c r t-7 b

C R T-7 bThe first transiting Super-Earth fully characterized inRadius & Mass (CoRoT+Harps)D. Rouan, A. Lger, J. Schneider, P. Barge, M. Fridlund, B. Samuel,and all the Corot Exoplanet Science Team ,ca bonus : a system of 2 Super-Earths

Pathways Towards Habitable Planets- Barcelonia - Sep 09

Short period planets: the small component 2006: first Super Earth detected with gravitational lensingBeaulieu et al. Nature 06Recent results from radial velocity point to a very significant population of Super-Earth: e.g.9.3 M Howard et al. 097.5 M Bouchy et al. 091.9 15.6 M Mayor et al. 09Today 32 planet w M < 0.1 MJupSize needed ! to derive the structure One major goal of CoRoTdetect transits of Super-Earthperformances allow itAnd indeed a first case !


The star CoRoT-7 Spectra UVES, HARPSParameters :G9V star - mV = 11.7Teff = 5250 KDistance = 130 pc 30 age 1.2 GyrVery active : emission feature in H and K Ca lines, 2% variability ! Spots clearly seen crossing the disk because of rotation rotation period = 23 days


The folded light curve0.033% ! Transits first detected by alarm mode 153 transits, all ~ seen when superimposed Extremely short period : P= 0.8536 days transit depth : F/F = 0.033%


A small planet ? The ennemy : the false positive ! produces a signal that mimics a transiting planet Grazing Eclipsing Binary

Eclipsing Binary in a dwarf/giant system

Eclipsing Binary or transiting giant planet in a triple system FOLLOW-UP IS MANDATORY !A big effort of the whole team


Follow-up : spectroscopy and imagingUVES and HARPS spectrano blend, K0V star exclude a dwarf/giant binary system ON/OFF photometry of neighboursNO mag > alarm exclude BEB at > 4Adaptive Optics + Angular Differential ImageNo BEB between 0.4 and 4 IR spectra with CRIRES-VLT:No late K or M earlier than M5VROSAT all sky surveyNo very close X binary (e.g. similar to YY Gem)


CoRoT colorsTriple system with a Jupiter transiting a second star ?CoRoT Colors : 3 Light CurvesBlue, Green, Redtransit is achromatic !Eliminate a triple system because star_2, and thus the transit signal, would be red


Follow-up: Radial Velocity with SOPHIEVelocimetry with SOPHIE2 points exclude a planet of mass > 21 M with 95% confidenceNO grazing Jupiter or white dwarf (exluded by timing anyway)corot-7b


All known cases of false positives practically eliminated with a high level of confidence(risk of a background blend = 8 10-4)

The transit should be due to a Super Earth planet of radius 1.7 R on a very close orbit with a fairly high probabilityLger, Rouan, Schneider et al., A&A, in press & Xarch


Today, The Plus : RV with HARPSHARPS Velocimetry (Queloz, Bouchy, Moutou, Hatzes et al. A&A in press) : 106 measurements (70h) during 4 months Difficulty : strong variablity of corot-7 affects the CCF bissector and FWHM correlates with photometryactivity : CaII S indexobvious correlation w rotation (23 days)Scargle analysis after filtering of rotation (3 harmonics) first peaks : 3.7 dayssubstracted : peak at 0.85 daysPhase of 0.85 d peak agrees w transit Clear confirmation of Corot-7b And a second planet !corot-7ccorot-7bpress release NOW


Follow-up : Radial Velocity with HARPS (2)Finally a two Super-Earth solution is found First case of a system with 2 Super-Earths, one in transit Corot-7b4.8 0.8 MP = 0.853 daysa = 0.017 AUR = 1.68 0.1 R Corot-7c8.4 0.9 MP = 3.70 daysa = 0.046 AU


Nature of Corot-7b ?First solid evidence for a rocky planet !A lot of exciting physics (Lger et al. in prep). For instance : Tidal forces :Phase-locked (tsynch< 100 yrs)Elongation under tidal forces < 150 kmTidal heating efficient if e 0Temperaturedark side : 50Kpretty cold !geothermal origindayside :1800-2600 K : pretty hot !no heat redistribution by atmosphere or groundThus a temperate region of 90 km width (270-370 K)life is however not possible : no water !


Nature of Corot-7b ?StructureFirst time density of a SE measured 5.6 g cm-3 (~Earth) rockylikely silicates mantle compatible w 20% of watershould have migratecore of Neptune or rocky telluric surface : ocean of liquid rock up to z = 50refractory oxydes: CaO, Al2O3continent or frost H2O, CO2 elsewhere Atmosphere escape of all volatiles in 0.1 to 1 Gyr composition : vaporised silicates tenuous : P = 5-0.05 10-5 bar


Corot-7b : a planet of mass and size cousin of Earth, around a star cousin of our Sun : a clear milestone on the pathway we are exploring at this conference Cabello perseguido por dos planetas (1968) Hair pursued by two planetsTwo planets pursued by astronomersJoan MirThanks extended to the whole CoRoT team and to the HARPS team


C R T-exo-7b


Planet characteristicsPeriod: P = 0.8536 d (one year = 20.5 h) a = 0.017 AU = 2.8 RA sun of 28 in the sky !


Planet characteristics

Rpl / R = 0.020 Rpl = 1.70 XX R


c r t-7 b

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