Massive stellar models: rotational evolution, metallicity effects

TL;DR

This paper reviews how fast rotation affects stellar structure and evolution, examining metallicity influences and comparing theoretical models with observations of B and Be stars in different galaxies.

Contribution

It provides a comprehensive review of the effects of rotation and metallicity on stellar evolution, including transport mechanisms and observational comparisons.

Findings

Rotation causes oblateness, mixing, and wind anisotropy in stars.

Metallicity influences the evolution of stellar rotational velocities.

Theoretical models align with observed properties of B and Be stars.

Abstract

The Be star phenomenon is related to fast rotation, although the cause of this fast rotation is not yet clearly established. The basic effects of fast rotation on the stellar structure are reviewed: oblateness, mixing, anisotropic winds. The processes governing the evolution of the equatorial velocity of a single star (transport mechanisms and mass loss) are presented, as well as their metallicity dependence. The theoretical results are compared to observations of B and Be stars in the Galaxy and the Magellanic Clouds.