Heat blanketing envelopes of neutron stars

TL;DR

This paper reviews the physical properties and models of heat blanketing envelopes of neutron stars, emphasizing their role in thermal insulation, composition effects, magnetic fields, and implications for understanding neutron star interiors.

Contribution

It provides a comprehensive overview of the physical processes, models, and effects influencing neutron star heat blanketing envelopes, highlighting their importance in thermal evolution studies.

Findings

Different models of heat blankets are compared.

Magnetic fields significantly affect heat conduction.

Envelope properties influence neutron star cooling.

Abstract

Near the surface of any neutron star there is a thin heat blanketing envelope that produces substantial thermal insulation of warm neutron star interiors and that relates the internal temperature of the star to its effective surface temperature. Physical processes in the blanketing envelopes are reasonably clear but the chemical composition is not. The latter circumstance complicates inferring physical parameters of matter in the stellar interiors from observations of the thermal surface radiation of the stars and urges one to elaborate the models of blanketing envelopes. We outline physical properties of these envelopes, particularly, the equation of state, thermal conduction, ion diffusion and others. Various models of heat blankets are reviewed, such as composed of separate layers of different elements, or containing diffusive binary ion mixtures in or out of diffusion equilibrium. The effects of strong magnetic fields in the envelopes are outlined as well as the effects of high temperatures which induce strong neutrino emission in the envelopes themselves. Finally, we discuss how the properties of the heat blankets affect thermal evolution of neutron stars and the ability to infer important information on internal structure of neutron stars from observations.