J/A+A/621/L3 Hyades tidal tails with Gaia DR2 (Meingast+, 2019)
Extended stellar systems in the solar neighborhood.
I. The tidal tails of the Hyades.
Meingast S., Alves J.
<Astron. Astrophys. 621, L3 (2019)>
=2019A&A...621L...3M 2019A&A...621L...3M (SIMBAD/NED BibCode)
ADC_Keywords: Clusters, open ; Positional data
Keywords: stars: kinematics and dynamics -
open clusters and associations: individual: Hyades
Abstract:
We report the discovery of two well-defined tidal tails emerging from
the Hyades star cluster. The tails were detected in Gaia DR2 data by
selecting cluster members in the 3D galactocentric cylindrical
velocity space. The robustness of our member selection is reinforced
by the fact that the sources depict an almost noiseless, coeval
stellar main sequence in the observational Hertzsprung-Russel diagram.
The spatial arrangement of the selected members represents a highly
flattened shape with respect to the direction of movement along the
clusters' orbit in the Galaxy. The size of the entire structure,
within the limits of the observations, measures about 200pc in its
largest extent, while being only about 25pc thick. This translates
into an on-sky extent of well beyond 100deg. Intriguingly, a top-down
view on the spatial distribution reveals a distinct S-shape,
reminiscent of tidal tails that have been observed for globular
clusters and also of tails that were modeled for star clusters bound
to the Galactic disk. Even more remarkable, the spatial arrangement as
well as the velocity dispersion of our source selection is in
excellent agreement with previously published theoretical predictions
for the tidal tails of the Hyades. An investigation into observed
signatures of equipartition of kinetic energy, that is, mass
segregation, remains unsuccessful, most likely because of the
sensitivity limit for radial velocity measurements with Gaia.
Description:
This table contains the final source selection as presented in the
associated letter. We provide basic Gaia DR2 information which
includes unique source identifiers. Furthermore, also the computed
Galactic Cartesian and Galactocentric Cylindrical coordinates are
included.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
hyades.dat 282 238 Hyades selection
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/243/386 : Hyades members distances (Schwan 1991)
J/A+A/331/81 : Hyades membership (Perryman+ 1998)
J/A+A/367/111 : A Hipparcos study of the Hyades cluster (de Bruijne+, 2001)
J/A+A/621/L2 : Hyades tidal tails revealed by Gaia DR2 (Roeser+, 2019)
J/A+A/622/L13 : Stellar stream in Gaia DR2 discovery (Meingast+, 2019)
Byte-by-byte Description of file: hyades.dat
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Bytes Format Units Label Explanations
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1- 28 A28 --- DR2Name Gaia DR2 Unique source designation,
Gaia DR2 NNNNNNNNNNNNNNNNNNN (designation)
30- 48 I19 --- Source Gaia DR2 Unique source identifier
(source_id)
50- 61 F12.8 deg RAdeg Gaia DR2 Right ascension (ICRS) at Ep=2015.5
(ra)
63- 74 F12.8 deg DEdeg Gaia DR2 Declination (ICRS) at Ep=2015.5
(dec)
76- 85 F10.6 mas Plx Gaia DR2 Parallax (parallax)
87- 96 F10.6 mas e_Plx Gaia DR2 Standard error of parallax
(parallax_error)
98-109 F12.6 mas/yr pmRA Gaia DR2 Proper motion in ra direction
(pmra)
111-120 F10.6 mas/yr e_pmRA Gaia DR2 Standard error of proper motion in
ra direction (pmra_error)
122-133 F12.6 mas/yr pmDE Gaia DR2 Proper motion in dec direction
(pmdec)
135-144 F10.6 mas/yr e_pmDE Gaia DR2 Standard error of proper motion in
dec direction (pmdec_error)
146-155 F10.6 mas amax Gaia DR2 The longest semi-major axis of the
5-d error ellipsoid (astrometricsigma5dmax)
157-163 F7.3 mag Gmag Gaia DR2 G-band mean magnitude
(photgmean_mag)
165-171 F7.3 mag BPmag ?=- Gaia DR2 Integrated BP mean magnitude
(photbpmean_mag)
173-179 F7.3 mag RPmag ?=- Gaia DR2 Integrated RP mean magnitude
(photrpmean_mag)
181-190 F10.6 km/s RV Gaia DR2 Radial velocity (radial_velocity)
192-201 F10.6 km/s e_RV Gaia DR2 Radial velocity error
(radialvelocityerror)
203-209 F7.3 pc X Galactic Cartesian X (X)
211-217 F7.3 pc Y Galactic Cartesian Y (Y)
219-225 F7.3 pc Z Galactic Cartesian Z (Z)
227-236 F10.3 pc gcR Galactocentric Cylindrical R (gc_R)
238-247 F10.3 pc gcPHI Galactocentric Cylindrical PHI (gc_PHI)
249-258 F10.3 pc gcZ Galactocentric Cylindrical Z (gc_Z)
260-266 F7.3 km/s gcvR Galactocentric Cylindrical vR (gc_vR)
268-274 F7.3 km/s gcvPHI Galactocentric Cylindrical vPHI (gc_vPHI)
276-282 F7.3 km/s gcvZ Galactocentric Cylindrical vZ (gc_vZ)
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Acknowledgements:
Stefan Meingast, stefan.meingast(at)univie.ac.at
Joao Alves, joao.alves(at)univie.ac.at
References:
Meingast et al., Paper II 2019A&A...622L..13M 2019A&A...622L..13M, Cat. J/A+A/622/L13
(End) Stefan Meingast [University of Vienna], Patricia Vannier [CDS] 11-Jan-2019