WRAY 977 (GX301-2): A HYPERGIANT WITH PULSAR COMPANION
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.
引用
@article{arxiv.astro-ph/9503003,
title = {WRAY 977 (GX301-2): A HYPERGIANT WITH PULSAR COMPANION},
author = {L. Kaper and H. J. G. L. M. Lamers and E. Ruymaekers and E. P. J. van den Heuvel and E. J. Zuiderwijk},
journal= {arXiv preprint arXiv:astro-ph/9503003},
year = {2016}
}
备注
uuencoded compressed postscript with figures, 7 pages