Tagging the Chemical Evolution History of the Large Magellanic Cloud Disk

TL;DR

This study uses high-resolution spectra to analyze the chemical and kinematic properties of stars in the LMC disk, revealing two main stellar populations with distinct formation histories and chemical signatures.

Contribution

It provides a detailed chemical and kinematic analysis of LMC disk stars, identifying two main populations and their likely formation epochs, offering insights into the galaxy's star formation history.

Findings

Two main stellar populations identified with distinct metallicities and alpha-element ratios.

The dominant population likely formed 3-4 Gyr ago, possibly due to tidal interactions.

Old globular cluster-like stars are rare in the LMC disk (<1%).

Abstract

We have used high-resolution spectra obtained with the multifiber facility FLAMES at the Very Large Telescope of the European Southern Observatory to derive kinematic properties and chemical abundances of Fe, O, Mg and Si for 89 stars in the disk of the Large Magellanic Cloud (LMC). The derived metallicity and [alpha/Fe], obtained as the average of O, Mg and Si abundances, allow us to draw a preliminary scheme of the star formation history occurred in this region of the LMC. The derived metallicity distribution shows two main components: one component (comprising ~ 84% of the sample) is peaked at [Fe/H] = -0.48 dex and it shows an [alpha/Fe] ratio slightly under solar ([alpha/Fe] ~ -0.1 dex). This population was probably originated by the main star formation event occurred 3-4 Gyr ago (possibly triggered by tidal capture of the Small Magellanic Cloud). The other component (comprising ~ 16% of the sample) is peaked at [Fe/H] ~ -1 dex and it shows an [alpha/Fe] ~ 0.2 dex. This population was probably generated during the long quiescent epoch of star formation in between the first episode and the most recent bursts. Indeed, in our sample we do not find stars with chemical properties similar to the old LMC globular clusters nor to the iron-rich and alpha-poor stars recently found in the LMC globular cluster NGC 1718 and predicted to be also in the LMC field, thus suggesting that both these components are small (< 1%) in the LMC disk population.