Transiting exoplanets with AST3 - bao.ac.cnaag.bao.ac.cn/Academic/xian/ppt/8.19pm/zhou_jilin.pdf ·...
Transcript of Transiting exoplanets with AST3 - bao.ac.cnaag.bao.ac.cn/Academic/xian/ppt/8.19pm/zhou_jilin.pdf ·...
Transiting exoplanets with AST3
Ji-Lin Zhou (周济林)
Nanjing University ([email protected])
Collaborating with:
Peking University (KIAA), Purple Mountain
Observatory, National Astronomical Observatory,
Yunnan Observatory, University of Science and
Technology of China,, University of Florida,
etc,…
Astronomy & Astrophysics in Antarctica
Detected exoplanets
• 473 planets detected (12 Aug 2010)
• 47 multiple planet systems
• Radial velocity and astrometry : 442
• Transit: 91
• Microlensing : 9
• Imaging: 11
• Timing : 8
(http://exoplanet.eu/)
2/1
1
2/1** )())((/30*
*
AUa
MM
M
Mp
a
GM
M
Mp
JsmV
Earth
K=10m/s
K=1m/s
Reviews on statistical properties:
Santos et al. 2005, Science
Marcy et al. 2005,PTPS Udry & Santos 2007, ARAA
http://exoplanet.eu/
(plot from Wikipedia )
67 Me/113Me 2)(~
*R
Rpf
-Why –transit?
J
Udry & Santos 2007
•Light curves only;
•know the orbital inclination rel. observer;
•deduce planet composition, thus physics…
What we want to know by transit?
Planet Formation: a general picture
(1) gravitational instability model
Boss A.
Classical Planet Formation Scenario
HR 8799 system
<1
Form MMSN:
4/1)(4.4 AUaQ
(2) Core accretion model
Formation of km size
planetesimals
Accretion of planetesimals
into planetary embryos
Gas accretion, giant impact
1cG
Q
www.planet.sci.kobe-u.ac.jp
type-II migration
planet’s perturbation
viscous diffusion
type-I migration
disk torque imbalance
MyrAU1
05.023
23
*
g
SNg,
Imig,
a
M
M
M
M
op
MM )10010(
MM )11.0(
MyrAU1
10
2
1
2
1
*
o
3
J
p
g
SNg,
IImig,
a
M
M
M
M
viscous disk accretion
Goldreich & Tremaine (1979),
Ward (1986, 1997), Tanaka et al. (2002)
Lin & Papaloizou (1985),....
Credit: D,Lin
Major problems
Aim 1: Find planets in the proto-stellar disk
Back ground:
•Theory: planet forms within
the proto-stellar disk
•Observation: YSOs
surround by accretion disk
•A few exoplanets
embedded in disk are
comfirmed, e.g. beta Pic b
(Lagrange et al. science 2010)
Combing with dynamical simulation..
• Earlier stellar environment: disk inner hole
• Disk density and viscosity;..
• Protostellar magnetic fields;…
Application : HD40307
Mayor et al. 2008
http://en.wikipedia.org/wiki/Moons_of_Jupiter
c.f. First 3 Galileans satellites of Jupiters 1:2: 4
A scenario for HD 40307 formation (Lin, Zhou et al. In Prep) :
Stop of type I migration
0 10 20 30 40 500
1000
2000
3000
4000
5000
6000
period (days)
(
g c
m-2)
The scenario:
1、planets were formed ~AU and
migrated inward
2、trapped in 1:2:4 one by one
3、tidal interactions with star
gradually dive them out of MMRs
Results: C1=0.3
C1=1
2:3:6
4:6:9
Different type-I speed
Tidal evolution
1、the final position error < 1.5%。
2、requirement : Q’p≤2000
C1 ~ 0.1
Tidal circulation
Compare with simulation
(1)Inner disk boundary (3-5 days)
(2)MRI A/D boundary (30-50 days)
(3)Snow line (2-3 AU)
OBS SIM
Liu,Zhou,Wang 2010
Aim 2- Planet physics
• Composition.
• Planetary atmosphere.
• Tidal factor Q.
• etc..
GJ 876 d
Zhou & Lin
2009
Aim-4 detect habitable planets around M-dwarf
1. Occurrence Rate of Giant Planets > 6-7%
Program Sample
No.
% stars with hot
Jupiters
% stars with giant planets Ref.
CORALIE 1120
0.8%
(>0.2MJ)(FGK)
>5.6%(<4AU)
Udry &
Santos 2007
Lick+Keck
+AAT
1330 1.2+/- 0.3%
(FGK)
>6.6%(<5AU,M<13MJ) Marcy et al.
2005
Aim 5 – more samples
2. Planet-host star tends to have high metellicity (Fischer & Valenti 2005)
Marcy et al. 2005
3. Correlation between stellar mass and occurrence of Jovian planets within 2.5AU
Johnson et al. 2007
1.8%(1.0%)
4.2%(0.7.0%)
8.9%(2.9%)
O B A F G K M M K G F A
subgiants
http://www.kepler.arc.nasa.gov/
KEPLER (2007)
COROT (2006)
http://smsc.cnes.fr/COROT/
Major Transit Missions
COROT (2007,CNES) (Convection Rotation and planetary Transits)
FOV= 2.8 x 2.8°, seismology +exoplanet, 6,000stars, > 2.5 years
KEPLER(2009,NASA), 4 years,10^5 stars, 50 terrestrial planets
Spactral band: 400nm -850nm, Earth of a MV=12 G2V star 4 sigma in 6.5h
Observed transiting planets
slop=
3
AST3
• From the revised Hipparcos catalogue
• Reference: ICRS (J2000.0) Epoch: J1991.25
• area:Dec<-35^o,with > 45^o of sky height
• ~ 30068
• distance:1.255pc-100kpc
• brightness:-0.5536mag - 13.767mag
Enough stars to be observed..
Main sequence stars: ~62%
O B A F G K M
~ 30068
Possible high i KBOs?
Also comes, Centaurs. Etc..
They are dark, cold, suitable in
optical or infrared bands.
They are some windows near South
pole.
Summary
• By transiting we can detect planets in close-
in orbits, which helps understanding the
physics of the planets, the disk, etc.
• AST3 have the potential to give more
transiting planets, possibly habitable planets
around M dwarfs.
Thank You!