Mass Loss in Evolved Stars

TL;DR

This paper reviews recent advances in understanding mass loss in evolved stars, emphasizing observational insights into the complex processes driving stellar winds during the AGB phase.

Contribution

It highlights new observational techniques and findings that shed light on the dynamic physics of mass loss in late-stage stellar evolution.

Findings

Radio and (sub)millimeter observations resolve stellar surfaces and atmospheres.

Recent studies reveal the interplay of pulsations, shocks, and dust formation.

Enhanced understanding of mass loss mechanisms in AGB stars.

Abstract

Intense mass loss through cool, low-velocity winds is a defining characteristic of low-to-intermediate mass stars during the asymptotic giant branch (AGB) evolutionary stage. Such winds return up ~80% of the initial stellar mass to the interstellar medium and play a major role in enriching it with dust and heavy elements. A challenge to understanding the physics underlying AGB mass loss is its dependence on an interplay between complex and highly dynamic processes, including pulsations, convective flows, shocks, magnetic fields, and opacity changes resulting from dust and molecule formation. I highlight some examples of recent advances in our understanding of late-stage stellar mass loss that are emerging from radio and (sub)millimeter observations, with a particular focus on those that resolve the surfaces and extended atmospheres of evolved stars in space, time, and frequency.