Doppler tomography of transiting exoplanets: A prograde, low-inclined orbit for the hot Jupiter CoRoT-11b

TL;DR

This study uses Doppler tomography to analyze the transiting hot Jupiter CoRoT-11b, revealing a nearly aligned, low-inclined orbit and providing insights into its tidal evolution and migration history.

Contribution

First Doppler shadow detection of CoRoT-11b showing a prograde, low-inclined orbit with detailed tidal evolution analysis.

Findings

Measured sky-projected obliquity of 0.1 +/- 2.6 degrees.

Indicates a primordial low obliquity consistent with inward migration.

Contradicts the trend of high obliquity in hot Jupiters around hot, massive stars.

Abstract

We report the detection of the Doppler shadow of the transiting hot Jupiter CoRoT-11b. Our analysis is based on line-profile tomography of time-series, Keck/HIRES high-resolution spectra acquired during the transit of the planet. We measured a sky-projected, spin-orbit angle of 0.1 +/- 2.6 degrees, which is consistent with a very low-inclined orbit with respect to the stellar rotation axis. We refined the physical parameters of the system using a Markov chain Monte Carlo simultaneous fitting of the available photometric and spectroscopic data. An analysis of the tidal evolution of the system shows how the currently measured obliquity and its uncertainty translate into an initial absolute value of less than about 10 degrees on the zero-age main sequence, for an expected average modified tidal quality factor of the star Q'* > 4 x 10^6. This is indicative of an inward migration scenario that would not have perturbed the primordial low obliquity of CoRoT-11b. Taking into account the effective temperature and mass of the planet host star (Teff=6440 K, M*=1.23 MSun), the system can be considered a new telling exception to the recently proposed trend, according to which relatively hot and massive stars (Teff>6250 K, M*>1.2 MSun) seem to be preferentially orbited by hot Jupiters with high obliquity.