Monitoring pulsating giant stars in M33: star formation history and chemical enrichment

TL;DR

This study used near-infrared monitoring of pulsating giant stars in M33 to reconstruct its star formation history and map dust production, revealing two epochs of enhanced star formation and quantifying dust output.

Contribution

Developed a new method utilizing pulsating giant stars to determine galaxy star formation history and dust production, applied to M33.

Findings

Identified two epochs of increased star formation in M33.

Measured dust production rates from pulsating giant stars.

Mapped star formation and dust production across M33.

Abstract

We have conducted a near-infrared monitoring campaign at the UK InfraRed Telescope (UKIRT), of the Local Group spiral galaxy M 33 (Triangulum). A new method has been developed by us to use pulsating giant stars to reconstruct the star formation history of galaxies over cosmological time as well as using them to map the dust production across their host galaxies. In first Instance the central square kiloparsec of M33 was monitored and long period variable stars (LPVs) were identified. We give evidence of two epochs of a star formation rate enhanced by a factor of a few. These stars are also important dust factories, we measure their dust production rates from a combination of our data with Spitzer Space Telescope mid-IR photometry. Then the monitoring survey was expanded to cover a much larger part of M33 including spiral arms. Here we present our methodology and describe results for the central square kiloparsec of M33 (Javadi et al. 2011 a,b,c, 2013) and disc of M33 (Javadi et al. 2015, 2016, 2017, and in preparation).