Determining Which Binary Component Hosts the TESS Transiting Planet

Abstract

The NASA TESS mission has discovered many transiting planets orbiting bright nearby stars, and high-resolution imaging studies have revealed that a number of these exoplanet hosts reside in binary or multiple star systems. In such systems, transit observations alone cannot determine which star in the binary system actually hosts the orbiting planet. The knowledge of which star the planet orbits is necessary for determining accurate physical properties for the planet, especially its true radius and mean bulk density. We derived the mean stellar densities for the components of 23 binary systems using the light curve transit shape and the binary flux ratio from speckle imaging, then tested the consistency with stellar models to determine which component is the host star. We found that 70% of the TESS transiting planets in our sample orbit the primary star.

Confirmation of a Sub-Saturn-size Transiting Exoplanet Orbiting a G Dwarf: TOI-1194 b and a Very Low Mass Companion Star: TOI-1251 B from TESS

“…Apart from the EBs mentioned in Section 1, the eclipses of nearby EBs are usually responsible for the high FP probability in exoplanet surveys as well. Approximately half of all discovered planets orbit stars with stellar companions (Howell et al 2021; Lester et al 2021a). However, follow-up photometric data and Gaia DR3 catalogs alone are not sufficient to distinguish such companions in regions between 10 and 100 au around the host stars.…”