Envelope Ejection Budget for the Supergiant Precursor of a High-Mass X-Ray Binary

This paper examines a 15 solar-mass supergiant, core 4.0 and envelope 11.0 solar masses at 650 solar radii, engulfing a 1.40 solar-mass neutron star and emerging near 28 solar radii as the precursor of a wind-fed high-mass X-ray binary. Using published input values and the standard energy comparison between envelope binding and orbital release, the calculation addresses the specific budget that decides the outcome for this pairing. The headline results are: binding_energy_erg = 2.751e+48; alpha_required = 8.491; af_alpha_0.5_Rsun = 1.91. The method, inputs and limitations are stated in full so that any reader can reproduce or rescale every number from the deposited calculation script. A neutron star paired with a supergiant envelope faces the least favourable mass ratio in ordinary binary evolution: the envelope outweighs the ejector by almost eight to one. Agreement and disagreement with published values for this class are reported at their actual size, and the conclusions are limited to what the budget arithmetic supports.