J/AJ/170/172 2MASS & Gaia DR3 phot. of YSOs in three clusters (Patel+, 2025)
Identification of outer galaxy cluster members using Gaia DR3 and
multidimensional simulation.
Patel V., Hora J.L., Ashby M.L.N., Vig S.
<Astron. J., 170, 172 (2025)>
=2025AJ....170..172P 2025AJ....170..172P
ADC_Keywords: Clusters, open; YSOs; Photometry, infrared; Optical;
Parallaxes, trigonometric; Proper motions; Stars, distances
Keywords: Clustering ; Young stellar objects ; Young star clusters ;
Star forming regions ; Computational astronomy ; Astrometry
Abstract:
The outer Galaxy presents a distinctive environment for investigating
star formation. This study develops a novel approach to identify true
cluster members based on unsupervised clustering using astrometry with
significant uncertainties. As a proof of concept, we analyze three
outer Galactic young stellar object (YSO) clusters at different
distances and densities within 65<l<265, each known to contain
>100 members based on the Star Formation in Outer Galaxy (SFOG;
E. Winston et al. (2020) catalog. The 618 YSO clusters in the SFOG
data set were based on 2D clustering. In this contribution, we apply
the Hierarchical Density-Based Spatial Clustering of Applications with
Noise (HDBSCAN*) algorithm to the precise Gaia DR3 astrometry to
assign YSO cluster membership. A Monte Carlo simulation coupled with
the HDBSCAN* (HDBSCAN-MC algorithm) addresses YSO astrometric
uncertainties through 5D clustering. We introduce the Generation Of
cLuster anD FIeld STar (GOLDFIST) simulation to enable robust
membership determination, performing an unsupervised clustering
analysis in higher-dimensional feature space while accommodating
measurement errors. In this study, we extended our approach to distant
outer galaxy YSOs and clusters with larger astrometric uncertainties.
The results include the discovery of new members in the previously
identified clusters. We also analyze the known stars in the clusters
and confirm their membership. The derived membership probabilities are
included in the provided cluster catalogs. The more accurately
predicted simulation distance estimates closely agree, within
uncertainty limits, with the median distance estimates derived from
Gaia data, and are compared with the kinematic distances from the
Wide- field Infrared Survey Explorer H ii survey.
Description:
To assess the performance of the HDBSCAN-MC (Campello+2013) technique,
the study tested it on Cluster 123, the W4/W5 complex (Cluster 257),
and Cluster 163 as a proof of concept. The HDBSCAN-MC technique, an
extension of the HDBSCAN algorithm, was used to assign YSO cluster
memberships while accounting for astrometric uncertainties. This
method employs 5D clustering through a Monte Carlo simulation to
robustly determine membership probabilities, even for distant clusters
with significant uncertainties.
The research sample was constructed using data from the Star Formation
in the Outer Galaxy (SFOG; Winston+2020, J/AJ/160/68) catalog, which
includes infrared observations from Spitzer, Wide-field Infrared
Survey Explorer (WISE, II/311), and 2MASS (II/246), as well as optical
data from the Gaia DR3 (I/355) catalog. The SFOG catalog initially
contained 47,405 YSOs, from which 142 duplicates were removed,
resulting in 47,263 unique YSOs.
Crossmatching with Gaia DR3 refined the sample, eliminating 94
spurious matches, 98 many-to-one matches, and 242 one-to-many matches.
Photometric criteria (e.g., infrared excess and magnitude comparisons
between optical and infrared bands) were applied to resolve chance
alignments and ensure accurate YSO-Gaia matches. Additional catalogs,
such as Marton+2023 (J/A+A/674/A21), GLIMPSE (II/293), SMOG (J/ApJ/880/9),
ALLWISE (II/328), and IRAC-WISE (Winston+2020, J/AJ/160/68), were
incorporated improve spectral coverage and cross-verification,
expanding the study sample. The final catalog included 26,230
Gaia-matched SFOG YSOs and 78,370 unique Gaia-only YSOs, totaling
104,600 YSOs.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table5.dat 518 1860 Cluster table
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
II/293 : GLIMPSE Source Catalog (I + II + 3D) (IPAC 2008)
II/311 : WISE All-Sky Data Release (Cutri+ 2012)
II/328 : AllWISE Data Release (Cutri+ 2013)
II/363 : The band-merged unWISE Catalog (Schlafly+, 2019)
II/365 : The CatWISE2020 catalog (updated version 28-Jan-2021) (Marocco+, 2021)
J/A+A/402/549 : UBVRIHalpha photometry of NGC 3293 (Baume+, 2003)
J/A+A/564/A79 : Proper motions of open clusters from UCAC4 (Dias+, 2014)
J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)
J/ApJS/245/32 : Newly identified star clusters in Gaia DR2 (Liu+, 2019)
J/ApJ/880/9 : Spitzer obs. of YSOs in the SMOG field (Winston+, 2019)
J/MNRAS/496/2021 : New Galactic open clusters (Ferreira+, 2020)
J/A+A/637/A95 : 16 open clusters UBVI and Gaia DR2 photometry (Perren+, 2020)
J/AJ/160/68 : GLIMPSE360: stellar objects phot. & classes (Winston+, 2020)
J/other/RAA/21.93 : 74 new open clusters found in Gaia DR2 (He+, 2021)
J/AJ/162/110 : Gaia EDR3 census of Taurus-Auriga complex (Krolikowski+, 2021)
J/ApJ/928/70 : Gaia EDR3 members stars of 55 FoF groups (Coronado+, 2022)
J/A+A/674/A39 : Gaia DR3. 95 extrasolar planets (Gaia Coll.+, 2023)
J/A+A/673/A114 : Improving the open cluster census. II. (Hunt+, 2023)
J/ApJ/954/134 : SPYGLASS. IV. Young stars from Gaia DR3 (Kerr+, 2023)
J/A+A/674/A21 : KYSO - The Konkoly Optical YSO catalogue (Marton+, 2023)
J/A+A/675/A67 : Cluster aggregates surrounding Pismis 5 in VMR (Qin+, 2023)
Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [123/257] Cluster number (1)
5- 12 A8 --- ID Unique source identifier; SMOG Field ID
14- 38 A25 --- IRname Infrared source name
40- 55 A16 --- 2MASS 2MASS (II/246) ID
57- 61 F5.1 --- Cluster [-1/509]? Cluster designation from
Winston+2020 (J/AJ/160/68) (4)
63- 65 F3.1 --- Class [1/3]? YSO classification from
Winston+2020 (J/AJ/160/68) (2)
67- 79 F13.9 deg RAdeg Right ascension (J2000)
81- 87 F7.4 mas e_RAdeg ? Right ascension uncertainty (J2000)
89- 100 F12.9 deg DEdeg Declination (J2000)
102- 108 F7.4 mas e_DEdeg ? Declination uncertainty (J2000)
110- 115 F6.3 mag Jmag [6.7/18.3]? Apparent 2MASS J-band Vega
magnitude
117- 121 F5.3 mag e_Jmag [0.01/0.31]? Uncertainty in Jmag
123- 131 F9.4 mJy FJ [0.16/1186]? J-band flux
133- 140 F8.5 mJy e_FJ [0.03/29.5]? Uncertainty in FJ
142- 147 F6.3 mag Hmag [5.8/17.1]? Apparent 2MASS H-band Vega
magnitude
149- 153 F5.3 mag e_Hmag [0.01/0.21]? Uncertainty in Hmag
155- 162 F8.4 mJy FH [0.3/973.4]? H-band flux
164- 171 F8.5 mJy e_FH [0.05/47.6]? Uncertainty in FH
173- 178 F6.3 mag Ksmag [5.4/15.9]? Apparent 2MASS Ks-band Vega
magnitude
180- 184 F5.3 mag e_Ksmag [0.01/0.27]? Uncertainty in Ksmag
186- 193 F8.4 mJy FKs [0.3/860.5]? Ks-band flux
195- 202 F8.5 mJy e_FKs [0.06/21.4]? Uncertainty in FKs
204- 209 F6.3 mag 3.6mag [6.6/15.5]? Apparent 3.6 micron IRAC band
1 Vega magnitude
211- 215 F5.3 mag e_3.6mag [0.01/0.21]? Uncertainty in 3.6mag
217- 224 F8.4 mJy F3.6 [0.1/614.4]? IRAC band 1 flux
226- 233 F8.5 mJy e_F3.6 [0.01/24.5]? Uncertainty in F3.6
235- 240 F6.3 mag 4.5mag [5.6/14.8]? Apparent 4.5 micron IRAC band
2 Vega magnitude
242- 246 F5.3 mag e_4.5mag [0.01/0.2]? Uncertainty in 4.5mag
248- 256 F9.4 mJy F4.5 [0.2/1020]? IRAC band 2 flux
258- 265 F8.5 mJy e_F4.5 [0.01/27.3]? Uncertainty in F4.5
267- 272 F6.3 mag W3mag [1.6/10]? Apparent WISE W3 Vega magnitude
from AllWISE (II/328)
274- 278 F5.3 mag e_W3mag [0.01/0.51]? Uncertainty in W3mag
280- 284 F5.3 mag W4mag [0.07/9.2]? Apparent WISE W4 Vega
magnitude from All WISE (II/328)
286- 290 F5.3 mag e_W4mag [0.009/0.51]? Uncertainty in W4mag
292- 319 A28 --- Designation Gaia DR3 (I/355) designation
321- 339 I19 --- GaiaDR3 ?=-1 Gaia DR3 (I/355) source identifier
341- 345 F5.2 mas plx [-3.17/4.53]? Gaia DR3 parallax
347- 350 F4.2 mas e_plx [0.01/2.87]? Uncertainty in plx
352- 357 F6.2 mas RPlx [-3.11/108.3]? Parallax over error
(plxOverErr)
359- 364 F6.2 mas/yr pmRA [-12.46/10.58]? Proper motion in
direction of right ascension
366- 369 F4.2 mas/yr e_pmRA [0.01/2.68]? Uncertainty in pmRA
371- 376 F6.2 mas/yr pmDE [-16.26/9.06]? Proper motion in direction
of declination
378- 381 F4.2 mas/yr e_pmDE [0.01/2.98]? Uncertainty in pmDE
383- 387 F5.3 --- RUWE [0.88/1.4]? Renormalized unit weight
error from Gaia DR3
389- 394 F6.3 mag Gmag [9.1/20.92]? Apparent Gaia G-band mean
Vega magnitude
396- 400 F5.3 mag e_Gmag [0.003/0.035]? Uncertainty in Gmag
402- 407 F6.3 mag BPmag [9.5/22.4]? Apparent GBP magnitude
409- 413 F5.3 mag e_BPmag [0.003/0.5]? Uncertainty in BPmag
415- 420 F6.3 mag RPmag [8.5/19.8]? Apparent GRP magnitude
422- 426 F5.3 mag e_RPmag [0.004/0.14]? Uncertainty in RPmag
428- 432 F5.3 mag BP-RP [0.8/5.9]? Gaia BP-RP color
434- 438 F5.3 mag BP-G [0.1/4.3]? Gaia BP-G color
440- 444 F5.3 mag G-RP [0.5/2.5]? Gaia G-RP color
446- 454 F9.3 pc Dist [345.7/11431]? ICRS source distance
456- 463 F8.3 pc e_Dist [269.9/6962.2]? Lower bound on Dist
465- 473 F9.3 pc E_Dist [579/13968]? Upper bound on Dist
475- 484 F10.3 pc Xgal [-14967/-7844]? Galactocentric
X-coordinate
486- 494 F9.3 pc Ygal [234.6/11391]? Galactocentric
Y-coordinate
496- 502 F7.3 pc Zgal [0.7/443.6]? Galactocentric Z-coordinate
504 I1 --- Memb [0/3] Membership flag for YSO cluster
(memFlag) (3)
506- 511 A6 --- Prob Membership probability
513- 518 A6 --- e_Prob Uncertainty in Prob
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Note (1): Cluster occurrences as follows:
123 = 563 occurrences
163 = 262 occurrences
257 = 1035 occurrences
Note (2): The numerical YSO class, as described in Section 3.4.1., which depends
on the slope, α, of the spectral energy distribution across the mid-IR
bandpasses. Classes as follows:
1.0 = Class 0/I: protostellar objects with a rising slope, α>0;
(178 occurrences)
2.0 = Class II: characterized by decreasing slopes in the range
-1.6<α<0; (1119 occurrences)
3.0 = Class IIa/III: class IIa sources lack optically thick emission from a
disk and possess decreasing slopes α←1.6, consistent with a
weak emission above a stellar photosphere. Truly diskless class III
objects show slopes in the range -2.7<α←2.0; (142 occurrences)
Note (3): Membership flag as follows:
0 = field YSO; 466 occurrences
1 = cluster member; 947 occurrences
2 = SFOG-only YSO identified as cluster member in Winston+2020 (J/AJ/160/68);
356 occurrences
3 = additional SFOG-only cluster member identified in this work based on
the 30th (70th for Cluster 163) percentile YSO density contour (see
Section 6); 91 occurrences
Note (4): A "-1" indicates that there was no cluster affiliation identified.
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History:
From electronic version of the journal
License: CC-BY-4.0
(End) Prepared by [AAS], Robin Leichtnam [CDS] 03-Jul-2026