Abstract
ABSTRACT Eclipsing binary stars are rare and extremely valuable astrophysical laboratories that make possible precise determination of fundamental stellar parameters. Investigation of early-type chemically peculiar stars in eclipsing binaries provides important information for understanding the origin and evolutionary context of their anomalous surface chemistry. In this study, we discuss observations of eclipse variability in six mercury–manganese (HgMn) stars monitored by the Transiting Exoplanet Survey Satellite (TESS) satellite. These discoveries double the number of known eclipsing HgMn stars and yield several interesting objects requiring further study. In particular, we confirm eclipses in HD 72208, thereby establishing this object as the longest-period eclipsing HgMn star. Among five other eclipsing binaries, reported here for the first time, HD 36892 and HD 53004 stand out as eccentric systems showing heartbeat variability in addition to eclipses. The latter object has the highest eccentricity among eclipsing HgMn stars and also exhibits tidally induced oscillations. Finally, we find evidence that HD 55776 may be orbited by a white dwarf companion.
Highlights
Mercury–manganese (HgMn) stars are late-B main-sequence objects distinguished by overabundance of heavy elements, slow rotation, and lack of strong magnetic fields
We reported observation of eclipses in six binaries with HgMn components
This doubles the number of such chemically peculiar stars known in Eclipsing binaries (EBs)
Summary
Mercury–manganese (HgMn) stars are late-B main-sequence objects distinguished by overabundance of heavy elements, slow rotation, and lack of strong magnetic fields. These stars exhibit some of the most extreme departures from the solar abundance pattern and relative isotope composition of heavy elements HgMn stars are frequent members of close binaries (Gerbaldi, Floquet & Hauck 1985). These systems are important objects for constraining the origin and long-term evolution of chemical peculiarities. Eclipses in two more spectroscopic binaries with HgMn primaries, HD 72208 and HD 161701, suspected based on lowquality photometric measurements by the STEREO satellite (Wraight et al 2011), are yet to be confirmed by independent observations
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