arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2101.01604astro-ph.SRastro-ph.GA
收藏

年轻星团径向速度弥散与年龄之间的关系:大质量密近双星形成情景的硬化证据

A relation between the radial velocity dispersion of young clusters and their age: Evidence for hardening as the formation scenario of massive close binaries

M. C. Ramírez-Tannus, F. Backs, A. de Koter, H. Sana, H. Beuther, A. Bik, W. Brandner, L. Kaper, H. Linz, Th. Henning, J. Poorta

摘要:

OB星协中的大部分大质量恒星($>8$ $\rm{M_{\odot}}$)都是在近距离双星系统中发现的。尽管如此,这些近距离大质量双星的形成机制还不清楚。使用文献数据,我们测量的径向速度色散($σ_\mathrm{RV}$)作为代理的密切的二元分数在10个OB协会在银河系和大麦云云,年龄范围从1到6百万年。我们发现这种分散与集群的年龄,这是符合二进制硬化的积极趋势。假设$f_\mathrm{bin}$的普适二进制分数= 0.7,我们将$σ_\mathrm{RV}$行为转换为最小轨道周期$P_\mathrm{cutoff}$的演化,从100万年时的$\sim$ 9.5年到$\sim$ 600万年时样本中最老的星团的$\sim$ 1.4天。我们的研究结果表明,双星形成在较大的分离,他们在大约1至2百万年硬化产生的周期分布在几百万年前的OB双星观察。这种向内的迁移可能是由与残留的吸积盘或系统中其他年轻恒星物体的相互作用驱动的。我们的研究结果构成了第一个经验证据,有利于移民作为一个方案,形成大规模的密切的二进制文件。

英文摘要:

The majority of massive stars ($>8$ $\rm{M_{\odot}}$) in OB associations are found in close binary systems. Nonetheless, the formation mechanism of these close massive binaries is not understood yet. Using literature data, we measured the radial-velocity dispersion ($σ_\mathrm{RV}$) as a proxy for the close binary fraction in ten OB associations in the Galaxy and the Large Magellanic Cloud, spanning an age range from 1 to 6 Myrs. We find a positive trend of this dispersion with the cluster's age, which is consistent with binary hardening. Assuming a universal binary fraction of $f_\mathrm{bin}$ = 0.7, we converted the $σ_\mathrm{RV}$ behavior to an evolution of the minimum orbital period $P_\mathrm{cutoff}$ from $\sim$9.5 years at 1 Myr to $\sim$1.4 days for the oldest clusters in our sample at $\sim$6 Myr. Our results suggest that binaries are formed at larger separations, and they harden in around 1 to 2 Myrs to produce the period distribution observed in few million year-old OB binaries. Such an inward migration may either be driven by an interaction with a remnant accretion disk or with other young stellar objects present in the system. Our findings constitute the first empirical evidence in favor of migration as a scenario for the formation of massive close binaries.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑