A comparison of the X-ray properties of X Persei and Gamma Cassiopeiae

The greater than 0.0001 solar mass/year loss rates required to power X-ray sources, if associated compact objects are white dwarfs, are many orders of magnitude greater than even the highest estimates for the main sequence Be stars Chi Per and Gamma Cas, confirming that the compact objects in these systems are neutron stars. While observed mass loss rates are of the order of that required to power the X-ray emission from a neutron star, X-ray measurements have established rates at least an order of magnitude above UV estimates, supporting earlier suggestions of an inclination dependence in the mass loss from rapidly rotating main sequence OB stars which results in mass loss rates in the orbital plane that are at least one order of magnitude higher, or terminal velocities that are at least a factor of 2.0 lower, than is indicated by UV measurements.