Determining Which Binary Component Hosts the TESS Transiting Planet

TL;DR

This study uses transit light curve analysis and high-resolution imaging to identify the host stars of TESS-discovered planets in binary systems, finding most orbit primary stars.

Contribution

It introduces a method combining transit shape and flux ratio data to determine the host star in binary systems, improving planet characterization accuracy.

Findings

70% of planets orbit primary stars

Method effectively distinguishes host stars in binaries

Enhances accuracy of planetary property measurements

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.