Revisiting the transits of CoRoT-7b at a lower activity level

Abstract

CoRoT-7b, the first super-Earth with measured radius discovered, has opened the new field of rocky exoplanets characterisation. To better understand this interesting system, new observations were taken with the CoRoT satellite. During this run 90 new transits were obtained in the imagette mode. These were analysed together with the previous 151 transits obtained in the discovery run and HARPS radial velocity observations to derive accurate system parameters. A difference is found in the posterior probability distribution of the transit parameters between the previous CoRoT run (LRa01) and the new run (LRa06). We propose this is due to an extra noise component in the previous CoRoT run suspected to be transit spot occultation events. These lead to the mean transit shape becoming V-shaped. We show that the extra noise component is dominant at low stellar flux levels and reject these transits in the final analysis. We obtained a planetary radius, $R_p=1.585\pm 0.064R_{\oplus }$, in agreement with previous estimates. Combining the planetary radius with the new mass estimates results in a planetary density of $1.19\pm 0.27{\rho }_{\oplus }$ which is consistent with a rocky composition. The CoRoT-7 system remains an excellent test bed for the effects of activity in the derivation of planetary parameters in the shallow transit regime.

13 pages, 13 figures, accepted to A&A

References in corpus (15)

• The Dartmouth Stellar Evolution Database
• DHP Framework: Digital Health Passports Using Blockchain -- Use case on international tourism during the COVID-19 pandemic
• Planets and Stellar Activity: Hide and Seek in the CoRoT-7 system
• Efficient identification of exoplanetary transit candidates from SuperWASP light curves
• Improving Stellar and Planetary Parameters of Transiting Planet Systems: The Case of TrES-2
• The Transit Light Curve Project. IX. Evidence for a Smaller Radius of the Exoplanet XO-3b
• PASTIS: Bayesian extrasolar planet validation. I. General framework, models, and performance
• The Photoeccentric Effect and Proto-Hot Jupiters I. Measuring photometric eccentricities of individual transiting planets
• The effect of stellar limb darkening values on the accuracy of the planet radii derived from photometric transit observations
• Characterizing the Orbital Eccentricities of Transiting Extrasolar Planets with Photometric Observations
• Could we identify hot Ocean-Planets with CoRoT, Kepler and Doppler velocimetry?
• Using Stellar Densities to Evaluate Transiting Exoplanetary Candidates
• ULTRACAM Photometry of the ultracompact binaries V407 Vul and HM Cnc
• Constraining physics of very hot super-Earths with the James Webb Telescope. The case of Corot-7b
• Searching for the secondary eclipse of CoRoT-Exo-2b and its transit timing variations

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