Binary evolution pathways of blue large-amplitude pulsators
Binary evolution pathways of blue large-amplitude pulsators
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DOI：
10.1093/mnras/stab2115
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发表时间：
2021-07
影响因子：
4.8
通讯作者：
C. Byrne;E. Stanway;J. Eldridge
中科院分区：
文献类型：
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作者：
C. Byrne;E. Stanway;J. Eldridge
蓝色大幅度脉冲星(BLAPS)是最近发现的一类脉动恒星，据信是原始白矮星，由红巨星在具有小氦核心时的大量剥离产生。一个悬而未决的问题是，为什么这类脉动星中的恒星根据表面引力似乎形成了两个截然不同的群体，尽管有预测称，它们之间的恒星也应该脉动。我们使用二进制种群合成模型来确定恒星可以通过哪些潜在的进化路径成为BLAP。我们发现，蓝晕既可以通过普通包络演化产生，也可以通过罗氏叶溢出产生，包络剥离由主序星或演化的致密天体负责。推断出的群星群的质量分布表明，在两组已知脉动星之间的质量范围内，预计会有较少的恒星，这表明该地区缺乏观测发现可能是前白矮星群的潜在群星的结果。我们还考虑了金属丰度的变化，并发现证据表明，在Z=0.010(半太阳)处的暗光在脉动上是不稳定的，而且可能更常见。基于这一分析，我们预计银河系将有大约12000个蓝光，并预测未来观测中预计的源的数密度，例如维拉鲁宾天文台的遗留空间和时间调查。
Blue large-amplitude pulsators (BLAPs) are a recently discovered class of pulsating star, believed to be proto-white dwarfs, produced by mass stripping of a red giant when it has a small helium core. An outstanding question is why the stars in this class of pulsator seem to form two distinct groups by surface gravity, despite predictions that stars in the gap between them should also pulsate. We use a binary population synthesis model to identify potential evolutionary pathways that a star can take to become a BLAP. We find that BLAPs can be produced either through common envelope evolution or through Roche lobe overflow, with a main-sequence star or an evolved compact object being responsible for the envelope stripping. The mass distribution of the inferred population indicates that fewer stars would be expected in the range of masses intermediate to the two known groups of pulsators, suggesting that the lack of observational discoveries in this region may be a result of the underlying population of pre-white dwarf stars. We also consider metallicity variation and find evidence that BLAPs at Z = 0.010 (half-solar) would be pulsationally unstable and may also be more common. Based on this analysis, we expect the Milky Way to host around 12 000 BLAPs and we predict the number density of sources expected in future observations such as the Legacy Survey of Space and Time at the Vera Rubin Observatory.