J/A+A/635/A45 570 new open clusters in the Galactic disc (Castro-Ginard+, 2020)
Hunting for open clusters in Gaia DR2: 582 new open clusters in the
Galactic disc.
Castro-Ginard A., Jordi C., Luri X., Alvarez Cid-Fuentes J., Casamiquela L.,
Anders F., Cantat-Gaudin T., Monguio M., Balaguer-Nunez L., Sola S.,
Badia R.M.
<Astron. Astrophys. 635, A45 (2020)>
=2020A&A...635A..45C 2020A&A...635A..45C (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Clusters, open ; Parallaxes, trigonometric ;
Proper motions ; Radial velocities
Keywords: surveys - open clusters and associations: general - astrometry -
methods: data analysis
Abstract:
Open clusters are key targets for studies of Galaxy structure and
evolution, and stellar physics. Since the Gaia data release 2 (DR2),
the discovery of undetected clusters has shown that previous surveys
were incomplete.
Our aim is to exploit the Big Data capabilities of machine learning to
detect new open clusters in Gaia DR2, and to complete the open cluster
sample to enable further studies of the Galactic disc.
We use a machine-learning based methodology to systematically search
the Galactic disc for overdensities in the astrometric space and
identify the open clusters using photometric information. First, we
used an unsupervised clustering algorithm, DBSCAN, to blindly search
for these overdensities in Gaia DR2 (l, b, varpi, mualpha*,
mudelta), then we used a deep learning artificial neural network
trained on colour-magnitude diagrams to identify isochrone patterns
in these overdensities, and to confirm them as open clusters.
We find 570 new open clusters distributed along the Galactic disc in
the region |b|<20°. We detect substructure in complex regions, and
identify the tidal tails of a disrupting cluster UBC 274 of ∼3Gyr
located at ∼2kpc.
Adapting the mentioned methodology to a Big Data environment allows us
to target the search using the physical properties of open clusters
instead of being driven by computational limitations. This blind
search for open clusters in the Galactic disc increases the number of
known open clusters by 45%.
Description:
Table 1 contains mean astrometric parameters for the detected
clusters.
Table 2 contains the member stars found for the new UBC open clusters
reported in the paper. The columns are for astrometric parameters for
the member stars, i.e. positions, parallax, proper motions and radial
velocity when available, as well as the photometric information in the
G, G_BP and G_RP bands. It also includes the Gaia source_id to allow
the cross-match with other catalogues.
Update: Total number of clusters is 570.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 310 570 Mean parameters for the reported UBC clusters
(updated, 07-Apr-2020)
table2.dat 247 33635 Members for the reported UBC clusters
(updated, 07-Apr-2020)
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/627/A35 : New open clusters in Galactic anti-centre (Castro-Ginard+ 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 6 A6 --- Cluster Cluster name (UBCNNN)
8- 27 F20.16 deg RAdeg Right Ascension mean (ICRS) at Ep=2015.5
29- 50 F22.18 deg e_RAdeg Right Ascension standard deviation
52- 72 F21.17 deg DEdeg Declination mean (ICRS) at Ep=2015.5
74- 93 F20.18 deg e_DEdeg Declination standard deviation
95-114 F20.16 deg GLON Galactic longitude mean
116-135 F20.18 deg e_GLON Galactic longitude standard deviation
137-158 F22.18 deg GLAT Galactic latitude mean
160-179 F20.18 deg e_GLAT Galactic latitude standard deviation
181-199 F19.17 mas plx Parallax mean
201-221 F21.19 mas e_plx Parallax standard deviation
223-244 F22.18 mas/yr pmRA Proper motion in right ascension mean,
pmRA*cosDE
246-265 F20.18 mas/yr e_pmRA Proper motion in right ascension
standard deviation
267-287 E21.16 mas/yr pmDE Proper motion in declination mean
289-308 F20.18 mas/yr e_pmDE Proper motion in declination
standard deviation
310-310 A1 --- Note [ab] Note (1)
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Note (1): Note as follows:
a = coincidence with Sim et al. (2019, J. Korean Astron. Soc., 52, 145) or
Liu & Pang (2019ApJS..245...32L 2019ApJS..245...32L), see Sect. 4.1.5
b = tentative identification with Kharchenko et al. (2013, Cat. J/A+A/558/A53),
see Sect. 4.1.3
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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- 19 I19 --- Source Gaia source_id
21- 41 E21.16 deg RAdeg Right Ascension (ICRS) at ep=2015.5
43- 64 F22.18 deg DEdeg Declination (ICRS) at ep=2015.5
66- 86 F21.17 deg GLON Galactic longitude
88-110 F23.19 deg GLAT Galactic latitude
112-130 F19.17 mas plx Parallax
132-153 E22.16 mas/yr pmRA Proper motion in right ascension, pmRA*cosDE
155-175 E21.16 mas/yr pmDE Proper motion in declination
177-198 F22.17 km/s RV ? Radial velocity
200-218 F19.16 mag Gmag Gaia G magnitude
220-240 F21.18 mag BP-RP ? Gaia BP_RP
242-247 A6 --- Cluster Cluster name
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Acknowledgements:
Alfred Castro-Ginard, acastro(at)fqa.ub.edu
History:
04-Mar-2020: on-line version
03-Apr-2020: tables corrected (from author)
07-Apr-2020: tables corrected (from author)
(End) Alfred Castro-Ginard [Univ. Barcelona], Patricia Vannier [CDS] 21-Jan-2020