J/ApJS/265/20 Reliable open cluster candidates from Gaia EDR3 (Chi+, 2023)
Identifying 46 new open cluster candidates in Gaia EDR3 using a hybrid pyUPMASK
and Random Forest method.
Chi H., Wei S., Wang F., Li Z.
<Astrophys. J. Suppl. Ser., 265, 20 (2023)>
=2023ApJS..265...20C 2023ApJS..265...20C
ADC_Keywords: Clusters, open; Parallaxes, trigonometric; Proper motions; Models
Keywords: Open star clusters
Abstract:
Open clusters (OCs) are regarded as tracers to understand stellar
evolution theory and validate stellar models. In this study, we
presented a robust approach to identifying OCs. A hybrid method
consisting of pyUPMASK (Pera+ 2021A&A...650A.109P 2021A&A...650A.109P) and the random
forest (RF) algorithm is first used to remove field stars and
determine more reliable members. An identification model based on the
RF algorithm built based on 3714 OC samples from Gaia DR2 and EDR3 is
then applied to identify OC candidates. The OC candidates are obtained
after isochrone fitting, advanced stellar population synthesis model
fitting, and visual inspection. Using the proposed approach, we
revisited 868 candidates and preliminarily clustered them by the
friends-of-friends algorithm in Gaia EDR3. Excluding OCs that have
already been reported, we focused on the remaining 300 unknown
candidates. From high to low fitting quality, these unrevealed
candidates were further classified into Class A (59), Class B (21),
and Class C (220). As a result, 46 new reliable OC candidates among
Classes A and B are identified after visual inspection.
Description:
In this study, we refer to the study of Li+ (2022, J/ApJS/259/19)
to obtain a data set of open cluster (OC) candidates using the FoF
algorithm. We then present an improved hybrid algorithm to identify
OCs from OC candidates found by FoF more robustly.
After obtaining the 801 OC candidates, we crossmatched our candidates
with published OC catalogs. See Section 3.2.
After isochrone fitting, we classified the OC candidates based on
their CMD morphologies and isochrone fitting results to facilitate our
manual visual inspection. See Section 3.4.
Among the 80 candidates (class A and class B), 46 candidates were
finally considered as possible real OCs (see Table 2).
Some of these 46 candidates are shown in Figure A2 in the Appendix.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 96 46 Parameters of the final 46 new open clusters (OCs)
in this work
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
J/A+A/558/A53 : MW global survey of star clusters. II. (Kharchenko+, 2013)
J/A+A/618/A59 : Gaia confirmed nearby open clusters (Castro-Ginard+, 2018)
J/A+A/618/A93 : Gaia DR2 open clusters in the MW (Cantat-Gaudin+, 2018)
J/AJ/156/121 : Likely open cluster NGC 6405 members (Gao, 2018)
J/A+A/623/A108 : Age of 269 GDR2 open clusters (Bossini+, 2019)
J/A+A/624/A126 : Open clusters in Perseus direction (Cantat-Gaudin+, 2019)
J/A+A/627/A35 : Open clusters in Gal. anti-centre (Castro-Ginard+, 2019)
J/AJ/158/122 : Local structure & SFH of the MW (Kounkel+, 2019)
J/ApJS/245/32 : Newly identified star clusters in Gaia DR2 (Liu+, 2019)
J/ApJ/885/131 : High-mass SFR plx & proper motion with VLBI (Reid+, 2019)
J/A+A/633/A99 : Gaia DR2 open clusters in the MW. II (Cantat-Gaudin+, 2020)
J/A+A/635/A45 : Open clusters in the Galactic disc (Castro-Ginard+, 2020)
J/MNRAS/496/2021 : New Galactic open clusters (Ferreira+, 2020)
J/AJ/160/279 : Untangling the Galaxy. II. Within 3kpc (Kounkel+, 2020)
J/MNRAS/504/356 : Updated parameters of 1743 open clusters (Dias+, 2021)
J/A+A/646/A104 : Improving the open cluster census. I. (Hunt+, 2021)
J/A+A/649/A7 : MC structure and properties (Gaia Collaboration+, 2021)
J/A+A/652/A102 : 3794 open clusters parameters (Hao+, 2021)
J/other/RAA/21.93 : 74 new open clusters found in Gaia DR2 (He+, 2021)
J/MNRAS/503/236 : UVIT cat. and membership of 6 open clusters (Jadhav+, 2021)
J/A+A/649/A3 : Gaia EDR3 photometric passbands (Riello+, 2021)
J/A+A/660/A4 : Gaia EDR3 new Galactic open clusters (Hao+, 2022)
J/A+A/661/A118 : Open clusters found with OCfinder (Castro-Ginard+, 2022)
J/ApJS/259/19 : LISC cat. of star clusters. I. Gal. disk (Li+, 2022)
J/ApJS/260/8 : 541 new open cluster candidates (He+, 2022)
J/ApJS/262/7 : 886 nearby star clusters (He+, 2022)
J/A+A/659/A59 : Structural param. of local open clusters (Tarricq+, 2022)
J/A+A/663/A131 : Parameters for 25 distant open clusters (Perren+, 2022)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 2 I2 --- Seq [0/45] Internal index number
4- 7 I04 --- ID [976/3595] Identifier
from Li+ 2022, J/ApJS/259/19
9- 15 F7.3 deg RAdeg [11.8/345] Right Ascension (ICRS) at Ep=2016.0
17- 21 F5.3 deg e_RAdeg [0.02/1.4] Uncertainty in RAdeg
23- 29 F7.3 deg DEdeg [-64/61.2] Declination (ICRS) at Ep=2016.0
31- 35 F5.3 deg e_DEdeg [0.01/1.4] Uncertainty in DEdeg
37- 41 F5.3 mas plx [0.2/3.5] Gaia EDR3 parallax
43- 47 F5.3 mas e_plx [0.008/0.1] Uncertainty in plx
49- 54 F6.3 mas/yr pmRA [-6.8/2.1] Proper motion along RA
56- 60 F5.3 mas/yr e_pmRA [0.1/0.8] Uncertainty in pmRA
62- 67 F6.3 mas/yr pmDE [-9.1/8.8] Proper motion along DE
69- 73 F5.3 mas/yr e_pmDE [0.1/0.8] Uncertainty in pmDE
75- 77 I3 --- Nmm [27/520] Number of members stars in the cluster
79- 81 I3 --- N17 [21/358] Total number of cluster member stars
with Gmag<17mag
83- 88 F6.4 [Sun] Z [0.0001/0.04] Metallicity
90- 94 F5.3 Gyr Age [0.04/3.1] Age
96- 96 A1 --- Cl [AB] Cluster class (1)
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Note (1): Class as follows:
A = Class A: nstar≥20, rn<0.1, d2<0.05 (31 occurrences)
B = Class B: nstar≥20, rn<0.1 (15 occurrences)
Where nstar is the number of member stars brighter than G<17mag;
d2 is the average square of the distance between cluster stars and
an isochrone used to measure the isochrone fitting errors.
rn is the narrowness of the main sequence in the CMD calculated as
|v1/v2|. v1 and v2 are the two eigenvalues of the covariance matrix of
the distribution of stars in the CMD.
See Section 3.4.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 13-Jun-2023