Submillimeter and Mid-infrared Variability of Young Stellar Objects in the M17 H II Region

We conducted a comprehensive analysis of young stellar object (YSO) variability at submillimeter and mid-infrared (mid-IR) wavelengths for the M17 H ii region using 3.5 yr monitoring data from the James Clerk Maxwell Telescope (JCMT) Transient Survey at 450 and 850 μ m and 9 yr mid-IR monitoring data from the NEOWISE mission. Our study encompasses observations of 198 and 164 bright submillimeter peaks identified within the deep JCMT coadded maps at 450 and 850 μ m, and 66 YSOs seen by NEOWISE W2 that were previously identified in mid-IR observations. We find one robust linear submillimeter variable, an intermediate mass protostar, with a 4% peak flux change in 3.5 yr of JCMT monitoring that sets a lower limit of 16% luminosity increase for the source. At mid-IR wavelengths, our analysis reveals secular and stochastic variability in 22 YSOs, with the highest fraction of secular variability occurring at the earliest evolutionary stage. This mid-IR fractional variability as a function of evolutionary stage result is similar to what has previously been found for YSO variability within the Gould Belt and the intermediate-mass star formation region M17 SWex, though overall less variability is detected in M17 in submillimeter and mid-IR. We suspect that this lower detection of YSO variability is due to both the greater distance to M17 and the strong feedback from the H ii region. Our findings showcase the utility of multiwavelength 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.

Abstract licence: CC BY

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