J/A+A/645/A84 Coronae of nearby star clusters (Meingast+, 2021)
Extended stellar systems in the solar neighborhood.
V. Discovery of coronae of nearby star clusters.
Meingast S., Alves J., Rottensteiner A.
<Astron. Astrophys. 645, A84 (2021)>
=2021A&A...645A..84M 2021A&A...645A..84M (SIMBAD/NED BibCode)
ADC_Keywords: Associations, stellar ; Milky Way ; Stars, nearby ;
Positional data ; Stars, distances ; Space velocities
Keywords: stars: kinematics and dynamics - solar neighborhood -
open clusters and associations: general
Abstract:
We present a novel view on the morphology and dynamical state of ten
prominent, nearby (≤500pc), and young (∼30-300Myr) open star clusters
with Gaia DR2: Per, Blanco 1, IC 2602, IC 2391, Messier 39, NGC 2451A,
NGC 2516, NGC 2547, Platais 9, and the Pleiades. We introduce a
pioneering member-identification method that is informed by cluster
bulk velocities and deconvolves the spatial distribution with a
mixture of Gaussians. Our approach enables inferring the true spatial
distribution of the clusters by effectively filtering field star
contaminants while at the same time mitigating the effect of positional
errors along the line of sight. This first application of the method
reveals vast stellar coronae that extend for ≳100pc and surround the
cluster cores, which are comparatively tiny and compact. The coronae
and cores form intertwined, coeval, and comoving extended cluster
populations, each encompassing tens of thousands of cubic parsec and
stretching across tens of degrees on the sky. Our analysis shows that
the coronae are gravitationally unbound but largely comprise the bulk
of the stellar mass of the populations. Most systems are in a highly
dynamic state, showing evidence of expansion and sometimes
simultaneous contraction along different spatial axes. The velocity
field of the extended populations for the cluster cores appears
asymmetric but is aligned along a spatial axis unique to each cluster.
The overall spatial distribution and the kinematic signature of the
populations are largely consistent with the differential rotation
pattern of the Milky Way. This finding underlines the important role
of global Galactic dynamics in the fate of stellar systems. Our
results highlight the complexity of the Milky Way's open cluster
population and call for a new perspective on the characterization and
dynamical state of open clusters.
Description:
This table contains the source selection as presented in the
associated paper. This table includes basic Gaia DR2 information
(source ID and coordinates), as well as parameters used in the paper.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
coronae.dat 108 7925 Cluster members
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
Byte-by-byte Description of file: coronae.dat
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Bytes Format Units Label Explanations
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1- 19 I19 --- GaiaDR2 Gaia DR2 Unique source identifier (source_id)
21- 32 F12.8 deg RAdeg Gaia DR2 Right ascension (ICRS) at ep=2015.5
34- 45 F12.8 deg DEdeg Gaia DR2 Declination (ICRS) at ep=2015.5
47- 53 F7.3 pc Dist(raw) Distance computed as 1/parallax
55- 61 F7.3 pc Dist(xd) Distance inferred from deconvolution
63- 70 F8.3 km/s UVel ? Galactic space velocity U
72- 78 F7.3 km/s VVel ? Galactic space velocity V
80- 86 F7.3 km/s WVel ? Galactic space velocity W
88- 97 F10.8 --- fc Fractional contamination
99-108 A10 --- Cluster Cluster name (1)
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Note (1): Clusters are IC 2391, IC 2602, Blanco 1, NGC 2516, NGC 2547,
NGC 7092, NGC 2451A, Platais 9, Melotte 20 and Melotte 22.
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Acknowledgements:
Stefan Meingast, stefan.meingast(at)univie.ac.at
Joao Alves, joao.alves(at)univie.ac.at
Alena Rottensteiner, a01619477(at)unet.univie.ac.at
References:
Meingast & Alves, Paper I 2019A&A...621L...3M 2019A&A...621L...3M, Cat. J/A+A/621/L3
Meingast et al., Paper II 2019A&A...622L..13M 2019A&A...622L..13M, cat. J/A+A/622/L13
Furnkranz et al., Paper III 2019A&A...624L..11F 2019A&A...624L..11F, Cat. J/A+A/624/L11
Ratzenbock et al., Paper IV 2020A&A...639A..64R 2020A&A...639A..64R, Cat. J/A+A/639/A64
(End) Stefan Meingast [University of Vienna], Patricia Vannier [CDS] 25-Dec-2020