Discovery of Extreme Carbon Stars in the Large Magellanic Cloud

TL;DR

This study identifies and characterizes 13 extreme carbon stars in the Large Magellanic Cloud using infrared observations, revealing their unique spectral features, high luminosities, and significant mass-loss rates, challenging existing models of dust and mass loss in low-metallicity environments.

Contribution

First identification and detailed spectral analysis of extreme carbon stars in the LMC, providing new insights into their properties and mass-loss processes.

Findings

13 extreme carbon stars identified in the LMC

High mass-loss rates between 4x10^-5 and 2x10^-4 Msol/yr

Spectral features indicating unique dust and molecular compositions

Abstract

Using Spitzer IRAC and MIPS observations of the Large Magellanic Cloud, we have identified 13 objects that have extremely red mid-IR colors. Follow-up Spitzer IRS observations of seven of these sources reveal varying amounts of SiC and C2H2 absorption as well as the presence of a broad MgS feature in at least two cases, indicating that these are extreme carbon stars. Preliminary estimates find these objects have luminosities of 4-11x10^3 Lsol and preliminary model fitting gives mass-loss rates between 4x10^-5 and 2x10^-4 Msol/yr, higher than any known carbon-rich AGB star in the LMC. These spectral and physical properties require careful reconsideration of dust condensation and mass-loss processes for carbon stars in low metallicity environments.