银河系中心X射线源CXOGC J174536的双星性质
The binary nature of the Galactic Centre X-ray source CXOGC J174536.1-285638
摘要：
对银河系中心2x0.8度区域的X射线和近红外线观测揭示了一群X射线明亮的大质量恒星。然而，这种发射的性质是不确定的，是源于风碰撞区还是通过吸积到致密物体上。为了解决这个问题，我们研究了发光X射线源CXOGC J174536.1-285638的性质。使用非LTE模式大气代码对近红外光谱的分析表明，它是一颗非常明亮的WN 9 h恒星，与演化轨迹的比较表明它的年龄为2- 250万年，初始质量约为110 Msun。CXOGC J174536.1-285638的X射线性质类似于拱门星团中的3颗WN 9 h恒星，也类似于其他质量很大的WNLh碰撞风双星。简单的分析论证证明了X射线发射和一个假定的WN 9 h+中O V-III双星之间的一致性。然而，我们可能不排除一个高质量的X射线二进制的解释，如果正确的话，将提供一个独特的见解（后SN）的极端质量的恒星的演化。无论次级的性质如何，CXOGC J174536.1-285638都增加了已知和候选WNLh二进制文件的数量。的子集的WNLh恒星的径向速度调查，我们发现一个下限的二进制分数的~45%，感兴趣的大规模恒星形成的研究，鉴于他们目前拥有最高的动态确定的质量的任何类型的恒星。[删节]
英文摘要：
X-ray and near-IR surveys of the central 2x0.8 degrees of the Galactic Centre have revealed a population of X-ray bright massive stars. However, the nature of the emission, originating in a wind collision zone or via accretion onto a compact object, is uncertain. In order to address this we investigated the nature of the luminous X-ray source CXOGC J174536.1-285638. An analysis of the near-IR spectrum with a non-LTE model atmosphere code demonstrated that it was an highly luminous WN9h star, for which comparison to evolutionary tracks suggests an age of 2-2.5Myr and an initial mass of ~110Msun. The X-ray properties of CXOGC J174536.1-285638 resemble those of 3 of the WN9h stars within the Arches cluster and in turn other very massive WNLh colliding wind binaries. Simple analytical arguments demonstrate consistency between the X-ray emission and a putative WN9h+mid O V-III binary. However, we may not exclude a high mass X-ray binary interpretation, which, if correct, would provide a unique insight into the (post-SN) evolution of extremely massive stars. Irrespective of the nature of the secondary, CXOGC J174536.1-285638 adds to the growing list of known and candidate WNLh binaries. Of the subset of WNLh stars subject to a radial velocity survey, we find a lower limit to the binary fraction of ~45%; of interest for studies of massive stellar formation, given that they currently possess the highest dynamically determined masses of any type of star. [ABRIDGED]
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