A hard and variable X-ray emission from the massive emission line star HD 157832
Abstract
We report the discovery of a hard-thermal (T ~ 130 MK) and variable X-ray emission from the Be star HD 157832, a new member of the puzzling class of gamma-Cas-like Be/X-ray systems. Recent optical spectroscopy reveals the presence of a large/dense circumstellar disc seen at intermediate/high inclination. With a B1.5V spectral type, HD 157832 is the coolest gamma-Cas analog known. In addition, its non detection in the ROSAT all-sky survey shows that its average soft X-ray luminosity varied by a factor larger than ~ 3 over a time interval of 14 yr. These two remarkable features, ``low'' effective temperature and likely high X-ray variability turn HD 157832 into a promising object for understanding the origin of the unusually high temperature X-ray emission in these systems.
Keywords
Cite
@article{arxiv.1102.4625,
title = {A hard and variable X-ray emission from the massive emission line star HD 157832},
author = {Raimundo Lopes de Oliveira and Christian Motch},
journal= {arXiv preprint arXiv:1102.4625},
year = {2015}
}
Comments
Accepted for publication in ApJL; 10 pages, 3 figures, 1 table