Transiting exoplanets with AST3

Ji-Lin Zhou (周济林)

Nanjing University (zhoujl@nju.edu.cn)

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!