J/A+A/627/A35 New open clusters in Galactic anti-centre (Castro-Ginard+, 2019)
Hunting for open clusters in Gaia DR2: the Galactic anticentre.
Castro-Ginard A., Jordi C., Luri X., Cantat-Gaudin T., Balaguer-Nunez L.
<Astron. Astrophys. 627, A35 (2019)>
=2019A&A...627A..35C 2019A&A...627A..35C (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Galactic center ; Clusters, open
Keywords: surveys - open clusters and associations: general -
astrometry - methods: data analysis
Abstract:
The Gaia Data Release 2 (DR2) provided an unprecedented volume of
precise astrometric and excellent photometric data. In terms of data
mining the Gaia catalogue, machine learning methods have shown to be a
powerful tool, for instance in the search for unknown stellar
structures. Particularly, supervised and unsupervised learning methods
combined together significantly improves the detection rate of open
clusters.
We systematically scan Gaia DR2 in a region covering the Galactic
anticentre and the Perseus arm (120°≤l≤205° and
-10°≤b≤10°), with the goal of finding any open clusters that
may exist in this region, and fine tuning a previously proposed
methodology and successfully applied to TGAS data, adapting it to
different density regions.
Our methodology uses an unsupervised, density-based, clustering
algorithm, DBSCAN, that identifies overdensities in the
five-dimensional astrometric parameter space
(l, b, ϖ, pmRA*, pmDE) that may correspond to physical clusters.
The overdensities are separated into physical clusters (open clusters)
or random statistical clusters using an artificial neural network to
recognise the isochrone pattern that open clusters show in a colour
magnitude diagram.
The method is able to recover more than 75% of the open clusters
confirmed in the search area. Moreover, we detected 53 open clusters
unknown previous to Gaia DR2, which represents an increase of more
than 22% with respect to the already catalogued clusters in this
region.
We find that the census of nearby open clusters is not complete.
Different machine learning methodologies for a blind search of open
clusters are complementary to each other; no single method is able to
detect 100% of the existing groups. Our methodology has shown to be a
reliable tool for the automatic detection of open clusters, designed
to be applied to the full Gaia DR2 catalogue.
Description:
This is Table 2 of the paper. The Table 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, GBP and GRP bands. It
also includes the Gaia source_id to allow the cross-match with other
catalogues.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
centres.dat 291 53 Mean parameters for the reported UBC clusters
members.dat 231 2793 Members for the reported UBC clusters
--------------------------------------------------------------------------------
See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/618/A59 : New nearby open clusters confirmed by Gaia DR2
(Castro-Ginard+, 2018)
Byte-by-byte Description of file: centres.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 5 A5 --- Cluster Cluster name (UBC33-UBC99)
7- 24 F18.15 deg RAdeg Right Ascension mean (ICRS) at epoch 2015.5
26- 45 F20.18 deg e_RAdeg Right Ascension standard deviation
47- 64 F18.15 deg DEdeg Declination mean (ICRS) at epoch 2015.5
66- 85 F20.18 deg e_DEdeg Declination standard deviation
87-104 F18.14 deg GLON Galactic longitude mean
106-125 F20.18 deg e_GLON Galactic longitude standard deviation
127-146 F20.17 deg GLAT Galactic latitude mean
148-167 F20.18 deg e_GLAT Galactic latitude standard deviation
169-187 F19.17 mas Plx Parallax mean
189-208 F20.18 mas e_Plx Parallax standard deviation
210-229 F20.17 mas/yr pmRA* Proper motion in right ascension mean
(pmRA*cosDE)
231-249 F19.17 mas/yr e_pmRA* Proper motion in right ascension
standard deviation
251-271 F21.18 mas/yr pmDE Proper motion in declination mean
273-291 F19.17 mas/yr e_pmDE Proper motion in declination
standard deviation
--------------------------------------------------------------------------------
Byte-by-byte Description of file: members.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 I19 --- Source Gaia source_id
21- 39 F19.16 deg RAdeg Right Ascension (ICRS) at Ep=2015.5
41- 59 F19.16 deg DEdeg Declination (ICRS) at Ep=2015.5
61- 78 F18.14 deg GLON Galactic longitude
80-100 F21.18 deg GLAT Galactic latitude
102-120 F19.17 mas Plx Absolute stellar parallax
122-142 F21.18 mas/yr pmRA* Proper motion in right ascension (pmRA*cosDE)
144-165 F22.19 mas/yr pmDE Proper motion in declination
167-186 E20.16 km/s RV ?=- Radial velocity
188-205 F18.15 mag Gmag Gaia G mean magnitude
207-225 E19.12 mag BP-RP ?=- Gaia BP-RP colour index
227-231 A5 --- Cluster Cluster name
--------------------------------------------------------------------------------
Acknowledgements:
Alfred Castro-Ginard, acastro(at)fqa.ub.edu
(End) Alfred Castro-Ginard [Univ. Barcelona], Patricia Vannier [CDS] 28-May-2019