氦白矮星与小质量主序星并合及脉动热亚矮星的形成

Helium White Dwarf-main Sequence Star Merger and Formation of Pulsating Hot Subdwarf Stars

sdBVrs型热亚矮星是一类特殊的热亚矮星,观测显示它们同时具有p模和g模的脉动.目前这一类热亚矮星的演化起源仍然缺乏完备的解释.对氦白矮星与小质量主序星并合模型进行详细计算表明,并合模型的结果符合sdBVrs型热亚矮星的表面有效温度、重力加速度等观测特征,并且能够激发出稳定的p模和g模脉动.因此,氦白矮星与小质量主序星并合是形成sdBVrs型热亚矮星可能的渠道之一.

sdBVrs is a particular type of hot subdwarfs which have both p-mode and g-mode pulsations. It is unclear of the formation channel of such hot subdwarfs stars. The merger of a He core white dwarf(HeWD) with a main sequence(MS) star can produce a hot subdwarf. We propose that sdBVrs may form from this channel. We compute the models of the remnants of some of these mergers, and perform detailed stability analysis. By comparing to observations, the evolutionary tracks of the remnants of mergers can match with the sdBVrs in surface gravity-effective temperature diagram.These models also have both p-mode and g-mode pulsations been excited. Our result indicates that the merger of a HeWD with a MS star might be one of the formation channels of sd BVrsstars.