A journey across the M33 disk

TL;DR

This study uses multiwavelength observations to analyze the gas and star formation history of M33, revealing insights into its disk structure, metallicity, and star-forming regions, challenging galaxy formation theories.

Contribution

It provides detailed constraints on M33's gas accretion and star formation history, highlighting the role of disk perturbations and low luminosity star-forming sites.

Findings

Weak bar detected in the galaxy's center.

Lack of strong metallicity and dust gradients across the disk.

Presence of numerous low luminosity star-forming regions.

Abstract

The Local Group member M33 is a pure disk galaxy bearing no prominent bulge or stellar halo. It constitutes a challenge for any hierarchical galaxy formation theory and an ideal laboratory for studying quiescent star formation. Using multiwavelength observations of the gas and stellar component in this nearby galaxy we are able to constrain the gas accretion and star formation history. In the centermost region we find kinematical evidence of a weak bar, which explains the central light excess and the enhanced metallicity. In the more extended disk the lack of strong gradients of metal and dust abundances supports the picture that the slow radial decline of the star formation rate is due to a change in the large scale disk perturbations: bright HII regions and giant molecular clouds being born only in the inner disk. The analysis of the infrared Spitzer maps has however revealed hundreds of low luminosity star forming sites in places with a variety of dust content. These are essential ingredients for understanding the overall gas to star formation process in M33 and in more distant late type galaxies.