Extended stellar systems in the solar neighborhood.

Stefan Meingast, João Alves, Verena Fürnkranz

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 100 pc. The structure was identified in a wavelet

decomposition of the 3D velocity space of all stars within 300 pc of the

Sun. Its members form a highly elongated structure with a length of at

least 400 pc, while its vertical extent measures only about 50 pc. 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 1.3 km s-1. 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 2000 M⊙, 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.


Full Table A.1 is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr

( or via cdsarc.u-strasbg.fr/viz-bin/qcat

Department of Astrophysics, Research Platform Data Science @ Uni Vienna
Astronomy & Astrophysics
No. of pages
Publication date
Publication status
Peer reviewed
Austrian Fields of Science 2012
103004 Astrophysics
stars: kinematics and dynamics, solar neighborhood, open clusters and associations: general
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