J/MNRAS/507/1699 Blue straggler stars in open clusters with Gaia (Jadhav+, 2021)
Blue straggler stars in open clusters using Gaia:
dependence on cluster parameters and possible formation pathway.
Jadhav V.V., Subramaniam A.
<Mon. Not. R. Astron. Soc. 507, 1699-1709 (2021)>
=2021MNRAS.507.1699J 2021MNRAS.507.1699J (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Stars, blue ; Stars, masses
Keywords: blue stragglers - open clusters and associations: general
Abstract:
Blue straggler stars (BSSs) are the most massive stars in a cluster
formed via binary or higher-order stellar interactions. Though the
exact nature of such formation scenarios is difficult to pin down, we
provide observational constraints on the different possible mechanism.
In this quest, we first produce a catalogue of BSSs using Gaia DR2
data. Among the 670 clusters older than 300Myr, we identified 868 BSSs
in 228 clusters and 500 BSS candidates in 208 clusters. In general,
all clusters older than 1Gyr and massive than 1000M☉ have BSSs.
The average number of BSSs increases with cluster age and mass, and
there is a power-law relation between the cluster mass and the maximum
number of BSSs in the cluster. We introduce the term fractional mass
excess (Me) for BSSs. We find that at least 54% of BSSs have Me<0.5
(likely to have gained mass through a binary mass transfer (MT)), 30%
in the 1.0<Me<0.5 range (likely to have gained mass through a merger)
and up to 16% with Me>1.0 (likely from multiple mergers/MT). We also
find that the percentage of low Me BSSs increases with age, beyond
1-2Gyr, suggesting an increase in formation through MT in older
clusters. The BSSs are radially segregated, and the extent of
segregation depends on the dynamical relaxation of the cluster. The
statistics and trends presented here are expected to constrain the BSS
formation models in open clusters.
Description:
This study aimed to explore the properties of BSSs as a function of
cluster parameters and identify potential clusters for further study.
The data of 868 BSSs in 228 clusters in the 0.3-10Gyr age and
102-104M☉ mass range are used to explore their properties.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 84 670 Parameters of clusters with and without blue
stragglers
tablea2.dat 88 1368 Coordinates and parameters of individual blue
stragglers and blue straggler candidates
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/618/A93 : Gaia DR2 open clusters in the Milky Way (Cantat-Gaudin+, 2018)
J/A+A/640/A1 : Portrait Galactic disc (Cantat-Gaudin+, 2020)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
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1- 17 A17 --- Cluster Cluster name
19- 22 F4.2 [yr] logAge Age (logt) of the cluster
24- 27 F4.2 mag AV Extinction Av of the cluster
29- 33 F5.2 mag MOD Distance modulus of the cluster
35- 39 F5.2 pc r Radius containing half the members
41- 47 F7.1 Msun Mass Mass of the cluster
49- 55 F7.3 pc-3 Density Number density of the cluster
57- 62 F6.2 --- Nrelax Number of relaxation periods passed
64- 65 I2 --- NBSS Number of bonafide blue stragglers
67- 68 I2 --- NpBS Number of probable blue stragglers
70- 76 F7.3 arcmin Reffcl Effective mean radius of Gaia members
78- 84 F7.3 arcmin ReffBSS ? Effective mean radius of blue stragglers
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Byte-by-byte Description of file: tablea2.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- Cluster Cluster name
18- 27 F10.6 deg RAdeg Right ascension (ICRS) at Ep=2015.5
29- 38 F10.6 deg DEdeg Declination (ICRS) at Ep=2015.5
40- 58 I19 --- GaiaDR2 Gaia DR2 source ID
60- 65 F6.3 mag Gmag G-band mean magnitude
67- 72 F6.3 mag BP-RP BP-RP colour
74- 78 F5.2 Msun Mass Mass of the star
80- 84 F5.3 --- Me Fractional mass excess
86- 88 A3 --- Class [BSS pBS] Class, blue straggler stars (BSS)
or probable blue straggler stars (pBS)
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Acknowledgements:
Vikrant V. Jadhav, vikrant.jadhav(at)iiap.res.in
(End) Patricia Vannier [CDS] 27-Aug-2021