From quark stars to hybrid stars

We show the possible existence of compact stars having a surface composed o f a mixed phase of quarks and hadrons. This scenario can be realized both f or self-bound stars, satisfying the so-called Witten-Bodmer hypothesis, and for gravitationally bound stars. This class of solutions of the Tolman-Opp enheimer-Volkoff equation can be obtained in all the models we discuss, wit hin a physically acceptable range of values of the model parameters. (C) 20 01 Elsevier Science B.V. All rights reserved.