Population I Stellar Structure and Evolution: facing the lingering difficulties to make a step forward

Abstract

The understanding of stellar structure, evolution and pulsations is a key piece of the proper understanding of the Universe. The interpretation of the luminosity and spectra of galaxies, the properties of star populations and of starbursts, the calibration of distances, the nucleosynthetic prescriptions etc... are all requiring good models of stellar structure and evolution. The many interesting and new results in the field have been presented in several recent reviews by Maeder (1991), Chiosi et al. (1992), Maeder & Conti (1994). Table 1 below presents a list of the recent grids of stellar models. The various columns give the author’s name, then the mass range, the metallicity Z range, the kind of convective assumption adopted, where “Schw.” means Schwarzschild’s criterion, “oversh” means with convective overshooting, “all” means that different assumptions have been used. In the last column, a few remarks are given. It is interesting to note that the models mentioned above often arrive to very different conclusions about the kind of mixing supported by the observations. Authors of models with overshooting generally conclude that overshooting is best supported, authors of models without overshooting favour the absence of overshooting, while authors who consider various convective assumptions generally favour semiconvection (Stothers & Chin 1991; Mowlawi & Forestini 1994).