Journal Article

Spectroscopic hint of a cold stream in the direction of the globular cluster NGC 1851

A. Sollima, R. G. Gratton, J. A. Carballo-Bello, D. Martínez-Delgado, E. Carretta, A. Bragaglia, S. Lucatello and J. Peñarrubia

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 426, issue 2, pages 1137-1143
Published in print October 2012 | ISSN: 0035-8711
Published online October 2012 | e-ISSN: 1365-2966 | DOI: https://dx.doi.org/10.1111/j.1365-2966.2012.21803.x
Spectroscopic hint of a cold stream in the direction of the globular cluster NGC 1851

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We present the results of a spectroscopic survey performed in the outskirts of the globular cluster NGC 1851 with VIsible MultiObject Spectrograph (VIMOS)/Very Large Telescope (VLT). The radial velocities of 107 stars in a region between 12 and 33 arcmin around the cluster have been derived. We clearly identify the cluster stellar population over the entire field of view, indicating the presence of a significant fraction of stars outside the tidal radius predicted by King models. We also find tentative evidence of a cold (σv ≤ 20 km s−1) peak in the distribution of velocities at vr ∼ 180 km s−1 constituted mainly by main-sequence stars whose location in the colour–magnitude diagram is compatible with a stream at a similar distance to this cluster. If confirmed, this evidence would strongly support the extragalactic origin of this feature.

Keywords: methods: data analysis; methods: observational; techniques: radial velocities; globular clusters: individual: NGC 1851; Galaxy: halo; Galaxy: stellar content

Journal Article.  5277 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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