Metallicity and mean age across M33

TL;DR

This study uses new near-infrared imaging data of M33 to analyze the distribution of AGB stars, deriving the galaxy's mean age and metallicity variations through comparison with theoretical models.

Contribution

It provides improved NIR data of M33 and applies a novel analysis of AGB star populations to map age and metallicity across the galaxy.

Findings

Distribution of super giant, C-rich, and O-rich AGB stars mapped

Derived mean age and metallicity gradients across M33

Enhanced understanding of M33's stellar population properties

Abstract

New wide-field near-infrared (NIR) imaging observations of M33 were obtained from UKIRT. These show a large population of intermediate-age stars considerably improving on previous NIR data. The spatial distribution of super giant stars, carbon-rich (C-rich or C stars) and oxygen-rich (O-rich or M stars) asymptotic giant branch (AGB) stars distinguished from the NIR colour-magnitude diagram (CMD) have been studied as well as the C/M ratio. The Ks magnitude distribution has been interpreted using theoretical models to derive the mean age and the mean metallicity across M33.