What we can learn from observations of cooling neutron stars

A generic toy model of a cooling neutron star (NS) is used to analyze cooling of NSs with nucleon and exotic compositions of the cores. The model contains the parameters which specify the levels of slow and fast neutrino emission as well as the lower and upper densities of the layer where the slow emission transforms into the fast one. The prospects to constrain these parameters from the present and future observations of isolated middle-aged NSs are discussed.