A survey of H$_2$O, CO$_2$ and CO ice features towards background stars and low mass YSOs using AKARI

TL;DR

This study uses AKARI satellite data to analyze ice features in molecular clouds and YSOs, revealing variations in ice profiles and providing data to understand initial star formation conditions.

Contribution

It introduces a new pipeline for near-infrared spectra analysis and presents the first comprehensive survey of H$_2$O, CO$_2$, and CO ice features towards background stars and YSOs.

Findings

H$_2$O ice profile varies across objects

Extended red wing may indicate evolutionary stage

Data helps benchmark initial conditions in star formation

Abstract

We present near infrared spectroscopic observations of 19 molecular clouds made using the AKARI satellite, and the data reduction pipeline written to analyse those observations. The 2.5 --~5 $\mu$m spectra of 30 objects -- 22 field stars behind quiescent molecular clouds and eight low mass YSOs in cores -- were successfully extracted using the pipeline. Those spectra are further analysed to calculate the column densities of key solid phase molecular species, including H$_2$O, CO$_2$, CO, and OCN$^-$. The profile of the H$_2$O ice band is seen to vary across the objects observed and we suggest that the extended red wing may be an evolutionary indicator of both dust and ice mantle properties. The observation of 22 spectra with fluxes as low as $<$~5 mJy towards background stars, including 15 where the column densities of H$_2$O, CO and CO$_2$ were calculated, provides valuable data that could help to benchmark the initial conditions in star-forming regions prior to the onset of star formation.