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Detection of transits of extrasolar planets with the GAIA new design Noël Robichon DASGAL - CNRS UMR 6633 depth of a transit m ≈ F/F = (RP/R*)2 QuickTime™ et un décompresseur GIF sont requis pour visualiser cette image. REarth = 0.1 RJup = 0.01 RSun Earth : m=10-4 Jupiter : m=10-2 HD 209458 : m=1.7 10-2 sG > 10-3 only Jupiter size objects with GAIA duration of a transit a Vcirc = 2pa/P Dt = 2R*/Vcirc 2R* ( if RP<<R* ) to the observer Dt/P = R*/pa = R*/pM*1/3P2/3 Earth : P = 1 yr Dt/P = 1.5 10-3 Jupiter : P = 11.3 yr Dt/P = 1.3 10-4 HD 209458 : P = 3.5 days Dt/P = 3.2 10-2 GAIA : # of observations 150-300 P < 10 days geometric probability of observation star 2R* planet a q cone of transit visibility pgeo=p(q<2R*/a)=2sin(R*/2a) pgeo=R*/a=R*/M*1/3P2/3 (if RP<<R*) Earth pgeo = 5 10-3 Jupiter pgeo = 4 10-4 HD 209458 pgeo = 0.1 in favor of very short periods Simulations • mass-MV and mass-radius relations from litterature • photometric error sG(G) • RP=1RJup or 1.3 RJup Monte Carlo simulation in bins of (b, G, MV, P) • Galaxy model (Haywood) N*(b, G, MV) • scanning law of the satellite PNobs/transit(b, N) • probability of having an observable transit star Pobs (P, MV) = Pgeo(MV, P) x 0.01 log(P+/P-)/log(10) • probability of detecting the transit Pdetec(N, G, MV) less than 10 % of false detection and N>5 or 7 (3 or 4 ≠ epochs) Number of transited stars if RP = 1.3 RJup Npts/transits>max(5, N(#false/#true<10%)) # of stars with transiting planet 10 4 1000 MG bins 4 5 6 7 8 9 10 >11 100 10 1 2 4 6 8 Period 10 12 14 16 TOTAL: 29000 stars Number of transited stars if RP = 1.0 RJup Npts/transits>max(5, N(#false/#true<10%)) # of stars with transiting planet 10 4 1000 MG bins 4 5 6 7 8 9 10 >11 100 10 1 2 4 6 8 Period 10 12 14 16 TOTAL: 10300 stars Number of transited stars as a function of G RP = 1.3 RJup Npts/transits>max(5, N(#false/#true<10%)) # of stars with transiting planet 10 4 MG bins 1000 4 5 6 7 8 9 10 >11 100 10 1 13 14 15 16 G 17 18 19 20 Summary of the results from simulations RP = 1.0 RJup Npts/transit>5 10300 RP = 1.3 RJup Npts/transit>5 29000 RP = 1.0 RJup Npts/transit>7 5800 RP = 1.3 RJup Npts/transit>7 15500 Conclusions • simulation predict 5.103 to 30.103 detectable transits things to improve: • countings of the Galaxy model -> less transited stars • better limits in G and MV -> more transited stars • better precision in AF photometry -> more transited stars • take account of variable stars: spots, grazing eclipsing binaries... • detection algorithm • recovering unbiased planet distribution = f(P, MP, M*…) unknowns: • statistics: % of HJ = f(ST)? • properties of planets: radii? Pmin?… Photometric precision sF/F = (RON2+SKY+F)1/2/F 0,1 sG per AF CCD sG per AF transit (9 CCDs) smag per MBP transit (sum of 10 bands + MSM) G2 star RP=1.3 RJup 0,01 smag G2 star RP=1 RJup 0.001 mag has been quadratically added in the simulation 0,001 0,0001 8 10 12 14 16 G 18 20 22 -0,01 -0,01 -0,005 -0,005 0 0 -0.000572226 -0.000572226 Simulation of HD 209458 for two different TC 0,005 0,005 0,01 0,01 0,015 0,015 0,02 0,02 0 0,2 0,4 0,6 0.802909 0,8 1 0 0,2 0,4 0,6 0.802909 0,8 1 distribution of number of points during a transit 25 P=10.25 days (dt/P = 1.7%) b = +5° (170 points) 20 percentage 15 P=3 days (dt/P = 3%) b = +35° (280 points) 10 5 0 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 # of points distribution of periods of known systems # of stars with planet 20 4 % of stars have an planetary system 15 1 % have a planet with P < 30 days 10 minimum period observed: 3 days 5 0 0,5 1 1,5 2 2,5 log P (days) 3 probability of having N points greater than ps 1 p=1.5 0,01 0,0001 p=2 10 -6 10 -8 p=3 p=2.5 10 -10 0 5 10 N 15 20