Number of eclipsing binaries Number of eclipsing binaries vs. transiting planets:vs. transiting planets:

preparation of follow-uppreparation of follow-up observations observations

Tristan Guillot (OCA), Frédéric Pont, Maxime Marmier, Didier Queloz (Obs.

Genève)

& A. Garnier, F. Fressin, E. Matter, P. Mathias (OCA), M. Vannier (ESO), S. Aigrain (Cambridge),

C. Moutou (LAM), M. Auvergne (LESIA)

25/05/2005 CoRoTWeek8 2

MotivationsMotivations

• Background eclipsing binaries (BEBs) represent a major source of confusion for planet detection– This is especially the case when looking for small planets (~10-3

luminosity drop)• We need numbers!

– # of expected transiting planets– # of expected BEBs– Fraction of BEBs that can be discriminated directly from a

lightcurve analysis (including the “color” information)– For the others, what are the observations that are most

appropriate• We need test cases!

– List of events (with all the stars in the mask)– Realistic lightcurves with instrument noise

25/05/2005 CoRoTWeek8 3

# events towards the gal. # events towards the gal. centercenter

backgroundeclipsing binaries

backgroundplanets

targetplanets

targetbinaries

About 130 BeB

1 CCD only

25/05/2005 CoRoTWeek8 4

COROTlux: PrincipleCOROTlux: Principle

Create a synthetic stellar field

Add double, triple stars

Add planetary companions

Create COROT masks

Determine contributions to each mask

For each mask, calculate 150 days lightcurve including:-Eclipses & transits-Stellar variability-Photon & instrumental noiseswww.obs-nice.fr/guillot/corotluxwww.obs-nice.fr/guillot/corotlux

25/05/2005 CoRoTWeek8 5

Ingredient 1: the stellar fieldIngredient 1: the stellar field• Presently: randomly generated

– Magnitude counts based on the Besançon model (BM) and direct observations

– Mass-radius-luminosity relations:• Previously used MS relations• Now based on fits from a corrected BM

• Present calculations underestimate the crowding, overestimate the # of target stars / CCD– Giant stars are not included– Fields are much more homogeneous than in reality

• Future improvements:– Direct use of the star list generated by the BM

• Work in progress (E. Matar & P. Mathias)

– Use real observations• (e.g. data from M. Deleuil, C. Moutou, H. Deeg)

25/05/2005 CoRoTWeek8 6

Ingredient 2: binaries & Ingredient 2: binaries & ternariesternaries

• Presently: based on Duquennoy & Mayor (1991)– Distribution of orbits– Distribution of mass ratios

• Are the # of BeBs sensitive to these hypotheses?– Yes!

• Future improvements:– Test using the OGLE data

• (Work by F. Pont)– After launch: Use COROT data to check the models

25/05/2005 CoRoTWeek8 7

Ingredient 3: the planetsIngredient 3: the planets• Mass-radius relations:

– Quite uncertain:• Can be fitted to the presently known transiting planets• but depends on the presence of a core & its mass, & on tidal, atmospheric effects

– This is an essential result to be obtained from COROT• Distributions of orbits & masses:

– 1st possibility: • use known radial velocity surveys results• hence, consider only massive planets (Saturn mass)

– 2nd possibility:• Known RV planets for large masses+ a large # of Uranus-sized planets (-Ara

like)• Distribution of mass ratios

– 3rd possibility:• Use theoretical predictions• e.g. Ida & Lin (2003)

25/05/2005 CoRoTWeek8 8

Outcome: a list of eventsOutcome: a list of events• What should be relatively accurate:

– # of planets of the mass of Saturn and above– # of eclipsing binaries

• What we don’t know:– # of small planets (below Saturn’s mass)

• A list of events in the mask– Physical parameters to be included:

• Position and shape of the mask in the CCD• For all stars with ∆m5 to 10:

– their position in the mask (or outside)– their magnitude– their color– their binarity

• Position within the mask– Needs to be combined to realistic instrumental noise – Test detection algorithms

25/05/2005 CoRoTWeek8 9

A possible pipeline for preparatory follow-up A possible pipeline for preparatory follow-up workwork

Preparatory observations of COROT fields

(LAM, IAC...)

Distributions of radii, BeBs, planetary transits...etc from known surveys

(Geneva/ESA, OCA...)

List of expected events (BeBs, transits...)

(OCA, Geneva/ESA...)

Add stellar noises

(Cambridge, Italy)

Add instrumental noises

(LAM, LESIA)

List of lightcurves

(LAM)Test detection algorithms

(LAM, Geneva/ESA, Cambridge, DLR, IAS, IAC, OCA...)

Prepare follow-up observations

(LAM, Geneva/ESA, Cambridge, DLR, IAS, IAC, OCA...)

Super Earth

Sub-giants

Giants

backgroundeclipsing binaries

targetplanets

Fiducial case for binary distribution + Ida-Lin planet Fiducial case for binary distribution + Ida-Lin planet distributiondistribution

backgroundeclipsing binaries

targetplanets

Pure gaussian binary distribution + RV planet distributionPure gaussian binary distribution + RV planet distribution