1995/03/01 by L. Kaper, Hjglm Lamers, Kaper, L. +7 · 1 citation
Engineering · Mathematics · Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics (astro-ph) #FOS: Physical sciences #Mechanics and Biomechanics Studies #Statistical and numerical algorithms
paper · pdf · doi:10.48550/arxiv.astro-ph/9503003
openalex publication_date 1995/03/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/01
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 ~1037 erg/s, in good agreement with the predicted X-ray luminosity resulting from accretion of a dense, low-velocity (vinfty = 400 km/s) stellar wind. A mass-loss rate of <= 10-5 Msun/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 Msun). Regarding current binary evolution scenarios, the empirical lower mass limit for BLACK-HOLE formation in a binary increases to Mzams >= 50 Msun.