J/A+A/677/A163 A Gaia astrometric view of three open clusters (Alfonso+, 2023)
A Gaia astrometric view of the open clusters Pleiades, Praesepe, and Blanco 1.
Alfonso J., Garcia-Varela A.
<Astron. Astrophys. 677, A163 (2023)>
=2023A&A...677A.163A 2023A&A...677A.163A (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, open ; Positional data ; Optical
Keywords: astrometry - methods: data analysis -
open clusters and associations: individual: Blanco 1 -
open clusters and associations: individual: Pleiades -
open clusters and associations: individual: Praesepe
Abstract:
Nearby open clusters, such as Pleiades, Praesepe, and Blanco 1, have
been extensively studied due to their proximity to the Sun. The Gaia
data provide the opportunity to investigate these clusters, because
they contain valuable astrometric and photometric information that can
be used to update their kinematic and stellar properties.
Our goal is to carry out a star membership study in these nearby open
clusters by employing an astrometric model with proper motions (PMs)
and an unsupervised clustering machine learning algorithm that uses
positions, PMs, and parallaxes. The star members are selected from the
cross-matching between both methods. Once we know the members, we
investigate the spatial distributions of these clusters and estimate
their distances, ages, and metallicities.
We used the Gaia DR3 catalogue to determine star members using two
approaches: a classical Bayesian model and the unsupervised machine
learning algorithm DBSCAN. For star members, we built radial density
profiles and spatial distributions, and computed the King parameters.
The ages and metallicities were estimated using the BASE-9 Bayesian
software. Results: We identified 958, 744, and 488 star members for
Pleiades, Praesepe, and Blanco 1, respectively. We corrected the
distances and built the spatial distributions, finding that Praesepe
and Blanco 1 have elongated shape structures. The distances, ages, and
metallicities obtained were consistent with those reported in the
literature.
We obtained catalogues of star members, and updated kinematic and
stellar parameters for these open clusters. We find that the PMs model
can find a similar number of members to the unsupervised clustering
algorithm when the cluster population forms an overdensity in the
vector point diagram. This allows us to select an adequate size of the
PMs region with which to run these methods. Our analysis found stars
that are being directed towards the outskirts of Praesepe and Blanco
1, which exhibit elongated shapes. These stars have high membership
probabilities and similar PMs to those within the tidal radius.
Description:
In this paper we identify star members of Pleiades, Praesepe, and
Blanco 1 using the Gaia DR3 catalogue. We employ both the PM model,
which estimates star membership probabilities using maximum likelihood
estimation (MLE) and a Markov Chain Monte Carlo (MCMC) algorithm, and
DBSCAN.
This file contains the members for the open clusters Pleiades,
Praesepe, and Blanco 1. All columns come from Gaia DR3.
Objects:
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RA (2000) DE Designation(s)
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03 46 24.24 +24 06 50.4 Pleiades = M 45
08 40 12.96 +19 37 15.5 Praesepe = NGC 2632
00 03 24.72 -29 57 28.8 Blanco 1 = Cl Blanco 1
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
members.dat 120 2190 Members of the open clusters
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
Byte-by-byte Description of file: members.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR3 Gaia DR3 source ID
21- 35 F15.11 deg RAdeg Right Ascension (ICRS) at Ep=2016.0
37- 51 F15.11 deg DEdeg Declination (ICRS) at Ep=2016.0
53- 70 F18.16 mas Plx Absolute stellar parallax
72- 90 F19.15 mas/yr pmRA Proper motion in right ascension direction
92-111 F20.16 mas/yr pmDE Proper motion in declination direction
113-120 A8 --- Cluster Cluster name
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Acknowledgements:
Jeison Alfonso, je.alfonso1(at)uniandes.edu.co
(End) Patricia Vannier [CDS] 03-Aug-2023