Variability of HgMn stars through the eyes of TESS

Mercury-manganese (HgMn) stars exhibit distinctive chemical peculiarities marked by an overabundance of Xe, P, Mn, and various heavy elements. Unlike their magnetic counterparts found in similar regions of the HR diagram, HgMn stars lack strong surface magnetic fields. Nonetheless, a subset of these stars displays subtle rotational modulation in spectral line profiles, suggestive of evolving surface spots. This inhomogeneous surface structure yields a faint photometric rotational modulation. The advent of the TESS satellite, conducting high-precision photometric surveys across nearly the entire sky, presents unparalleled opportunities to explore the variability of HgMn stars. Such investigations can constrain the prevalence of surface spot formation and probe variability arising from other phenomena such as pulsations and binarity. In this presentation, I provide an overview of recent studies conducted on HgMn stars utilizing TESS data. Our comprehensive variability survey revealed that up to 84% of HgMn stars exhibit evidence of surface spots and doubled the known population of HgMn stars in eclipsing binaries. Moreover, intriguing instances of ellipsoidal and heartbeat variability have emerged, alongside several cases featuring multi-periodic SPB and tidally-induced pulsations in HgMn stars. Lastly, ongoing research delves into the investigation of long-term spot variability on HgMn stars, leveraging TESS light curves spanning multiple cycles.