J/A+A/679/A122 Radial migration in open clusters (Viscasillas Vazquez+, 2023)
The role of radial migration in open cluster and field star populations
with Gaia DR3.
Viscasillas Vazquez C., Magrini L., Spina L., Tautvaisiene G.,
Van der Swaelmen M., Randich S., Sacco G.G.
<Astron. Astrophys., 679, A122 (2023)>
=2023A&A...679A.122V 2023A&A...679A.122V (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Clusters, open ; Optical ; Stellar distribution
Keywords: Galaxy: disk - Galaxy: evolution - Galaxy: abundances -
Galaxy: kinematics and dynamics -
open clusters and associations: general
Abstract:
The survival time of a star cluster depends on its total mass,
density, and thus size, as well as on the environment in which it was
born and in which lies. Its dynamical evolution is influenced by
various factors such as gravitational effects of the Galactic bar,
spiral structures, and molecular clouds. Overall, the factors that
determine the longevity of a cluster are complex and not fully
understood.
This study aims to investigate whether open clusters and field stars
respond differently to the perturbations that cause radial migration.
In particular, we aim to understand the nature of the oldest surviving
clusters.
We compared the time evolution of the kinematic properties of two Gaia
DR3 samples. The first sample is composed of ∼40 open clusters and
the second one of ∼66000 main sequence turn off field stars. Both
of the samples are composed of stars selected with the same quality
criterion, and they belong to the thin disc, are in a similar
metallicity range, are located in the same Galactocentric region
[7.5-9kpc], and have ages greater than 1 Gyr. We performed a
statistical analysis comparing the properties of the samples of the
field stars and of the open clusters.
A qualitative comparison of kinematic and orbital properties revealed
that clusters younger than 2-3Gyr are more resistant to perturbations
than field stars, and they move along quasi-circular orbits.
Conversely, clusters older than approximately 3Gyr have more
eccentric and inclined orbits than isolated stars in the same age
range. Such orbits lead the older clusters to reach higher elevations
on the Galactic plane, maximising their probability to survive several
more gigayears. A formal statistical analysis revealed that there are
differences among the time evolution of most of the kinematic and
orbital properties of the field stars and open clusters. However, the
comparison between some properties (e.g., Vphi and LZ) do not
reach a sufficient statistical significance.
Our results suggest that the oldest surviving clusters are usually
more massive and move on orbits with a higher eccentricity. Although
they are still reliable tracers of the Galaxy's past composition, they
do not reflect the composition of the place where they are currently
found. Therefore, we cannot avoid considering kinematic properties
when comparing data and models of chemical evolution and also taking
into account the intrinsic differences between clusters and isolated
stars. To validate the results, new studies that increase the sample
of open clusters, especially at older ages, are needed.
Description:
We conducted a purely observational study using high-quality
spectroscopic Gaia DR3 data to identify the differences between the
kinematics of a selected population of field stars and open clusters.
For a meaningful comparison between the kinematic and dynamical
properties of clusters and field stars, we restricted our sample to
the radial region [7.5-9kpc]. Furthermore, we restricted our sample
to clusters older than 1 Gyr because our aim was to estimate the
effect of migration, which is negligible for younger clusters. We
selected a sample of field stars around the MSTO so as to have a
better determination of their ages. We compared the velocity
components, the orbital parameters, and orbital actions of our sample
of ∼66000 field stars and 41 open clusters.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tablea1.dat 107 41 Properties of the open clusters used in this
study
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See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
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- 16 A16 --- Cluster Cluster name
18- 23 F6.3 [-] [M/H] Calibrated metallicity (1)
25- 30 F6.3 [-] [alpha/Fe] Abundance [alpha/Fe] (1)
32- 36 F5.3 Gyr Age Age (2)
38- 43 F6.1 pc RGC Galactocentric radius (1)
45- 49 F5.3 --- e Eccentricity (3)
51- 55 F5.3 kpc Zmax Maximun height above the plane (3)
57- 63 F7.3 km/s VR Radial velocity (3)
65- 71 F7.3 km/s Vphi tangential velocity (3)
73- 78 F6.3 km/s |VZ| Absolute vertical velocity (3)
80- 86 F7.3 kpc.km/s JR Radial action (3)
88- 93 F6.3 kpc.km/s JZ Vertical action (3)
95-102 F8.3 kpc.km/s LZ azimuthal action (3)
104-107 I4 --- N Number of member stars (2)
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Note (1): The stellar parameters and abundances of member stars (calibrated
metallicity and [alpha/Fe]) are from the Gaia General Stellar Parametrizer from
spectroscopy (GSPspec) (Recio-Blanco et al., 2023A&A...674A..29R 2023A&A...674A..29R, Cat. I/355)
Note (2): the membership of stars and ages are taken from Cantat-Gaudin et al.
(2020A&A...640A...1C 2020A&A...640A...1C, Cat. J/A+A/640/A1).
Note (3): orbital parameters are recomputed in the present work.
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 05-Mar-2024