Download PowerPoint 簡報

A Turtorial Lecture on Exoplanets
Wing-Huen Ip
Institutes of Astronomy and Space
Science
National Central University
August 31, 2012
Introduction
Planets before 1995…
small rocky planets close to the Sun
gas-giant planets more distant from the star
You are here!
Discovery of the first exoplanet: Peg 51b in 1995
http://spiff.rit.edu/classes/phys230/lectures/planets/planets.html
Periodic Variation of the Spectral Lines
http://www.cfa.harvard.edu/afoe/51Peg.html
http://lcogt.net/spacebook/radial-velocity-method
Doppler Effect
http://mail.colonial.net/~hkaiter/Doppler_Effect_Shift.html
Red Shift Effect and Hubble Constant
http://www.answersingenesis.org/articles/tba/universe-confirms-bible
http://astronomy21st.blogspot.tw/2010/03/universe-expansion-is-speeding-up.html
Mass vs semi-major axis
http://jila.colorado.edu/~pja/planets/extrasolar.html
A new class of planets:
Super-Earths!
GJ1214
Neptune/GJ436
Earth
Kepler 10b
CoRoT-7b
11
55 Cnc e
Mp sin I Effect
Sin i : large
Mayor & Queloz, 1995
Sin i : small
Exoplanet Transit
http://www.astro.caltech.edu/people/faculty/wasp10_transit_600.jpg
-What are these planets actually like?
(atmospheric composition? thermal properties?)
- Why are they as they are?
Habitable Zone
https://www.e-education.psu.edu/astro801/content/l12_p4.html
There is more to mass and radius…
The Hot Jupiters
Orbital distribution
Thermal evaporation of the
atmosphere of hot Jupiters
http://star.herts.ac.uk/RoPACS/JoGo.html
WASP-12b
Space Weather
The Hot Jupiters
• Tidal interaction and/or electromagnetic effects
(Cuntz and Shkolnik, 2002)?
• Superflares from star-planet interaction )Rubenstein
and Schaefer (2000)?
Star-planet Magnetic Interaction
Three Types of Magnetic Coupling
Power = VB2L2 ergs/s
~ 1027 ergs/s
Ip, Kopp and Hu (2004)
Magnetospheric Substorms
Observational Test
• Detection of excessive Ca II H and K line emissionsynchronized to orbital period of the Hot Jupiter ( Skholnik et
al. 2005)
• On/off nature of such hot spots (Skholnik et al., 2008)
Kepler Observations
• Maehara et al. (2012):
Superflares on solar-type
stars
• 9751 sola-type stars in
Kepler field
• 365 superflares (>1035 ergs)
in 148 stars
Kepler Observations
• Maehara et al. (2012):
Superflares on solar-type
stars
• 9751 sola-type stars in
Kepler field
• 365 superflares (>1035 ergs)
in 148 stars
• None of them has Hot
Jupiter!
Sun spots and star spots
http://go.owu.edu/~physics/StudentResearch/2003/BethCademartori/index.html
Kepler Observations
• Maehara et al. (2012):
Superflares on solar-type stars
• 9751 sola-type stars in Kepler field
• 365 superflares (>1035 ergs) in 148 stars
• One million times stronger than
the biggest solar flares ever obeserved.
• Frequency is about once every
5000 years
• None of them has Hot Jupiter!
Could Superflares happen
on the Sun?
Space weather
http://www.eee.metu.edu.tr/~etulunay/ytulunay/
Electricity black out on March 13, 1989
Electricity blackout of August 14, 2003,
in New York
Electricity blackout in July, 2012
Search for Earth-like
Habitable Exoplanets by the
Kepler Mission:
New Results from IAU GA, Beijing
(20-31, 8, 2012)
The Kepler Mission
• The scientific objective of Kepler is to explore the structure and
diversity of planetary systems.[45] This spacecraft observes a large
sample of stars to achieve several key goals:
• To determine how many Earth-size and larger planets there are in
or near the habitable zone (often called "Goldilocks planets")[46] of a
wide variety of spectral types of stars.
• To determine the range of size and shape of the orbits of these
planets.
• To estimate how many planets there are in multiple-star systems.
• To determine the range of orbit size, brightness, size, mass and
density of short-period giant planets.
• To identify additional members of each discovered planetary system
using other techniques.
• Determine the properties of those stars that harbor planetary
systems.
Kepler FOV 115 sq. deg.
Planetary candidates observed by
Kepler III. Analysis of the first 16
months of data
• Batalha, N. et al.
• arXiv:1202.5852, 2012
Kepler-20: A sun-like star with threesub-Naptune exoplanets and two
Earth-size candidates
• Gautier, T.N., et al.
• ApJ, 749, 15, 1, 2012
Two Earth-sized planets orbiting
Kepler-20
• Fressin, F. et al.
• Nature, 482, 195, 2012
Kepler-20e and 20f
Kepler-20 (also designated as KOI 070, KIC 6850504 and
2MASS J19104752+4220194) is a G8V star of Kepler
magnitude 12.497 and celestial coordinates right
ascension α = 19 h 10 min 47.5 s and declination δ =
+42° 20′ 19.38′′. The stellar properties are listed in Table
1. The photometric data used for this work were
gathered between 13 May 2009 and 14 March 2011
(quarter 1 to quarter 8), and comprise 29,595
measurements at a cadence of 29.426 min (black dots).
The Kepler photometry phase-binned in 30-min
intervals (blue dots with 1σ standard error of the mean
(s.e.m.) error bars) for Kepler-20 e (a) and Kepler-20 f (b)
is displayed as a function of time, with the data
detrended4 and phase-folded at the period of the two
transits. Transit models (red curves) smoothed to the
29.426-min cadence are overplotted. These two signals
are unambiguously detected in each of the eight
quarters of Kepler data, and have respective signal-tonoise ratios of 23.6 and 18.5, which cannot be due to
stellar variability, data treatment or aliases from the
other transit signals4.
Keplere-20e and 20f
Kepler-20 e and Kepler-20 f theoretical mass and observed
radius ranges (1σ) are plotted as orange- and green-shaded
areas, while the other transiting planets with dynamically
determined masses are plotted in black, with 1σ error bars.
The curves are theoretical constant-temperature mass–
radius relations27. The solid lines are homogeneous
compositions: water ice (solid blue), MgSiO3 perovskite
(solid red), and iron (magenta). The non-solid lines are
mass–radius relations for differentiated planets: 75% water
ice, 22% silicate shell and 3% iron core (dashed blue);
Ganymede-like with 45% water ice, 48.5% silicate shell and
6.5% iron core (dot-dashed blue); 25% water ice, 52.5%
silicate shell and 22.5% iron core (dotted blue);
approximately Earth-like with 67.5% silicate mantle and
32.5% iron core (dashed red); and Mercury-like with 30%
silicate mantle and 70% iron core (dotted red). The dashed
magenta curve corresponds to the density limit from a
formation model24. The minimum density for Kepler-20 e
corresponds to a 100% silicate composition, because this
highly irradiated small planet could not keep a water
reservoir. The minimum density for Kepler-20 f follows the
75% water-ice composition, representative of the
maximum water content of comet-like mix of primordial
material in our Solar System28.
Architecture and dynamics of Kepler’s
candidate multiple transiting planet
system
• Lissauer, J., et al.
• ApJ Suppl. Series, 197, 1, 2011
Systems of 4-6 Planets
Kepler-47b and c: A planetary system
orbiting around a binary star
(8/29/2012)
NASA's Kepler Discovers Multiple Planets Orbiting a Pair of Stars
Published by Klaus Schmidt on Wed Aug 29, 2012 12:37 pm via: NASA
Share
More share options
Tools
Suggest NewsReport Article
Add CommentPrint Article
Tags
NASA, Kepler, Exoplanets, Kepler-47c, Kepler-47b
MOFFETT FIELD, Calif. — NASA’s Kepler mission has discovered
multiple transiting planets orbiting two suns for the first time. The
system, known as a circumbinary planetary system, is 4,900 light-years
from Earth in the constellation Cygnus.
Coming less than a year after the announcement of the first circumbinary
planet, Kepler-16b, this discovery proves that more than one planet can form
and persist in the stressful realm of a binary star. The discovery demonstrates
the diversity of planetary systems in our galaxy.
NASA Press Conference at IAU
at Beijing on August 29, 2012 by Dr. Natalie Batalha
and Prof. William Welsh
Star War!
http://articles.businessinsider.com/2011-09-27/home/30207350_1_kepler-spacecraft-telescopes-european-southernobservatory
Prof. Chung-Ming Ko on ET
Thank You!