Prof Suzanne Aigrain

Abstract:

We measure the angle between the planetary orbit and the stellar rotation axis in the transiting planetary system CoRoT-1, with new HIRES/Keck and FORS/VLT high-accuracy photometry. The data indicate a highly tilted system, with a projected spin-orbit angle λ = 77° ± 11°. Systematic uncertainties in the radial velocity data could cause the actual errors to be larger by an unknown amount, and this result needs to be confirmed with further high-accuracy spectroscopic transit measurements. Spin-orbit alignment has now been measured in a dozen extra-solar planetary systems, and several show strong misalignment. The first three misaligned planets were all much more massive than Jupiter and followed eccentric orbits. CoRoT-1, however, is a jovian-mass close-in planet on a circular orbit. If its strong misalignment is confirmed, it would break this pattern. The high occurrence of misaligned systems for several types of planets and orbits favours planet-planet scattering as a mechanism to bring gas giants on very close orbits. © 2009 The Authors. Journal compilation © 2009 RAS.

Abstract:

Context. The space telescope CoRoT searches for transiting extrasolar planets by continuously monitoring the optical flux of thousands of stars in several fields of view. Aims. We report the discovery of CoRoT-10b, a giant planet on a highly eccentric orbit (e = 0.53 ± 0.04) revolving in 13.24 days around a faint (V = 15.22) metal-rich K1V star. Methods. We used CoRoT photometry, radial velocity observations taken with the HARPS spectrograph, and UVES spectra of the parent star to derive the orbital, stellar, and planetary parameters. Results. We derive a radius of the planet of 0.97 ± 0.07 RJup and a mass of 2.75 ± 0.16 MJup. The bulk density, ρp = 3.70 ± 0.83 g cm-3, is ∼2.8 that of Jupiter. The core of CoRoT-10b could contain up to 240 M⊕ of heavy elements. Moving along its eccentric orbit, the planet experiences a 10.6-fold variation in insolation. Owing to the long circularisation time, τcirc > 7 Gyr, a resonant perturber is not required to excite and maintain the high eccentricity of CoRoT-10b. © 2010 ESO.