number of eclipsing binaries vs. transiting planets: preparation of follow-up observations tristan...
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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
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