The close binary fraction of He-rich hot subdwarfs from SALT and TESS

Abstract

The Southern African Large Telescope (SALT) survey of He-rich hot subdwarfs has identi-fied several binary candidates from variable or anomalous radial velocities, or unusually high rotational velocities. Many SALT survey objects have also been observed by the Transiting Exoplanet Survey Satellite (TESS). TESS light curves provide orbital periods and can also give clues about the nature of binary systems by distinguishing ellipsoidal variations from reflection effects. We present a summary of the candidate binary fraction within the SALT survey, as well as a breakdown of the identified candidates by spectral and helium class.