Constraining Mass-Loss & Lifetimes of Low Mass, Low Metallicity AGB Stars

TL;DR

This paper develops a method to constrain the lifetimes and mass-loss processes of low-mass, low-metallicity TP-AGB stars by comparing models with observed stellar populations, highlighting the importance of pre-dust driven mass loss.

Contribution

It introduces a framework for constraining TP-AGB star models using resolved stellar populations and demonstrates the significance of pre-dust mass-loss prescriptions.

Findings

Models with efficient pre-dust mass loss match observations

Low-mass TP-AGB stars at low metallicity have lifetimes under 1.2 million years

Pre-dust mass loss influences the evolution and observable properties of TP-AGB stars

Abstract

The evolution and lifetimes of thermally pulsating asymptotic giant branch (TP-AGB) stars suffer from significant uncertainties. We present a detailed framework for constraining model luminosity functions of TP-AGB stars using resolved stellar populations. We show an example of this method that compares various TP-AGB mass-loss prescriptions that differ in their treatments of mass loss before the onset of dust-driven winds (pre-dust). We find that models with more efficient pre-dust driven mass loss produce results consistent with observations, as opposed to more canonical mass-loss models. Efficient pre-dust driven mass-loss predicts for [Fe/H] < -1.2, lower mass TP-AGB stars (M < 1 Msun) must have lifetimes less than about 1.2 Myr.