J/AJ/168/122 3.5yr monitoring of M17 SWex with JCMT & NEOWISE (Park+, 2024) ================================================================================ Submillimeter and mid-infrared variability of young stellar objects in the M17SWex intermediate-mass star-forming region. Park G., Johnstone D., Pena C.C., Lee J.-E., Liu S.-Y., Herczeg G., Mairs S., Chen Z., Hatchell J., Kim K.-T., Kim M.-R., Qiu K., Wang Y.-T., Zhang Xu, The JCMT Transient Team =2024AJ....168..122P ================================================================================ ADC_Keywords: Molecular clouds; Photometry, millimetric/submm; Photometry, infrared; YSOs; Star Forming Region Keywords: Star formation ; Star forming regions ; Young stellar objects ; Protostars ; Pre-main sequence stars ; Variable stars ; Infrared astronomy ; Submillimeter astronomy Abstract: We present a comprehensive analysis of young stellar object (YSO) variability within the M17 Southwest Extension (M17 SWex), using 3.5yr of monitoring data from the James Clerk Maxwell Telescope (JCMT) Transient Survey at submillimeter and 9yr from the NEOWISE mission at mid-infrared (mid-IR). Our study encompasses observations of 147 bright submillimeter peaks identified within our deep JCMT coadded map as well as 156 YSOs in NEOWISE W1 and 179 in W2 that were previously identified in Spitzer surveys. We find three robust submillimeter 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 M17 SWex at both the submillimeter and mid-IR. We suspect that this lower fraction is due to the greater distance to M17 SWex. 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. Description: The primary aim of the James Clerk Maxwell Telescope (JCMT) Transient Survey is to measure the submillimeter variability of protostars using the Submillimetre Common User Bolometer Array 2 (SCUBA-2) instrument on the JCMT in Hawaii. In 2020, the program expanded to also include monitoring of fields within four massive star-forming regions (DR21, M17, M17 SWex, and S255). Observations are conducted simultaneously at 450 and 850um with effective beam sizes of 9.8" and 14.6", respectively. The final data set for this paper consists of 23 epochs of SCUBA-2 850um imaging of M17 SWex from 2020 February until 2023 August. From 2010 January through September, the Wide-field Infrared Survey Explorer (WISE) surveyed the entire sky using four mid-IR bands at 3.4um (W1), 4.6um (W2), 12um (W3), and 22um (W4) with angular resolutions of 6.1", 6.4", 6.5", and 12", respectively. The Near-Earth Object WISE (NEOWISE) continues to operate, with twice-yearly all-sky observations after 2013. The data release used here contains observations through 2022 December. Objects: ---------------------------------------------------------- RA (ICRS) DE Designation(s) ---------------------------------------------------------- 18 18 30 -16 51 24 M17 SWex = NAME M17 SWex ---------------------------------------------------------- File Summary: -------------------------------------------------------------------------------- FileName Lrecl Records Explanations -------------------------------------------------------------------------------- ReadMe 80 . This file tablea1.dat 53 663 Statistics of all submillimeter sources tableb1.dat 177 47 Properties of NEOWISE light curves for potential variable mid-infrared sources tableb2.dat 130 132 Statistics of NEOWISE light curves for nonvariable mid-infrared sources -------------------------------------------------------------------------------- See also: VIII/65 : 1.4GHz NRAO VLA Sky Survey (NVSS) (Condon+ 1998) II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008) II/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012) II/328 : AllWISE Data Release (Cutri+ 2013) J/AJ/121/3160 : JHK photometry near the Trapezium region (Carpenter+, 2001) J/A+A/479/827 : UBVR LCs of weak-line T Tauri stars (Grankin+, 2008) J/AJ/140/2025 : KH 15D (V582 Mon) VI light curves (Herbst+, 2010) J/ApJ/714/L285 : YSO candidates in M17 SWex (Povich+, 2010) J/AJ/142/35 : The VLBA Galactic Plane Survey (VGaPS) (Petrov+, 2011) J/A+A/557/A77 : VR light curves of AA Tau in 2007-2013 (Bouvier+, 2013) J/A+A/549/A45 : ATLASGAL Compact Source Catalog: 330 in Simbad) and Povich & Whitney (2010, J/ApJ/714/L285; <[PW2010] NNN> in Simbad). Kuhn+ (2021) utilize the SPICY (Spitzer/IRAC Candidate YSO) numbering system, while Povich & Whitney (2010) refer to sources by their GLIMPSE Archive (GLMA) coordinates. SPICY IDs are numerical, whereas GLMA IDs are presented in a Galactic coordinate format. Note (G2): In accordance with the determinations by Kuhn+ (2021, J/ApJS/254/33). -------------------------------------------------------------------------------- History: From electronic version of the journal ================================================================================ (End) Prepared by [AAS], Emmanuelle Perret [CDS] 27-Nov-2024