Effects of temperature on the stability of protoneutron stars with hyperons

In the framework of the relativistic mean field theory, the stability of thermal protoneutron stars is investigated. There is a highest possible temperature for a stable protoneutron star. A stable protoneutron star may be a metastable one if its mass is too large. As the temperature increases, the metastable mass range of protoneutron stars narrows. With the increase of temperature, the probability that a stable protoneutron star is a metastable one increases. A really stable protoneutron star with higher temperature can contain more species of hyperons. The case of SN 1987A is analyzed connected with the results in this article.