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PLANET/Robonet : searching for low
mass extra solar planets via
microlensing.
Jean-Philippe Beaulieu,
Institut d’Astrophysique de Paris
Target Field in the Central Galactic Bulge
Galactic center
8 kpc
Sun
1-7 kpc from Sun
Light curve
Source star
and images
Lens star
and planet
Observer
A planetary companion
tE  20 j, M  0.3 Msun :
tp  q t E
Jupiter : q  3 10 -3  t p  1 j

Terre : q  105  t p  1.5 h
Hunting for planets via microlensing
Detecting real time microlensing event : OGLE-III and MOA 2
Detecting anomalies real time :
Networks of telescopes to do 24 hours monitoring : PLANET/RoboNET, microFUN
Accurate photometry (Image subtraction since 2006)
Real time analysis and modeling
OGLE-III has an online anomaly detector (EWS)
MOA-II
Selecting microlensing event with good planet detection efficiency
Two schools :
- Mainly high magnification events and alerted anomalies (microFUN)
- Monitoring a larger number of events (PLANET/ROBONET)
All. data, models, are shared immediately among the microlensing community.
Cooperation is the way to go !
PLANET collaboration :
Probing Lensing Anomaly
NETwork (current members)
http://planet.iap.fr
Boyden 1.5m
M. D. Albrow, J.P. Beaulieu, D. Bennett, D. Bramich, S. Brillant, J. A. R. Caldwell,
H. Calitz, A Cassan, K. Cook, C. Coutures, M. Dominik, J. Donatowicz, D.
Dominis, P. Fouqué, J. Greenhill, K. Hill, M. Hoffman, K. Horne, U. Jorgensen,
S. Kane, D. Kubas, R. Martin, J. Menzies, P. Meintjes, K. R. Pollard, K. C. Sahu,
Y. Tsapras,J. Wambsganss, A. Williams, M. Zub
Institut d'Astrophysique de Paris, INSU CNRS, Paris, France
Univ. of Canterbury, Dept. of Physics & Astronomy, Christchurch, New Zealand
South African Astronomical Observatory, South Africa
Boyden Observatory, Bloemfountein, South Africa
Canopus observatory, Univ. of Tasmania, Hobart, Australia
Niels Bohr Institute, Copenhagen, Denmark
Univ. of Potsdam, Potsdam, Germany
Space Telescope Science Institute, Baltimore, U.S.A.
Perth Observatory, Perth, Australia
PLANET/RoboNet
SITES
Boyden 1.5m
ESO Danish 1.54m 2003-2008
Sutherland, SAAO 1m 2002+
Boyden, 1.5m, CCD 2006, 2007
Perth 0.6m 2002-2007+
Hobart 1m, 2002-2007+
Brazil 0.6m, 2007+
Robonet :
Liverpool 2m, Canary 2005+
Faulkes North 2m, Hawaii 2006+
Faulkes South 2m, Australia 2007+
Goals at each site :
- 1 % photometry,
- Adapted Sampling rate
- Online analysis.
OBSERVING STRATEGY, DECISION TAKING
Homebase checks :
- OGLE, MOA alert pages
- results from Bayesian PSPL fits to OGLE data (Albrow)
- results from K.Horne priority pages
- data collected by PLANET/RoboNet and current fits
He can ask for data to be re-reduced to double check anomalies.
Then he decides an observing strategy, sampling rates for different events
He issues anomaly alerts to the community.
Homebase should be on the deck 24 hours a day for 2-3 weeks
PLANET DATA PROCESSING
At each site :
-relative photometry for all stars real time
- keep an eye on light curve of prime target
Data from all sites are uploaded to Paris (every ~10 min) :
RoboNet
SAAO
Boyden
Chile
Every day, homebase checks :
data, light curve fits, BAP,
StAndrews priorities algo,
Choose strategy, sampling, …
Alert the community if anomalies
Hobart
Perth
OGLE-2005-BLG-390
?????????
 ????????
!
  !
  !
   
   
A bump in the night… a planet ??????
A binary lens ??????
A planet !
OGLE-2005-BLG-390
Coopération : PLANET/RoboNET, OGLE-III, MOA-II
AT LAST, A TEXT BOOK MICROLENSING EVENT
Gould Loeb 1992, Bennett & Rhie 1996, …
Data in the anomaly from : PLANET-Danish, OGLE, MOA-II, PLANET-Perth
Data outside the anomaly from : PLANET/Robonet, PLANET-Hobart
PROBABILITY DENSITIES OF THE
STAR AND ITS PLANET
A companion to this frozen super Earth ?
Kubas et al., 2007 submitted
Excluding at :
50 % Jupiter over 1.1-2.3 AU
70 % 3 Jupiter over 1.5-2.2 AU
Core accretion models by Idal & Lin
OGLE-2005-BLG-169Lb : a weak Neptune planet signal
Gould et al. 2006, MicroFUN, OGLE, RoboNet
A new Jovian analogue
a resonnant caustic system
45
5 microlensing planets, their time scale.
KB-07-197
Do gas giants prefer host stars that cause longer events ?
Ie more massive ones ?
Current status of microlensing planet hunting
PLANET/Robonet/HOLMES (network of 9 telescopes). Now – 200?
MicroFUN Now-200?
OGLE III and MOA-2
- Constraints on Jupiters and low mass planets (down to few Earth mass)
- Monitoring of high mag events PLANET/RoboNet, MicroFUN, OGLE, MOA
- Monitoring of any mag events (PLANET/RoboNet, OGLE)
Las cumbres plans ?
A 1m observing in J from Antartica ?
Network of wide field imager Earth Hunter + OGLE-IV + MOA-2 2011+ ?
Statistics on Cool Earth mass planets, possibly habitable zone.
NASA mission MPF ( PI Bennett) to be re-submitted ?
ESA DUNE mission (cosmic shear + 3 months/Yr of planet search )
Abundance of planets in habitable zone.
MPF : 36 months, 200 million stars, 4 fields of 0.66 sq2, FWHM=0.25 arcsec
~100 q Earth, ~6000 q Jupiter (q fraction of stars with planets),
Mars detectable
Operational remarks 1995-2007
Small dedicated telescopes, with very dedicated people.
Retired people, volunteers, important financial supporters (David Warren)
Enthusiasm, dedication and friendship among a core part of PLANET.
Good image quality
Good and stable CCD cameras
Well sampled PSF (4 pix in FWHM is excellent)
Size of telescope does not matter that much
Real time online analysis is vital :
The Hummer approach : 1996-2005 PLANET pipeline (PSF fitting)
The Ferrari approach : WISIS, image subtraction techniques (since 2006)
3 different image sub pipelines (WISIS, pySIS, DIA-robonet)
Coordination effort : sharing/combining all data on short time scales
Automatic tools for efficient prediction of behavior of microlens events
Fits, predictions of high mag, detection efficiency calculations
Experienced guys on the mountains, with support from dedicated people in office.
CONCLUSION
Operating a network of telescopes for 12 years.
5 microlensing planets for 3 scenarios :
•2 Strong caustic
•2 High mag central caustic
• 1 Planetary caustic
3 ~Jupiters, 1 ~5.5 Earth, 1 ~13 Earth
(Probability of detecting Jupiters is ~50 times larger)
Giant planets are rare, suggests 1-15 MEARTH might be common
Giant planets in events with large tE ?
~Earth mass planets on ~AU orbits to be discovered soon…
1996, sensitivity to Earths depends on source size
Earth mass
planet signal is
washed out for
giant source stars
If planetary Einstein Ring < source star disk: planetary microlensing
effect is washed out (Bennett & Rhie 1996)
For a typical bulge giant source star, the limiting mass is ~10 M
For a bulge, solar type main sequence star, the limiting mass is ~ 0.1 M
Need to monitor small stars to get low mass planets.
Using high magnification events,
Griest & Safizadeh 1998
« We show that by focusing on high-magnification events,
the probability of detecting planets of Jupiter mass or greater
in the lensing zone [(0.6
1.6)RE] is nearly 100%,
with the probability remaining high down to Saturn masses
and substantial even at 10 Earth masses. »
Planetary caustic
Central caustic
Detection ≠ characterization