Wind Accretion
The X-ray luminosity of some HMXBs may be powered by gravitational capture of
some fraction of the primary star's wind. The dynamics of wind accretion are
characterized by the presence of a bowshock, whose size is determined by the
relative velocity of the stellar wind.
An important issue in this case is the role of X-ray photoionization,
which can make the wind transparent to the UV luminosity of the primary
and hence quench the radiative force driving the stellar wind.
