Submillimeter and Mid-Infrared Variability of Young Stellar Objects in the M17SWex Intermediate-Mass Star-Forming Region

TL;DR

This study analyzes the variability of young stellar objects in the M17SWex region using multi-year sub-millimeter and mid-infrared data, revealing different variability patterns and their dependence on evolutionary stage, with fewer variables observed compared to closer regions.

Contribution

It provides the first comprehensive multi-wavelength variability analysis of YSOs in M17SWex, highlighting the importance of long-term monitoring across different star-forming environments.

Findings

Identified three robust sub-mm variables, including candidate YSOs and an extragalactic source.

Detected secular and stochastic mid-IR variability in 47 YSOs, mostly at early stages.

Observed lower overall variability compared to closer star-forming regions, likely due to distance.

Abstract

We present a comprehensive analysis of young stellar object (YSO) variability within the M17 Southwest Extension (M17 SWex), using 3.5 years of monitoring data from the JCMT Transient Survey at sub-millimeter (sub-mm) and 9 years from the NEOWISE mission at mid-infrared (mid-IR). Our study encompasses observations of 147 bright sub-mm peaks identified within our deep JCMT co-added map as well as 156 YSOs in NEOWISE W1 and 179 in W2 that were previously identified in Spitzer surveys. We find three robust sub-mm variables: two are candidate YSOs and one is a likely extragalactic source. At mid-IR wavelengths, our analysis reveals secular and stochastic variability in 47 YSOs, with the highest fraction of secular variability occurring at the earliest evolutionary stage. This is similar to what has previously been observed for low-mass YSO variability within the Gould Belt. However, we observe less overall variability in M17SWex at both the sub-mm and mid-IR. We suspect that this lower fraction is due to the greater distance to M17 SWex. Our findings showcase the utility of multi-wavelength observations to better capture the complex variability phenomena inherent to star formation processes and demonstrate the importance of years-long monitoring of a diverse selection of star-forming environments.