论文标题
最近发现的黑洞可能没有三重配置
The nearest discovered black hole is likely not in a triple configuration
论文作者
论文摘要
最近，HR 6819被认为是围绕黑洞（BH）和B III型星的内部二进制系统的巨大轨道中的恒星的分层三重系统。我们认为，由于三个原因，该系统不太可能是分层三重：（i）鉴于该系统的发现是有限的明亮星形目录，因此，银河系的预期数量约为$ 10^4 $，而这种系统的预算估计为$ 10^2-10^2-10^3 $ Systems在一定的假设下。如此巨大的差距无法予以核对，因为否则它很可能会溢出BHS的MW预算； （ii）该系统的动力稳定性在外部BE BE恒星的轨道分离上设置了下限，而Gaia没有解决其投影的天空分离的上限。我们表明，这两个约束将暗示外轨道的狭窄范围，而无需诉诸几何微调。 （iii）在内部二进制中BH形成之前，三重系统应在恒星进化中幸存下来。我们进行数值模拟，从该系统的保守初始条件开始，并表明BH祖细胞巨星质量损失，BH NATAL踢和初始轨道分离可以重现HR 6819的较小参数空间。
HR 6819 was recently claimed to be a hierarchical triple system of a Be star in a wide orbit around an inner binary system of a black hole (BH) and a B III type star. We argue that this system is unlikely to be a hierarchical triple due to three reasons: (i) Given that this system is discovered in a magnitude limited Bright Star Catalog, the expected number of such systems in the Milky Way amounts to about $10^4$ while the estimate for the MW budget for such systems is between $10^2-10^3$ systems under generous assumptions. Such a large gap cannot be reconciled as it would otherwise likely overflow the MW budget for BHs; (ii) The dynamical stability of this system sets lower bounds on the orbital separation of the outer Be star, while it not being resolved by Gaia places an upper limit on its projected sky separation. We show that these two constraints would imply a narrow range for the outer orbit without resorting to geometrical fine-tuning; (iii) The triple system should have survived the stellar evolution prior to the formation of the BH in the inner binary. We perform numerical simulations starting with conservative initial conditions of this system and show that a small parameter space for BH progenitor star's mass loss, BH natal kicks, and initial orbital separation can reproduce HR 6819. Therefore, we propose this system is a chance superposition of a Be star with a binary.
