Gas and dust budget of the Large Magellanic Cloud

TL;DR

This study quantifies the gas and dust contributions of AGB stars and supernovae to the Large Magellanic Cloud's interstellar medium, revealing regional variations in sources and implications for ISM properties.

Contribution

It provides new mid-infrared spectral data and establishes mass-loss rate versus colour relations for carbon-rich AGB stars in the LMC.

Findings

Integrated mass-loss rate from carbon-rich AGB stars is 8.5x10^-3 solar masses/year.

Gas mass-loss rate varies between the bar and outside regions, with supernovae dominating in the bar.

Supernovae contribute significantly to the gas budget, especially in regions with recent star formation.

Abstract

Recent observations from the Spitzer Space Telescope enable us to study the mid-infrared dust excess of Asymptotic giant branch (AGB) stars in the Large Magellanic Cloud (LMC). Using mid-infrared spectra, together with photometric data from the SAGE programme, we establish a colour selection of carbon-rich AGB stars with intermediate and high mass-loss rates. We also established mass-loss rate versus colour relations for carbon-rich AGB stars. The integrated mass-loss rate over all intermediate and high mass-loss rate carbon-rich AGB candidates in the LMC is 8.5x10^-3 solar mass per year. This number could be almost doubled if oxygen-rich stars are included. Gas mass-loss rate from these stars is 4-5x10^-4 solar mass per year per kpc2 in the bar and1x10^-4 solar mass per year per kpc^2 outside of the bar. AGB stars are one of the most important dust sources in the LMC, and the dominant gas source outside of the bar. As a consequence of recent increases in the star-formation rate, supernovae are the most important gas source in the LMC bar and around 30 Dor. These differences in dust and gas sources impact on the gas-to-dust ratio and dust properties of the local ISM, because the injection from SNe could have a higher gas-to-dust ratio, resulting in a higher gas-to-dust ratio for the ISM in certain regions of the LMC.