J/A+A/647/A137 800pc tital tail of Hyades (Jerabkova+, 2021)
The 800pc long tidal tails of the Hyades star cluster. Possible discovery of
candidate epicyclic overdensities from an open star cluster.
Jerabkova T., Boffin H.M.J., Beccari G., de Marchi G., de Bruijne J.H.J.,
Prusti T.
<Astron. Astrophys. 647, A137 (2021)>
=2021A&A...647A.137J 2021A&A...647A.137J (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Proper motions
Keywords: open clusters and associations: individual: Hyades - ISM: clouds -
open clusters and associations: general - astrometry -
solar neighborhood - stars: kinematics and dynamics
Abstract:
The tidal tails of stellar clusters provide an important tool for
studying the birth conditions of the clusters and their evolution,
coupling, and interaction with the Galactic potential.
The Gaia satellite, with its high-quality astrometric data, opened
this field of study, allowing us to observe large-scale tidal tails.
Theoretical models of tidal-tail formation and evolution are
available. However, the exact appearance of tidal features as seen in
the Gaia catalogue has not yet been studied. Here we present the
$N-$body evolution of a Hyades-like stellar cluster with
backward-integrated initial conditions on a realistic 3D orbit in the
Milky Way (MW) galaxy computed within the AMUSE framework. For the
first time, we explore the effect of the initial cluster rotation and
the presence of lumps in the Galactic potential on the formation and
evolution of tidal tails. For all of our simulations we present Gaia
observables and derived parameters in the CP diagram.
We show that the tidal tails are not naturally clustered in any
coordinate system and that they can span up to 40 km/s relative to the
cluster centre in proper motions for a cluster age of 600-700Myr.
Models with initial rotation result in significant differences in the
cluster mass loss and follow different angular momentum time
evolution. Thus the orientation of the tidal tails relative to the
motion vector of the cluster and the current cluster angular momentum
constrain the initial rotation of the cluster.
We highlight the use of the standard CP method in searches for
co-moving groups and introduce a new compact CP (CCP) method that
accounts for internal kinematics based on an assumed model. Using the
CCP method, we are able to recover candidate members of the Hyades
tidal tails in the Gaia Data Release 2 (DR2) and early Data Release 3
(eDR3) reaching a total extent of almost 1kpc.
We confirm the previously noted asymmetry in the detected tidal tails.
In the eDR3 data we recovered spatial overdensities in the leading and
trailing tails that are kinematically consistent with being epicyclic
overdensities and thus would present candidates for the first such
detection in an open star cluster. We show that the epicyclic
overdensities are able to provide constraints not only on the cluster
properties, but also on the Galactic potential. Finally, based on
N-body simulations, a close encounter with a massive Galactic lump can
explain the observed asymmetry in the tidal tails of the Hyades.
Description:
We performed N body simulations of Hyades-like star clusters on a
realistic orbit in the Galactic potential within the AMUSE
computational environment. We explored the effect of initial cluster
rotation and presence of Galactic lumps in addition to the smooth
Galactic potential on the evolution of the tidal tail.
Objects:
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RA (2000) DE Designation(s)
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04 26 54.00 +15 52 00.0 Hyades cluster = Cl Melotte 25
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File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
tableb1.dat 118 1109 Final selection of tidal tail members in
Gaia DR2 data based on model M1
tableb2.dat 111 862 Final selection of tidal tail members in
Gaia eDR3 data based of model M5
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
Byte-by-byte Description of file: tableb1.dat
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Bytes Format Units Label Explanations
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1- 4 I4 --- Seq [0/1108] Sequential number
6- 24 I19 --- GaiaDR2 Gaia DR2 source ID
26- 45 F20.16 deg RAdeg Gaia DR2 Right Ascension (ICRS) at Ep=2015.5
47- 67 F21.17 deg DEdeg Gaia DR2 Declination (ICRS) at Ep=2015.5
75- 95 F21.17 mas/yr pmRA Gaia DR2 Proper motion in Right Ascension,
pmRA*cosDE
97-118 F22.17 mas/yr pmDE Gaia DR2 Proper motion in Declination
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Byte-by-byte Description of file: tableb2.dat
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Bytes Format Units Label Explanations
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1- 3 I3 --- Seq [0/861] Sequential number
5- 23 I19 --- GaiaEDR3 Gaia EDR3 source ID
25- 44 F20.16 deg RAdeg Gaia EDR3 Right Ascension (ICRS) at Ep=2016.0
46- 66 F21.17 deg DEdeg Gaia EDR3 Declination (ICRS) at Ep=2016.0
68- 88 F21.17 mas/yr pmRA Gaia EDR3 Proper motion in Right Ascension,
pmRA*cosDE
90-111 F22.17 mas/yr pmDE Gaia EDR3 Proper motion in Declination
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Acknowledgements:
Tereza Jerabkova, Tereza.Jerabkova(at)esa.int
(End) Patricia Vannier [CDS] 19-Feb-2021