  We study the possible existence of deconfined quark matter in the interior of
neutron stars using the Nambu-Jona-Lasinio model to describe the quark phase.
We find that typical neutron stars with masses around 1.4 solar masses do not
possess any deconfined quark matter in their center. This can be traced back to
the property of the NJL model which suggests a large constituent strange quark
mass over a wide range of densities.
