AKARI Near Infrared Spectroscopy: Detection of H2O and CO2 Ices toward Young Stellar Objects in the Large Magellanic Cloud

TL;DR

This study reports the first infrared spectroscopic detection of water and carbon dioxide ices toward young stellar objects in the Large Magellanic Cloud, revealing higher CO2/H2O ratios than in our galaxy.

Contribution

First spectroscopic confirmation of YSOs in the LMC and measurement of their ice composition, highlighting environmental effects on ice chemistry.

Findings

Detected H2O and CO2 ices in LMC YSOs

Measured CO2/H2O ratio of 0.45, higher than in the Milky Way

Suggests UV radiation and dust temperature influence ice composition

Abstract

We present the first results of AKARI Infrared Camera near-infrared spec- troscopic survey of the Large Magellanic Cloud (LMC). We detected absorption features of the H2O ice 3.05 um and the CO2 ice 4.27 um stretching mode toward seven massive young stellar objects (YSOs). These samples are for the first time spectroscopically confirmed to be YSOs. We used a curve-of-growth method to evaluate the column densities of the ices and derived the CO2/H2O ratio to be 0.45 pm 0.17. This is clearly higher than that seen in Galactic massive YSOs (0.17 pm 0.03). We suggest that the strong ultraviolet radiation field and/or the high dust temperature in the LMC may be responsible for the observed high CO2 ice abundance.