A hard and variable X-ray emission from the massive emission line star HD 157832

Дата и время публикации : 2011-02-22T21:16:30Z

Авторы публикации и институты :
Raimundo Lopes de Oliveira (Universidade de São Paulo, IFSC/USP, Brazil)
Christian Motch (Observatoire Astronomique de Strasbourg, France)

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: Accepted for publication in ApJL; 10 pages, 3 figures, 1 table
Первичная категория: astro-ph.SR

Все категории : astro-ph.SR

Краткий обзор статьи: 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.

Category: Physics