J/A+A/656/A49 Decoding the morphological evolution of open clusters (Hu+, 2021)
Decoding the morphological evolution of open clusters.
Hu Q., Zhang Y., Esamdin A.
<Astron. Astrophys. 656, A49 (2021)>
=2021A&A...656A..49H 2021A&A...656A..49H (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Morphology
Keywords: Galaxy: stellar content - methods: statistical -
open clusters and associations: general
Abstract:
The properties of open clusters such as metallicity, age, and
morphology are useful tools in studies of the dynamic evolution of
open clusters. The morphology of open clusters can help us better
understand the evolution of such structures.
We aim to analyze the morphological evolution of 1256 open clusters by
combining the shapes of the sample clusters in the proper motion space
with their morphology in the two-dimensional spherical Galactic
coordinate system, providing their shape parameters based on a member
catalog derived from Gaia Second Data Release as well as data from the
literature.
We applied a combination of a nonparametric bivariate density
estimation with the least square ellipse fitting to derive the shape
parameters of the sample clusters.
We derived the shape parameters of the sample clusters in the
two-dimensional spherical Galactic coordinate system and that of the
proper motion space. By analyzing the dislocation of the sample
clusters, we find that the dislocation, d; is related to the X-axis
pointing toward the Galactic center, Y-axis pointing in the direction
of Galactic rotation, and the Z-axis (log(|H|/pc)) that is positive
toward the Galactic north pole. This finding underlines the important
role of the dislocation of clusters in tracking the external
environment of the Milky Way. The orientation (qpm) of the clusters,
with epm≥0.4, presents an aggregate distribution in the range of
-45° to 45°, comprising about 74% of them. This probably
suggests that these clusters tend to deform heavily in the direction
of the Galactic plane. NGC 752 is in a slight stage of expansion in
the two-dimensional space and will become deformed, in terms of its
morphology, along the direction perpendicular to the original
stretching direction in the future if no other events occur. The
relative degree of deformation of the sample clusters in the
short-axis direction decreases as their ages increase. On average, the
severely distorted sample clusters in each group account for about
26%∼9%. This possibly implies a uniform external environment in the
range of |H|≤300pc if the sample completeness of each group is not
taken into account.
Description:
Parameters of 1256 open clusters in this study.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 143 1256 The parameters of 1256 open clusters
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See also:
J/A+A/640/A1 : Portrait Galactic disc (Cantat-Gaudin+, 2020)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 18 A18 --- Cluster Cluster name
20- 25 F6.4 --- ecore Ellipticity of the core
27- 32 F6.4 --- e_ecore Error corresponding to ellipticity of the core
34- 41 F8.4 deg qcore Orientation of the core
43- 48 F6.4 --- eall Ellipticity of the overall
50- 55 F6.4 --- e_eall Error corresponding to ellipticity
of the overall
57- 64 F8.4 deg qall Orientation of the overall
66- 71 F6.4 deg acore Half-length axes of the core
73- 78 F6.4 deg e_acore Error corresponding to half-length axes
of the core
80- 85 F6.4 deg ccore Half-short axes of the core
87- 92 F6.4 deg e_ccore Error corresponding to half-short axes
of the core
94- 99 F6.4 deg aall Half-length axes of the overall
101-106 F6.4 deg e_aall Error corresponding to half-length axes
of the overall
108-113 F6.4 deg call Half-short axes of the overall
115-120 F6.4 deg e_call Error corresponding to half-short axes
of the overall
122-127 F6.4 --- epm Ellipticity in proper motion
129-134 F6.4 --- e_epm Error of ellipticity in proper motion
136-143 F8.4 deg qpm Orientation in proper motion
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Acknowledgements:
Qingshun Hu, huqingshun(at)xao.ac.cn
(End) Qingshun Hu [Urumqi, Xinjiang, China], Patricia Vannier [CDS] 29-Oct-2021