Properties and Evolution of a Protoneutron Star in the Enlarged SU(3) Model

Protoneutron stars are hot and lepton rich objects formed as a result of type II supernovae explosion. This paper describes results of analysis of protoneutron star models constructed under the assumptions that strange particles are present in the core. All calculations have been performed for the neutrino opaque matter when the entropy per baryon is of the order 2. The equation of state which is crucial for the structure and composition of a star has been obtained in the framework of the chiral SU(3) model and compared with the one involving derivative coupling of baryons to mesons. Of special interest in this paper is the comparison of the two protoneutron star models with those formed when neutrinos leak out of the system, described as cool, deleptonized neutron stars. It has been shown that the maximum mass of the hot protoneutron star with trapped neutrinos is close to 1.9 M (the Sun Mass) in case of the SU(3) model. However, deleptonization reduces the value of stable protoneutron star mass significantly to 1.5 M.