The Transformative Journey of HD 93521
The Transformative Journey of HD 93521
复制标题
DOI：
10.3847/1538-3881/ac43be
复制
发表时间：
2021-12
期刊：
影响因子：
--
通讯作者：
D. Gies;K. Shepard;P. Wysocki;R. Klement
中科院分区：
文献类型：
--
作者：
D. Gies;K. Shepard;P. Wysocki;R. Klement
HD 93521是一颗大质量、快速旋转的星星，位于银河系盘面上方约1千秒差距处，估计其质量的演化年龄远小于它被抛出盘面的飞行时间。在这里，我们提出了一个重新评估的进化和运动的时间尺度HD 93521。我们根据盖亚EDR3的距离和自行以及径向速度测量结果的总结计算出飞行时间为39 ± 300万年。然后，我们确定恒星的光度使用旋转模型结合所观察到的光谱能量分布和距离。与Brott等人的旋转恒星演化轨迹比较，得出的演化年龄约为500万年± 200万年。我们建议，解决时间尺度的差异是，HD 93521是一个恒星合并的产品。它很可能是从银河系盘中弹射出来的，当时它是一个由低质量恒星组成的近距离双星系统，最终合并成了我们今天观察到的快速旋转的单一大质量星星。
HD 93521 is a massive, rapidly rotating star that is located about 1 kpc above the Galactic disk, and the evolutionary age for its estimated mass is much less than the time of flight if it was ejected from the disk. Here we present a reassessment of both the evolutionary and kinematical timescales for HD 93521. We calculate a time of flight of 39 ± 3 Myr based upon the distance and proper motions from Gaia EDR3 and a summary of radial velocity measurements. We then determine the stellar luminosity using a rotational model combined with the observed spectral energy distribution and distance. A comparison with evolutionary tracks for rotating stars from Brott et al. yields an evolutionary age of about 5 ± 2 Myr. We propose that the solution to the timescale discrepancy is that HD 93521 is a stellar merger product. It was probably ejected from the Galactic disk as a close binary system of lower-mass stars that eventually merged to create the rapidly rotating and single massive star we observe today.