  In this paper we investigate the thermal evolution of hybrid stars, objects
composed of a quark matter core, enveloped by ordinary hadronic matter. Our
purpose is to investigate how important are the microscopic properties of the
quark core to the thermal evolution of the star. In order to do that we use a
simple MIT bag model for the quark core, and a relativistic mean field model
for the hadronic envelope. By choosing different values for the microscopic
parameters (bag constant, strange quark mass, strong coupling constant) we
obtain hybrid stars with different quark core properties. We also consider the
possibility of color superconductivity in the quark core. With this simple
approach, we have found a set of microscopic parameters that lead to a good
agreement with observed cooling neutron stars. Our results can be used to
obtain clues regarding the properties of the quark core in hybrid stars, and
can be used to refine more sophisticated models for the equation of state of
quark matter.
