One of the most massive stars in the Galaxy may have formed in isolation
One of the most massive stars in the Galaxy may have formed in isolation
复制标题
银河系中质量最大的恒星之一可能是孤立形成的
DOI：
10.1093/mnras/stt1817
复制
发表时间：
2013
影响因子：
4.8
通讯作者：
A. Liermann
中科院分区：
文献类型：
--
作者：
L. M. Oskinova;M. Steinke;W.-R. Hamann;A. Sander;H. Todt;A. Liermann
比太阳重100倍的超大质量恒星很少见。目前还不知道这样的恒星是孤立形成的，还是只能在星团中形成。这个问题的答案至关重要。我们银河系的中心区域是研究位于同一环境中的超大质量恒星和星团的理想地点。我们使用档案红外图像来研究银河系中心(GC)中目前已知的明显孤立的大质量恒星的周围环境。我们发现，两颗这样孤立的大质量恒星表现出弓形激波，因此可能是从它们的出生地“逃跑”的。因此，GC区域中一些孤立的大质量恒星可能是在该区域已知的星团中诞生的。然而，孤立恒星WR-102ka(牡丹星云恒星)周围没有探测到弓形激波，这是银河系中质量最大、亮度最高的恒星之一。这颗恒星位于一个伴生的星周星云的中心。为了研究一个星团是否可能隐藏在WR-102ka的周围，为了获得这颗恒星新的更好的光谱，并测量它的径向速度，我们在欧洲南方天文台的甚大望远镜上用积分场光谱仪SINFONI进行了观测。我们的观测证实了WR-102ka是银河系中质量最大的恒星之一，并揭示了这颗恒星与星团无关。我们认为WR-102ka是在相对孤立的环境中诞生的，在任何大质量星团之外。
Very massive stars, 100 times heavier than the sun, are rare. It is not yet known whether such stars can form in isolation or only in star clusters. The answer to this question is of fundamental importance. The central region of our Galaxy is ideal for investigating very massive stars and clusters located in the same environment. We used archival infrared images to investigate the surroundings of apparently isolated massive stars presently known in the Galactic Centre (GC). We find that two such isolated massive stars display bow shocks and hence may be ‘runaways’ from their birthplace. Thus, some isolated massive stars in the GC region might have been born in star clusters known in this region. However, no bow shock is detected around the isolated star WR 102ka (Peony nebula star), which is one of the most massive and luminous stars in the Galaxy. This star is located at the centre of an associated circumstellar nebula. To study whether a star cluster may be ‘hidden’ in the surroundings of WR 102ka, to obtain new and better spectra of this star, and to measure its radial velocity, we obtained observations with the integral-field spectrograph SINFONI at the ESO's Very Large Telescope. Our observations confirm that WR 102ka is one of the most massive stars in the Galaxy and reveal that this star is not associated with a star cluster. We suggest that WR 102ka has been born in relative isolation, outside of any massive star cluster.