Hyperons and Neutron Stars

In this lecture I will briefly review some of the effects of hyperons on the properties of neutron and proto-neutron stars. In particular, I will revise the problem of the strong softening of the EoS, and the consequent reduction of the maximum mass, induced by the presence of hyperons, a puzzle which has become more intringuing and difficult to solve due the recent measurements of the unusually high masses of the millisecond pulsars PSR J1903+ 0327 (1.667 +/- 0.021M(circle dot)), PSR J16142230 (1.97 +/- 0.04M(circle dot)), and PSR J0348+ 0432 (2.01 +/- 0.04M(circle dot)). Finally, I will also examine the role of hyperons on the cooling properties of newly born neutron stars and on the so-called r-mode instability.