New eclipsing binaries with mercury-manganese stars

TL;DR

This paper reports the discovery of six eclipsing binary stars with mercury-manganese peculiarities, doubling the known cases, and provides detailed observations revealing unique orbital and stellar characteristics.

Contribution

It presents the first observations of several eclipsing HgMn stars, including the longest-period and most eccentric systems, expanding understanding of chemically peculiar star binaries.

Findings

Discovered six new eclipsing HgMn stars.

Confirmed eclipses in HD 72208, the longest-period HgMn eclipsing binary.

Identified heartbeat variability and potential white dwarf companion.

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 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.