio interference and the influence of the propagation media, to increase the sensitivity and
resolution, and to solve many problems with higher efficiency. In recent years such synchronous
observations were carried out for the Sun, Jupiter, Saturn, interplanetary medium, pulsars,
exoplanets, transients using radio telescopes UTR-2, URAN, GURT, NDA, NenuFAR, LOFAR and other.
Parallel observations with the missions WIND, STEREO, Cassini and Juno also facilitate improvement
of the quality and reliability of low-frequency radio astronomical experiments.
47
Session 6: Wednesday, Oct. 26, 11:30-11:45
HeRO: A space-based low frequency interferometric observatory
for heliophysics enabled by novel vector sensor technology
M. Knapp (1), D. Gary (2), M. Hecht (3), F. Lind (3), C. Lonsdale (3), F. Robey (4), and the HeRO team
(1) Earth, Atmospheric, and Planetary Science, Massachusetts Institute of Technology (MIT),
Cambridge, MA, USA <[email protected]>
(2) New Jersey Institute of Technology (NJIT), University Heights Newark, NJ, USA
(3) Haystack Observatory, MIT, Westford, MA, USA
(4) Lincoln Laboratory, MIT, Lexington, MA, USA
HeRO (Heliophysics Radio Observer) is a proposed space-based interferometric array composed of
vector sensors mounted on free-flying CubeSats. HeRO will explore conditions and disturbances in a
key region of the heliosphere, from two to tens of solar radii, using interferometric observations of
solar radio bursts at frequencies that do not reach the ground. This will provide precise positions and
basic structural information. The morphology of CME shock fronts will be traced via type II burst
emissions, and heliospheric magnetic field geometries will be probed by measuring precise
trajectories of type III bursts. Refraction in the heliospheric plasma on large and intermediate scales
will be investigated throughout large volumes via the frequency dependence of accurate
interferometric positional data on bursts. The data will also be information-rich with high resolution
in time, frequency and spatial position, and high SNR, creating fertile ground for discovery of new
phenomena.
48
Session 6: Wednesday, Oct. 26, 11:45-12:00
Anticipated plasma wave measurements
onboard Exomars 2020 Surface Platform
I. Kolmasova (1), O. Santolik (1), and A. Skalsky (2)
(1) Institute of Atmospheric Physics, Czech Academy of Sciences, Czech Republic
<[email protected]>
(2) Space Research Institute, Russian Academy of Sciences, Moscow, Russia
The ExoMars 2020 Surface Platform will conduct environmental and geophysical measurements with
the aim to study the Martian surface and subsurface environment at the landing location. The
Surface Platform instrumentation will include the Wave analyzer module (WAM) as a European
contribution to the Russian‐led Martian ground electromagnetic tool (MAIGRET) instrument. The
wave analyzer module will be dedicated to measurements of magnetic-field fluctuations in the
frequency band from 100 Hz to 20 kHz. The scientific questions which we plan to address by
measurements of the WAM have never been answered by direct measurements of the fluctuating
magnetic fields in the appropriate range of frequencies directly on the surface of the planet. The
immediate questions related to these targets are: 1. Can we observe electromagnetic radiation from
electric discharges in Martian dust storms? 2. Can we observe electromagnetic radiation propagating
from the interplanetary space down to the surface of the planet?
49
Session 7: Thursday, Oct. 27, 09:00-09:30, invited talk
LOFAR tied-array imaging and spectroscopy of solar radio bursts
D. Morosan (1), R. Fallow (2), P. Zucca (3), P.T. Gallagher (1), and the LOFAR Solar and Space Weather
Key Science Project
(1) School of Physics, Trinity College, Dublin, Ireland <[email protected]>
(2) ASTRON, Dwingeloo, The Netherlands
(3) LESIA, Observatoire de Paris, Meudon, France
LOFAR is a new-generation radio interferometric array operating at frequencies of 10–240 MHz.
LOFAR is capable of both interferometric and beam formed modes, with unprecedented sensitivity
compared to previous radio telescopes due to the large number of LOFAR antennas. With the recent
commissioning of LOFAR, the low frequency Sun can now be studied with unprecedented spectral,
spatial and temporal resolution. In this talk, I will review recent progress of LOFAR observations of
the Sun using beam-formed modes, in particular tied-array beams. Due to the nature of some solar
radio bursts (short timescales and fine frequency structures), high cadence (<50 ms), tied-array
imaging has been developed with LOFAR to be used instead of standard interferometric imaging
which is currently limited to just a few images per second. This new imaging method already
produced substantial results on the spatial characteristics of a multitude of Type III radio bursts and
solar S bursts and continues to be applied to solar observations. Solar S bursts, in particular, have
been imaged for the first time using this observational mode.
50
Session 7: Thursday, Oct. 27, 09:30-09:45
Properties of groups of solar S-bursts at the decameter band
V. Dorovskyy (1), V.N. Melnik (1), A.A. Konovalenko (1), A.I. Brazhenko (2), S. Poedts (3), H.O. Rucker
(4), and M. Panchenko (5)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) Poltava Gravimetric Observatory, Poltava, Ukraine
(3) KU Leuven/Centrum voor mathematische Plasma-Astrofysica, Belgium
(4) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
(5) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Solar S-bursts are known to be the shortest bursts among all types of solar sporadic radio emission.
Their durations are mostly less than 1 s with the shortest reported value reaching 20 ms [McConnell,
1982, Solar Phys. 78, 253-269]. These bursts are observed exclusively at meter and decameter waves
[Melnik et al., 2010, Solar Phys. 264, 103-117; Morosan et al., 2015, A&A 580, id.A65]. Due to short
durations and low intensity, S-bursts can only be investigated by large ground-based radio telescope
equipped with high-resolution and sensitive back-ends, such as LOFAR, NenuFAR, LWA, UTR-2, etc.
The most recent study of the S-bursts parameters was performed by Morosan et al. [2015, A&A 580,
id.A65]. These authors have analyzed about 3000 individual S-bursts observed on 9 July 2013 by
LOFAR tied-array in the frequency band 20-80 MHz. They also obtained the image of the source. That
day the UTR-2 and URAN-2 radio telescopes were also on duty. So we decided to supplement the
above research with data obtained by different instruments at lower frequencies, namely from 9 to
32 MHz. On 9 July 2013 from 5:30 UT till 13:28 UT more than 1000 S-bursts were recorded in the
frequency band 9 - 32 MHz. All S-bursts were very poor events with an average flux of about 10 s.f.u.
and a minimum flux reaching 0.2 s.f.u., what makes their detection using small instruments
practically impossible. General dependences of S-bursts parameters on frequency were obtained.
They are in good agreement with previously reported ones. The degree of circular polarization was
high with the sense opposite to that of accompanying type III and IIIb bursts.
The essential feature of the observed S-bursts is that they often appear in dense groups by 5-10
individual bursts separated in time by approximately the doubled half-power duration of one burst.
There were few S-bursts which had the appearance of a solid line on the dynamic spectrum while
drifting from its highest to lowest frequencies. The majority of them look like dashed lines with a
frequency width of one fragment varying from 0.5 to 2 MHz.
There was an interesting phenomenon when the fragments of successive S-bursts of a group form a
kind of chain drifting in frequency. During the session more than 20 of such chains were identified.
These chains have exclusively positive frequency drift rates varying from 1 to 5 MHz/s and consisted
of 4 to 16 elements. The frequency widths of the chains varied from 1.5 to 6 MHz. Such chains were
never described before. From the viewpoint of plasma emission mechanism the observed chains of Sbursts fragments could be the manifestation of a plasma inhomogeneity moving towards the Sun
with an average velocity of 0.1 c, where c is the speed of light.
51
Session 7: Thursday, Oct. 27, 09:45-10:00
Oscillation of solar radio emission at coronal acoustic cut-off frequency
T. Zaqarashvili (1), O.S. Pylaev (2), A.I. Brazhenko (2), V.N. Melnik (3), and A. Hanslmeier (1)
(1) Institute of Physics, University of Graz, Austria <[email protected]>
(2) Institute of Geophysics, Poltava Gravimetrical Observatory, Poltava, Ukraine
(3) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
Recent SECCHI COR2 observations onboard STEREO-A spacecraft detected density structures at the
distance of 2.5-15 R_0 propagating with a periodicity of about 90 minutes. The observations showed
that the density structures are probably formed in the lower corona. We used the large Ukrainian
radio telescope URAN-2 to observe type IV radio burst at the frequency range of 8-32 MHz during the
time interval of 08:15-11:00 UT on 1 August 2011. Radio emission at this frequency range is
originated at the heights of 1.1-2.5 R_0 according to different density models of the solar corona. A
Morlet wavelet analysis showed the periodicity of 80 min in radio emission intensity at all
frequencies, which indicates to the quasi-periodic variation of coronal density at all heights. The
observed periodicity corresponds to the acoustic cut-off frequency of stratified corona with a
temperature of 1 MK. We suggest that continuous perturbations of the coronal base in a form of
jets/explosive events generate acoustic pulses, which propagate upwards and leave the wake behind
oscillating at the coronal cut-off frequency. This wake may transform into recurrent shocks due to
the density decrease with height, which leads to the observed periodicity in the radio emission.
52
Session 7: Thursday, Oct. 27, 10:00-10:15
Progress in the heliographic study using the UTR-2 radio telescope
at decameter wavelengths
A. Stanislavsky (1), A. Koval (2), E. Abranin (1), A. Konovalenko (1), and Y. Volvach (1)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) Institute of Space Sciences, Shandong University, Weihai, China
Since 2009 the broadband analog-digital heliograph based on the UTR-2 radio telescope gives solar
corona images in the frequency range 9-33 MHz with the frequency resolution 4 kHz, the time
resolution up to 1 ms, and under the dynamic range of about 90 dB. Although the instrument was
originally put into operation in the late seventies of the last century, when the radio astronomy
observations with the UTR-2 array were made only near to several fixed frequencies (10.0, 12.5, 14.7,
16.7, 20.0 and 24.8 MHz), the antenna system capabilities in frequency broadbandness were much
greater. The modern digital technology has served as an impetus to the development of this tool. The
instrument has been upgraded significantly [Stanislavsky et al., 2011, Radio Phys. and Radio Astron.
2, 197-204, https://arxiv.org/abs/1112.1044]. It has a hybrid scheme that combines the most positive
features of both digital and analog approaches at a relatively low price.
This device works on the parallel-series principle by using five equi-spaced array pattern beams
which scan the solar corona at a predetermined rate. Consequently, each solar image presents a
frame of 5 × 8 pixels with the space resolution 25' × 25' at 25 MHz. Each pixel indicates a signal level
from the corresponding antenna pattern beam, and the signal itself is measured in real time with a
new digital receiver/spectrometer. In this report we present a detailed overview of the heliograph
and its features. As examples, the tool potential is demonstrated by measurements of the solar
corona image for the quiet Sun [Stanislavsky et al., 2013, Astron. Nachrichten 334, 1086-1092] and
the radio imaging of decameter solar stationary type IV radio burst [Koval et al., 2016, submitted,
https://arxiv.org/abs/1606.00990]. Further development of this equipment is discussed.
53
Session 7: Thursday, Oct. 27, 10:15-10:30
Radio manifestation of CME observed on April 7, 2011
in the frequency band 8-32 MHz
V. Melnik (1), A.I. Brazhenko (2), G. Mann (3), A.A. Konovalenko (1), A.V. Frantzusenko (2), H.O.
Rucker (4), and M. Panchenko (5)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) Poltava Gravimetric Observatory, Poltava, Ukraine
(3) Leibniz-Institut für Astrophysik, Potsdam, Germany
(4) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
(5) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
The behind-limb CME at 12:00 UT on April 7, 2011 was initiated by the active region NOAA 1176. This
CME was associated with a type IV burst, type II bursts and groups of J-bursts and type III bursts.
Groups of J-bursts and type III bursts were observed from 10:50 to 11:15 UT. There was a group of Jbursts from 10:50 to 10:55 UT, which was apparently a radio emission of electrons propagating along
high magnetic loops connected with the active region NOAA 1176. Their fluxes were not larger than
10-30 s.f.u. and polarizations did not exceed 20%. The group of type III bursts continued from 11:00
to 11:15 UT. Mainly their fluxes were some tens of s.f.u., but some of them had fluxes of hundreds of
s.f.u. Polarizations of type III bursts were also not higher than 20%. There were a lot of spikes and
type IIIb bursts with polarizations up to 80% during the group of type III bursts. The type IV burst
began at 11:15 UT and continued for more than 3 hours. Its maximum flux was about 200 s.f.u. and
polarization achieved 40%. There were 3 type II bursts against the type IV burst. Their drift rates
were different, and it appears they were radio emissions from different regions of the spherical
shock produced by the CME. Fine structures of all type II bursts were consequences of tadpoles.
Tadpoles had “heads” and “tails”. Their durations were 4 s and 2 s and their polarizations were about
20% and 10%, correspondingly. The frequency band of “tail” was up to 10 MHz. The frequency drift
rates of “tail” could be positive and negative ones and changed from 0.4 MHz/s to 1.4 MHz/s. Both
the fundamental and harmonic radio emissions of tadpoles were observed for all type II bursts. The
mechanism of generation of tadpoles is discussed.
54
Session 8: Thursday, Oct. 27, 11:00-11:30
Observations of the Sun with the radio telescope LOFAR
G. Mann (1), C. Vocks (1), F. Breitling (1), LOFAR’s solar KSP team, and LOFAR team at ASTRON
(1) Leibniz-Institut für Astrophysik, Potsdam, Germany <[email protected]>
LOFAR (Low Frequency Array) is a novel radio interferometer originally designed for the frequency
range 10-240 MHz at ASTRON in the Netherlands. It presently consists of 50 stations distributed over
central Europe. It is operated as the International LOFAR Telescope (ILT) by several European
countries. The radio signals of each individual station are transferred via a high data rate link to
ASTRON, where they are correlated to a radio map of the sky.
Since the radio emission of active processes of the Sun takes place in LOFAR's frequency range and
because of LOFAR's imaging and spectroscopic capabilities, LOFAR is highly interesting for the solar
physics community for observing flares, coronal mass ejections and related phenomena in the
corona. Hence, the science with LOFAR is coordinated in terms of the Key Science Project (KSP) “Solar
Physics and Space Weather with LOFAR”. 32 scientists from 10 European countries participate in this
KSP. We report on first observations of the Sun with LOFAR and demonstrate that LOFAR is really
able to work as a dynamic spectroscopic radio imager of the Sun. This allows for the first time to
track fast moving electron beams in the corona. That provides a better understanding of the nature
of type III radio bursts as discussed.
55
Session 8: Thursday, Oct. 27, 11:30-11:45
Solar imaging using low frequency radio arrays
C. Lonsdale (1), L. Benkevitch (1), I. Cairns (2), M. Crowley (3), Ph. Erickson (1), M. Knapp (4), K.
Kozarev (5), F. Lind (1), P. McCauley (2), J. Morgan (6), and D. Oberoi (7)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
Haystack Observatory, MIT, Westford, MA, USA <[email protected]>
University of Sydney, Sydney, Australia
University of Massachusetts, Boston, MA, USA
Massachusetts Institute of Technology (MIT), Cambridge, MA, USA
Center for Astrophysics (CfA), Harvard University, Cambridge, MA, USA
Curtin University, Perth, Australia
National Center for Radio Astrophysics (NCRA), Pune, India
Low frequency imaging radio arrays such as MWA, LWA and LOFAR have been recently
commissioned, and significantly more advanced and flexible arrays are planned for the near term.
These powerful instruments offer new opportunities for direct solar imaging at high time and
frequency resolution. They can also probe large volumes of the heliosphere simultaneously, by virtue
of very large fields of view. They allow highly detailed, spatially resolved study of solar and
heliospheric radio bursts, which are complemented by heliospheric propagation studies using both
background astronomical radio emissions as well as the bursts themselves. In this paper, the state of
the art in such wide field solar and heliospheric radio studies will be discussed, including recent
results from the Murchison Widefield Array (MWA). The prospects for major advances in
observational capabilities in the near future will be reviewed, with particular emphasis on the RAPID
system developed at Haystack Observatory.
56
Session 8: Thursday, Oct. 27, 11:45-12:00
Multiwavelength study of twenty jets emanating from the periphery
of active regions
S. Mulay (1), D. Tripathi (2), G. Del Zanna (1), and H. Mason (1)
(1) Centre for Mathematical Sciences, University of Cambridge, Cambridge, UK
<[email protected]>
(2) Inter-University Centre for Astronomy and Astrophysics, Pune, India
We present a multiwavelength analysis of 20 EUV jets which occurred at the periphery of active
regions close to sunspots. We discuss the physical parameters of the jets and their relation with
other phenomena such as Hα surges, nonthermal type-III radio bursts and hard X-ray emission (HXR).
These jets were observed between August 2010 and June 2013 by the Atmospheric Imaging
Assembly (AIA) instrument onboard the Solar Dynamic Observatory (SDO). We selected events which
were observed on the solar disk within +/- 60◦ latitude. Using AIA wavelength channels sensitive to
coronal temperatures, we studied the temperature distribution in the jets using the line-of-sight
(LOS) Differential Emission Measure (DEM) technique. We also investigated the role of the
photospheric magnetic field using the LOS magnetogram data from the Helioseismic and Magnetic
Imager (HMI) onboard SDO.
It has been observed that most of the jets originated from the western periphery of active regions.
Their lifetimes range from 5 to 39 minutes with an average of 18 minutes, and their velocities range
from 87 to 532 km/s with an average of 271 km/s. Most of the jets are co-temporal with nonthermal
type-III radio bursts observed by the Wind/WAVES spacecraft in the frequency range from 20 kHz to
13 MHz. We confirm the source region of these bursts using the Potential Field Source Surface (PFSS)
technique. Using Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) observations, we
found that half of the jets produced HXR emission, and they often shared the same source region as
the HXR emission. 10 out of 20 events showed that the jets originated in a region of flux cancellation
and 6 jets in a region of flux emergence. 4 events showed flux emergence and then cancellation
during the jet evolution. DEM analyses showed that for most of the spires of the jets, the DEM
peaked at around log T [K] = 6.2/6.3 (∼2 MK). In addition, we derived an emission measure (EM) and
a lower limit of electron number density (Ne) at the location of the spire (jet 1 : log EM = 28.6, Ne =
1.3×1010 cm-3 ; jet 2 : log EM = 28.0, Ne = 8.6×109 cm-3) and the footpoint (jet 1 - log EM = 28.6, Ne =
1.1×1010 cm-3 ; jet 2 : log EM = 28.1, Ne = 8.4×109 cm-3).
The observation of flux cancellation, the association with HXR emission and emission of nonthermal
type-III radio bursts, suggests that the initiation and therefore, heating is taking place at the base of
the jet. This is also supported by the high temperature plasma revealed by the DEM analysis in the jet
footpoint (peak in the DEM at log T [K] = 6.5). Our results provide substantial constraints for
theoretical modelling of the jets and their thermodynamic nature.
57
Session 8: Thursday, Oct. 27, 12:00-12:15
Interplanetary type III bursts and density fluctuations in the solar wind
V. Krupar (1), O. Santolik (1), J. Soucek (1), O. Kruparova (1), M. Maksimovic (2), E. Kontar (3), and J.
Eastwood (4)
(1) Department of Space Physics, Institute of Atmospheric Physics, Czech Academy of Sciences,
Prague, Czech Republic <[email protected]>
(2) LESIA, Observatoire de Paris, Meudon, France
(3) University of Glasgow, Glasgow, UK
(4) Imperial College London, London, UK
Type III bursts are generated by beams of fast electrons originated from reconnection sites of solar
flares. These beams propagate outwards from the Sun along open magnetic field lines in the corona
and in the interplanetary (IP) medium while exciting radio emission at the local plasma frequency fp
and/or its second harmonic 2 fp. We performed a statistical survey of 152 simple and isolated IP type
III bursts observed by STEREO/Waves instruments between May 2007 and February 2013. We
investigated their time-frequency profiles in order to derive decay times as a function of frequency.
Next, we performed Monte Carlo simulations to study a role of scattering due to random density
fluctuations on time-frequency profiles of radio emissions generated in the IP medium. Derived
decay times from observations and simulations were compared. We conclude that relative electron
density fluctuations ⟨δne⟩/ne at the outer scale of turbulence in the solar wind are 0.15 and 0.30
assuming the fundamental and harmonic emission, respectively.
58
Session 8: Thursday, Oct. 27, 12:15-12:30
The investigations of the solar wind beyond Earth's orbit by IPS observations
at decameter wavelengths: Present state and perspectives
M. Kalinichenko (1), M.R. Olyak (1), A.A. Konovalenko (1), R. Fallows (2), P. Zarka (3), H.O. Rucker (4),
A. Lecacheux (3), I.N. Bubnov (1), S.N. Yerin (1), A.I. Brazhenko (5), O.L. Ivantishin (6), V.V. Koshovy
(6), and O.A. Lytvynenko (1)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) ASTRON, Dwingeloo, The Netherlands
(3) LESIA, Observatoire de Paris, Meudon, France
(4) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
(5) Gravimetrical observatory of Geophysical Institute, Poltava, Ukraine
(6) Institute of Physics and Mechanics, National Academy of Sciences of Ukraine, L'viv, Ukraine
The observations of the interplanetary scintillations (IPS) are very useful for studying the solar wind.
At high frequencies, they allow one to obtain the solar wind parameters at distances less than 1 AU.
At large solar elongations (at distances more than 1 AU from the Sun), the high frequencies are
weakly scattered due to the decrease of electron density with radial distance, while the decameter
wavelengths still show measurable scintillations index. This fact allows us to carry out the complex
investigations of the solar wind in the outer heliosphere by IPS observations at decameter
wavelengths. Our investigations include the elaboration of the scintillation theory applied to low
frequencies and the observations of IPS with the decameter radio telescopes UTR-2 - URAN (8 - 32
MHz). The experiments allow us to obtain the main parameters of the solar wind, to find and to track
the high-speed solar wind flows in the outer heliosphere.
Since 2003 we have been regularly observing the IPS at large elongations. Observations are usually
carried out with the radio telescope UTR-2 and synchronously with several decameter radio
telescopes of the URAN system. The solar wind parameters are obtained by fitting model power
spectra and dispersion dependences (calculated by using an elaborated method based on Feynman
path-integral technique) to observed ones. The brief results of the observations are the following. In
most cases we detect the presence of several solar wind flows with different velocities, densities and
thicknesses along the line of sight. We manage to trace the movements of high-speed streams of
different origins. The variations of the solar wind velocity and the scintillation index are usually in
good agreement with the behavior of the plasma parameters measured by spacecraft on Earth orbit.
Future investigations will require improvement in spatial resolution which can be reached by using a
larger number of scintillating radio sources and more radio telescopes. In this connection the
creation of the Giant Ukrainian Radio Telescopes (GURT) (frequency range 10 – 80 MHz, Gracove,
Ukraine) arouses considerable interest. In this report we also will discuss perspectives of joint
synchronous nightside observations of the same radio sources with UTR-2 (8 - 32 MHz) - URAN (8 - 32
MHz) - GURT (10 - 80 MHz) and LOFAR - KAIRA (10 - 80 MHz) radio telescopes. Such observations
allow us to answer several important questions connected with interplanetary and ionospheric
scintillations.
59
Session 9: Thursday, Oct. 27, 14:00-14:30, invited talk
The search for radio emission from giant exoplanets
J-M. Grießmeier (1,2)
(1) LPC2E - University of Orléans, Orléans, France <[email protected]>
(2) CNRS & Nançay Radio Observatory, Observatoire de Paris - CNRS/INSU, France
The intensity of Jupiter's auroral radio emission quickly gave rise to the question whether a
comparable coherent emission from the magnetosphere of an exoplanet could be detectable. An
exoplanetary radio emission would have to be at least 1000 times more intense than Jupiter's
emission to be detectable with current radio telescopes. Theoretical models suggest that, at least in
certain cases, the radio emission of giant exoplanets may indeed reach the required intensity. At the
same time, in order to generate such an emission, an exoplanet would have to have a sufficiently
strong intrinsic planetary magnetic field. Extrasolar planets are indeed expected to have a planetary
magnetic field, but to date, their magnetic field has never been detected. We will show that the most
promising technique to observe exoplanetary magnetic fields is indeed to search for the planetary
auroral radio emission. The detection of such an emission would thus constitute the first
unambiguous detection of an exoplanetary magnetic field. We will review recent theoretical studies
and discuss their results for the two main parameters, namely the maximum emission frequency and
the intensity of the radio emission. The predicted values should allow the detection using modern
low-frequency radio telescopes. We will present an ongoing observation program with the Low
Frequency Array (LOFAR), which has the potential to detect exoplanetary radio emission.
60
Session 9: Thursday, Oct. 27, 14:30-14:45
Magnetospheres of Hot Jupiters: on the physical phenomena
potentially observable in radio
M. Khodachenko (1), I.F. Shaikhislamov (2), I.I. Alexeev (3), E.S. Belenkaya (3), and H. Lammer (1)
(1) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
<[email protected]>
(2) Institute of Laser Physics SB, Russian Academy of Sciences, Novosibirsk, Russia
(3) Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University, Moscow,
Russia
The identification of possible sources of electromagnetic emissions in exoplanetary magnetospheres
and the estimation of their efficiency, as well as potential detectability, is a challenging task of the
present day theoretical astrophysics. It is closely related with the understanding and consistent
description of the key physical processes in the nearby exoplanetary space plasmas, and requires first
of all an appropriate model of an exoplanetary magnetosphere. A comparative look at physical
conditions in known and well measured magnetospheres of the solar system planets and those
expected by exoplanets, shows that a direct application of the scenarios and views developed for the
solar system planets to exoplanets, in spite of certain importance, may not always correctly reflect
the specifics of the exoplanets. This first of all concerns the case of the so-called Hot Jupiters – giant
exoplanets, orbiting close to their host stars. The existence, power efficiency, and detectability of
various sources of electromagnetic emission in the magnetospheres of Hot Jupiters are nowadays
widely investigated. In that respect, we present here a generalized model of a Hot Jupiter large scale
magnetosphere and consider several phenomena which might influence the exoplanetary radiation.
Our approach is based on a combination of two kinds of models: 1) a generalized paraboloid
magnetosphere model (PMM), which calculates a large-scale magnetosphere topology produced by
the whole variety of magnetic field and electric current sources, e.g., planetary magnetic dipole,
magnetopause and magnetotail currents, etc.; and 2) a 2D multi-fluid MHD model of the upper
atmosphere of a planet, heated and ionized by the stellar XUV radiation, which incorporates the
basic hydrogen photo-chemistry, gravitational and rotational forces, and takes into account a realistic
solar-type XUV spectrum. A key feature of the specific conditions in the magnetosphere of a closeorbit giant exoplanet, which we consequently take into consideration in our modelling, consists in
the presence of an expanding atmospheric material which forms a kind of escaping planetary wind
(PW), not typical for the solar system planets.
The interaction of outflowing plasma of the PW with the rotating planetary magnetic dipole field
results in the formation of an extended current-carrying magnetodisk around the planet. According
to the PMM modelling, the magnetic field produced by magnetodisk ring currents, usually dominates
above the contribution of intrinsic planetary magnetic dipole of an exoplanet and finally determines
the size and structure of the whole planetary magnetosphere [Khodachenko et al., 2012, ApJ 744,
id.70]. It results in 40 - 70 % larger magnetosphere scales, as compared to those traditionally
estimated with taking into account only the planetary dipole. The larger magnetosphere scales of Hot
Jupiters have to be properly taken into consideration during the estimation of power of the related
electromagnetic radiation sources. Besides of that, the dynamical MHD modelling of the
61
magnetodisk reveals a cyclic character of its behavior, comprised of consequent phases of the disk
formation followed by the magnetic reconnection with the ejection of a ring-type plasmoid
[Khodachenko et al., 2015, ApJ 813, id.50]. Such quasi-periodic dynamics might cause the specific
sources of electromagnetic radiation inside the magnetosphere which could be considered for
detection.
Acknowledgements: This work was supported by the projects S11606-N16 and S11607-N16 of the
Austrian Science Foundation (FWF), as well as by grants № 14-29-06036, 16-52-14006 of the Russian
Fund of Basic Research. MLK also acknowledges the FWF projects I2939-N27, P25587-N27, P25640N27 and Leverhulme Trust grant IN-2014-016.
62
Session 9: Thursday, Oct. 27, 14:45-15:00
On the Cyclotron Maser Instability in ionospheres of Hot Jupiters
Ch. Weber (1), H. Lammer (1), J.M. Chadney (2,3), H.O. Rucker (4), Ch. Vocks (5), W. Macher (1), I.F.
Shaikhislamvo, (6), M. Khodachenko (1), P. Odert (1), K.G. Kislyakova (1), and J.-M. Grießmeier (7)
(1) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
<[email protected]>
(2) Department of Physics and Astronomy, University of Southampton, Southampton, UK
(3) Department of Physics, Imperial College London, London, UK
(4) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
(5) Leibniz-Institut für Astrophysik, Potsdam, Germany
(6) Institute of Laser Physics SB, Russian Academy of Sciences, Novosibirsk, Russia
(7) LPC2E - Université d'Orléans/CNRS, Orléans, France
We present a study of the plasma conditions in the atmospheres of the Hot Jupiters HD 209458b and
HD 189733b and for an HD 209458b-like planet at orbit locations between 0.2-1 AU around a Sun-like
star. We discuss how these conditions influence the radio emission we expect from their planetary
magnetospheres. We find that the environmental conditions for the cyclotron maser instability
(CMI), the process which is the most probable mechanism responsible for the generation of radio
waves at magnetic planets in the solar system, most likely will not operate at Hot Jupiters. We find
that hydrodynamically expanding atmospheres possess extended ionospheres whose plasma
densities within the magnetosphere are too large, i.e. the plasma frequency is much higher than the
cyclotron frequency, which contradicts the necessary condition for the production of radio emission
and prevents the escape of radio waves for close-in extrasolar planets at distances <0.05 AU from a
Sun-like host star. The upper atmosphere structure of Hot Jupiters around stars similar to the Sun
changes between 0.2 to 0.5 AU from the hydrodynamic to a hydrostatic regime which results in
conditions where the plasma frequency can be lower than the cyclotron frequency, because a region
of depleted plasma between the exobase and magnetopause can form. Like on Earth, in such
environment a beam of highly energetic electrons can propagate and be accelerated along the field
lines towards the planet to produce radio emission. Moreover, if the CMI could operate the extended
ionosphere plasmas are too dense to let the radio emission escape from the planet.
63
Session 9: Thursday, Oct. 27, 15:00-15:15
Searching for brown dwarfs at low radio frequencies
J.E. Enriquez (1,2), G. Ramsay (3), P. Zarka (4), and H. Falcke (2)
(1)
(2)
(3)
(4)
University of California, Berkeley, CA, USA
Radboud University Nijmegen, Nijmegen, The Netherlands <[email protected]>
Armagh Observatory, Northern Ireland, UK
LEISA, Observatoire de Paris, Meudon, France
The unexpected first detection of a radio flare from a brown dwarf has puzzled our understanding of
magnetic field generation from Ultra Cool Dwarfs (UCDs). This emission does not follow the radio to
X-ray relation seen in the Sun and other low-mass stars, implying a different mechanism for the
formation of the magnetic field. Radio observations are important diagnostic tools to determine the
magnetic field configuration and the nature of plasma-emitting regions around UCDs. Current
theories are limited by detections at GHz frequencies, and therefore MHz observations can
potentially create a broader theory for UCD emission. MHz emission is expected to be emitted in
regions of lower magnetic field strengths and thus probe the plasma conditions there. I will discuss
current efforts for the MHz detection of these objects. I will show results from the recently released
TGSS ADR1 catalog at 150 MHz, as well as results from targeted observations with LOFAR in the
range of 110-190 MHz. I will put these results in the context of our current understanding of UCD
emission mechanisms.
64
Session 9: Thursday, Oct. 27, 15:15-15:30
New insight in atmospheres of extrasolar planets through plasma processes
Ch. Helling (1) and the LEAP group
(1) School of Physics & Astronomy, University of St. Andrews, St. Andrews, UK
<[email protected]>
Earth, Jupiter, and Saturn are cloudy solar system planets for which atmospheric discharges in form
of lightning are confirmed observationally in radio and in optical wavelengths. Space exploration and
ground based observations have shown that lightning is a process universal in the solar system, and
even more fundamental, also that charge and discharge processes occur in a large diversity in solar
system environments.
The occurrence of lightning is determined by the presence of clouds, the charging of the cloud
particles, and on cloud dynamics. Theory and observation have demonstrated that clouds are present
in extrasolar planets and their sibling-brown dwarfs. We model the formation of mineral clouds in
planetary atmospheres by a kinetic approach which allows us to predict the size distribution and
material composition of the cloud particles. These results have been used to study how such clouds
charge and under which conditions an electric field breakdown, the pre-courser for lightning and
other transient luminous events, may occur.
We have shown that the signature of atmospheric lightning can be imprinted on a pre-existing
radiation, and that a stronger atmospheric ionisation does not correlate with a stronger signal. The
magnetic coupling of a planetary atmosphere is possible, alone through thermal processes in the
upper atmosphere above the clouds. Cosmic rays, which further increase the ionisation in the upper
atmosphere, trigger the formation of pre-biotic molecules. This presentation aims to summarise
how various ionisation processes affect the atmospheres of extrasolar planets and how this leads to
new observational challenges.
65
Session 9: Thursday, Oct. 27, 15:30-15:45
Radio emission of lightning on exoplanets and brown dwarfs:
the case study of HAT-P-11b
G. Hodosán (1), Ch. Helling (1), and P.B. Rimmer (1)
(1) University of St. Andrews, St. Andrews, UK <[email protected]>
To date thousands of extrasolar objects, planets and brown dwarfs have been discovered. This large
number and the always-advancing technology allow us to focus on the characterization of these
objects, including atmospheric chemistry and dynamics, and internal composition. Lightning is one of
the most spectacular phenomena on Earth. It is important in sustaining the global electric circuit, it
gives information on cloud dynamics, and it might be important for the formation of life as the
Miller-Urey experiment suggests it. Therefore, it could be an excellent tool in characterizing
exoplanetary atmospheres if we could observe its presence. Lightning induced radio emission is wellknown from the Solar system. It has been observed on Earth, Jupiter and Saturn and maybe on
Venus, Uranus and Neptune. Several attempts have been carried out to observe radio emission
coming from an exoplanet, however without success. Brown dwarfs, on the other hand, show very
strong radio emission. Recently, the first auroral radio emission has been observed from such an
object [Hallinan et al., 2015, Nature 523, 568-571], which indicates that these processes can be
orders of magnitude stronger than what we know from the Solar system. These objects may be the
key to detect gas giant planets in the radio wavelengths.
We apply knowledge of lightning radio emission from Earth, Jupiter, and Saturn to estimate what
could be expected on extrasolar objects in terms of lightning energy release and radio emission. We
study the possibility of producing very-energetic lightning flashes by building a model based on
Earth-lightning modeling efforts of the return stroke of the lightning flash and exploring its
parameter space. This model determines the radio emission of such lightning flashes and estimates
the observability of such emission.
We first estimate whether lightning with Earth and Saturnian-like radiating characteristics could be
observed from an exoplanet. In 2009 Lecavelier des Etangs et al. [2013, A&A 552, id.A65] observed a
tentative radio emission from the planet HAT-P-11b in a radio band centered at 150 MHz. They reobserved the object in 2010, but this attempt was unsuccessful. Assuming the signal was real, we
estimated whether such emission could be produced by a sustained thunderstorm. Out results show
that flash densities (flashes km-2 h-1) 106 times larger than the largest Earth-storms have is needed to
produce the observed emission [Hodosán et al., 2016, MNRAS 461, 1222-1226]. Such thunderstorm
would produce an optical emission comparable to that of the star. However, our chemical study
showed, that an orders of magnitude smaller (but still larger, than Earth-storms) lightning activity
would produce HCN molecules that would be observable years after the storm. We conclude that it is
unlikely that the observed radio signal was produced by lightning.
66
Abstracts
Poster presentations
67
68
Poster 01
The Radio Jove Project: Citizen science for radio astronomy
Ch. Higgins (1), J. Thieman (2), S. Fung (3), F. Reyes (4), D. Typinski (5), W. Greenman (6), R. Flagg (7),
J. Brown (8), T. Ashcraft (9), N. Towne (10), J. Sky (11), L. Garcia (12), and B. Cecconi (13)
(1) Department of Physics and Astronomy, Middle Tennessee State University, Murfreesboro,
TN, USA <[email protected]>
(2) University of Maryland, Baltimore County, MD, USA
(3) NASA, Goddard Space Flight Center, Greenbelt, MD, USA
(4) University of Florida, Gainesville, FL, USA
(5) AJ4CO Observatory, USA
(6) LGM Observatory, USA
(7) Windward CC Observatory, USA
(8) HNRAO Observatory, USA
(9) Heliotown Observatory, USA
(10) Towne Observatory, USA
(11) Radio-Sky Publishing, USA
(12) Wyle, Inc., Goddard Space Flight Center, Greenbelt, MD, USA
(13) LESIA, CNRS-Observatoire de Paris, Meudon, France
The Radio Jove Project (http://radiojove.gsfc.nasa.gov) has been operating as an educational activity
for 18 years to introduce radio astronomy activities to students, teachers, and the general public.
Participants may build a simple radio telescope kit, make scientific observations, and interact with
radio observatories in real-time over the Internet. Recently some of our dedicated citizen science
observers have upgraded their systems to better study radio emission from Jupiter and the Sun by
adding dual-polarization spectrographs and wide-band antennas in the frequency range of 15-30
MHz. Some of these observations are being used in conjunction with professional telescopes such as
the Long Wavelength Array (LWA), the Nanҫay Decametric Array (NDA), and the Ukrainian URAN2
Radio Telescope. In particular, there is an effort to support the Juno mission radio waves instrument
at Jupiter by using citizen science ground-based data for comparison and polarization verification.
These data will be archived through a Virtual European Solar and Planetary Access (VESPA) archive
(https://voparis-radiojove.obspm.fr/radiojove/welcome) for use by the amateur and professional
radio science community. Another effort will be coordinated observations to study the ionosphere
during the upcoming solar eclipse for North America in August, 2017. We overview the citizen
science program and display recent observations that will be of interest to the radio science
community.
69
Poster 02
Total flux measurement of Jupiter’s synchrotron radiation
during the Hisaki and Juno campaign periods
F. Tsuchiya (1), H. Misawa (1), and H. Kita (2)
(1) Planetary Plasma and Atmospheric Research Center, Tohoku University, Sendai, Japan
<[email protected]>
(2) Graduate School of Science, Tohoku University, Sendai, Japan
Ground-based radio monitoring of Jupiter’s synchrotron radiation is a useful probe to measure shortterm variations in Jupiter’s electron radiation belt. Previous studies showed correlations between the
short-term variation and the solar EUV flux, suggesting that enhanced radial diffusion in the heart of
the radiation belt is driven by electric field fluctuations generated in Jupiter’s upper atmosphere. In
addition, some studies reported a possible relationship between the synchrotron radiation and the
solar wind. But more observations are needed to obtain a definitive conclusion. Here, we will report
a preliminary result of the total flux measurement of Jupiter’s synchrotron radiation with Iitate
planetary radio telescope (IPRT) in 2015 and 2016. During these periods, the Hisaki satellite observed
brightnesses of both Io plasma torus and Jupiter’s aurora continuously in the EUV wavelength range
and monitored magnetospheric activities which were caused by both the solar wind and internal
processes in the magnetosphere. In May to July 2016, the Juno spacecraft was approaching Jupiter
and monitored the solar wind parameters upstream of Jupiter. The total flux measurement of the
synchrotron radiation with the single dish telescope was done by the drift scan method at 325 MHz.
We obtained several scans of Jupiter in one day. Some calibration sources (e.g. 3C274) were used to
calibrate the total gain of the radio telescope. We will report preliminary results of the total flux
measurement of Jupiter’s synchrotron radiation during the Hisaki-Juno campaign periods.
70
Poster 03
Variation characteristics of Jupiter’s hectometric radiation
during the Iogenic plasma enhancement period
H. Misawa (1), F. Tsuchiya (1), T. Kimura (2), Y. Kasaba (3) and A. Kumamoto (3)
(1) Planetary Plasma & Atmospheric Research Center, Tohoku University, Sendai, Japan
<[email protected]>
(2) RIKEN Nishina Center for Accelerator-Based Science, Tokyo, Japan
(3) Graduate School of Science, Tohoku University, Sendai, Japan
Around Jupiter's oppositions to the Earth in 2014 and 2015, remote observations for Jupiter had
been made intensively by the Hisaki satellite. In particular in the 2015 campaign period, sudden
enhancement of Iogenic gas and plasma emissions was detected in the middle of January and the
enhancement had lasted for more than two months [Yoneda et al., 2015, Icarus 261, 31-33]. This
phenomenon would give a good opportunity to evaluate how the Iogenic plasma affects
magnetosphere's variations.
We have analyzed Jupiter's hectometric radiations (HOM) for the period using the radio wave data of
the WIND spacecraft placed around the L1 point of the Earth. HOM is known to be one of the
indicators reflecting Jupiter's global magnetospheric activities [e.g. Louarn et al., 2014, JGR 119,
4495-4511], and to have two components; i.e., one has some relations with solar wind variations
(‘solar wind HOM’) and another one has almost no relation (‘non solar wind HOM’) [Nakagawa et al.,
2000, Adv. Space Res. 26, 1541-1544]. In the presentation, we will introduce the following results
from the preliminary analysis: 1) activity of (non-solar wind) HOM increased after the Iogenic plasma
enhancement, 2) the enhancement is generally intermittent and quasi-periodic as if it reflected the
occurrence of substorm like events in the magnetosphere, and 3) intensity variations of Jupiter’s
aurora and HOM are similar, but not always the same.
Acknowledgements: We greatly appreciate M. Kaiser and the WIND/WAVES team for providing the
radio wave data through the WIND/WAVES home page.
71
Poster 04
Feasibility of the exploration of the subsurface structures
of Jupiter’s icy moons by Jovian hectometric radiation
A. Kumamoto (1), Y. Kasaba (1), F. Tsuchiya (1), H. Misawa (1), W. Puccio (2), J.-E. Wahlund (2), and J.
Bergman (2)
(1) Tohoku University, Sendai, Japan <[email protected]>
(2) Swedish Institute of Space Physics, Uppsala, Sweden
A new method for the detection of subsurface structures in the ice crust of Jupiter’s moons by using
interference patterns found in the spectrogram of the Jovian hectometric radio emissions (HOM) has
been proposed. For the Jupiter icy moon explorer (JUICE) mission, plasma wave observations around
icy moons are planned by using the radio and plasma wave instrument (RPWI). In these observations,
we will be able to obtain spectrograms of HOM propagating from Jupiter. Because the emissions
directly from Jupiter can be interfered with the emissions reflected at the icy moon’s surface and
subsurface boundaries, we will find interference patterns in the measured spectrograms. In case of
the Earth's Moon, the lunar orbiter SELENE detected the interference patters in the spectrograms of
auroral kilometric radiation (AKR) [Ono et al., 2010, SSR 154, 145-192; Goto et al., 2011, EP&S 63, 4756]. Because the interference occurs between AKR directly from the Earth and AKR reflected at the
lunar surface, the amplitude of the interference patterns is almost constant. In case of Jupiter’s icy
moons, we can expect the interference among HOM directly from Jupiter, HOM reflected at the ice
crust surface, and HOM reflected at the fully-freezed / partial-melted or high/low-porosity boundary
in the ice crust. Due to the slight phase difference between HOM reflected at the surface and
subsurface boundaries, the amplitude of the interference patterns will be modulated. The depth of
the subsurface boundaries can be determined from the frequency width of the modulation. In the
estimation of expected subsurface echo power, we should note that the attenuation rate in the ice is
highly dependent on the ice temperature [Chyba et al., 1998, Icarus 134, 292-302; Moore, 2000,
Icarus 147, 292-300; Fujita et al., 2000]. In the vicinity of the ice crust surface, the loss rate in the ice
is as large as 0 dB/km due to an ice temperature which is much lower than the melting temperature
of the ice (~270 K). On the other hand, in the vicinity of the boundary between ice crust and liquid
ocean, the loss rate extremely increases to 50 dB/km due to an ice temperature which is as high as
270 K. So, the detection of the ice crust and liquid ocean boundary seem to be difficult while we can
expect detection of shallower subsurface structures in the ice crust.
We are planning to implement onboard software functions at JUICE/RPWI for above observations. In
order to apply the method using interference among direct and reflected HOM, the emission should
be coherent at least for a period of ~3 msec, which is as long as the delay time of reflected HOM
when the spacecraft height is 500 km. So, in order to apply in case that the emission doesn't keep
coherence for more than 3 msec, we also prepare another onboard software function for autocorrelation analysis of waveforms including direct and reflected HOM emissions.
72
Poster 05
Search for Io, Ganymede and Europe induced radio emissions
from Cassini/RPWS integrated power time series
L. Lamy (1)
(1) LESIA, Observatoire de Paris, Meudon, France <[email protected]>
The Cassini mission flew by Jupiter in December 2000 and routinely observed Jupiter radio emissions
with its Radio and Plasma Wave Science experiment (RPWS) regularly over the interval 2000-2001,
between a few kHz and 16 MHz, hence only missing the high frequency portion of decametric
emissions. This database therefore provides an excellent basis to perform statistical studies, such as
the search of Jupiter-satellite interactions. Tracking individual structures such as ‘arcs’ in dynamic
spectra recorded too close to Jupiter is difficult, owing to the large variety of observed emissions,
and in turn prevents to plot their occurrence through usual drawings of the satellite phase as a
function of the observer’s longitude. Nonetheless, with long-term power time series, we can build
similar plots directly using the intensity of the emission itself, once integrated over a chosen spectral
range. This approach reveals clear signatures of emissions induced by Io, but also Ganymede and
Europe which confirm their detection by other different techniques [see Louis et al. and Zarka et al.,
this issue].
73
Poster 06
1977-2017: 40 years of observations of Jupiter and the Sun
with the Nançay Decameter Array
L. Lamy (1), L. Denis (2), P. Zarka (1), B. Cecconi (1), and S. Masson (1)
(1) LESIA, Observatoire de Paris, Meudon, France <[email protected]>
(2) USN, Observatoire de Paris, France
The Nançay Decameter Array (NDA) was built in 1977 within the radioastronomy station nearby the
village of Nançay (Sologne, France) to routinely observe heliospheric radio emissions in the 10-100
MHz range from the ground. Despite its modest size (144 helical antennae, ~7000 m2 area), it
observed since then Jupiter and the Sun on a daily basis with a collection of different receivers. The
NDA observations funded numerous studies of jovian and solar radio emissions and now form a
unique long-term database spanning 3.5 solar cycles and 3.3 Jupiter revolutions. The NDA
additionally brought a fruitful support to spatial radio observatories of Jupiter (such as
Voyager/Galileo and now Juno) and the Sun (Wind/Stereo and soon Solar Orbiter), to multiwavelength analysis of solar activity (through Radio Monitoring or BASS2000 databases) and
contributes to the development of space weather services (for instance with the project FEDOME).
Here, we briefly describe the NDA characteristics and latest instrumental developments, review
some recent studies and present perspectives for the next decade in terms of observations and data
distribution.
74
Poster 07
ISaAC, a Jupiter magnetic field model constrained by the auroral footprints
of the Galilean satellites
S. Hess (1), L. Lamy (2), and B. Bonfond (3)
(1) DESP/ONERA, Toulouse, France <[email protected]>
(2) LESIA, Observatoire de Paris, Meudon , France
(3) LPAP, Université de Liège, Liège, Belgium
The Jovian magnetic field is the strongest amongst the planetary magnetic fields, generating a huge
magnetosphere that interacts with plasma and large satellites to generate bright auroras. In order to
study the Jovian magnetosphere, and in particular to correctly map auroras from the planet top to
the equatorial plane where the interactions occur, it is needed to use an as accurate as possible
magnetic field model. The few flybys performed by early space missions and the farther Galileo orbits
brought an incomplete map of the magnetic field that can only constrain a limited number of
magnetic moments. Would the Jovian magnetic field be essentially dipolar, this could be sufficient to
allow for magnetospheric studies, but the huge Jovian metallic core produces large high order
magnetic moments that strongly impact the mapping of the equatorial plane to the surface. To build
a more accurate magnetic field model, we use the discrepancy between the mapped and observed
satellite footprint. By minimizing it we can constrain higher order moments. We will present the InSitu and Auroral Contrained (ISaAC) magnetic model that we built for magnetospheric studies.
75
Poster 08
Io’s ultraviolet spot emission as a probe of the Jovian magnetic field model
V. Shaposhnikov (1,2), G. Litvinenko (3), H.O. Rucker (4), V. Zaitsev (1), and A. Konovalenko (3)
(1) Institute of Applied Physics, Russian Academy of Sciences, Nizhny Novgorod, Russia
<[email protected]>
(2) National Research University High School of Economics, Nizhny Novgorod, Russia
(3) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
(4) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
The creation of the model of the Jovian magnetic field is the object of many papers. The
measurements of the magnetic field in situ by Pioneer, Voyager, and Ulysses and remote
observations of the positions of ultraviolet (UV) emission sources located in Jupiter’s ionosphere
along the trace of footprints of the Jovian satellites Io, Europe, and Ganymede were used for the
modeling. This provided the modeling of the internal magnetic field in a region close to the planet
quite accurate. However, these data is not sufficient for allowing an accurate modeling in a distance
from the planet surface and from regions not sampled by spacecraft. In the present report we discuss
the possibility to use the UV emissions from the sources located in the atmosphere of Io as a probe
of the Jovian magnetic field near Io’s orbit. We base it on the fact that the brightness of Io’s UV
emission observed from the compact sources (UV equatorial spots) at Io’s atmosphere demonstrates
strong correlation with the magnetic longitude of the moon. According to our model of the UV
equatorial spots the brightness of the UV emission (FUV) from the spots is proportional to the forth
degree of the value of the planetary magnetic field (B), FUV ~ B4, along Io’s obit. Comparing the
modeled and observed UV brightness from the equatorial spots gives a possibility to refine the Jovian
magnetic field model near Io’s orbit.
76
Poster 09
Analysis of the observational characteristics of shadow-effects
in the Jovian DAM emission
G. Litvinenko (1), A. Konovalenko (1), V. Zakharenko (1), I. Vasilieva (1), P. Zarka (2), A. Lecacheux (2),
V. Shaposhnikov (3), H.O. Rucker (4), M. Panchenko (5), and O. Ulyanov (1)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) LESIA, Observatoire de Paris, UMR CNRS, Meudon, France
(3) National Research University High School of Economics, Nizhny Novgorod, Russia
(4) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
(5) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
Despite the fact that so-called “shadow effects” (bursts in absorption) in the Jovian Io-modulated
decameter emission have been observed for the first time a long time ago, their physical origin still
has not a clear understanding. This fact can be explained by the non-frequent appearance of such
features in the Jovian DAM dynamic spectra. As result, analysis of the effects has minor interest and
only a small number of researchers engaged a detailed study of them. In our opinion, the study of
even such rare effects is important for understanding both the physical processes in the Jupiter radio
emission sources and astrophysics in whole.
In the given work we present the analysis of the observational characteristics of shadow-effects in
the Jovian DAM emission obtained by the UTR-2 radio telescope during the past and recent (January
2016) measurement campaigns. The dynamic range of the used receiving equipment was an order of
magnitude higher than the observed signal level; that allows us to be sure that the obtained effects
really belong to the Jovian DAM emission. The following parameters were studied: time-frequency
scale for effect appearance, frequency bandwidth and time duration for simple event, variation of
the burst width over the time axis, radiation intensity dependence in the time-frequency plane, sign
and value of frequency drift, absorption depth (i.e. a selection of the galactic background level). We
also made a simple comparative analysis of the specific properties of shadow effects in the Jupiter
decameter emission with the parameters of the quasi-similar effect (absorption burst) of the solar
radiation in decameter range.
77
Poster 10
Jovian DAM linear polarization study from coordinated, distant, groundbased radio telescopes
A. Lecacheux (1), M. Imai (2), T. Clarke (3), C. Higgins (4), M. Panchenko (5), A. Konovalenko (6), and
A. Brazhenko (7)
(1) CNRS - Observatoire de Paris, Meudon, France <[email protected]>
(2) Department of Physics and Astronomy, University of Iowa, Iowa City, IA, USA
(3) Remote Sensing Division, US Naval Research Laboratory, DC, USA
(4) Middle Tennessee State University, Murfreesboro, TN, USA
(5) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
(6) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
(7) Institute of Geophysics, Gravimetric Observatory, Poltava, Ukraine
Ground-based, complete measurement of Jovian DAM polarisation ellipse is a difficult task, due to
various terrestrial ionosphere effects encountered along the propagation path of the radiation:
scintillations strongly modulate the received intensity, and the uncertainty on the (Faraday) rotation
measure is of the same order of magnitude as the position angle to be measured.
Simultaneous observations of Jupiter from distant ground based radio telescopes, - as those which
were obtained in 2015-2016 by using LWA1 (USA), URAN2 (Ukraine) and Nançay Decameter Array
(France) -, may solve this ambiguity, since the local ionosphere effects can, in principle, be
disentangled from common Jovian radiation properties.
The measurement method is discussed, in particular how each wideband polarimeter can be
accurately calibrated and how the (Faraday) rotation measure can be confidently estimated.
Some preliminary results as well as their theoretical implications are discussed.
78
Poster 11
Jupiter radio fine structures observed in decametric frequency range
by URAN-2 radio telescope
J. Schiemel (1), M. Panchenko (2), H.O. Rucker (1), A.I. Brazhenko (3), and A.A. Konovalenko (4)
(1) Commission for Astronomy, Austrian Academy of Sciences, Graz, Austria
<[email protected]>
(2) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
(3) Institute of Geophysics, Gravimetric Observatory, Poltava, Ukraine
(4) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
We report the observations of fine radio structures in Jovian decametric radio emission. In our study
we have used the data obtained by the large ground-based radio telescope URAN-2 during four
observation campaigns from September 2012 to March 2016. The campaigns included long-term
continuous observation of Jovian radio emission (during periods of Jupiter's visibility) in the
frequency range 8-32 MHz, with time-frequency resolution 0.1 s and 4 kHz. A unique observational
material has been obtained including many events of Io controlled DAM, non-Io DAM as well as fine
spectral radio structures such as trains of S-bursts, quasi-continuous narrowband emissions, narrowband splitting events and zebra stripe-like patterns. We performed a preliminary statistical analysis
of observations of narrow band events. Such parameters as occurrence in Central Meridian
Longitude of Jupiter, intensity, duration of the events, frequency range and frequency drift have
been defined. The first results are presented.
79
Poster 12
Re-processing and re-analysis of Planetary Radio Astronomy (PRA)
of Voyager 1 & 2
B. Cecconi (1), A. Pruvot (1), L. Lamy (1), P. Zarka (1), C. Louis (1), S.L.G. Hess (2), D.R. Evans (3), and
D. Boucon (4)
(1)
(2)
(3)
(4)
LESIA, Observatoire de Paris, Meudon, France <[email protected]>
ONERA, Toulouse, France
Radiophysics Inc., Boulder, CO, USA (retired)
CNES, Toulouse, France
We have re-processed the Voyager/PRA (Planetary Radio Astronomy) data from digitized tapes
archived at CNES. The data covers the Jupiter and Saturn flybys of both Voyager probes. We have
also reconstructed goniopolarimetric datasets (flux and polarization) at the highest resolution. These
datasets are not currently available to the community, but they are of primary interest for the
analysis of the Cassini data at Saturn, and the Juno data at Jupiter, as well as for the preparation of
the JUICE mission. We present the first results derived from the re-analysis of this dataset.
80
Poster 13
Characteristics of Saturn's short-term kilometric radio bursts in 2005-2006
when Cassini stayed close to the equatorial plane
Y. Kasaba (1), T. Kimura (2), C. Jackman (3), B. Cecconi (4), L. Lamy (4), D. Maruno (1), and A. Morioka
(1)
(1)
(2)
(3)
(4)
Tohoku University, Sendai, Japan <[email protected]>
RIKEN Nishina Center for Accelerator-Based Science, Tokyo, Japan
University of Southampton, Southhampton, UK
LESIA, Observatoire de Paris, Meudon, France
This paper presents a trial of the statistical study for the northern and southern Saturn kilometric
radiation (SKR) bursts observed by the Cassini Radio and Plasma Wave Science investigation (RPWS)
in 2005-2006 when Cassini stayed around the equatorial region. The north SKR (N-SKR) and south
SKR (S-SKR) are independently modulated by the planetary rotation with different intervals known as
the north and south SKR phases, respectively.
We picked up the SKR burst events as short-term flux enhancements of lower frequency extension,
like terrestrial aurora kilometric radiation (AKR) bursts associated with substorms. We investigated
the N- and S-SKR bursts from 2005 DOY 250 to 2006 DOY 200 when Cassini stayed in the equatorial
region and could simultaneously observe the N- and S-SKR. We identified 38 SKR burst events,
including 16 N-SKR and 36 S-SKR ones. The occurrence rate, flux level, time evolution, and burst
timings associated with N- and S-SKR phases were compared for N- and S-SKR bursts.
Associated with this study, we identified an artificial masking effect, with the SKR flux from the
weaker hemisphere not being detected when the SKR from the opposite hemisphere was
continuously stronger. We still try to escape this problem, but in this study we assumed that the
occurrence of N- and S-SKR bursts could be synchronous. The main band S-SKR bursts (100–400 kHz)
were, on average, ~10 dB stronger than the N-SKR bursts, while the flux and frequency extension of
the low-frequency S-SKR (10–50 kHz) did not greatly differ from the N-SKR. The occurrence of N- and
S-SKR bursts was strongly correlated with the S-SKR phase, with 63 % of N-SKR bursts, 81 % of S-SKR
bursts, and 79 % of earlier SKR bursts occurring during S-SKR phases of 270°–60°, in the sector where
the SKR power rises to its maximum with time. Only a weak or no correlation was observed with the
N-SKR phase.
81
Poster 14
The seasonal variation of Saturn's auroral radio emissions in 2004-2015:
The correlation with solar wind activity and solar EUV flux
A. Sasaki (1), Y. Kasaba (1), T. Kimura (2), C. Tao (3), L. Lamy (4), and B. Cecconi (4)
(1)
(2)
(3)
(4)
Department of Geophysics, Tohoku University, Sendai, Japan <[email protected]>
RIKEN Nishina Center for Accelerator-Based Science, Tokyo, Japan
National Institute of Information and Communications Technology (NICT), Japan
LESIA, Observatoire de Paris, Meudon, France
Saturn emits intense radio emissions, Saturn Kilometric Radiation (SKR), from the northern and
southern polar regions at 3-1200 kHz. SKR is generated by field-aligned energetic auroral electrons
via the Cyclotron Maser Instability (CMI) at the local cyclotron frequency. Evaluation of Saturn’s
rotation period is based on the occurrence period of SKR because the SKR source is fixed in the
planetary magnetic field with highly anisotropic beaming and forms a corotating searchlight of radio
emission. For Saturn’s magnetic field direction, the right-handed circularly polarized (RH) emissions
are from the northern region and the left-handed (LH) ones from the southern region. Cassini
observations in the southern summer (2004-2009) showed that the period of SKR daily variation is
variable [Kurth et al., 2008, JGR 113, A05222]. It was slightly longer in the southern (summer)
hemisphere [Gurnett et al., 2009, Geophys. Res. Lett. 36, L16102], but close to each other near the
equinox (September 2009) [Gurnett et al., 2010, Geophys. Res. Lett. 37, L24101]. We also studied the
flux variation between northern and southern SKR in 2004-2010, and show that the LH (summer,
south) is stronger than the RH (winter, north) on average [Kimura et al., 2013, JGR 118, 7019-7035].
Those characteristics could be related to the north-south asymmetry in the polar ionospheric
conductivities, which are related to the seasonal variations of the solar EUV flux illuminating the
polar region. However, its comprehensive explanation has not yet been established. In 2010-2013,
the observations during the northern summer also show northern and southern SKR periods merge
together without clear separation [Provan et al., 2014, JGR 119, 7380-7401; Fischer et al., 2015,
Icarus 254, 72-91].
In this study, we extend our last SKR flux variation study from 2004-2010 [Kimura et al., 2013, JGR
118, 7019-7035] toward the northern summer (- 2015, DOY264). We note that the simple extension
of the analysis period is not adequate because of the bias in the Cassini orbit. Since the SKR is
stronger on the dawn side, we only used the data when Cassini was at the dawn side (2 h-10 h LT).
And, in order to avoid the visibility effect of SKR caused by its propagation, we also limited the data
by Cassini’s latitude (-5 to +30 deg. (RH), +5 to -30 deg. (LH)) and the distance from Saturn (10 - 100
RS). However, because Cassini’s apokrone after 2007 was gradually shifted from dawn to dusk, the
same criteria prevents from collecting enough dataset for the analysis.
For this study, we kept the same latitude and distance criteria but didn’t adopt a LT condition. In the
data when Cassini was close from the equator, both northern and southern SKR are observed
simultaneously. Therefore we selected the data when Cassini was in the latitude within +-5deg and
verified the result. The variation of SKR peak intensity was evaluated by a running median with a
window of +-35 days. In this result, the intensity of LH component in 2004-2009 (south, summer) was
~+10 dB stronger than RH (north, winter), which is consistent with the result in Kimura et al. [2013,
82
JGR 118, 7019-7035]. In 2010-2012 both SKR intensities got close to each other. After 2013, RH
(north, summer) was stronger by a few dB than LH (south, winter). Those variations of the flux ratio
between northern and southern SKR after 2010 seem to be linked with those of the northern and
southern SKR periods. We also note that the flux ratio was more than 10 in southern summer but
only 2.5 - 5 in northern summer, in the analyzed term.
In this paper, we will also show the correlations of the SKR flux variations to the solar activity, solar
EUV flux in 2004-2015, as extension of the results from 2004-2010 done by Kimura et al. [2013, JGR
118, 7019-7035].
83
Poster 15
A diagnosis for the auroral field-aligned acceleration processes at Saturn
using the brightness ratio of H Lyman-α/H2 bands in FUV auroral emissions
C. Tao (1), L. Lamy (2), R. Prangé (2), N. André (3), and S.V. Badman (4)
(1) National Institute of Information and Communications Technology (NICT), Japan
<[email protected]>
(2) LESIA, Observatoire de Paris-CNRS, Meudon, France
(3) IRAP, Université de Toulouse/UPS-OMP/CNRS, Toulouse, France
(4) Lancaster University, Lancaster, UK
Magnetospheric dynamics produce various field-aligned current systems. The current transfers
energy and momentum between the planetary magnetosphere and the ionosphere-thermosphere,
which are visualized as aurorae. We proposed that the ratio of the auroral brightness of H Lyman-α
to that of far ultraviolet H2 and the absolute value of the H2 brightness provide good indicators of
the acceleration versus nonacceleration processes for field-aligned auroral electron precipitation in
the Saturn magnetosphere-ionosphere coupled system. This finding is based on model results
indicating that this ratio is a decreasing function of the auroral electron energy over the whole
auroral energy range, as previously suggested by Cassini observations. For electron energies above 5
keV, the results agree with the Knight relation, as in the environments of the Earth and Jupiter. On
the other hand, decreasing electron flux with increasing electron energies below a few keV is also
found and alternately explained as a nonacceleration reflecting the magnetospheric plasma
distribution and/or wave-particle interactions. Radio sources are expected to be keV electrons,
therefore associated with a large variety of auroral components.
We will also discuss applications of this method to the Jupiter’s auroral spectra taken by the Hubble
Space Telescope.
84
Poster 16
Study of SED’s emission parameters
K. Mylostna (1), V.V. Zakharenko (1), and G. Fischer (2)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
The present research is devoted to the analysis of parameters of Saturn Electrostatic Discharges
(SED) emission according to the data obtained during the observations of the initial period of the
storm J (December 2010) with the UTR-2 radio telescope [Konovalenko et al., 2016, Exp. Astron. 42,
11-48]. The achieved sensitivity of the records allows us to resolve the microstructure of lightning
discharges [Farrell et al., 2007, Geophys. Res. Lett. 34, L06202]. In our previous investigations
[Mylostna et al., 2014, Radio Phys. and Radio Astron. 19, 10-19] the submillisecond structure was
revealed: SED-signals have components with a typical duration of tens and hundreds of
microseconds. It is important to note that the features with a time scale less than 1 microsecond
have not been identified. But this fact is planned to be studied. An interesting feature was found – on
the beginning of a few lightning flashes – bursts starts with a peak with the duration of less than 10
microseconds. The different types of electromagnetic spectra of terrestrial intra-cloud lightning
found in VLF range show peaks at different frequencies ranging between 1.5 to 6 kHz. The peak at
those particular frequencies may be related to the complex mechanism of breakdown process of an
intra-cloud lightning. So we expect to find the peak in LF spectrum of SED to be in range 1-17 kHz.
Due to the enormous number of events we had a great opportunity to provide statistical calculations
of such SED’s parameters as duration, band width, intensity and respectively energy. The last one
was earlier estimated in the range of 107-1013 J [Farrell et al., 2007, Geophys. Res. Lett. 34, L06202]. A
burst consists of several tens microsecond duration peaks that lead us to the inference based on the
conclusions of the paper [Farrell et al., 2007, Geophys. Res. Lett. 34, L06202] that the SED energy is
very likely to be 10(12-13) J.
We determined the average signal's dispersion delay for a session that is equal to (4.4±0.8)×10-5 pc
cm-3. It is close to the predicted value along the path from the storm to the observer [Mylostna et al.,
2014, Radio Phys. and Radio Astron. 19, 10-19]. A catalog of SED radio emission was formed
according to the data with a time resolution 10 ms. At the present time we are providing a
comparison of UTR-2 and RPWS receiver (operated on the board of spacecraft Cassini) data. The
search for the most short and intense bursts is in process. We pay special attention to the search of
regularities in the SED fine structure and the analysis of dispersion measure variations. The study of
the latter is a unique probe of the interplanetary medium. As a result we expect to determine its
characteristic and their variations in time.
Poster 17
85
Short antennas on a large spacecraft
G. Fischer (1), B. Cecconi (2), J. Bergman (3), J. Girard (4,5), G. Quinsac (2), and J.-E. Wahlund (3)
(1) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
<[email protected]>
(2) LESIA, Observatoire de Paris, PSL Research University, CNRS, Meudon, France
(3) Swedish Institute of Space Physics, Uppsala, Sweden
(4) SKA-SA, Rhodes University, Grahamstown, South Africa
(5) AIM/IRFU/SAP-CEA Saclay/Université Paris Diderot, France
Short dipole or monopole radio antennas are defined as being small in length relative to the
wavelength of the frequency of operation. The reception properties of short linear antennas can be
described by the so-called effective length vector which is pointing along the direction of minimum
gain in the toroidal radiation pattern. We deal here with such antennas, and additionally the word
"short" also means a small antenna with respect to a large spacecraft body. Using numerical
computer simulations we calculate the reception properties of an antenna system consisting of three
short monopoles positioned on a large spacecraft body. It turns out that such a configuration has a
major disadvantage, because the angular separation between its three effective length vectors is
quite small, which would lead to large errors in polarization and direction finding measurements. We
will show ways how to overcome this problem by changing the configuration to an antenna triad
consisting of three short dipoles mounted on a boom.
86
Poster 18
Science objectives and implementation of Software-type Wave-Particle
Interaction Analyzer (SWPIA) by RPWI for JUICE
Y. Katoh (1), H. Kojima (2), K. Asamura (3), Y. Kasaba (1), F. Tsuchiya (1), Y. Kasahara (4), T. Imachi (4),
H. Misawa (1), A. Kumamoto (1), S. Yagitani (4), K. Ishisaka (5), T. Kimura (6), Y. Miyoshi (7), M. Shoji
(7), M. Kitahara (1), O. Santolik (8), and J.-E. Wahlund (9)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Graduate School of Science, Tohoku University, Sendai, Japan <[email protected]>
Research Institute for Sustainable Humanosphere (RISH), Kyoto University, Kyoto, Japan
Institute of Space and Astronautical Science (ISAS), JAXA, Sagamihara City, Japan
Kanazawa University, Kanazawa, Japan
University of Toyama, Toyama Pref., Japan
RIKEN Nishina Center for Accelerator-Based Science, Tokyo, Japan
Institute for Space-Earth Environmental Research (ISEE), Nagoya University, Nagoya, Japan
Charles University, Prague, Czech Republic
Swedish Institute of Space Physics, Uppsala, Sweden
We present science objectives of Software-type Wave-Particle Interaction Analyzer (SWPIA), which
will be realized as a software function of the Low-Frequency receiver (LF) running on the DPU of
RPWI (Radio and Plasma Waves Investigation; PI: J.-E. Wahlund, IRF-Uppsala, Sweden) for the ESA
JUICE mission. SWPIA conducts onboard computations of physical quantities indicating the energy
exchange between plasma waves and energetic ions. Onboard inter-instruments communications are
necessary to realize SWPIA, which will be implemented by efforts of RPWI, PEP (Particle Environment
Package; PI: Stas Barabash, IR-Kiruna, Sweden) and J-MAG (JUICE Magnetometer; PI: M. Dougherty,
Imperial College London, UK). By providing the direct evidence of ion energization processes by
plasma waves around Jovian satellites, SWPIA contributes scientific output to JUICE as much as
possible with keeping its impact on the telemetry data size to a minimum.
SWPIA measures the energy transfer process between energetic particles and electromagnetic
plasma waves [Fukuhara et al., 2009, EP&S 61, 765-778; Katoh et al., 2013, Ann. Geophys. 31, 503512]. SWPIA will be firstly realized in the ERG satellite mission of JAXA to measure interactions
between relativistic electrons and whistler-mode chorus in the Earth's inner magnetosphere. We will
apply SWPIA to ion-scale wave-particle interactions occurring in the Jovian magnetosphere. SWPIA
clarifies where/when/how heavy ions are energized by waves in the region close to Ganymede and
other Jovian satellites. In SWPIA of RPWI for JUICE, we focus on the interactions between energetic
ions (a few to tens of keV) and ion cyclotron waves (typically less than 1 Hz). SWPIA uses wave
electromagnetic field and ion velocity vectors provided by RPWI sensors and PEP, respectively, with
referring to three-components of the background magnetic field detected by J-MAG.
SWPIA measures a relative phase angle between the velocity vector vi of the i-th particle of charge qi
and the wave electric field vector at the timing of particle's detection (E(t i)) and computes an inner
product of W(ti) = qiE(ti)・vi, where W(ti) corresponds to the variation of the kinetic energy of the i-th
energetic particle. We accumulate W for detected particles to obtain Wint = Σi W(ti), and we expect
statistically significant values of Wint for the case of the measurement at the site of efficient waveparticle interactions. In this presentation, we discuss details of the implementation of SWPIA of RPWI
87
and inter-instruments communications among RPWI-PEP-J-MAG of JUICE.
88
Poster 19
Radio emissions from electrical activity in Martian dust storms
W. Majid (1)
(1) Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA
<[email protected]>
Dust storms on Mars are predicted to be capable of producing electrostatic fields and discharges,
even larger than those in dust storms on Earth. There are three key elements in the characterization
of Martian electrostatic discharges: dependence on Martian environmental conditions, frequency of
occurrence, and the strength of the generated electric fields. We will describe a program at NASA’s
Madrid Deep Space Communication Complex to carry out a long term monitoring campaign to search
for and characterize the entire Mars hemisphere for powerful discharges during routine tracking of
spacecraft at Mars on an entirely non-interfering basis. The detection and characterization of electric
activity in Martian dust storms has important implications for atmospheric chemistry and the
understanding of the global electrical circuit. In addition, these measurements have important
implications for habitability, and preparations for human exploration of the red planet. Because of
the continuous Mars telecommunication needs of NASA’s Mars-based assets, the Deep Space
Network (DSN) is the only facility in the world that combines long term, high cadence, observing
opportunities with large sensitive telescopes, making it a unique asset worldwide in searching for and
characterizing electrostatic activity at Mars from the ground.
89
Poster 20
The role of small-scale Alfvén waves in the magnetosphere-ionosphere
transition region: Recent developments
S. Hatch (1), J.W. LaBelle (1), and C.C. Chaston (2,3)
(1) Department of Physics and Astronomy, Dartmouth College, Hanover, NH, USA
<[email protected]>
(2) Space Sciences Laboratory, University of California, Berkeley, CA, USA
(3) School of Physics, University of Sydney, Sydney, Australia
Using FAST satellite measurements in the magnetosphere-ionosphere transition region together with
previously published Alfvén wave identification methodologies [Stasiewicz et al., 2000; SSR 92, 423533; Chaston et al., 2003, JGR 108, A4, pp. SMP 4-1; Chaston et al., 2007, Geophys. Res. Lett. 34,
L07101], we have assembled a large statistical database of more than 230,000 small-scale Alfvén
wave observations between October 1996 and November 1999, and have also identified several
periods during which broad regions of Alfvénic activity are observed at FAST altitudes.
Broadband aurora (sometimes referred to as „Alfvénic“ aurora) is known to be highly responsive to
geomagnetic activity [Newell et al., 2009, JGR 114, A09207]. We therefore partition Alfvén wave–
associated statistics of ion outflow, electromagnetic and particle energy deposition, and frequency of
observation by geomagnetic storm phase [Hatch et al., 2016, JGR 121, 7828-7846]. From this analysis
we find the frequency of Alfvén wave observations increase by nearly an order of magnitude on both
dayside and nightside, and that Alfvén wave–associated ion outflow increases by up to two orders of
magnitude in some local time sectors. We also find that main phase is associated with as much as
50% of all ion outflow observed in coincidence with Alfvén waves [Hatch and LaBelle, 2016,
submitted to Radio Sci.].
Partitioning Alfvén wave statistics by prevailing IMF conditions, we find that Alfvénic power
integrated over the northern and southern hemispheres appears to obey a roughly linear
relationship with southward IMF Bz, in agreement with simulated integrated Alfvénic power [Zhang
et al., 2014, JGR 119, 3259-3266], and we find evidence of generation of dayside Alfvénic power in
response to periods during which the magnitude of IMF By is steady and large.
Recent theoretical analyses [Singh, 2006, JGR 11, A06215; Verkhoglyadova et al., 2013, JGR 118,
7695-7702] indicate complexities in both the propagation and dissipation of these and other lowfrequency waves. To experimentally explore these predictions, we have attempted to employ a
recently published methodology [Bellan, 2016, JGR 121, doi:10.1002/2016JA022827] for
determination of the wave vector k with a single spacecraft on the basis of field and particle data,
and to compare the results of this analysis with previously published estimates of k at FAST altitudes.
Building on the large body of research on dispersive Alfvén waves that has come forward primarily in
the past two decades, each of these studies aim to provide a better understanding of the role of
Alfvén waves in coupling the solar wind with the magnetosphere and the ionosphere.
90
Poster 21
The ECMI in turbulent reconnecting current layers in strong guide fields
R.A. Treumann (1), and W. Baumjohann (2)
(1) Department of Geophysics, Munich University, Munich, Germany <[email protected]>
(2) Space Research Institute, Austrian Academy of Sciences, Graz, Austria
The ECMI is excited when an at least weakly relativistic electron distribution is anisotropic exhibiting
higher occupations at perpendicular than parallel velocities. It requires strong magnetisation and
plasma dilution ß < 1, satisfied whenever electric fields expel electrons from some region. This is the
case in planetary auroral regions, and coronae of magnetised stars like the sun. Loss-cone
distributions on the global scale are one candidate for the ECMI. On the small scale, localised electric
fields like in electron holes can provide the required dilution and anisotropy. They are excited by
strong field-aligned currents preferentially in high density regions thus violating the dilution
condition. The ECMI causes radiation trapped in the holes if the holes are sufficiently extended.
Escape of radiation takes place after the hole propagates along the field into a region where the
frequency exceeds the lower X-mode cut-off. Holes are, however, small-scale entities. A more
promising candidate for the EMCI is spontaneous reconnection in strong guide fields along current
flow. Reconnection generates ion-scale and thus meso-scale electron exhausts. In guide fields they
satisfy the ß-condition and produce perpendicular anisotropies (mainly electron beams) on the
distribution function. Such conditions are in favour of ECMI. Since reconnection takes place in many
small-scale electron filaments, large numbers of such reconnection exhausts in plasma, like in plasma
undergoing turbulence, may cause high emissivities of radio waves. In sufficiently strong guide fields
the escape condition is not problematic. Moreover, O-modes and higher X-harmonics can also be
excited in this way. This may cause relatively weak polarisations. Spontaneous reconnection in
regions of magnetically turbulent plasmas in strong magnetic fields, present for instance in extended
field aligned current sheets, but also in large volumes containing magnetic turbulence that are
penetrated by strong guide fields, might in this way become source regions of the ECMI and radiate
in moderately strong radio waves. In particular large-scale plasmas embedded in relatively strong
magnetic fields and exhibiting turbulence would in this case shine in nearly stationary radio waves of
such non-thermal and non-synchrotron origin caused by the ECMI in many distributed reconnection
exhausts if only a sufficiently strong large-scale magnetic guide field penetrates the plasma. Such a
model will be investigated semi-quantitatively.
91
Poster 22
AKR Cyclotron Maser Instability as self-organized criticality system
M. Marek (1), and R. Schreiber (1)
(1) Space Research Centre, Polish Academy of Sciences, Torun, Poland <[email protected]>
Data gathered by the POLRAD swept frequency radiospectrograph (Interball-2 mission) have been
used for a preliminary analysis of Auroral Kilometric Radiation (AKR) elementary burst numbers as a
function of their intensity. AKR intensity samples consisted of data snapshots integrated over 6 ms
time periods. Histograms based on data sets containing up to a few thousands samples exhibit a
power law fall for higher intensities, characteristic for Self-Organized Criticality. The consequences of
such behaviour will be discussed. The SOC approach has been already used for interpretation of
some magnetospheric processes, but never for AKR.
92
Poster 23
Low frequency solar scrutiny with the Polish LOFAR stations
B.P. Dabrowski (1), A. Krankowski (1), L. Blaszkiewicz(1,2), K. Kotulak (1), and A. Fron (1)
(1) Space Radio-Diagnostics Research Center, University of Warmia and Mazury, Olsztyn, Poland
<[email protected]>
(2) Faculty of Mathematics and Computer Sciences, University of Warmia and Mazury, Olsztyn,
Poland
The LOw-Frequency ARray (LOFAR) is a radio interferometer operating in the frequency range 10–
240 MHz (corresponding to wavelengths of 30–1.2 m). Its scientific program is vast. Important issues,
between others, are solar and space weather investigations. We are expecting that the LOFAR
telescope will bring interesting discoveries in these fields. Three new LOFAR stations were built in
Poland in 2015 and have been operating since the beginning of 2016. Including these stations to the
ILT (International LOFAR Telescope) improved significantly the resolution and sensitivity of the whole
interferometer. Using a single LOFAR station, spectroscopic observations of the Sun can be
performed; more stations allow us to obtain solar radio images.
93
Poster 24
Database of solar radio bursts observed by solar radio
spectro-polarimeter AMATERAS
F. Tsuchiya (1), H. Misawa (1), K. Iwai (2), K. Kaneda (1), S. Matsumoto (1), A. Kumamoto (3), M. Yagi
(4), and B. Cecconi (5)
(1) Planetary Plasma and Atmospheric Research Center, Tohoku University, Sendai, Japan
<[email protected]>
(2) National Institute of Information and Communication Technology, Koganei, Japan
(3) Graduate School of Science, Tohoku University, Sendai, Japan
(4) RIKEN, Kobe, Japan
(5) LESIA, Observatoire de Paris, Meudon, France
Solar radio bursts in a frequency range from 150 to 500 MHz with fine time and spectral resolutions
have been observed with AMATERAS (the Assembly of Metric-band Aperture TElescope and Realtime Analysis System) installed on the Iitate Planetary Radio Telescope (IPRT), Japan since 2010 [Iwai
et al., 2012, Solar Phys. 277, 447-457]. AMATERAS consists of a wideband and low-noise front-end
receiver and a digital spectrometer (Aquiris AC240 (2 Gs/sec, 8bit)) as a back-end receiver. The
combination of the large aperture area of the telescope (511.5 square meters) and the digital
receiver enables us to observe the radio bursts with high dynamic range and fine spectral resolution
(10 msec and 61 kHz). Simultaneous observations for both RCP and LCP are possible. From
observations with AMATERAS, we found fine spectral structures in the radio bursts and derived
information on energetic particle acceleration and fundamental plasma processes that occurred in
the solar corona [Iwai et al., 2013, ApJ 768, L2; Katoh et al., 2014, ApJ 787, 45; Iwai et al., 2014, ApJ
789, 4; Kaneda et al., 2015, ApJ 808, L45]. Here we will introduce the AMATERAS database which is
open in public. After a daily observation of the Sun, a data processing pipeline in the observatory
generates high and low resolution data set. The low resolution data with reduced resolutions of 1
sec, 1 MHz, and 8 bits is converted to the FITS format and open in public through the AMATERAS web
page [1] soon after the observation. A quick look with the PNG format and metadata of the FITS
format data are also registered to the Virtual European Solar and Planetary Access (VESPA) [2] and
metadata database on Inter-university Upper atmosphere Global Observation NETwork (IUGONET).
The high resolution data set keeps high time and frequency resolutions but dynamic range is reduced
to 8 or 16 bits depending on the strength of the observed radio burst. The high resolution data is
currently provided on request basis. We expect that the AMATERAS data is useful for solar and space
physicists to investigate plasma physics in the solar corona.
[1] “http://pparc.gp.tohoku.ac.jp/data/iprt/index.html”
[2] “http://voparis-europlanet-dev.obspm.fr/planetary/data/display/?resource_access_url
=http://130.34.116.199/__system__/tap/run/tap&resource_schema=pparc_r&resource_type=epn&
query_conditions=” (note that this is currently a developing version)
94
Poster 25
Brightness temperature of decameter solar bursts with high-frequency cut-off
Y. Volvach (1), A. Stanislavsky (1), and A. Koval (2)
(1) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
<[email protected]>
(2) Institute of Space Science, Shandong University, Weihai, China
The determination of source sizes of solar bursts at low frequencies is a hot topic intensively studied
in recent years with new radio instruments (see for example, Morosan et al. [2015, A&A 580, id.A65]
and references therein). Usually, the sources are resolved with interferometers and heliographs. But
this requires huge antenna fields for low-frequency observations, and often the angular resolution of
the instruments used is mostly not sufficient. An alternative approach to establishing the source sizes
may be realized when solar flares occur on the far side of the Sun, nearby behind the limb, where the
occultation of a part of the source region by the corona permits one to evaluate the vertical
extension of the radio-wave emitting region. Our report is just devoted to such events.
In this work we consider the solar bursts with high-frequency cut-off, simultaneously observed with
several ground-based radio observatories located at significant distances from each other. We have
analyzed features of solar bursts with high-frequency cut-off observed in 17-19 August of 2012
[Stanislavsky et al., 2016, Sun and Geosphere 11, 91-95]. The events were conditioned with the
emergence of a new group of solar spots on the far side of the Sun. The cut-off effect in dynamic
spectra of the solar bursts indicates the fact that their radiating sources were occulted by solar
corona for observers situated on Earth. Due to coronal mass ejections (CMEs) the accompanied
behind-limb bursts become available for the study of their source size features. By using the radio
occultation of the low-frequency burst sources in the solar corona, we have found their angular sizes
in various frequencies from ordinary spectral studies. In addition, the spectral results of our
observations have been accurately calibrated in solar flux unites. This allowed us to obtain the
dynamic spectra of the solar bursts with high-frequency cut-off in brightness temperature.
95
Poster 26
Getting to know the nearest stars: intermittent radio emission from Ross 614
M. Knapp (1), D. Winterhalter (2), and T. Bastian (3)
(1) Department of Earth, Atmospheric, and Planetary Science, Massachusetts Institute of
Technology (MIT), Cambridge, MA, USA <[email protected]>
(2) NASA Jet Propulsion Laboratory, Caltech, Pasadena, CA, USA
(3) National Radio Astronomy Observatory (NRAO), Charlottesville, VA, USA
We present results from a VLA survey of the 10 nearest stars in the Northern sky in P, L, and S bands.
The purpose of this survey is to set firm upper limits on radio emission from stars and yetundiscovered planets orbiting our nearest stellar neighbors. Bounding the radio emission from these
stars will inform discussions of habitability for any planets discovered in these systems. We report
strong detections of stellar radio emission at 3 GHz from Ross 614 during March 2016, but not in
later observations. We also present upper limits on radio emission from the other survey targets.
96
Poster 27
The search for radio emission from the 55 Cnc exoplanetary system
using LOFAR
J. Turner (1), J.-M. Grießmeier (2), P. Zarka (3), and I. Vasylieva (4)
(1) Department of Astronomy, University of Virginia, VA, USA < [email protected]>
(2) Laboratoire de Physique et Chemie de l’Environment et de l’Espace (LPC2E) Université
d’Orléans/CNRS, Orléans, France
(3) LESIA & USN, Observatoire de Paris, Meudon, France
(4) Institute of Radio Astronomy, National Academy of Sciences of Ukraine, Kharkov, Ukraine
Detection of radio emission from exoplanets can provide information on the star-planet system that
is very difficult or impossible to study otherwise, such as the planet’s magnetic field, magnetosphere,
rotation period, orbit inclination, and star-planet interactions. Such a detection in the radio domain
would open up a whole new field in the study of exoplanets, however, currently there are no
confirmed detections of an exoplanet at radio frequencies. In this study, we search for non-thermal
radio emission from 55 Cnc, an exoplanetary system with 5 planets. 55 Cnc is among the best targets
for this search according to theoretical predictions. We observed for 18 hours with the LowFrequency Array (LOFAR) in the frequency range 26-73 MHz with full-polarization and covered the
entire orbital phases of the innermost planet. During the observations four beams were recorded
simultaneously on 55 Cnc, a patch of nearby “empty” sky, the nearby pulsar B0823+26, and a bright
radio source in the field. The extra beams make this setup unique since they can be used for control
of the telescope gain and to verify that a detection in the exoplanet beam is not a false-positive
detection (e.g. ionospheric fluctuations). An automatic pipeline was created to automatically find
Radio Frequency Interference (RFI) and to search for emission in the exoplanet beam. Conclusions
reached at the time of the meeting, about detection of or upper limit to the planetary signal, will be
presented. In the near future, we will apply this observational technique and pipeline to some more
planetary targets, which were selected on the basis of theoretical predictions.
97
98