Spectroscopy of red giants in the globular cluster Terzan 8: Kinematics and evidence for the surrounding sagittarius stream

A. Sollima*, E. Carretta, V. D'Orazi, R. G. Gratton, A. Bragaglia, S. Lucatello

*Corresponding author for this work

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    We present the results of a spectroscopic survey of red giants in the globular cluster Terzan 8 with the aim of studying its kinematics. We derived accurate radial velocities for 82 stars located in the innermost 7 arcmin from the cluster centre identifying 48 bona fide cluster members. The kinematics of the cluster have been compared with a set of dynamical models accounting for the effect of mass segregation and a variable fraction of binaries. The derived velocity dispersion appears to be larger than that predicted for mass-segregated stellar systems without binaries, indicating that either the cluster is dynamically young or it contains a large fraction of binaries (>30 per cent). We detected seven stars with a radial velocity compatible with the cluster systemic velocity but with chemical patterns which stray from those of both the cluster and the Galactic field. These stars are likely members of the Sagittarius stream surrounding this stellar system.

    Original languageEnglish
    Article numberstu1264
    Pages (from-to)1425-1432
    Number of pages8
    JournalMonthly Notices of the Royal Astronomical Society
    Issue number2
    Publication statusPublished - 11 Sep 2014

    Bibliographical note

    Copyright 2014 The Authors. First published in Monthly Notices of the Royal Astronomical Society, 443(2), 1425-1432. The original publication is available at http://doi.org/10.1093/mnras/stu1264, published by Oxford University Press on behalf of the Royal Astronomical Society. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.


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