发表机构
Université de Genève; Gravitational Wave Science Center (GWSC), Université de Genève; University of Florida; Tel Aviv University; Northwestern University（日内瓦大学; 引力波科学中心（GWSC），日内瓦大学; 佛罗里达大学; 特拉维夫大学; 西北大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用POSYDON双星模型分析不同金属丰度下WR双星的周期分布，发现低金属丰度下长周期WR双星缺失，稳定质量转移主导WR双星形成且无金属丰度依赖性。
AI 中文摘要
对小麦哲伦云（SMC）和大麦哲伦云（LMC）中沃尔夫-拉叶星（WR）双星的观测表明，它们倾向于拥有短周期（轨道周期P≲30天），而长周期系统中似乎不存在WR星。银河系的WR双星族虽延伸至更长周期，但与作为其前身的O型星族相比，长周期WR双星存在缺失。在这些星族中，已观测到双星比例几乎恒定。本研究旨在表征不同金属丰度下WR双星的星族特征，确定这些系统形成的金属丰度依赖性，重点关注周期分布。我们使用POSYDON的详细双星演化模型，预测金属丰度为0.01、0.1、0.2、0.45和1Z⊙时的WR双星星族，分析所得的周期分布和形成通道，并将其与SMC、LMC和银河系的观测星族进行比较。研究发现，SMC中（可能还有LMC中）更宽的WR双星缺失，可通过稳定的B型质量转移仅部分剥离供体星，结合低金属丰度下WR星风强度不足以剥离剩余包层来解释。因此，太阳金属丰度（Zsun）下存在的B型质量转移产生的长周期峰值，在低金属丰度下消失。此外，稳定质量转移（SMT）通过A型质量转移产生短周期峰值（P≈5-10天），与不同金属丰度下的观测结果高度吻合。进一步发现，SMT和非相互作用系统是所有金属丰度下WR双星的主要形成通道，其相对贡献无金属丰度依赖性，这表明SMT通道与孤立WR星形成具有相同的金属丰度依赖性。同时，我们发现共包层演化主要产生具有黑洞伴星的短周期（P<1天）WR双星。
英文摘要
Observations of Wolf-Rayet (WR) stars in binaries in the SMC and LMC suggest a preference for short period ($P\lesssim30$ days) orbits, with an apparent absence of WRs in long-period systems. The Galactic population does extend to longer periods but shows a deficit in long-period WR binaries compared to their progenitors, the O-star population. Across these populations a nearly constant binary fraction has been observed. We aim to characterize the population of WR binaries across a range of metallicity and determine the metallicity dependence of the formation of these systems, specifically focusing on the period distribution. We use detailed binary evolution models from POSYDON to predict the population of WR binaries at 0.01, 0.1, 0.2, 0.45, and $1Z_\odot$, analyzing the resulting period distribution and formation channels, while comparing them against the observed population in the SMC, LMC, and Milky Way. We find that the absence of wider WR binaries in the SMC, and potentially in the LMC, can be explained by stable, Case-B mass transfer only partially stripping the donor star, combined with WR winds at low metallicity being insufficiently strong to strip the remaining envelope. As a result, the long-period peak from Case-B mass transfer, present at Zsun, disappears at low metallicity. We additionally find that stable mass transfer (SMT) produces a short-period peak through Case-A mass transfer (P~5-10 days) that closely matches observations across metallicity. Furthermore, SMT and non-interacting systems are the dominant formation channels of WR binaries at all metallicities, with their relative contribution showing no metallicity dependence. This result implies that the SMT channel has the same metallicity-dependence as isolated WR formation. At the same time, we find that common envelope evolution primarily produces short-period ($P<1$ day) WR binaries with black-hole companions.
CommentsSubmitted to A&A. Comments welcome
