A Method to Identify and Characterize Binary Candidates—A Study of CoRoT Data

Abstract

The analysis of the CoRoT space mission data was performed aiming to test a method that selects, among the several light curves observed, the transiting systems that likely host a low-mass star orbiting the main target. The method identifies stellar companions by fitting a model to the observed transits. Applying this model, which uses equations such as Kepler’s third law and an empirical mass-radius relation, it is possible to estimate the mass and radius of the primary and secondary objects, as well as the semimajor axis and inclination angle of the orbit. We focus on how the method can be used in the characterization of transiting systems having a low-mass stellar companion with no need to be monitored with radial-velocity measurements or ground-based photometric observations. The model, which provides a good estimate of the system parameters, is also useful as a complementary approach to select possible planetary candidates. A list of confirmed binaries is presented, together with our estimate of their parameters. The characterization of the first 12 detected CoRoT exoplanetary systems was also performed and agrees very well with the results of their respective announcement articles. The comparison with confirmed systems validates our method, especially when the radius of the secondary companion is smaller than 1.5 R_Jup, in the case of planets, or larger than 2 R_Jup, in the case of low-mass stars. Intermediate situations are not conclusive.

The CoRoT space mission, launched on 2006 December 27, was developed and is operated by the CNES, with participation of the Science Programs of ESA, ESA’s RSSD, Austria, Belgium, Brazil, Germany, and Spain.