On the pre-supernova parameters of the Hercules X-1 system

On the assumption that, at the moment of the supernova explosion, the presently nondegenerate companion of Her X-1 was a Main-Sequence star with polytropic index n = 3, it is found that the effects of impact and ablation cannot have removed more than about 10% of its pre-supernova mass. A remnant mass for a neutron star of 1.4 Msub(sun) was adopted. The effects of impact and ablation were calculated in the manner given by Wheeler et al. (1975). Depending on the ejection velocity of the SN shell, it is found that with a pre-SN mass of 2.2 Msub(sun) (i.e., the maximum possible value) for the degenerate component, the initial binary period was in the range 2-4 days. (orig.)