The {\it TESS} periodograms of the SALT survey catalogue of hydrogen-deficient stars were searched for evidence of short-period variability. Periodic light curve variations were identified in 16 stars out of 153 catalogue objects, of which 10 were false positives. From the remaining 6 identified variables, Ton S 415 is a known close binary system and the sixth close binary containing a hydrogen-deficient hot subdwarf. Radial velocity and SED analyses ruled out the remaining 5 as close binary systems; the causes of their variability remain uncertain. With one or more K-type companions, BPS CS 22956-0094 may be a wide binary or triple. From this SALT+{\it TESS} sample, the fraction of close binaries stands at 1/29≈3.5% for intermediate helium hot subdwarfs and 0/124=0% for extreme helium subdwarfs.
@article{arxiv.2501.13656,
title = {A search for close binary systems in the SALT survey of hydrogen-deficient stars using {\it TESS}},
author = {E. J. Snowdon and C. S. Jeffery and S. Schlagenhauf and M. Dorsch},
journal= {arXiv preprint arXiv:2501.13656},
year = {2025}
}