Bibcode
Marino, A. F.; Milone, A. P.; Yong, D.; Dotter, A.; Da Costa, G.; Asplund, M.; Jerjen, H.; Mackey, D.; Norris, J.; Cassisi, S.; Sbordone, L.; Stetson, P. B.; Weiss, A.; Aparicio, A.; Bedin, L. R.; Lind, K.; Monelli, M.; Piotto, G.; Angeloni, R.; Buonanno, R.
Referencia bibliográfica
Monthly Notices of the Royal Astronomical Society, Volume 442, Issue 4, p.3044-3064
Fecha de publicación:
8
2014
Número de citas
64
Número de citas referidas
57
Descripción
NGC 1851 is surrounded by a stellar component that extends more than 10
times beyond the tidal radius. Although the nature of this stellar
structure is not known, it has been suggested to be a sparse halo of
stars or associated with a stellar stream. We analyse the nature of this
intriguing stellar component surrounding NGC 1851 by investigating its
radial velocities and chemical composition, in particular in comparison
with those of the central cluster analysed in a homogeneous manner. In
total we observed 23 stars in the halo with radial velocities consistent
with NGC 1851, and for 15 of them we infer [Fe/H] abundances. Our
results show that (i) stars dynamically linked to NGC 1851 are present
at least up to ˜2.5 tidal radii, supporting the presence of a halo
of stars surrounding the cluster; (ii) apart from the NGC 1851 radial
velocity-like stars, our observed velocity distribution agrees with that
expected from Galactic models, suggesting that no other substructure
(such as a stream) at different radial velocities is present in our
field; (iii) the chemical abundances for the s-process elements Sr and
Ba are consistent with the s-normal stars observed in NGC 1851; (iv) all
halo stars have metallicities, and abundances for the other studied
elements Ca, Mg and Cr, consistent with those exhibited by the cluster.
The complexity of the whole NGC 1851 cluster+halo system may agree with
the scenario of a tidally disrupted dwarf galaxy in which NGC 1851 was
originally embedded.
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