Revisiting the archetypical wind accretor Vela X-1 in depth. Case study of a well-known X-ray binary and the limits of our knowledge

Vol. 647
7. Stellar structure and evolution

Revisiting the archetypical wind accretor Vela X-1 in depth. Case study of a well-known X-ray binary and the limits of our knowledge

A star as a guide. In this paper, which is more similar to a review in some respects, Kretschmar and collaborators used the X-ray binary Vela X-1 to investigate any aspect of wind accretion limiting our knowledge. Vela X-1 is a bright X-ray source that was discovered by Uhuru, the first X-ray satellite, and the optical companion is a bright (V~6.9) and early O star. We do not miss data at any wavelength. The neutron star spins slowly (~280 s) and orbits the more massive star on a slightly eccentric orbit (~0.1) every ~9 days. This allows the neutron star to act as a probe of the O-star stellar wind and of the accretion process itself. This article triggered a discussion amongst the editors of A&A as well. We welcome this kind of review article on single objects, as a "spoke-object" of its astronomical class.