Cooling simulations of neutron stars are performed assuming that stellar cores consist of neutrons, protons and electrons and using realistic density profiles of superfluid critical temperatures T_cn(\rho) and T_cp(\rho) of neutrons and protons. Taking a suitable profile of T_cp(\rho) with maximum ~ 6^.10⁹ K one can obtain smooth transition from slow to rapid cooling with increasing stellar mass M. Adopting the same profile one can explain the majority of observations of thermal emission from isolated middle-aged neutron stars by cooling of neutron stars with different M either with no neutron superfluidity in the core or with a weak superfluidity, T_cn <~ 10⁸K. The required masses range from 1.2 M_Sun for (hot and young) RX J0822-43 and (old and warm) PSR 1055-52 to ~ 1.45 M_Sun for the (much colder) Geminga and Vela pulsars. Observations constrain the T_cn(\rho) and T_cp(\rho) profiles with respect to the threshold density of direct Urca process and maximum central density of neutron stars.

Page design by Alexander Potekhin (palex@astro.ioffe.rssi.ru).
Page created on April 2, 2001, updated on April 4, 2001.