J/A+A/622/L13 Stellar stream in Gaia DR2 discovery (Meingast+, 2019)
Extended stellar systems in the solar neighborhood.
II. Discovery of a nearby 120° stellar stream in Gaia DR2.
Meingast S., Alves J., Fuernkranz V.
<Astron. Astrophys. 622, L13 (2019)>
=2019A&A...622L..13M 2019A&A...622L..13M (SIMBAD/NED BibCode)
ADC_Keywords: Positional data ; Stars, nearby
Keywords: stars: kinematics and dynamics - solar neighborhood -
open clusters and associations: general
Abstract:
We report the discovery of a large, dynamically cold, coeval stellar
stream that is currently traversing the immediate solar neighborhood
at a distance of only 100pc. The structure was identified in a wavelet
decomposition of the 3D velocity space of all stars within 300pc of
the Sun. Its members form a highly elongated structure with a length
of at least 400pc, while its vertical extent measures only about 50pc.
Stars in the stream are not isotropically distributed but instead form
two parallel lanes with individual local overdensities, that may
correspond to a remnant core of a tidally disrupted cluster or OB
association. Its members follow a very well-defined main sequence in
the observational Hertzsprung-Russel diagram and also show a
remarkably low 3D velocity dispersion of only 1.3km/s. These findings
strongly suggest a common origin as a single coeval stellar
population. An extrapolation of the present-day mass function
indicates a total mass of at least 2000M☉, making it larger than
most currently known clusters or associations in the solar
neighborhood. We estimated the age of the stream to be around 1 Gyr
based on a comparison with a set of isochrones and giant stars in our
member selection and find a mean metallicity of [Fe/H]=-0.04. This
structure may very well represent the Galactic disk counterpart to the
prominent stellar streams observed in the Milky Way halo. As such, it
constitutes a new valuable probe to constrain the Galaxy's mass
distribution.
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
stream.dat 285 256 Stream selection
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
J/A+A/621/L3 : Hyades tidal tails with Gaia DR2 (Meingast+, 2019)
Byte-by-byte Description of file: stream.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)
203-210 F8.3 pc X Galactic Cartesian X (X)
212-219 F8.3 pc Y Galactic Cartesian Y (Y)
221-228 F8.3 pc Z Galactic Cartesian Z (Z)
230-239 F10.3 pc gcR Galactocentric Cylindrical R (gc_R)
241-250 F10.3 pc gcPHI Galactocentric Cylindrical PHI (gc_PHI)
252-261 F10.3 pc gcZ Galactocentric Cylindrical Z (gc_Z)
263-269 F7.3 km/s gcvR Galactocentric Cylindrical vR (gc_vR)
271-277 F7.3 km/s gcvPHI Galactocentric Cylindrical vPHI (gc_vPHI)
279-285 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>
Verena Fuernkranz, verena.fuernkranz(at)univie.ac.at>
References:
Meingast & Alves, Paper I 2019A&A...621L...3M 2019A&A...621L...3M, Cat. J/A+A/621/L3
(End) Stefan Meingast [University of Vienna], Patricia Vannier [CDS] 25-Jan-2019