Leo T Dissected with the MUSE-Faint Survey

TL;DR

This study uses advanced spectroscopic and photometric data to analyze Leo T, revealing its stellar populations, metallicity, and gas dynamics, and highlighting the role of rapidly rotating massive stars in metal-poor environments.

Contribution

It provides a detailed spectroscopic analysis of Leo T with a significantly increased sample size, identifying stellar populations, metallicity, and gas-star kinematic links using MUSE and HST data.

Findings

Identified two stellar populations with similar metallicity around [Fe/H] -1.5 dex.

Discovered three emission line Be stars indicating rapid rotation in metal-poor stars.

Linked the young stellar population's dynamics with the cold neutral gas component.

Abstract

Leo T is the lowest mass galaxy known to contain neutral gas and to show signs of recent star formation, which makes it a valuable laboratory for studying the nature of gas and star formation at the limits of where galaxies are found to have rejuvenating episodes of star formation. Here we discuss a novel study of Leo T that uses data from the MUSE integral field spectrograph and photometric data from HST. The high sensitivity of MUSE allowed us to increase the number of Leo T stars observed spectroscopically from 19 to 75. We studied the age and metallicity of these stars and identified two populations, all consistent with similar metallicity of [Fe/H] $\sim$ -1.5 dex, suggesting that a large fraction of metals were ejected. Within the young population, we discovered three emission line Be stars, supporting the conclusion that rapidly rotating massive stars are common in metal-poor environments. We find differences in the dynamics of young and old stars, with the young population having a velocity dispersion consistent with the kinematics of the cold component of the neutral gas. This finding directly links the recent star formation in Leo T with the cold component of the neutral gas.