Role of pion excitations in nucleon medium in the problem of the neutron star luminosity

The role of collective effects of a nucleon medium in the neutron star luminosity problem is being studied. It is shown that, due to a consecutive account of collective effects in a dense nucleon medium, the unit volume luminosities from both the midified URCA-process and suggested new one-nucleon processes, related to the presence of thermal excitations of the pion field in the nucleon medium, can become several orders of magnitude greater. This is probably sufficient to explain the experimentally known upper limits for the neutron star surface temperatures