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
<Astron. J., 168, 122 (2024)>
=2024AJ....168..122P 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:
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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
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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<l<21 (Contreras+, 2013)
J/AJ/147/82 : Monitoring of disk-bearing stars in NGC 2264 (Cody+, 2014)
J/ApJ/792/30 : NEOWISE magnitudes for near-Earth objects (Mainzer+, 2014)
J/MNRAS/443/1555 : ATLASGAL massive star forming clumps (Urquhart+, 2014)
J/other/PASA/33.30 : MALT90 Catalogue (Rathborne+, 2016)
J/A+A/599/A49 : PMS stars evolutionary models (Kunitomo+, 2017)
J/MNRAS/478/1512 : ALMA calibrator continuum obs. catalog (Bonato+, 2018)
J/MNRAS/495/3614 : IR and sub-mm variability in protostars (Contreras+, 2020)
J/ApJS/254/33 : Gal. midplane Spitzer/IRAC cand. YSOs (SPICY) (Kuhn+, 2021)
J/ApJ/920/132 : NEOWISE 6.5yr variability in YSOs (Park+, 2021)
J/A+A/659/A145 : A WISE view on extreme AGB stars (Groenewegen, 2022)
J/ApJ/929/60 : K-band & smm LCs of the protostar HOPS 373 (Yoon+, 2022)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Rank [1/663] Rank; by brightness
5- 11 A7 --- --- [JCMTPP_]
12- 27 A16 --- JCMTPP JCMT Peak Position (JCMTPP; JHHMMSS.s+DDMMSS)
29- 36 F8.2 mJy/beam Fmean [13/14337] Mean peak flux
38- 43 F6.2 mJy/beam e_Fmean [6.6/216.1] Standard deviation in Fmean
45- 48 F4.2 --- SD/SDfid [0.47/4.11] Ratio of the standard
deviation to the fiducial standard deviation
50- 53 F4.2 --- S/DelS [0.01/5.92] Absolute value of the slope to
its uncertainty ratio
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Byte-by-byte Description of file: tableb1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [1/47] Running sequence number
4- 25 A22 --- ID Identifier (G1)
27- 34 F8.4 deg RAdeg [274.3/275] Right ascension (J2000)
36- 43 F8.4 deg DEdeg [-17.2/-16.5] Declination (J2000)
45- 46 I2 --- Nw1 [15/18] Number of W1 epochs
48- 52 F5.3 mag DelW1mag [0.15/4.44] W1 band differential magnitude
54- 58 F5.3 mag SDW1mag [0.038/1.2] W1 band standard deviation
60- 64 F5.3 mag SigW1mag [0.03/0.3] W1 band σ
66- 72 F7.3 %/yr Sw1 [-20.4/15.8]? W1 best fit linear slope
74- 79 F6.3 yr PerW1 [0.66/13.15]? W1 LSP period for periodic or
curved sources
81- 87 E7.2 --- FAPlinW1 [2.2e-10/1] W1 Linear fit false alarm
probability
89- 95 E7.2 --- FAPlspW1 [3e-09/0.6] W1 Lomb-Scargle periodogram false
alarm probability
97- 105 A9 --- TypeW1 W1 variable type
107- 108 I2 --- Nw2 [15/18] Number of W2 epochs
110- 114 F5.3 mag DelW2mag [0.2/3.4] W2 band differential magnitude
116- 120 F5.3 mag SDW2mag [0.049/0.93] W2 band standard deviation
122- 126 F5.3 mag SigW2mag [0.03/0.25] W2 band σ
128- 134 F7.3 %/yr Sw2 [-17.3/25.2]? W2 best fit linear slope
136- 141 F6.3 yr PerW2 [0.7/13.2]? W2 LSP period for periodic or
curved sources
143- 149 E7.2 --- FAPlinW2 [6e-09/1] W2 linear fit false alarm
probability
151- 157 E7.2 --- FAPlspW2 [3e-08/0.9] W2 Lomb-Scargle periodogram false
alarm probability
159- 167 A9 --- TypeW2 W2 variable type
169- 171 A3 --- Class YSO classification (1)
173 A1 --- Out All sources are presumed to be associated with
M17 SWex, unless marked as "outside" (Y) (G2)
175 A1 --- Corr The Spearman correlation between WISE W1 and
W2 light curves (A=strong correlation) (2)
177 A1 --- f_Corr h: notable differences between the original
and simulated data
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Note (1): Classification as follows:
0/I = Class 0/I object (26 occurrences)
II = Class II object (20 occurrences)
III = Class III object (1 occurrence)
Note (2): Categories are as follows:
A = strong positive correlation,
B = moderate-to-strong positive correlation,
C = weak-to-moderate positive correlation,
D = No or very weak correlation.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tableb2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 I3 --- Seq [1/132] Running sequence number
5- 26 A22 --- ID Identifier (G1)
28- 35 F8.4 deg RAdeg [274.3/275.6] Right ascension (J2000)
37- 44 F8.4 deg DEdeg [-17.2/-16.5] Declination (J2000)
46- 47 I2 --- Nw1 [12/18] Number of W1 epochs
49- 53 F5.3 mag DelW1mag [0.07/2.8] W1 band differential magnitude
55- 59 F5.3 mag SDW1mag [0.02/1.1] W1 band standard deviation
61- 65 F5.3 mag SigW1mag [0.037/0.5] W1 band σ
67- 73 E7.2 --- FAPlinW1 [0.004/1] W1 linear fit false alarm
probability
75- 81 E7.2 --- FAPlspW1 [0.003/1] W1 Lomb-Scargle periodogram false
alarm probability
83- 84 I2 --- Nw2 [12/18] Number of W2 epochs
86- 90 F5.3 mag DelW2mag [0.08/1] W2 band differential magnitude
92- 96 F5.3 mag SDW2mag [0.026/0.25] W2 band standard deviation
98- 102 F5.3 mag SigW2mag [0.038/0.3] W2 band σ
104- 110 E7.2 --- FAPlinW2 [0.0016/1] W2 linear fit false alarm
probability
112- 118 E7.2 --- FAPlspW2 [0.0005/1] W2 Lomb-Scargle periodogram false
alarm probability
120- 128 A9 --- Class YSO classification (1)
130 A1 --- Out All sources are presumed to be associated with
M17 SWex, unless marked as "outside" (Y) (G2)
--------------------------------------------------------------------------------
Note (1): Classification as follows:
0/I = Class 0/I object (36 occurrences)
II = Class II object (89 occurrences)
III = Class III object (4 occurrences)
uncertain = 3 occurrences
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Global notes
Note (G1): All source identifiers are based on designations from two key
references: Kuhn+ (2021, J/ApJS/254/33; 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).
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 27-Nov-2024