Present status of two-dimensional ESTER models: Application to Be stars

TL;DR

This paper reviews the current state of two-dimensional ESTER models for fast rotating stars, demonstrating their success with some systems and limitations with others, and explores their implications for stellar evolution and Be star phenomena.

Contribution

It presents the latest developments in 2D ESTER models, compares them with observational data, and discusses their role in understanding the evolution and mass ejection in fast rotating stars.

Findings

Models successfully match parameters of delta Velorum components.

Failed to reproduce Achernar data, indicating it has left the main sequence.

Evolution increases criticality in fast rotators, possibly causing Be phenomena.

Abstract

ESTER two-dimensional models solve the steady state structure of fast rotating early-type stars including the large scale flows associated with the baroclinicity of the radiative zones. Models are compared successfully to the fundamental parameters of the two main components of the triple system $\delta$ Velorum that have been derived from interferometric and orbit measurements. Testing the models on the Be star Achernar ($\alpha$ Eri), we cannot reproduce the data and conclude that this star has left the main sequence and is likely crossing the Herzsprung gap. Computing main sequence evolution of fast rotating stars at constant angular momentum shows that their criticality increases with time suggesting that the Be phenomenon and the ensuing mass ejections is the result of evolution.