Stellar models: firm evidence, open questions and future developments

TL;DR

This paper reviews recent advances in stellar modeling, highlighting improved understanding of stellar evolution, while discussing persistent uncertainties and their implications for interpreting stellar populations.

Contribution

It provides a comprehensive review of the main sources of uncertainty in stellar models and their effects on population synthesis methods.

Findings

Improved understanding of stellar physical behavior over the last decade.

Identification of key uncertainties affecting stellar evolution models.

Discussion of the impact of these uncertainties on observational comparisons.

Abstract

During this last decade our knowledge of the evolutionary properties of stars has significantly improved. This result has been achieved thanks to our improved understanding of the physical behavior of stellar matter in the thermal regimes characteristic of the different stellar mass ranges and/or evolutionary stages. This notwithstanding, the current generation of stellar models is still affected by several, not negligible, uncertainties related to our poor knowledge of some thermodynamical processes and nuclear reaction rates, as well as the efficiency of mixing processes. These drawbacks have to be properly taken into account when comparing theory with observations, to derive evolutionary properties of both resolved and unresolved stellar populations. In this paper we review the major sources of uncertainty along the main evolutionary stages, and emphasize their impact on population synthesis techniques.