J/ApJ/880/9 Spitzer obs. of YSOs in the SMOG field (Winston+, 2019)
A census of star formation in the outer galaxy: the SMOG field.
Winston E., Hora J., Gutermuth R., Tolls V.
<Astrophys. J., 880, 9 (2019)>
=2019ApJ...880....9W 2019ApJ...880....9W
ADC_Keywords: Photometry, infrared; YSOs; Spectral types; Stars, ages;
Galactic plane
Keywords: circumstellar matter; infrared: stars; stars: formation;
stars: pre-main sequence; stars: protostars
Abstract:
In this paper we undertake a study of the 21deg2 SMOG field, a
Spitzer cryogenic mission Legacy program to map a region of the outer
Milky Way toward the Perseus and outer spiral arms with the IRAC and
MIPS instruments. We identify 4648 YSOs across the field. Using the
DBSCAN method, we identify 68 clusters or aggregations of YSOs in the
region, having eight or more members. We identify 1197 Class I
objects, 2632 Class II objects, and 819 Class III objects, of which 45
are candidate transition disk objects, utilizing the MIPS 24
photometry. The ratio of YSOs identified as members of clusters was
2872/4648, or 62%. The ratios of Class I to Class II YSOs in the
clusters are broadly consistent with those found in the inner Galactic
and nearby Gould Belt young star formation regions. The clustering
properties indicate that the protostars may be more tightly bound to
their natal sites than the Class II YSOs, and the Class III YSOs are
generally widely distributed. We further perform an analysis of the
WISE data of the SMOG field to determine how the lower resolution and
sensitivity of WISE affects the identification of YSOs as compared to
Spitzer: we identify 931 YSOs using combined WISE and 2MASS
photometry, or 20% (931/4648) of the total number identified with
Spitzer. Performing the same clustering analysis finds 31 clusters
that reliably trace the larger associations identified with the
Spitzer data. Twelve of the clusters identified have previously
measured distances from the WISE HII survey. SEDFitter modeling of
these YSOs is reported, leading to an estimation of the initial mass
function in the aggregate of these clusters that approximates that
found in the inner Galaxy, implying that the processes behind stellar
mass distribution during star formation are not widely affected by the
lower density and metallicity of the outer Galaxy.
Description:
The Spitzer Mapping of the Outer Galaxy (SMOG; Prog. ID 50398) survey
was a Spitzer Cryogenic Cycle 5 program to map a 3°x7° region
of the outer Milky Way with IRAC and MIPS. The field covers 21deg2
over 102°<l<109° and 0°<b<3°, covering the FWHM of the
gas disk at R∼20kpc, and tracing the warp of the Galactic plane in the
second quadrant. The IRAC data were taken from January 26, 2009 to
February 2, 2009. The MIPS data were taken from August 25, 2008 to
August 28, 200
The SMOG data products, including mosaics and point-source archive,
were downloaded from the Infrared Science Archive (IRSA).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 274 4648 SMOG field young stellar objects: photometry table
table2.dat 87 191 SMOG field young stellar objects: SIMBAD matches
within 1 arcsec
table3.dat 9914 68 SMOG field young stellar objects: clusters
table5.dat 256 712 SMOG field young stellar objects: SED fitter results
table7.dat 168 931 SMOG field young stellar objects: WISE photometry
--------------------------------------------------------------------------------
See also:
VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
J/ApJ/669/493 : Spitzer/Chandra YSOs in Serpens cloud core (Winston+, 2007)
J/ApJ/674/336 : Spitzer observations of NGC 1333 (Gutermuth+, 2008)
J/AJ/136/2413 : Galactic midplane Spitzer red sources (Robitaille+, 2008)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/AJ/137/4810 : LMC-SAGE AGB star candidates (Srinivasan+, 2009)
J/AJ/140/266 : NGC 1333 X-ray luminous YSOs properties (Winston+, 2010)
J/ApJ/743/166 : X-ray and infra-red study of RCW 38 (Winston+, 2011)
J/MNRAS/430/1125 : RMS survey: NIR spectroscopy of massive YSOs (Cooper+, 2013)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/ApJS/220/11 : SEDs of Spitzer YSOs in the Gould Belt (Dunham+, 2015)
J/ApJ/827/96 : WISE census of YSOs in Canis Major (Fischer+, 2016)
J/ApJ/839/108 : YSOs in the star-forming regions W51 & W43 (Saral+, 2017)
J/A+A/620/A27 : Taurus ultra-wide pairs. II. (Joncour+, 2018)
J/ApJS/240/26 : YSO cand. in Canis Major OB1 association (Sewilo+, 2019)
http://irsa.ipac.caltech.edu/data/SPITZER/GLIMPSE/overview.html : Spitzer data
covering the Galactic Plane on IRSA
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Field SMOG field identifier (SRC0 to SRC4647)
9- 16 A8 --- --- [SSTSMOGA]
18- 34 A17 --- ID GLIMPSE identifier from SMOG Archive
(GLLL.llll+BB.bbbb)
36- 51 A16 --- 2MASS 2MASS identifier (HHMMSSss+DDMMSSs; J2000) if any
53- 62 F10.6 deg RAdeg [327.96/346.45] Right Ascension (J2000)
64- 72 F9.6 deg DEdeg [56.49/62.34] Declination (J2000)
74 I1 --- I-Det [0/1] IRAC photometry selection code
(1=selected)
76 I1 --- M-Det [0/1] MIPS photometry selection code
(1=selected)
78 I1 --- U-Det [0/1] UKIRT photometry selection code
(1=selected)
80- 85 F6.3 mag J2mag [5.63/17.26]? 2MASS J band magnitude
87- 91 F5.3 mag e_J2mag [0.018/0.53]? Uncertainty in J2mag
93- 98 F6.3 mag H2mag [4.58/16.2]? 2MASS H band magnitude
100-104 F5.3 mag e_H2mag [0.017/0.27]? Uncertainty in H2mag
106-111 F6.3 mag Ks2mag [3.99/15.78]? 2MASS Ks band magnitude
113-117 F5.3 mag e_Ks2mag [0.015/10]? Uncertainty in Ks2mag
119-125 F7.3 mag JUmag [0/20.23]?=-99.999 UKIRT J band magnitude
127-133 F7.3 mag e_JUmag [0/0.3]?=-99.999 Uncertainty in JUmag
135-141 F7.3 mag HUmag [0/19.4]?=-99.999 UKIRT H band magnitude
143-149 F7.3 mag e_HUmag [0/0.2]?=-99.999 Uncertainty in HUmag
151-156 F6.3 mag KUmag [9/18]?=0 UKIRT K band magnitude
158-162 F5.3 mag e_KUmag [0.001/0.2]?=0 Uncertainty in KUmag
164-170 F7.3 mag 3.6mag [3.6/17.5]?=-99.999 Spitzer/IRAC 3.6um magnitude
172-178 F7.3 mag e_3.6mag [0.02/0.3]?=-99.999 Uncertainty in 3.6mag
180-186 F7.3 mag 4.5mag [3.6/16.7]?=-99.999 Spitzer/IRAC 4.5um magnitude
188-194 F7.3 mag e_4.5mag [0.015/0.21]?=-99.999 Uncertainty in 4.5mag
196-202 F7.3 mag 5.8mag [3.3/15]?=-99.999 Spitzer/IRAC 5.8um magnitude
204-210 F7.3 mag e_5.8mag [0.014/0.21]?=-99.999 Uncertainty in 5.8mag
212-218 F7.3 mag 8.0mag [3.1/14.1]?=-99.999 Spitzer/IRAC 8um magnitude
220-226 F7.3 mag e_8.0mag [0.013/0.22]?=-99.999 Uncertainty in 8.0mag
228-233 F6.3 mag 24mag [0.37/11.4]? Spitzer/MIPS 24um band magnitude
235-239 F5.3 mag e_24mag [0/0.61]? Uncertainty in 24mag
241-247 F7.3 --- alpha-I [-11/14.1] SED slope from IRAC photometry
249-255 F7.3 --- alpha-M [-11/14.1] SED slope from IRAC+MIPS photometry
257-259 F3.1 --- Class-I [1/3] Evolutionary class: IRAC bands
261-263 F3.1 --- Class-M [1/3] Evolutionary class: IRAC+MIPS bands
265-267 F3.1 --- Class-T [0/2.3] Evolutionary class: Transition
Disk Candidate
269-270 I2 --- Seq [0/67]?=-1 Number of cluster (as in Table 3)
containing YSO
272-274 I3 --- SubC [0/16]?=-1 Number of subcluster containing YSO
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Field SMOG field identifier
9- 16 A8 --- --- [SSTSMOGA]
18- 34 A17 --- ID GLIMPSE identifier from SMOG Archive
(GLLL.llll+BB.bbbb)
36- 60 A25 --- Simbad Simbad identifier
62- 75 A14 --- OType Simbad object classification type
77- 87 A11 --- SpType Simbad spectral type
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 I2 --- Seq [0/67] Internal cluster index number
4- 15 A12 --- Name Cluster identifier (GLLL.ll+B.bb)
17- 19 I3 --- YSO [8/428] Number of YSOs in the cluster
21- 22 I2 --- SubC [0/17] Subcluster number
24- 36 F13.9 deg RAdeg [328.18/346.17] Right Ascension (J2000)
38- 50 F13.10 deg DEdeg [57.5/62.1] Declination (J2000)
52- 56 F5.3 deg Rad [0.03/0.81] Circular radius
58- 62 F5.3 deg Len [0.01/0.08] Branch length
65- 181 A117 --- WISE WISE H II sources (1)
184-9914 A9731 --- Simbad Simbad sources (1)
--------------------------------------------------------------------------------
Note (1): Where the sources are comma delimited.
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 7 A7 --- Field SMOG Field ID (SRC6 to SRC4634)
9- 10 I2 --- Seq [0/66] Cluster number as in Table 3
12- 14 F3.1 kpc Dist [2.5/7.8] Distance
16 I1 --- Np [3/8] Number of data points
18- 22 F5.3 --- chi2 [0/3] Model χ2 value
24- 28 F5.3 --- e_chi2 [0/3] Lower uncertainty in chi2
30- 35 F6.3 --- E_chi2 [8.9/26.7] Upper uncertainty in chi2
37- 42 F6.3 mag Av [0/40] Extinction in the V band
44- 49 F6.3 mag e_Av [0/24.63] Lower uncertainty in Av
51- 56 F6.3 mag E_Av [5.3/40] Upper uncertainty in Av
58- 63 F6.3 Msun M* [0.1/13.6] Stellar mass
65- 69 F5.3 Msun e_M* [0.1/5.2] Lower uncertainty in M*
71- 76 F6.3 Msun E_M* [1.2/27.4] Upper uncertainty in M*
78- 86 E9.3 yr Age [1078/9891000] Age
88- 96 E9.3 yr e_Age [1008/1523000] Lower uncertainty in Age
98-106 E9.3 yr E_Age [212500/9988000] Upper uncertainty in Age
108-116 E9.3 Msun Md [3.5e-9/0.21] Disk mass
118-126 E9.3 Msun e_Md [0/0.0012] Lower uncertainty in Md
128-136 E9.3 Msun E_Md [0.0019/1.3] Upper uncertainty in Md
138-146 E9.3 Msun Menv [1.3/18.1]? Stellar envelope mass
148-156 E9.3 Msun e_Menv [1.1/5.7]? Lower uncertainty in Menv
158-166 E9.3 Msun E_Menv [3.8/30.2] Upper uncertainty in Menv
168-176 E9.3 Msun/yr Mdot [0/0.005] Accretion rate
178-186 E9.3 Msun/yr e_Mdot [0/2.5e-05] Lower uncertainty in Mdot
188-196 E9.3 Msun/yr E_Mdot [0/0.009] Upper uncertainty in Mdot
198-206 E9.3 K T* [2626/21850] Stellar temperature
208-216 E9.3 K e_T* [2536/10800] Lower uncertainty in T*
218-226 E9.3 K E_T* [4430/30680] Upper uncertainty in T*
228-236 E9.3 Lsun L* [0.2/3961] Stellar total luminosity
238-246 E9.3 Lsun e_L* [0.07/529] Lower uncertainty in L*
248-256 E9.3 Lsun E_L* [2.9/30990] Upper uncertainty in L*
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- WISE WISE identifier (JHHMMSS.ss+DDMMSS.s)
21- 28 A8 --- --- [SSTSMOGA]
30- 46 A17 --- ID GLIMPSE identifier from SMOG Archive
(GLLL.llll+BB.bbbb)
48- 58 F11.7 deg RAdeg [328.54/346.54] Right Ascension (J2000)
60- 69 F10.7 deg DEdeg [56.49/62.3] Declination (J2000)
71- 76 F6.3 mag J2mag [7.271/18.63]? 2MASS J band magnitude
78- 82 F5.3 mag e_J2mag [0.018/0.3]? Uncertainty in J2mag
84- 89 F6.3 mag H2mag [5.9/17.2]? 2MASS H band magnitude
91- 95 F5.3 mag e_H2mag [0.015/0.4]? Uncertainty in H2mag
97-102 F6.3 mag Ks2mag [5.3/15.4]? 2MASS Ks band magnitude
104-108 F5.3 mag e_Ks2mag [0.015/0.2]? Uncertainty in Ks2mag
110-115 F6.3 mag 3.5mag [5/15.3] WISE W1 (3.5 micron) band magnitude
117-121 F5.3 mag e_3.5mag [0.01/0.3] Uncertainty in 3.5mag
123-128 F6.3 mag 4.6mag [3.74/13.6] WISE W2 (4.6 micron) band magnitude
130-134 F5.3 mag e_4.6mag [0.007/0.2] Uncertainty in 4.6mag
136-141 F6.3 mag 12mag [1.13/10] WISE W3 (12 micron) band magnitude
143-147 F5.3 mag e_12mag [0.006/0.51] Uncertainty in 12mag
149-154 F6.3 mag 22mag [-1.51/9.2] WISE W4 (22 micron) band magnitude
156-160 F5.3 mag e_22mag [0.005/0.5]? Uncertainty in 22mag
162-164 F3.1 --- Class [1/2.3] Evolutionary classification
166-168 F3.1 --- IRAC [0/1] Also detected as an IRAC source (1=yes)
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 18-Dec-2020