Stellar companions of exoplanet host stars

In total, 176 binaries, 27 hierarchical triples, and one hierarchical quadruple system are detected among more than 1300 exoplanet host stars, whose multiplicity is investigated, yielding a multiplicity rate of the exoplanet host stars of at least about 15 per cent.

The detected companions and the exoplanet host stars 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 0.078 and 1.4M_{sun}_ with a peak in their mass distribution between 0.15 and 0.3M{sun}_. The companions are separated from the exoplanet host stars by about 20 up to 9100au, but are found most frequently within a projected separation of 1000au.