J/A+A/687/A291 Morphological coherence in open clusters (Hu+, 2024)
Exploration of morphological coherence in open clusters with "core-shell"
structure.
Hu Q., Zhang Y., Qin S., Zhong J., Chen L., Luo Y.
<Astron. Astrophys. 687, A291 (2024)>
=2024A&A...687A.291H 2024A&A...687A.291H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Morphology ; Optical
Keywords: open clusters and associations: general - solar neighborhood -
Galaxy: stellar content
Abstract:
The morphology of open clusters plays a major role in the study of
their dynamic evolution. The study of their morphological coherence,
namely, the three-dimensional (3D) difference between the inner and
outer morphologies of open clusters, allows us to obtain a better
understanding of the morphological evolution of open clusters.
We aim to investigate the morphological coherence of 132 open clusters
with up to 1kpc from the Sun in the three-dimensional (3D) space
within the heliocentric cartesian coordinate frame. The 132 open
clusters have a 3D core-shell structure and conform to the ellipsoidal
model, with all of them coming from a catalog of publicly available
clusters in the literature.
We employed the ellipsoid fitting method to delineate the 3D spatial
structure of the sample clusters, while using the morphological
dislocation (MD) defined in our previous work and the ellipticity
ratio (ER) of the clusters' inner and outer structures to
characterize the morphological coherence of the sample clusters.
The results show an inverse correlation between the ER of the sample
clusters and the number of their members, indicating that sample
clusters with a much more elliptical external morphology than internal
shape generally tend to host a large number of members. Meanwhile, a
slight shrinking of the MD of the sample clusters with their
members' number may shed light on the significant role of the
gravitational binding of the sample clusters in maintaining their
morphological stability. Moreover, there are no correlations between
the MD and ER of the sample clusters and their age. They are also not
significantly correlated with the X-axis, the Y-axis, their orbital
eccentricities, and the radial and vertical forces on them. However,
the ER of the sample clusters displays some fluctuations in the
distributions between it and the above covariates, implying that the
morphologies of the sample clusters are sensitive to the external
environment if sample effects are not taken into account. Finally, the
analysis of the 3D spatial shapes of sample clusters with a small ER
or a large ER demonstrates that the number of members lays an
important foundation for forming a dense internal system for sample
clusters. At the same time, the MD of the sample clusters can serve
well as an indicator of their morphological stability, which is built
upon a certain amount of member stars.
We present a new insight into the morphological coherence of open
clusters, attributed to the combination of their gravitational binding
capacity and external environmental perturbations.
Description:
This work is based on the biggest census catalog of open clusters and
their member star catalogs from Gaia-DR3, from which 132 open clusters
with a 3D core-shell structure that fit the ellipsoidal model have
been selected as our sample.
Overall parameters of sample clusters in this study.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 116 132 Overall parameters of sample clusters
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See also:
J/A+A/660/A4 : Gaia EDR3 new Galactic open clusters (Hao+, 2022)
J/A+A/673/A114 : Improving the open cluster census. II. (Hunt+, 2023)
Byte-by-byte Description of file: tablea1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 13 A13 --- Name Cluster name
15- 20 F6.2 deg RAdeg Right ascension (J2000)
22- 27 F6.2 deg DEdeg Declination (J2000)
29- 32 I4 --- Npge0.5 Number of sample cluster members with
probability more than or equal to 0.5
34- 37 F4.2 [yr] logt Cluster age
39- 45 F7.2 pc X Cluster X coordinate within
heliocentric Cartesian coordinates frame
47- 53 F7.2 pc Y Cluster Y coordinate within
heliocentric Cartesian coordinates frame
55- 61 F7.2 pc Z Cluster Z coordinate within
heliocentric Cartesian coordinates frame
63- 66 F4.2 --- d Morphological dislocation
68- 71 F4.2 --- e_d Error of morphological dislocation
73- 76 F4.2 --- ell Ellipticity ratio (ecore/eouter)
78- 81 F4.2 --- e_ell Error of ellipticity ratio
83- 89 F7.2 --- FR Radial force (in 2piGM/pc+2 unit)
91- 94 F4.2 --- e_FR Error of radial force (in 2piGM/pc+2 unit)
96-101 F6.2 --- Fz Vertical force (in 2piGM/pc+2 unit)
103-106 F4.2 --- e_Fz Error of vertical force (in 2piGM/pc+2 unit)
108-111 F4.2 --- ecc Orbital eccentricity
113-116 F4.2 --- e_ecc Error of orbital eccentricity
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Acknowledgements:
Qingshun Hu, qingshun0801(at)163.com
(End) Qingshun Hu [Nanchong, China], Patricia Vannier [CDS] 02-May-2024