论文标题
相互作用的大量供体：金属性的影响
Massive donors in interacting binaries: effect of metallicity
论文作者
论文摘要
已知金属性会显着影响巨大恒星的径向膨胀：金属性越低，恒星越紧凑，尤其是在其后MS演化期间。我们在二进制进化的背景下研究这种效果。使用恒星进化代码台面，我们计算了不同金属度的恒星的进化轨道，探讨了已知影响径向膨胀的因素的变化（例如，半注射，过冲，旋转）。我们发现对进化的观察支持，其中已经以金属性为$ 0.2z _ {\ odot} $巨星在Hertzprung-Gap（HG）阶段保持相对紧凑，并且它们的大部分扩展发生在核心螺旋燃烧期间（CHEB）。因此，我们表明金属性对二元系统中传质演化的类型有很大的影响。在太阳金属性时，MS结束后不久就开始了Case-B传质，而巨型供体几乎总是迅速扩展的HG恒星。在较低的金属性下，从更演变的CHEB恒星中传播的参数空间急剧增加。这意味着在低金属环境中的包膜剥离和形成氦星在供体的后期发生，这意味着狼射线相的持续时间（即使是数量级）和更高的最终核心质量的持续时间。这种金属性效应与金属依赖性恒星风的影响无关。在非常低的金属性下，二进制文件中的大量恒星很大一部分参与了质量转移的第一集，很晚才能进化，当时它们已经具有发达的CO核心。剩余的寿命（$ <10^4 $ yr）不可能足以剥离整个H富含H的信封。我们还简要讨论了在二进制黑洞合并形成的背景下，从大规模对流 - 内玻璃供体的传质的参数空间。
Metallicity is known to significantly affect the radial expansion of a massive star: the lower the metallicity, the more compact the star, especially during its post-MS evolution. We study this effect in the context of binary evolution. Using the stellar-evolution code MESA, we computed evolutionary tracks of stars at different metallicities, exploring variations of factors known to affect the radial expansion (e.g. semiconvection, overshooting, rotation). We find observational support for an evolution in which already at metallicity $0.2Z_{\odot}$ massive stars remain relatively compact during the Hertzprung-Gap (HG) phase and most of their expansion occurs during core-helium burning (CHeB). Consequently, we show that metallicity has a strong influence on the type of mass transfer evolution in binary systems. At solar metallicity, a case-B mass transfer is initiated shortly after the end of MS, and a giant donor is almost always a rapidly expanding HG star. At lower metallicity, the parameter space for mass transfer from a more evolved CHeB star increases dramatically. This means that envelope stripping and formation of helium stars in low-metallicity environments occurs later in the evolution of the donor, implying a much shorter duration of the Wolf-Rayet phase (even by an order of magnitude) and higher final core masses. This metallicity effect is independent of the impact of metallicity-dependent stellar winds. At very low metallicities, a significant fraction of massive stars in binaries engages in the first episode of mass transfer very late into their evolution, when they already have a well-developed CO core. The remaining lifetime ($< 10^4$ yr) is unlikely to be enough to strip the entire H-rich envelope. We also briefly discuss the extremely small parameter space for mass transfer from massive convective-envelope donors in the context of binary black hole merger formation.
