J/ApJS/245/32 Newly identified star clusters in Gaia DR2 (Liu+, 2019)
A catalog of newly identified star clusters in Gaia DR2.
Liu L., Pang X.
<Astrophys. J. Suppl. Ser., 245, 32 (2019)>
=2019ApJS..245...32L 2019ApJS..245...32L
ADC_Keywords: Clusters, open; Milky Way; Proper motions;
Parallaxes, trigonometric; Stars, ages; Abundances;
Cross identifications; Associations, stellar
Keywords: catalogs ; galaxies: star clusters: general ; methods: data analysis ;
open clusters and associations: general
Abstract:
We present the Star cluster Hunting Pipeline (SHiP) that can identify
star clusters in Gaia second data release (DR2) data and establish a
star cluster catalog for the Galactic disk. A friend-of-friend-based
cluster finder method is used to identify star clusters using
five-dimensional stellar parameters, l,b,ω,µαcosδ,
and µδ. Our new catalog contains 2443 star cluster
candidates identified from disk stars located within |b|=25° and
with G<18mag. An automatic isochrone fitting scheme is applied to all
cluster candidates. With a combination of parameters obtained from
isochrone fitting, we classify cluster candidates into three classes
(Class 1, 2, and 3). Class 1 clusters are the most probable star
cluster candidates with the most stringent criteria. Most of these
clusters are nearby (within 4kpc). Our catalog is crossmatched with
three Galactic star cluster catalogs, Kharchenko+ (2013, J/A+A/558/A53),
Cantat-Gaudin+ (2018, J/A+A/618/A93 and 2019, J/A+A/624/A126), and
Bica+ (2019, J/AJ/157/12). The proper motion and parallax of matched
star clusters are in good agreement with these earlier catalogs. We
discover 76 new star cluster candidates that are not listed in these
three catalogs. The majority of these are clusters older than
log(age/yr)=8.0 and are located in the inner disk with |b|<5°. The
recent discovery of new star clusters suggests that current Galactic
star cluster catalogs are still incomplete. Among the Class 1 cluster
candidates, we find 56 candidates for star cluster groups.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 140 2443 Parameters of the 2443 star cluster candidates
identified by the Star cluster Hunting Pipeline
(SHiP) in this work
table3.dat 101 76 The 76 new star cluster candidates classified
as Class 1 (likely genuine star clusters)
group.dat 146 152 *Star cluster group candidate members
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Note on group.dat: A total of 56 candidates of star cluster group are
identified by the FoF group finder based on star clusters' 3D
positions. They are distributed within 2kpc of the Sun, between the
Perseus and Sagittarius spiral arms. Further investigations are
necessary to confirm the nature of these group candidates.
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See also:
B/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2015)
I/317 : The PPMXL Catalog (Roeser+ 2010)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/477/165 : Nearby open clusters tidal radii and masses (Piskunov+, 2008)
J/A+A/543/A156 : Milky Way global survey of star clusters (Kharchenko+, 2012)
J/A+A/558/A53 : MW global survey of star clusters. II. (Kharchenko+, 2013)
J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)
J/A+A/600/A106 : RAVE open cluster pairs, groups and complexes (Conrad+, 2017)
J/A+A/601/A19 : Gaia DR1 open cluster members (Gaia+, 2017)
J/A+A/615/A12 : 24 nearby open clusters TGAS and HSOY reanalysis (Yen+, 2018)
J/A+A/615/A49 : TGAS stars membership in 128 open cl. (Cantat-Gaudin+, 2018)
J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)
J/A+A/618/A59 : Gaia DR2 confirmed new nearby open cl. (Castro-Ginard+, 2018)
J/A+A/619/A155 : Open cluster kinematics with Gaia DR2 (Soubiran+, 2018)
J/AJ/157/12 : Star clusters, assoc., & candidates in the MW (Bica+, 2019)
J/A+A/623/A108 : Age of 269 GDR2 open clusters (Bossini+, 2019)
J/A+A/624/A126 : New open clusters in Perseus direction (Cantat-Gaudin+, 2019)
J/A+A/627/A35 : New open clusters in Gal. anti-centre (Castro-Ginard+, 2019)
J/A+A/633/A99 : Gaia DR2 open clusters in the MW. II (Cantat-Gaudin+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [0/2442] Friend of Friend identifier
6- 12 F7.3 deg GLON Galactic longitude (G1)
14- 18 F5.3 deg e_GLON [0.01/1.3] Uncerainty in GLON
20- 26 F7.3 deg GLAT [-23.31/23.1] Galactic latitude (G1)
28- 32 F5.3 deg e_GLAT [0.01/0.8] Uncerainty in GLAT
34- 38 F5.3 deg rmax [0.05/3.6] Maximum cluster member's distance to
average position
40- 44 F5.3 mas plx [0.2/6.6] Parallax (G1)
46- 50 F5.3 mas e_plx [0.006/0.3] The 1σ uncertainty in plx
52- 58 F7.3 mas/yr pmRA [-24.7/16] Proper motion along RA
times cos(DE) (G1)
60- 64 F5.3 mas/yr e_pmRA [0.1/1.2] The 1σ uncertainty in pmRA
66- 72 F7.3 mas/yr pmDE [-26.7/23.4] Proper motion along DE (G1)
74- 78 F5.3 mas/yr e_pmDE [0.1/1.7] The 1σ uncertainty in pmDE
80- 84 I5 --- nTot [50/10576] Total number of stars
in primary sample
86- 91 F6.3 Gyr Age [0.004/12.9] Star cluster age (G2)
93- 98 F6.4 Gyr e_Age [0.0002/0.8] The 1σ uncertainty in Age
100-104 F5.2 [Sun] Z [-2/0.5] Metallicity (G2)
106-106 I1 --- Class [1/3] Class code (1: likely genuine
star cluster) (1)
108-111 I4 --- K13 [0/3005]?=-1 Kharchenko+ 2013, J/A+A/558/A53
identifier (G3)
113-116 I4 --- CG18 [2/1274]?=-1 Cantat-Gaudin+ 2018, J/A+A/618/A93
or 2019, J/A+A/624/A126 identifier (G3)
118-122 I5 --- B19 [10/10931]?=-1 Bica+ 2019, J/AJ/157/12
identifier (G3)
124-140 A17 --- Name Other name
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Note (1): Class code as follows:
1 = likely star cluster candidate:
nG<17≥50, tage>5Myr, rn<0.1, d2<0.05 (569 occurrences);
2 = nearby star cluster candidate that need further confirmation:
nG<17≥50, tage>5Myr, rn<0.1 (127 occurrences);
3 = star cluster candidate that need further confirmation (1747 occurrences).
Where rn is the narrowness of the main sequence in the
color-magnitude diagram; d2 is the average square of the distance
between cluster stars and an isochroner; nG<17 is the number of
bright stars with G<17mag included in the isochrone fitting, and
tage is the age of star clusters derived from isochrone fitting.
See Section 3.3 and 4.1 for further explanations.
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- ID [5/2442] Friend of Friend identifier
6- 12 F7.3 deg GLON [12.8/360] Galactic longitude (G1)
14- 18 F5.3 deg e_GLON [0.02/1.1] Uncerainty in GLON
20- 26 F7.3 deg GLAT [-13.8/6.3] Galactic latitude (G1)
28- 32 F5.3 deg e_GLAT [0.02/0.8] Uncerainty in GLAT
34- 38 F5.3 deg r [0.07/3.6] Cluster member's distance to
average position
40- 44 F5.3 mas plx [0.2/5.7] Parallax (G1)
46- 50 F5.3 mas e_plx [0.01/0.2] The 1σ uncertainty in plx
52- 58 F7.3 mas/yr pmRA [-12/3] Proper motion along RA times cos(DE) (G1)
60- 64 F5.3 mas/yr e_pmRA [0.1/1] The 1σ uncertainty in pmRA
66- 72 F7.3 mas/yr pmDE [-21.3/7.1] Proper motion along DE (G1)
74- 78 F5.3 mas/yr e_pmDE [0.1/1.1] The 1σ uncertainty in pmDE
80- 82 I3 --- nTot [59/482] Total number of stars in primary sample
84- 88 F5.3 Gyr Age [0.006/3.2] Star cluster age (G2)
90- 95 F6.4 Gyr e_Age [0.0004/0.2] The 1σ uncertainty in Age
97-101 F5.2 [Sun] Z [-2/0.5] Metallicity (G2)
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Byte-by-byte Description of file: group.dat
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Bytes Format Units Label Explanations
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1- 2 I02 --- Group [0/55] Group number
4- 7 I4 --- ID [30/2441] Friend of Friend identifier
of the cluster
9- 15 F7.3 deg GLON [9.8/358] Galactic longitude (G1)
17- 21 F5.3 deg e_GLON [0.03/0.9] Uncerainty in GLON
23- 29 F7.3 deg GLAT [-21/17.2] Galactic latitude (G1)
31- 35 F5.3 deg e_GLAT [0.02/0.6] Uncerainty in GLAT
37- 41 F5.3 deg r [0.1/3.4] Cluster member's distance to
average position
43- 47 F5.3 mas plx [0.2/6.6] Parallax (G1)
49- 53 F5.3 mas e_plx [0.013/0.2] The 1σ uncertainty in plx
55- 61 F7.3 mas/yr pmRA [-24.7/15.9] Proper motion along RA
times cos(DE) (G1)
63- 67 F5.3 mas/yr e_pmRA [0.1/1.1] The 1σ uncertainty in pmRA
69- 75 F7.3 mas/yr pmDE [-26.7/23.4] Proper motion along DE (G1)
77- 81 F5.3 mas/yr e_pmDE [0.14/1.05] The 1σ uncertainty in pmDE
83- 86 I4 --- nTot [54/1880] Total number of stars in primary sample
88- 93 F6.3 Gyr Age [0.005/12.9] Star cluster age (G2)
95- 99 F5.2 [Sun] Z [-2/0.5] Metallicity (G2)
101 I1 --- Class [1] Class code (always "1":
nG<17≥50, tage>5Myr, rn<0.1, d2<0.05)
103-106 I4 --- K13 [16/2969]?=-1 Kharchenko+ 2013, J/A+A/558/A53
identifier (G3)
108-111 I4 --- CG18 [2/1273]?=-1 Cantat-Gaudin+ 2018, J/A+A/618/A93
or 2019, J/A+A/624/A126 identifier (G3)
113-117 I5 --- B19 [527/10861]?=-1 Bica+ 2019, J/AJ/157/12
identifier (G3)
119-127 F9.3 pix x [-1959.3/4056] x value
129-137 F9.3 pix y [-2680.2/2685] y value
139-146 F8.3 pix z [-167.4/245.4] z value
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Global notes:
Note (G1): Calculated as the average value of all cluster members.
Note (G2): Uncertainties of age and metallicity are estimated as half a step in
the isochrone table (see Sec. 3.2.1 for more details). These are 6%
[100.5*Δ(log(t/yr)] for ages and 0.125 for metallicities.
Note (G3): All IDs start with 0 and correspond to the line
number in the catalog (not the MWSC number as in K13).
For CG18+19, IDs in the ranges 0-1228 and 1229-1274 correspond to star
clusters in Cantat-Gaudin+ 2018, J/A+A/618/A93 and 2019, J/A+A/624/A126 ;
respectively. For convenience, in table 1, the names of the matched
star clusters in CG18+19 are also presented.
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History:
From electronic version of the journal for Tables 1 and 3
Group members downloaded from:
http://github.com/liulei/gaia_ship/tree/master/data/group
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 01-Apr-2020