标题： WRAY 977 (GX301-2)：具有脉冲星伴星的超巨星 显示英文标题

标题： WRAY 977 (GX301-2): A HYPERGIANT WITH PULSAR COMPANION

摘要： Wray 977，X射线脉冲星GX301-2的B超巨星伴星，应根据其光学谱与zeta1 Sco的比较进行分类，zeta1 Sco是一个著名的B超巨星，也是银河系中最明亮的恒星之一，分类为B1~Ia+。 将Wray 977分类为超巨星导致了双星系统的新的距离测定，即5.3 kpc（之前为1.8 +/- 0.4 kpc）。 脉冲星的“平均”X射线光度约为10^37 erg/s，与通过致密、低速度（v_infty = 400 km/s）恒星风吸积预测的X射线光度相符。 从Halpha轮廓估计的质量损失率小于等于10^-5 M_sun/yr。 推导出了系统倾角的新上限，这提供了Wray 977（48 M_sun）当前质量的下限。 关于当前的双星演化情景，双星中黑洞形成的经验质量下限增加到M_zams >= 50 M_sun。 显示英文摘要

摘要： Wray 977, the B supergiant companion of the X-ray pulsar GX301-2, should be classified as B1~Ia+, based on a comparison of its optical spectrum to that of zeta1 Sco, a well-known B hypergiant and ONE OF THE BRIGHTEST STARS IN THE GALAXY. The classification of Wray 977 as a hypergiant results in a new distance determination of the binary system, i.e. 5.3 kpc (previously 1.8 +/- 0.4 kpc). The ``average'' X-ray luminosity of the pulsar is then ~10^37 erg/s, in good agreement with the predicted X-ray luminosity resulting from accretion of a dense, low-velocity (v_infty = 400 km/s) stellar wind. A mass-loss rate of <= 10^-5 M_sun/yr is estimated from the Halpha profile. A new upper limit for the inclination of the system is derived which provides a lower limit to the (present) mass of Wray 977 (48 M_sun). Regarding current binary evolution scenarios, the empirical lower mass limit for BLACK-HOLE formation in a binary increases to M_zams >= 50 M_sun.