J/A+A/675/A89 Multiplicity fractions in Gaia open clusters (Donada+, 2023)
The multiplicity fraction in 202 open clusters from Gaia.
Donada J., Anders F., Jordi C., Masana E., Gieles M., Perren G.I.,
Balaguer-Nunez L., Castro-Ginard A., Cantat-Gaudin T., Casamiquela L.
<Astron. Astrophys. 675, A89 (2023)>
=2023A&A...675A..89D 2023A&A...675A..89D (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, open ; Optical
Keywords: open clusters and associations: general - Galaxy: evolution -
solar neighborhood - methods: data analysis - methods: statistical -
binaries: general
Abstract:
In this study we provide a large homogeneous catalogue of multiplicity
fractions in open clusters, including the unresolved and total (close-
binary) multiplicity fractions of main-sequence systems with mass
ratio larger than 0.6+0.05-0.15 for 202 open clusters in the
extended solar neighbourhood (closer than 1.5kpc from the Sun).
The unresolved multiplicity fractions are estimated applying a
flexible mixture model to the observed Gaia colour-magnitude diagrams.
Then we use custom Gaia simulations to account for the resolved
systems and derive the total multiplicity fractions. The studied open
clusters have ages between 6.6Myr and 3.0Gyr (146 are older than 50Myr
and their member lists are taken from Tarricq et al.
(2022A&A...659A..59T 2022A&A...659A..59T, Cat. J/A+A/659/A59), while the remaining 56 are
younger than 50Myr and their member lists are taken from Cantat-Gaudin
et al. (2020A&A...640A...1C 2020A&A...640A...1C, Cat. J/A+A/640/A1). Their total
high-mass-ratio multiplicity fractions range between 6% and 80%, with
a median of 18%. The multiplicity fractions increase with the mass of
the primary star, as expected. The average multiplicity fraction per
cluster displays an overall decreasing trend with the open cluster age
up to ages about 100Myr, above which the trend increases.
Our simulations show that most of this trend is caused by complex
selection effects (introduced by the mass dependence of the
multiplicity fraction and the magnitude limit of our sample).
Furthermore, the multiplicity fraction is not significantly correlated
with the clusters' position in the Galaxy. The spread in
multiplicity fraction decreases significantly with the number of
cluster members (used as a proxy for cluster mass). We also find that
the multiplicity fraction decreases with metallicity, in line with
recent studies using field stars.
Description:
We model the observed G vs. (BP-RP) Gaia colour-magnitude diagram
(CMD) of the selected main-sequence members of each open cluster as a
mixture distribution of single stars and unresolved binaries,
considering that two Gaussian distributions centred on the single
sequence and binary sequence loci introduce the observed scatter in G
magnitude. We perform Markov chain Monte Carlo (MCMC) fits for a
likelihood function depending (amongst others) on the open cluster's
high-mass ratio unresolved multiplicity fraction (integrated over the
colour index of the cluster's CMD). We thus derive the high-mass
ratio unresolved multiplicity fraction for 202 open clusters. Using a
sample of simulated Gaia-like open clusters we estimate that the
lowest mass ratio of the systems taken into account in this unresolved
multiplicity fraction is 0.6+0.05-0.15; and we estimate too the
total multiplicity fraction of systems (both resolved and unresolved)
having a mass ratio larger than this value.
Catalogue obtained applying the MCMC fits of our model to the sample
of 202 open clusters. It contains their structural parameters taken
from Cantat-Gaudin et al. (2020A&A...640A...1C 2020A&A...640A...1C, Cat. J/A+A/640/A1),
the number of selected main-sequence members and their minimum and
maximum BP-RP intrinsic colour index, the MCMC-fitted parameters of
the model (including the unresolved multiplicity fraction of systems
with a mass ratio q>Msecondary/Mprimary>0.6+0.05-0.15) and
also the estimated total multiplicity fraction (of both resolved and
unresolved systems having a mass ratio larger than this value).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
catalog.dat 248 202 Open cluster unresolved and total multiplicity
fractions of main-sequence systems with mass
ratio q>0.6+0.05-0.15
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
J/A+A/640/A1 : Portrait Galactic disc (Cantat-Gaudin+, 2020)
J/A+A/659/A59 : 389 local open clusters structural parameters (Tarricq+, 2022)
Byte-by-byte Description of file: catalog.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Cluster Open cluster name (Cluster)
19- 25 F7.3 deg RAdeg Mean right ascension of members (ICRS)
at Ep=2015.5 (RA_ICRS)
27- 33 F7.3 deg DEdeg Mean declination of members (ICRS)
at Ep=2015.5 (DE_ICRS)
35- 41 F7.3 deg GLON Mean Galactic longitude of members (GLON)
43- 49 F7.3 deg GLAT Mean Galactic latitude of members (GLAT)
51- 55 F5.3 deg r50 Radius containing half the members (r50)
57- 62 F6.3 mas plx Mean parallax of members (plx)
64- 68 F5.3 mas e_plx Standard deviation of parallax of members
(e_plx)
70- 73 F4.2 [yr] logAgeNN Age (logt) of the cluster (AgeNN)
75- 78 F4.2 mag AVNN Extinction Av of the cluster (AVNN)
80- 85 F6.1 pc DistPc Distance in parsecs (DistPc)
87- 93 F7.1 pc X X position in Galactic cartesian
coordinates (X)
95-101 F7.1 pc Y Y position in Galactic cartesian
coordinates (Y)
103-108 F6.1 pc Z Z position in Galactic cartesian
coordinates (Z)
110-115 F6.1 pc Rgc Distance from Galactic centre assuming
the Sun is at 8340pc (Rgc)
117-120 I4 --- nbMSmemb Number of selected main-sequence systems of
the open cluster (nbMSmembers)
122-127 F6.3 mag BP-RP0min Intrinsic colour index BP-RP of the bluest
selected system (BPRP0_min)
129-133 F5.3 mag BP-RP0max Intrinsic colour index BP-RP of the reddest
selected system (BPRP0_max)
135-139 F5.3 mag MSwidth BP-RP0max minus BP-RP0min (MS_width)
141-145 F5.3 Msun MassMin Mass interpolated for BP-RP0max using
Parsec isochrone logage=7.2 (mass_min)
147-151 F5.3 Msun MassMax Mass interpolated for BP-RP0min using
Parsec isochrone logage=7.2 (mass_max)
153-157 F5.3 Msun MassMean Mean mass of the open cluster's selected
main-sequence members (mean_mass)
159-163 F5.3 --- fbqlim0.6 Unresolved multiplicity fraction of systems
having mass ratio larger than
0.6+0.05-0.15 (posterior pdf's 50th
percentile) (fbqlim0point650)
165-169 F5.3 --- E_fbqlim0.6 Unresolved multiplicity fraction posterior
pdf's 84th percentile
(fbqlim0point6sigu)
171-175 F5.3 --- e_fbqlim0.6 Unresolved multiplicity fraction posterior
pdf's 16th percentile
(fbqlim0point6sigl)
177-182 F6.3 mag DG G magnitude offset between the polynomial
functions fitted to the single and binary
sequences (posterior pdf's 50th
percentile) (DG_50)
184-188 F5.3 mag E_DG DG_50 pdf's 84th percentile (DG_sigu)
190-194 F5.3 mag e_DG DG_50 pdf's 16th percentile (DG_sigl)
196-200 F5.3 mag sS Standard deviation in G magnitude of the
single-sequence fitted Gaussian
(posterior pdf's 50th percentile) (sS_50)
202-206 F5.3 mag E_sS sS_50 pdf's 84th percentile (sS_sigu)
208-212 F5.3 mag e_sS sS_50 pdf's 16th percentile (sS_sigl)
214-218 F5.3 mag sB Standard deviation in G magnitude of the
binary-sequence fitted Gaussian
(posterior pdf's 50th percentile) (sB_50)
220-224 F5.3 mag E_sB sB_50 pdf's 84th percentile (sB_sigu)
226-230 F5.3 mag e_sB sB_50 pdf's 16th percentile (sB_sigl)
232-236 F5.3 --- fbtotqlim0.6 Total multiplicity fraction
(fbtotqlim0point6)
238-242 F5.3 --- E_fbtotqlim0.6 Total multiplicity fraction 84th percentile
(fbtotqlim0point6_sigu)
244-248 F5.3 --- e_fbtotqlim0.6 Total multiplicity fraction 16th percentile
(fbtotqlim0point6_sigl)
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Acknowledgements:
Judit Donada Oliu, donada.judit(at)gmail.com
(End) Patricia Vannier [CDS] 02-May-2023