Mass Loss in 2D ZAMS Stellar Models

TL;DR

This study uses 2D stellar models to analyze how rapid rotation affects radiatively driven mass loss and angular momentum loss, revealing significant latitudinal variations and differences from traditional 1D models.

Contribution

It introduces 2D models to quantify the impact of rotation on mass and angular momentum loss, highlighting differences from 1D predictions and deriving new scaling relations.

Findings

Mass loss rate decreases with increasing rotation at constant mass.

2D models predict less equatorial and more polar mass loss than 1D models.

Rotating models lose less angular momentum in 2D than in 1D.

Abstract

A large number of massive stars are known to rotate, resulting in significant distortion and variation in surface temperature from the pole to the equator. Radiatively driven mass loss is temperature dependent, so rapid rotation produces variation in mass loss and angular momentum loss rates across the surface of the star, which is expected to affect the evolution of rapidly rotating massive stars. In this work, we investigate the two dimensional effects of rotation on radiatively driven mass loss and the associated loss of angular momentum in ZAMS models with solar metallicity. Using 2D stellar models, which give the variation in surface parameters as a function of co-latitude, we implement two different mass loss prescriptions describing radiatively driven mass loss. We find a significant variation in mass loss rates and angular momentum loss as a function of co-latitude. We find that the mass loss rate decreases as the rotation rate increases for models at constant initial mass, and derive scaling relations based on these models. When comparing 2D to 1D mass loss rates, we find that although the total angle integrated mass loss does not differ significantly, the 2D models predict less mass loss from the equator and more mass loss from the pole than the 1D predictions using von Zeipel's law. As a result, rotating models lose less angular momentum in 2D than in 1D, which will change the subsequent evolution of the star. The evolution of these models will be investigated in future work.