Neutron Star Fe Atmospheres from OPAL Opacities

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Session 78 -- Pulsars and Neutron Stars
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[78.11] Neutron Star Fe Atmospheres from OPAL Opacities

M. Rajagopal and R.W.Romani (Stanford University)

Astrophysical opacities incorporating more accurate treatments of M shell transitions in heavy elements at $\sim 10^{5.5}$K have recently become available; these have made significant changes to models for a number of stellar astrophysics problems. Neutron stars, which have $T_{eff}$ in this range for $\sim 10^6$y and may have surfaces dominated by heavy elements, represent a case where the new opacities should have a maximal effect. We present calculations of LTE neutron star atmospheres and emergent spectra for low $B$ stars in the range $10^5 < T_{eff} < 10^{6.5}$, using new Fe opacities produced by the OPAL group. The results are compared with earlier models based on Los Alamos Opacity Library data. We find that the photospheres are convective in certain regions for some $T_{eff}$, and that this, as well as the surface composition, can have a significant effect on the atmospheric fluxes in the UV to soft X-ray range. We comment on the implications for soft X-ray observations of young cooling neutron stars.

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