CoRoT-24: a new Transiting Multi-planet System

Transiting exoplanets from the CoRoT space mission: XXIV. CoRoT-24: A transiting multi-planet system

Authors:

Alonso et al

Abstract:

We present the discovery of a candidate multiply-transiting system, the first one found in the CoRoT mission. Two transit-like features with periods of 5.11 and 11.76d are detected in the CoRoT light curve, around a main sequence K1V star of r=15.1. If the features are due to transiting planets around the same star, these would correspond to objects of 3.7±0.4 and 5.0±0.5 R_earth respectively. Several radial velocities serve to provide an upper limit of 5.7 M_earth for the 5.11~d signal, and to tentatively measure a mass of 28+11−11 M_earth for the object transiting with a 11.76~d period. These measurements imply low density objects, with a significant gaseous envelope. The detailed analysis of the photometric and spectroscopic data serve to estimate the probability that the observations are caused by transiting Neptune-sized planets as >26× higher than a blend scenario involving only one transiting planet, and >900× higher than a scenario involving two blends and no planets. The radial velocities show a long term modulation that might be attributed to a 1.5 M_jup planet orbiting at 1.8~A.U. from the host, but more data are required to determine the precise orbital parameters of this companion.