J/PASP/130/L4101 NGC 2112, 2477, 7789 and Col 261 members (Gao+ 2018)
Memberships, distances, and proper motions of the open clusters
NGC 2112, NGC 2477, NGC 7789, and Collinder 261 from Gaia-DR2.
Gao X.-H.
<Publ. Astron. Soc. Pac., 130, l4101 (2018)>
=2018PASP..130l4101G 2018PASP..130l4101G (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Populations, stellar
Keywords: methods: statistical - (Galaxy:) open clusters and associations:
individual (NGC 2112, NGC 2477, NGC 7789, Collinder 261) -
methods: data analysis - astrometry
Abstract:
Membership determination of open clusters in high-noise environments
is still an open question. This paper aims to evaluate the
effectiveness of the Gaussian mixture model (GMM) in segregating
likely cluster members of open clusters in high-noise environments. We
use the GMM method to segregate likely cluster members of four low
Galactic latitude open clusters: NGC 2112, NGC 2477, NGC 7789, and
Collinder 261, based on the high-precision astrometric data of the
Gaia Data Release 2 (Gaia-DR2). The GMM method is used to calculate
the membership probabilities of the stars in the field of each
cluster; five astrometric parameters (positions, parallaxes, and
proper motions) are taken into account. We quantitatively evaluate the
goodness of the cluster-field segregation for each cluster, and find
that the GMM method is effective for segregating likely cluster
members of these clusters, even if these clusters suffer from heavy
field star contamination. We estimate the distances and absolute
proper motions of these clusters using reliable cluster members; our
results suggest the existence of a significant zero-point offset in
Gaia-DR2 parallaxes. NGC 2112, NGC 2477, NGC 7789, and Collinder 261
are found to have a mean distance of =1104±4, 1437±2, 2067±4
and 2802±21pc, respectively. Mean proper motions of
(<µαcosδ>, <µδ>)=(-2.714±0.012,
4.272±0.012), (-2.449±0.006, 0.876±0.006), (-0.919±0.004,
-1.938±0.004), and (-6.348±0.006, -2.714±0.006)mas/yr are
determined for NGC 2112, NGC 2477, NGC 7789, and Collinder 261,
respectively.
Description:
Based on the high-precision astrometry from Gaia-DR2, we have used the
GMM method to segregate likely cluster members of the four low
Galactic latitude open clusters, NGC 2112, NGC 2477, NGC 7789, and
Collinder 261.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 80 4 Fundamental parameters of the four open clusters,
taken from Dias et al. (2002A&A...389..871D 2002A&A...389..871D,
Cat. B/ocl)
table8.dat 102 7878 Likely cluster members of the four open clusters
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Cluster Cluster code
4- 16 A13 --- Name Cluster name
19- 26 F8.4 deg RAdeg Cluster center right ascension (J2000) (1)
28- 35 F8.4 deg DEdeg Cluster center declination (J2000) (1)
37- 38 I2 arcmin Diam Angular diameter (1)
40- 43 I4 pc Dist Cluster distance (1)
45- 48 F4.2 mag E(B-V) Reddening (1)
50- 54 F5.2 mas/yr pmRA* Proper motion along RA, pmRA*cosDE (1)
56- 59 F4.2 mas/yr e_pmRA* rms uncertainty on pmRA* (1)
61- 65 F5.2 mas/yr pmDE Proper motion along DE (1)
67- 70 F4.2 mas/yr e_pmDE rms uncertainty on pmDE (1)
72- 75 F4.2 [yr] logAge Age (1)
77- 80 I4 --- Nmemb Number of members in table8.dat
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Note (1): from Dias et al. (2002A&A...389..871D 2002A&A...389..871D, Cat. B/ocl).
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Byte-by-byte Description of file: table8.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- Cluster Cluster code (1)
4- 18 F15.11 deg RAdeg Gaia DR2 Right ascension (ICRS) at Epoch=2015.5
20- 34 F15.11 deg DEdeg Gaia DR2 Right ascension (ICRS) at Epoch=2015.5
36- 41 F6.4 mas Plx Gaia DR2 Parallax
43- 48 F6.4 mas e_Plx rms uncertainty on Plx
50- 55 F6.3 mas/yr pmRA* Gaia DR2 proper motion along RA (pmRA*cosDE)
57- 61 F5.3 mas/yr e_pmRA* rms uncertainty on pmRA*
63- 68 F6.3 mas/yr pmDE Gaia DR2 proper motion along DE
70- 74 F5.3 mas/yr e_pmDE rms uncertainty on pmDE
76- 82 F7.4 mag Gmag Gaia DR2 magnitude
84- 89 F6.4 mag e_Gmag rms uncertainty on Gmag
91- 96 F6.4 mag G-RP Gaia DR2 G-RP colour index
98-102 F5.3 --- Pmemb Membership probability calculated in this work
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Note (1): Cluster code as follows:
C1 = NGC 2112
C2 = NGC 2477
C3 = NGC 7789
C4 = Collinder 261
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 08-Apr-2019