Model atmospheres for X-ray bursting neutron stars

Abstract

The results of 17 model atmospheres for neutron stars ranging in effective temperature from 0.25 to 3 keV, in gravity from 10 to the 14th to 10 to the 15th cm/sq s, and in helium and iron abundances are presented. For those models with solar helium abundance, the iron abundances (Fe/H) ranged from 0 to 1, relative to solar abundance. It is found that the spectrum significantly differs from a blackbody radiating at the effective temperature. The differences are associated with the effects of surface cooling and back warming due to the highly nongray nature of the absorption coefficient, mainly important at low effective temperatures, and the depressed emissivity of the source function caused by electron scattering, which becomes more important for high effective temperatures.