J/AJ/170/125 JCMT fluxes & transient statistics of M17 submm YSOs (Chen+, 2025)
Submillimeter and mid-infrared variability of young stellar objects in the M17
HII region.
Chen Z., Johnstone D., Contreras Pena C., Lee J.-E., Liu S.-Y.,
Herczeg G., Mairs S., Park G., Kim K.-T., Kim M.-R., Qiu K., Wang Y.-T.,
Zhang Xu, Reiter M., The JCMT Transient Team
<Astron. J., 170, 125 (2025)>
=2025AJ....170..125C 2025AJ....170..125C
ADC_Keywords: YSOs; Photometry, millimetric/submm; Millimetric/submm sources;
H II regions; Stars, variable; Infrared
Keywords: Young stellar objects ; Protostars ; Variable stars ;
Infrared astronomy ; Submillimeter astronomy ; Time domain astronomy
Abstract:
We conducted a comprehensive analysis of young stellar object (YSO)
variability at submillimeter and mid-infrared (mid-IR) wavelengths for
the M17 HII region using 3.5yr monitoring data from the James Clerk
Maxwell Telescope (JCMT) Transient Survey at 450 and 850um and 9yr
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 850um, 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 3.5yr 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.
Description:
The James Clerk Maxwell Telescope (JCMT) Transient Survey is designed
to measure the submillimeter variability of protostars using the
Submillimetre Common User Bolometer Array 2 (SCUBA2) instrument on the
JCMT at the summit of Maunakea, Hawaii. SCUBA2 observations are
performed simultaneously at 450 and 850um with effective beam sizes
being 10.0±0.6" and 14.4±0.3", or 0.1 and 0.14pc at the distance
of M17, respectively.
SCUBA2 monitoring observations for M17 started on 2020 February 22,
with a monthly cadence as long as the region is visible by JCMT.
During the period from 2020 February to 2023 August, 24 epochs of
observations were carried out.
Objects:
-----------------------------------------------
RA (2000) DE Designation(s)
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18 20 47.00 -16 10 17.9 M17 = HD 168520
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table4.dat 42 198 JCMT transient statistics of bright sources
(>0.65Jy/beam at 450um) in M17
table5.dat 41 164 JCMT transient statistics of bright sources
(>0.14Jy/beam at 850um) in M17
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See also:
II/386 : VPHAS+ DR3 survey (Drew+, 2025)
J/MNRAS/363/405 : SIMBA observations of cold cores (Hill+, 2005)
J/ApJ/644/990 : Sub-mm clumps at 450 and 850µm in M17 (Reid+, 2006)
J/ApJS/175/277 : Submillimeter-Continuum SCUBA detections (Di Francesco+, 2008)
J/A+A/481/345 : SED evolution in massive young stellar obj. (Molinari+, 2008)
J/ApJ/696/1278 : The extended star-forming environment of M17 (Povich+, 2009)
J/ApJ/714/L285 : YSO candidates in M17 SWex (Povich+, 2010)
J/MNRAS/416/178 : 1.2-mm dust clumps with luminous water masers (Breen+, 2011)
J/AJ/144/192 : Spitzer survey of Orion A and B. I. YSO catalog (Megeath+, 2012)
J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)
J/MNRAS/440/2036 : VPHAS+ survey synthetic colours (Drew+, 2014)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/MNRAS/465/3011 : VVV high amplitude NIR var. stars (Contreras Pena+, 2017)
J/A+A/599/A49 : Pre-main sequence stars evolutionary models (Kunitomo+, 2017)
J/AJ/155/99 : IR variab. among YSOs the Serpens South cluster (Wolk+, 2018)
J/ApJ/870/32 : Kinematics in young star clusters & associations (Kuhn+, 2019)
J/MNRAS/495/3614 : IR and sub-mm variability in protostars (Contreras+, 2020)
J/ApJS/254/33 : Gal. midplane Spitzer/IRAC candidate YSOs (SPICY) (Kuhn+, 2021)
J/AJ/162/191 : 2011-2021 calibrator observations of SCUBA-2 (Mairs+, 2021)
J/ApJ/920/132 : NEOWISE 6.5yr variability in YSOs (Park+, 2021)
J/AJ/162/52 : Census of variable stars toward Serpens Main (Yin+, 2021)
J/A+A/657/A131 : Ten new systems with O stars (Maiz Apellaniz+, 2022)
J/MNRAS/510/3389 : High-mass star formation evolution. trends (Urquhart+, 2022)
J/ApJ/930/114 : 44GHz VLA obs. of methanol masers in DR21(OH) (Wenner+, 2022)
J/AJ/168/122 : 3.5yr monitoring of M17 SWex with JCMT & NEOWISE (Park+, 2024)
Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [1/198] Index number (Index)
5- 27 A23 --- ID Source identifier
29- 33 I5 mJy/beam Flux [660/73765] Mean peak flux at 450um
35- 38 I4 mJy/beam Std [85/2184] Standard deviation of peak flux (SD)
40- 42 F3.1 --- NStd [0.5/1.7] Normalized standard deviation of
peak flux (SD/SDfid) (G1)
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/164] Index number (Index)
5- 27 A23 --- ID Source identifier
29- 33 I5 mJy/beam Flux [140/17954] Mean peak flux at 850um
35- 37 I3 mJy/beam Std [10/233] Standard deviation of peak flux (SD)
39- 41 F3.1 --- NStd [0.5/1.8] Normalized standard deviation of
peak flux (SD/SDfid) (G1)
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Global notes:
Note (G1): The normalized standard deviation of peak flux is SD/SDfid,
with SD the standard deviation and SDfid the fiducial SD as proposed by
Johnstone+ (2018ApJ...854...31J 2018ApJ...854...31J).
History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Robin Leichtnam [CDS] 17-Jun-2026