The evolution of massive stars is influenced by the mass lost to stellar winds over their lifetimes. These winds limit the masses of the stellar remnants (such as black holes) that the stars ultimately produce. We used radio astrometry to refine the distance to the black hole x-ray binary Cygnus X-1, which we found to be 2.22−0.17+0.18 kiloparsecs. When combined with archival optical data, this implies a black hole mass of 21.2 ± 2.2 solar masses, which is higher than previous measurements. The formation of such a high-mass black hole in a high-metallicity system (within the Milky Way) constrains wind mass loss from massive stars.

中文翻译：

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天鹅座X-1包含一个21–太阳质量的黑洞-对大质量恒星风有影响

大质量恒星的演化受到恒星风在其一生中损失的质量的影响。这些风限制了恒星最终产生的恒星残余物（例如黑洞）的质量。我们使用射电天文法来细化到黑洞X射线二进制天鹅座X-1的距离，我们发现这是2.22-0.17+0.18千帕秒。当与档案光学数据结合时，这意味着黑洞质量为21.2±2.2太阳质量，这比以前的测量结果要高。在高金属性系统中（银河系内）如此高质量的黑洞的形成限制了大质量恒星的风量损失。