Received 1 July 2020; Revised 29 August 2020; Accepted 18 September 2020 DOI: xxx/xxxx ARTICLE TYPE Gaia Search for stellar Companions of TESS Objects of Interest M. Mugrauer* | K.-U. Michel 1Astrophysikalisches Institut und Universitäts-Sternwarte Jena The first results of a new survey are reported, which explores the 2nd data release Correspondence of the ESA-Gaia mission, in order to search for stellar companions of (Community) M. Mugrauer, Astrophysikalisches Institut und Universitäts-Sternwarte Jena, TESS Objects of Interest and to characterize their properties. In total, 193 binary and Schillergäßchen 2, D-07745 Jena, Germany. 15 hierarchical triple star systems are presented, detected among 1391 target stars, Email:
[email protected] which are located at distances closer than about 500 pc around the Sun. The com- panions and the targets are equidistant and share a common proper motion, as it is expected for gravitationally bound stellar systems, proven with their accurate Gaia astrometry. The companions exhibit masses in the range between about 0.08 M⊙ and 3 M⊙ and are most frequently found in the mass range between 0.13 and 0.6 M⊙. The companions are separated from the targets by about 40 up to 9900 au, and their frequency continually decreases with increasing separation. While most of the detected companions are late K to mid M dwarfs, also 5 white dwarf companions were identified in this survey, whose true nature is revealed by their photometric properties. KEYWORDS: binaries: visual, white dwarfs, stars: individual (TOI 249 C, TOI 1259 B, TOI 1624 B, TOI 1703 B, CTOI 53309262 B) 1 INTRODUCTION explored the 2nd data release of the European Space Agency (ESA) Gaia mission (Gaia DR2 from hereon, Gaia Collabora- A key aspect in the diversity of exoplanets is the multiplicity tion, Brown, Vallenari, et al., 2018), which provides manifold of their host stars.