Fast cooling of neutron stars: Superfluidity versus heating and accreted envelope

It is generally considered that the neutron star cooling scenarios involving fast neutrino emission, from a kaon or pion condensate, quark matter, or the direct Urea process, require the presence of baryon pairing in the central core of the star to control the strong neutrino emission and to produce surface temperatures compatible with observations. I show here that within the kaon condensate scenario, pairing is nor necessary if (1) the equation of state is stiff enough for the star to have a thick crust in which sufficient friction can occur to heat the star and (2) a thin layer, of mass Delta M larger than similar to 10(-12) M., of light elements (H and He) is present at the stellar surface. Both the occurrence of heating and the presence of H and/or He at the surface (deposited during the late postsupernova accretion) can possibly be confirmed or refuted by future observations.