论文标题
WR + O麦芽素云二进制中O星的自旋速率
The spin rates of O stars in WR + O Magellanic Cloud binaries
论文作者
论文摘要
一些大规模合并的黑洞（BH）可能是二元O星的后代。这些O恒星之间的演变和传质决定了其后代BH的旋转。这些将通过未来的重力波检测器进行测量，从而激发了二进制中O恒星旋转的测量。我们之前测量了银河狼射线（WR） + O二进制中O恒星的旋转。在这里，我们在WR + O二进制中测量了四个LMC和两个SMC O星的VSINI，以确定较低的金属性是否可能影响自旋速率。我们发现分别为银河和麦哲伦WR +O二进制的O恒星分别显示平均vsini = 258 +/- 18 km/s和270 +/- 15 km/s。在连续夜晚测得的两个LMC O星可显示出显着的线宽度可变性，这可能是由于轨道相位不同的O恒星的不同部分，其WR伴侣的照亮不同。尽管有这种可变性，但在所有这些二进制文件中，Vsini还是高度超同步但对于O恒星而言明显的亚临界。因此，我们得出的结论是，必须存在WR + O二进制中O恒星的有效机制。这种机制可能与Robe Lobe溢出的发电机磁场有关，可防止这些恒星中RLOF运行时预期的近100％的分解自旋速率。 Spruit-Tayler Dynamo和O Star Wind可能就是这种机制。
Some massive, merging black holes (BH) may be descendants of binary O stars. The evolution and mass transfer between these O stars determines the spins of their progeny BH. These will be measurable with future gravitational wave detectors, incentivizing the measurement of the spins of O stars in binaries. We previously measured the spins of O stars in Galactic Wolf-Rayet (WR) + O binaries. Here we measure the vsini of four LMC and two SMC O stars in WR + O binaries to determine whether lower metallicity might affect the spin rates. We find that the O stars in Galactic and Magellanic WR + O binaries display average vsini = 258 +/- 18 km/s and 270 +/- 15 km/s, respectively. Two LMC O stars measured on successive nights show significant line width variability, possibly due to differing orbital phases exhibiting different parts of the O stars illuminated differently by their WR companions. Despite this variability, the vsini are highly super-synchronous but distinctly subcritical for the O stars in all these binaries; thus we conclude that an efficient mechanism for shedding angular momentum from O stars in WR + O binaries must exist. This mechanism, probably related to Roche lobe overflow-created dynamo magnetic fields, prevents nearly 100% breakup spin rates, as expected when RLOF operates, as it must, in these stars. A Spruit-Tayler dynamo and O star wind might be that mechanism.
