Title:
HD66051, an eclipsing binary hosting a highly peculiar, HgMn-related
star

Author: Ewa Niemczura, Astronomical Institute, University of Wroclaw, Poland

Abstract:
HD66051 is an eclipsing system with an orbital period of about 4.75d
that exhibits out-of-eclipse variability with the same period. New
multicolour photometric observations confirm the longevity of the
secondary variations, which we interpret as a signature of surface
inhomogeneities on one of the components. Using archival and newly
acquired high-resolution spectra, we have performed a detailed abundance
analysis. The primary component is a slowly rotating late B-type star
with a highly peculiar composition reminiscent of the singular
HgMn-related star HD65949, which seems to be its closest analogue. Some
light elements as He, C, Mg, Al are depleted, while Si and P are
enhanced. Except for Ni, all the iron-group elements, as well as most of
the heavy elements, and in particular the REE elements, are
overabundant. The secondary component was estimated to be a slowly
rotating A-type star. The unique configuration of HD66051 opens up
intriguing possibilities for future research, which might eventually and
significantly contribute to the understanding of such diverse phenomena
as atmospheric structure, mass transfer, magnetic fields, photometric
variability and the origin of chemical anomalies observed in HgMn stars
and related objects.