Search for (sub)stellar companions of exoplanet hosts by exploring the second ESA-Gaia data release

TL;DR

This study investigates the multiplicity of 289 exoplanet host stars within 500 pc using Gaia DR2 data, identifying 61 companions and revealing a 16% multiplicity rate among these systems.

Contribution

It provides the first comprehensive multiplicity survey of exoplanet hosts using Gaia DR2, detecting new stellar and substellar companions and analyzing their properties.

Findings

Detected 61 companions around 289 exoplanet hosts.

Found a multiplicity rate of approximately 16%.

Companions range from brown dwarfs to stars up to 1.66 M$_\odot$.

Abstract

We present the latest results of an ongoing multiplicity survey of exoplanet hosts, which was initiated at the Astrophysical Institute and University Observatory Jena, using data from the second data release of the ESA-Gaia mission. In this study the multiplicity of 289 targets was investigated, all located within a distance of about 500 pc from the Sun. In total, 41 binary, and 5 hierarchical triple star systems with exoplanets were detected in the course of this project, yielding a multiplicity rate of the exoplanet hosts of about 16 %. A total of 61 companions (47 stars, a white dwarf, and 13 brown dwarfs) were detected around the targets, whose equidistance and common proper motion with the exoplanet hosts were proven with their precise Gaia DR2 astrometry, which also agrees with the gravitational stability of most of these systems. The detected companions exhibit masses from about 0.016 up to 1.66 M$_\odot$ and projected separations in the range between about 52 and 9555 au.