2025AJ....170..125C

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 μm 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 μm, 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.