J/ApJS/254/33 Gal. midplane Spitzer/IRAC candidate YSOs (SPICY) (Kuhn+, 2021)
SPICY: the Spitzer/IRAC candidate YSO catalog for the inner Galactic midplane.
Kuhn M.A., de Souza R.S., Krone-Martins A., Castro-Ginard A., Ishida E.E.O.,
Povich M.S., Hillenbrand L.A. (The COIN Collaboration)
<Astrophys. J. Suppl. Ser., 254, 33 (2021)>
=2021ApJS..254...33K 2021ApJS..254...33K
ADC_Keywords: YSOs; Cross identifications; Photometry, infrared; Galactic plane;
Photometry, RI; Proper motions; Associations, stellar; Surveys
Keywords: Young stellar objects ; Milky Way disk ; Star formation ;
Star forming regions ; Stellar associations
Abstract:
We present ∼120000 Spitzer/IRAC candidate young stellar objects (YSOs)
based on surveys of the Galactic midplane between l∼255° and
110°, including the GLIMPSE I, II, and 3D, Vela-Carina, Cygnus X,
and SMOG surveys (613 square degrees), augmented by near-infrared
catalogs. We employed a classification scheme that uses the
flexibility of a tailored statistical learning method and curated YSO
data sets to take full advantage of Spitzer's spatial resolution and
sensitivity in the mid-infrared ∼3-9µm range. Multiwavelength
color/magnitude distributions provide intuition about how the
classifier separates YSOs from other red IRAC sources and validate
that the sample is consistent with expectations for
disk/envelope-bearing pre-main-sequence stars. We also identify areas
of IRAC color space associated with objects with strong silicate
absorption or polycyclic aromatic hydrocarbon emission. Spatial
distributions and variability properties help corroborate the youthful
nature of our sample. Most of the candidates are in regions with
mid-IR nebulosity, associated with star-forming clouds, but others
appear distributed in the field. Using Gaia DR2 distance estimates, we
find groups of YSO candidates associated with the Local Arm, the
Sagittarius-Carina Arm, and the Scutum-Centaurus Arm. Candidate YSOs
visible to the Zwicky Transient Facility tend to exhibit higher
variability amplitudes than randomly selected field stars of the same
magnitude, with many high-amplitude variables having light-curve
morphologies characteristic of YSOs. Given that no current or planned
instruments will significantly exceed IRAC's spatial resolution while
possessing its wide-area mapping capabilities, Spitzer-based catalogs
such as ours will remain the main resources for mid-infrared YSOs in
the Galactic midplane for the near future.
Description:
We cross-match our YSO candidates to the Zwicky Transient Facility
(ZTF) DR3 (Masci+ 2019PASP..131a8003M 2019PASP..131a8003M) catalog using a match radius of
1", and use ZTF sources with at least 10 measurements in the r band
between 2018 April and 2019 June, excluding observations from the
high-cadence deep-drilling program; the median number of observations
is ∼130. This yields 7585 YSO candidates with usable ZTF light curves.
See Section 8.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 413 117446 Spitzer/IRAC Candidate YSOs (SPICY)
table2.dat 81 406 *YSO groups from HDBSCAN
fig25.dat 239 1045306 ZTF light curves for 7585 YSO candidates
showing strong variability
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Note on table2.dat: We choose the algorithm "Hierarchical Density-Based Spatial
Clustering of Applications with Noise" (HDBSCAN; Campello R. J.,
Moulavi D. and Sander J. 2013 Pacific-Asia Conf. on Knowledge
Discovery and Data Mining ed J. Pei et al (Berlin: Springer) 160).
See Section 7.
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
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)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
II/360 : Gaia DR2 x AllWISE catalogue (Marton+, 2019)
II/364 : VIRAC. The VVV Infrared Astrometric Catalogue (Smith+, 2019)
II/368 : The Spitzer (SEIP) source list (SSTSL2) (Spitzer Science Center, 2021)
J/ApJ/670/428 : Bubbles in the galactic disk. II. (Churchwell+, 2007)
J/ApJ/663/1149 : Spitzer survey of Serpens YSO population (Harvey+, 2007)
J/ApJ/669/327 : S3MC: YSOs in N66, in SMC (Simon+, 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/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)
J/ApJS/184/18 : Spitzer survey of young stellar clusters (Gutermuth+, 2009)
J/ApJ/706/83 : Embedded YSO candidates in W51 (Kang+, 2009)
J/ApJ/693/L81 : Extinction in star-forming regions (McClure, 2009)
J/ApJ/696/1278 : The extended star-forming environment of M17 (Povich+, 2009)
J/AJ/138/1116 : A Spitzer view of NGC 2264 (Sung+, 2009)
J/ApJ/720/679 : Optical spectroscopy in Cygnus X region (Beerer+, 2010)
J/ApJ/714/778 : YSOs in the Serpens Molecular Cloud (Oliveira+, 2010)
J/ApJS/194/14 : A Pan-Carina YSO catalog (Povich+, 2011)
J/ApJS/193/25 : The NAN complex. II. MIPS observations (Rebull+, 2011)
J/MNRAS/424/2442 : Catalog of bubbles from Milky Way Project (Simpson+, 2012)
J/ApJS/208/11 : Red MSX Source Survey: massive protostars (Lumsden+, 2013)
J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)
J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)
J/A+A/566/A122 : JHK and IRAC photometry of Sh2-90 YSOs (Samal+, 2014)
J/A+A/578/A51 : Near-IR photometry of AGB stars in IC 1613 (Chun+, 2015)
J/AJ/149/64 : MIPSGAL 24µm point source catalog (Gutermuth+, 2015)
J/ApJ/802/60 : Structure of young stellar clusters. II. (Kuhn+, 2015)
J/MNRAS/447/2307 : Galactic HII region IRAS 16148-5011 content (Mallick+, 2015)
J/MNRAS/458/3479 : SVM selection of WISE YSO Candidates (Marton+, 2016)
J/MNRAS/465/3011 : VVV high amplitude NIR var. stars (Contreras Pena+, 2017)
J/A+A/597/A90 : rho Oph proper motions and photometry (Ducourant+, 2017)
J/A+A/617/A33 : HRS sample, dust, gas mass functions (Andreani+, 2018)
J/MNRAS/473/3671 : Galactic bubble infrared fluxes (Bufano+, 2018)
J/AJ/156/71 : K2 Campaign 2: young disk-bearing stars (Cody+, 2018)
J/ApJS/236/27 : APOGEE-2 survey of Orion Complex (OSFC). I. (Cottle+, 2018)
J/AJ/156/271 : The stellar membership of the Taurus SFR (Luhman, 2018)
J/A+A/620/A172 : Solar neighbourhood young stars 3D mapping (Zari+, 2018)
J/ApJ/878/111 : Members in Serpens with Gaia DR2 (Herczeg+, 2019)
J/MNRAS/488/1141 : MW Project DR2 bubbles & bow shocks (Jayasinghe+, 2019)
J/AJ/158/122 : Local structure & SFH of the MW (Kounkel+, 2019)
J/ApJ/880/9 : Spitzer obs. of YSOs in the SMOG field (Winston+, 2019)
J/A+A/635/A45 : New open clusters in Galactic disc (Castro-Ginard+, 2020)
J/AJ/160/279 : Untangling the Galaxy. II. within 3kpc (Kounkel+, 2020)
J/AJ/159/200 : YSOs in Lupus star-forming region (Melton, 2020)
J/A+A/633/A51 : Distances to molecular clouds in SFR (Zucker+, 2020)
J/ApJS/249/18 : The ZTF catalog of periodic variable stars (Chen+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 I6 --- SPICY [1/117446]? SPICY designation
8- 17 F10.6 deg RAdeg [125.6/346.5] Right ascension (ICRS)
19- 28 F10.6 deg DEdeg [-64/62.4] Declination (ICRS)
30- 39 F10.6 deg GLON Galactic longitude (GLON)
41- 49 F9.6 deg GLAT Galactic latitude (GLAT)
51- 58 F8.6 --- p1 [0/1]? YSO random forest score from
IRAC+2MASS photometry (1)
60- 67 F8.6 --- p2 [0/1]? YSO random forest score from
IRAC+UKIDSS photometry (1)
69- 76 F8.6 --- p3 [0/1]? YSO random forest score from IRAC+VVV
photometry (1)
78- 86 A9 --- class YSO class (2)
88 I1 --- Si [0/1] Flag for a possible strong silicate
feature (silicate)
90 I1 --- PAH [0/1] Flag for a possible strong PAH feature
92-113 D22.15 --- alpha [-3.1/6.1]? Spectral index used for YSO
class (3)
115- 125 F11.8 --- alpha8 [-2.4/6.1]? Spectral index derived from the
[4.5]-[8.0] color (alpha8)
127- 137 F11.8 --- alpha24 [-3.1/3.2]? Spectral index derived from the
[4.5]-[24] color (alpha24)
139- 149 F11.8 --- alphaW4 [-2.3/3.5]? Spectral index derived from the
[4.5]-W4 color (alphaW4)
151- 157 A7 --- Env Classification of the YSO environment from
the 3'x3' IRAC cutout (4)
159- 168 A10 --- Group HDBSCAN group (as in Table 2) to which
the star is assigned
170 I1 --- var [1/3]? ZTF light-curve variability flag
(3=high variability) (5)
172- 174 I3 --- o_ZTFrmag [10/319]? Number of good ZTF r-band
observations used (n_ZTFrmag)
176- 182 F7.4 --- ZTFrmag [12.4/21.5]? ZTF mean magnitude in the r-band
184- 189 F6.4 --- e_ZTFrmag [0.009/1.2]? ZTF light-curve σvar
standard deviation in the rband
191- 197 F7.4 --- skew [-10/11.1]? ZTF light-curve skew in the rband
(skewness)
199- 224 A26 --- Spitzer Spitzer source designation from GLIMPSE
("SSTCYGXC", "SSTGLMC", "SSTSMOGC" or
"SSTVELC" sources)
226- 231 F6.3 mag 3.6mag [7/17] Spitzer/IRAC 3.6um band magnitude
233- 237 F5.3 mag e_3.6mag [0.016/0.4] Uncertainty on the 3.6mag
239- 244 F6.3 mag 4.5mag [6.5/14.5] Spitzer/IRAC 4.5um band magnitude
246- 250 F5.3 mag e_4.5mag [0.014/0.4] Uncertainty on the 4.5mag
252- 257 F6.3 mag 5.8mag [4.5/14.1]? Spitzer/IRAC 5.8um band magnitude
259- 263 F5.3 mag e_5.8mag [0.01/0.4]? Uncertainty on the 5.8mag
265- 270 F6.3 mag 8.0mag [4/13.3]? Spitzer/IRAC 8um band magnitude
272- 276 F5.3 mag e_8.0mag [0.009/0.4]? Uncertainty on the 8.0mag
278 I1 --- csf [0/2]? GLIMPSE close source flag (6)
280- 281 I2 --- o_3.6mag [1/24]? Number of detections in the 3.6um
band (n_3.6mag)
283- 284 I2 --- o_4.5mag [1/18]? Number of detections in the 4.5um
band (n_4.5mag)
286- 287 I2 --- o_5.8mag [0/24]? Number of detections in the 5.8um
band (n_5.8mag)
289- 290 I2 --- o_8.0mag [0/20]? Number of detections in the 8.0um
band (n_8.0mag)
292- 307 A16 --- 2MASS 2MASS source name (HHMMSSss+DDMMSSs; J2000)
309- 327 A19 --- UKIDSS UKIDSS source designation (JHHMMSS.ss+DDMMSS.s)
329- 337 I9 --- VIRAC ? VIRAC DR1 source designation
339- 357 I19 --- GaiaDR2 ? Gaia DR2 source designation
359- 376 A18 --- MIPS Spitzer/MIPS source designation
378- 396 A19 --- WISEA AllWISE source designation
(JHHMMSS.ss+DDMMSS.s) (AllWISE)
398- 413 I16 --- ZTFDR3 ? ZTF DR3 source designation
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Note (1): Random forest scores range from 0 to 1, where higher scores indicate
a greater chance that an object is a YSO. We include sources with
scores >0.5 from one of the classifiers.
Note (2): Candidate YSO classes are as follows:
ClassI = Class I YSO (α>0.3; 15943 occurrences)
FS = flat SED YSO (0.3≤α<-0.3; 23810 occurrences)
ClassII = Class II YSO (-0.3≤α<-1.6, stars with disks;
59949 occurrences)
ClassIII = Class III YSO (α≤-1.6, systems where the disk has mostly
dispersed; 5352 occurrences)
uncertain = candidate YSOs with uncertain classes due to missing
photometry (12392 occurrences)
Note (3): This α combines the results from Columns alpha8, alpha24 and
alphaW4 as described in Section 5.5.
Note (4): The environment classes are as follows:
EnvI = no or minimal nebulosity (32790 occurrences),
EnvII = mixed category (15462 occurrences),
EnvIII = cloud-like environment (66539 occurrences),
Outlier = (2433 occurrences)
Note (5): Variability code as follows:
1 = weak or statistically insignificant variability (4976 occurrences),
2 = moderate variability (914 occurrences),
3 = high variability (1695 occurrences).
Note (6): GLIMPSE code from II/293 as follows:
0 = no Archive source within 3.0" of the source
1 = Archive sources between 2.5" and 3.0" of the source
2 = Archive sources between 2.0" and 2.5" of the source
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 10 A10 --- Group Group designation (GLL.l+B.b)
12- 20 F9.5 deg GLON Central Galactic longitude (l0) (1)
22- 29 F8.5 deg GLAT [-2.62/3.63] Central Galactic latitude (b0) (1)
31- 35 F5.3 mas plx [0.05/1.7]? Mean parallax (1)
37- 41 F5.3 mas e_plx [0.04/0.7]? Parallax uncertainty (1)
43- 49 F7.3 --- pmGLON [-14/1]? Mean proper motion in GLON (pml) (1)
51- 56 F6.3 --- e_pmGLON [0.07/3.1]? pmGLON uncertainty (e_pml) (1)
58- 64 F7.3 --- pmGLAT [-4.3/6.6]? Mean proper motion in GLAT (pmb) (1)
66- 70 F5.3 --- e_pmGLAT [0.07/2.6]? pmGLAT uncertainty (e_pmb) (1)
72- 75 I4 --- Ntot [30/3662]? Total number of constituents (n)
77- 79 I3 --- N5G [0/412]? Number of constituents with
five-parameter Gaia astrometric solutions (nG)
81 A1 --- Flag [f] Flag for potential model problems
(see Section 7.1)
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Note (1): Median astrometric properties, including group parallax and proper
motion, are inferred from the hierarchical Bayesian modeling of the
Gaia DR2 astrometry. The group parallaxes and proper motions in this
table are in the Gaia DR2 system, with no correction for zero-point
offsets. We report formal (MAD) uncertainties from our model added in
quadrature to the ±0.04mas and ±0.07mas/yr spatially correlated
systematic errors on DR2 zero points (Lindegren+ 2018A&A...616A...2L 2018A&A...616A...2L).
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Byte-by-byte Description of file: fig25.dat
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Bytes Format Units Label Explanations
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1- 16 I16 --- ID ? Object identifier (oid)
18- 26 I9 --- ExpID [44350541/109212187]? Exposure ID
28- 43 F16.8 d HJD Heliocentric Julian Date
45- 57 F13.7 d MJD [58197.5/58846.2] Modified Julian Date
(HJD-24000000.5)
59- 65 F7.4 mag mag [12.22/22.23] ZTF magnitude
67- 72 F6.4 mag e_mag [0/0.5] Uncertainty in mag (magerr)
74- 77 I4 --- Flags [0/4352]? Catalog flags for source from
PSF-fitting catalog (catflags)
79- 80 A2 --- Filt [zr] Catalog filter code; always "zr" = R-band
observations (filtercode)
82- 92 F11.7 deg RAdeg Right ascension (J2000) (ra)
94- 104 F11.7 deg DEdeg Declination (J2000) (dec)
106- 111 F6.3 --- chi2 [0.03/35] Chi-squared statistic for PSF fit
(chi)
113- 121 F9.6 --- sharp [-2/3.3] Sharpness of source
123- 136 I14 --- FracDay ? Exposure file time stamp, with decimal
representation YYYYMMDDdddddd: year, month,
day, and fractional day (filefracday)
138- 141 I4 --- Field [280/1861]? Field identifier
143- 144 I2 --- CCD [1/16]? CCD number (ccdid)
146 I1 --- qID [1/4]? Quadrant ID
148- 152 F5.2 mag magLim [17.7/22.1] Approximate 5-sigma limiting
magnitude corresponding to epoch-based
PSF-fit catalog (limitmag)
154- 162 F9.6 mag magZP [25.39/26.5] Magnitude zeropoint from
photometric calibration
164- 169 F6.4 mag e_magZP [0.01/0.05] RMS deviation in magnitude
zeropoint (magzprms)
171- 176 F6.3 --- Col [-0.016/0.2] Color coefficient from linear
fit (clrcoeff)
178- 188 E11.5 --- e_Col [1.3e-6/0.0007] Color coefficient uncertainty
from linear fit (clrcounc)
190- 191 I2 s Exp [30] Exposure time from scheduler (always "30")
(exptime)
193- 197 F5.3 --- Airmass [1/2.91] Airmass at approximately the center
of the focal plane at time of exposure
199 I1 --- PID [1/3]? Program ID (programid)
201- 205 A5 --- --- [SPICY]
207- 212 I6 --- SPICY [53590/117446] SPICY designation
214- 239 A26 --- Spitzer Designation of the Spitzer source (sst_desig)
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History:
From electronic version of the journal
(End) Emmanuelle Perret [CDS] 19-Aug-2021