084031

gamma Cas stars are Oe-Be stars that display an intriguing bright and hard X-ray emission. The origin of this X-ray emission could be either accretion by a compact companion or an interaction between the Be star and its decretion disk. Evidence favouring the latter scenario was obtained over recent years. This includes observations of a quasi-simultaneous decrease by a factor 10 of the X-ray emission of HD45314 as the disk of this star nearly dissipated in 2016. We aim at further constraining the gamma Cas phenomenon by taking advantage of such spectacular variations. For this purpose comma we propose observing a gamma Cas star next time that its disk undergoes either an outburst or in case it clears away.

仙后座γ型星（gamma Cas stars）属于Oe型Be星（Oe-Be stars），该类天体展现出引人关注的明亮硬X射线辐射。此类X射线辐射的起源主要有两种假说：一是致密伴星的吸积作用，二是Be星与其抛射盘（decretion disk）之间的相互作用。近年来已有观测证据支持后一种假说，其中包括2016年对HD45314的观测结果：当该星的抛射盘几乎完全消散时，其X射线辐射出现了准同时性的一个数量级衰减。本研究旨在借助这类显著的辐射变化，进一步明确仙后座γ型星现象的物理机制。为此，我们提议在仙后座γ型星的抛射盘出现爆发或彻底消散时，对其开展观测。