J/A+A/618/A93 Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)
A Gaia DR2 view of the open cluster population in the Milky Way.
Cantat-Gaudin T., Jordi C., Vallenari A., Bragaglia A., Balaguer-Nunez L.,
Soubiran C., Bossini D., Moitinho A., Castro-Ginard A., Krone-Martins A.,
Casamiquela L., Sordo R., Carrera R.
<Astron. Astrophys. 618, A93 (2018)>
=2018A&A...618A..93C 2018A&A...618A..93C (SIMBAD/NED BibCode)
ADC_Keywords: Surveys ; Clusters, open
Keywords: stars: distances - Galaxy: disk - Galaxy: structure -
open clusters and associations: general
Abstract:
Open clusters are convenient probes of the structure and history of
the Galactic disk. They are also fundamental to stellar evolution
studies. The second Gaia data release contains precise astrometry at
the submilliarcsecond level and homogeneous photometry at the mmag
level, that can be used to characterise a large number of clusters
over the entire sky. In this study we aim to establish a list of
members and derive mean parameters, in particular distances, for as
many clusters as possible, making use of Gaia data alone. We compiled
a list of thousands of known or putative clusters from the literature.
We then applied an unsupervised membership assignment code, UPMASK, to
the Gaia DR2 (Cat. I/345) data contained within the fields of those
clusters. We obtained a list of members and cluster parameters for
1229 clusters. As expected, the youngest clusters are seen to be
tightly distributed near the Galactic plane and to trace the spiral
arms of the Milky Way, while older objects are more uniformly
distributed, deviate further from the plane, and tend to be located at
larger Galactocentric distances. Thanks to the quality of Gaia DR2
astrometry, the fully homogeneous parameters derived in this study are
the most precise to date. Furthermore, we report on the serendipitous
discovery of 60 new open clusters in the fields analysed during this
study.
Description:
Mean cluster parameters (Table 1) and individual membership
probabilities established from Gaia DR2 (Cat. I/345) astrometry.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 208 1229 Summary of mean parameters for the OCs
characterised in this study
table1.fits 2880 55 Fits version of table1.dat
members.dat 257 401448 Membership probabilities of all individual stars
members.fits 2880 28859 Fits version of members.dat
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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- 17 A17 --- Cluster Cluster name (cluster)
19- 25 F7.3 deg RAdeg [] Mean right ascension of members (J2000)
(ra)
27- 33 F7.3 deg DEdeg Mean declination of members (J2000) (dec)
35- 41 F7.3 deg GLON Mean Galactic longitude of members (l)
43- 49 F7.3 deg GLAT Mean Galactic latitude of members (b)
51- 55 F5.3 deg r50 Radius containing half the members (r50)
57- 60 I4 --- Nstars Number of members (probability over 0.5)
(nbstars)
62- 68 F7.3 mas/yr pmRA Mean proper motion along RA of members (pmra)
70- 74 F5.3 mas/yr s_pmRA Standard deviation of pmRA of members
(sigpmra)
76- 80 F5.3 mas/yr e_pmRA Standard deviation of pmRA of members over
square root of nbstars (uncertpmra)
82- 88 F7.3 mas/yr pmDE Mean proper motion along DE of members(pmdec)
90- 94 F5.3 mas/yr s_pmDE Standard deviation of pmdec of members
(sigpmdec)
96-100 F5.3 mas/yr e_pmDE Standard deviation of pmdec of members over
square root of nbstars (uncertpmdec)
102-107 F6.3 mas plx Mean parallax of members (par)
109-113 F5.3 mas s_plx Standard deviation of parallax of members
(sigpar)
115-119 F5.3 mas e_plx Standard deviation of parallax of members
over square root of nbstars (uncertpar)
121-127 F7.1 pc d05 5th percentile distance confidence interval
(d05)
129-135 F7.1 pc d16 16th percentile distance confidence interval
(d16)
137-143 F7.1 pc dmode Most likely distance (dmode)
145-151 F7.1 pc d84 84th percentile distance confidence interval
(d84)
153-159 F7.1 pc d95 95th percentile distance confidence interval
(d95)
161-166 F6.1 pc dmode+01 Distance if +0.1mas added to parallax
(dmodePLUS01)
168-174 F7.1 pc dmode-01 ? Distance if -0.1mas added to parallax null
if mean parallax under 0.1mas (dmodeMINUS01)
176-183 F8.1 pc X X coordinate in Galactic coordinates (X)
185-192 F8.1 pc Y Y coordinate in Galactic coordinates (Y)
194-200 F7.1 pc Z Z coordinate in Galactic coordinates (Z)
202-208 F7.1 pc Rgc Distance from Galactic centre assuming the
Sun is at 8340pc (Rgc)
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Byte-by-byte Description of file: members.dat
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Bytes Format Units Label Explanations
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1- 15 F15.11 deg RAdeg [] Gaia DR2 right ascension (ICRS)
at Ep=2015.5 (ra)
17- 31 F15.11 deg DEdeg Gaia DR2 declination (ICRS)
at Ep=2015.5 (dec)
33- 51 I19 --- Source Gaia DR2 source_id (source_id)
53- 66 F14.10 deg GLON [] Gaia DR2 Galactic longitude (l)
68- 81 F14.10 deg GLAT Gaia DR2 Galactic latitude (b)
83- 92 F10.4 mas plx Gaia DR2 parallax (parallax)
94- 99 F6.4 mas e_plx Gaia DR2 parallax error (parallax_error)
101-109 F9.3 mas/yr pmRA Gaia DR2 proper motion along RA (pmra)
111-115 F5.3 mas/yr e_pmRA Gaia DR2 pmRA error (pmra_error)
117-125 F9.3 mas/yr pmDE Gaia DR2 proper motion along DE (pmdec)
127-131 F5.3 mas/yr e_pmDE Gaia DR2 pmDE error (pmdec_error)
133-139 F7.4 --- RADEcor Gaia DR2 correlation factor (radeccorr)
141-147 F7.4 --- RAPlxcor Gaia DR2 correlation factor
(raparallaxcorr)
149-155 F7.4 --- RApmRAcor Gaia DR2 correlation factor (rapmracorr)
157-163 F7.4 --- RApmDEcor Gaia DR2 correlation factor (rapmdeccorr)
165-171 F7.4 --- DEPlxcor Gaia DR2 correlation factor
(decparallaxcorr)
173-179 F7.4 --- DEpmRAcor Gaia DR2 correlation factor (decpmracorr)
181-187 F7.4 --- DEpmDEcor Gaia DR2 correlation factor
(decpmdeccorr)
189-195 F7.4 --- PlxpmRAcor Gaia DR2 correlation factor
(parallaxpmracorr)
197-203 F7.4 --- PlxpmDEcor Gaia DR2 correlation factor
(parallaxpmdeccorr)
205-211 F7.4 --- pmRApmDEcor Gaia DR2 correlation factor
(pmrapmdeccorr)
213-215 I3 --- o_Gmag Gaia DR2 number of G observations
(photgn_obs)
217-225 F9.6 mag Gmag Gaia DR2 mean G magnitude (photgmean_mag)
227-235 F9.6 mag BP-RP ? Gaia DR2 BP minus RP colour null
if missing in DR2 (bp_rp)
237-239 F3.1 --- PMemb Membership probability (proba)
241-257 A17 --- Cluster Corresponding cluster (cluster)
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Acknowledgements:
Tristan Cantat-Gaudin, tcantat(at)fqa.ub.edu
(End) T. Cantat-Gaudin [INAF-OAPd, Italy], Patricia Vannier [CDS] 26-Jul-2018