Bibcode
Law, D. R.; Schiavon, R. P.; Meszaros, Sz.; Smith, V. V.; Wilson, J. C.; Johnson, J.; Bizyaev, D.; Garcia Perez, A.; Frinchaboy, P. M.; Damke, G.; Beers, T. C.; Allende-Prieto, C.; Cunha, K. M.; Zasowski, G.; Hasselquist, Sten; Holtzman, J. A.; Johnston, K. V.; Nidever, D.; Lokas, E.; Majewski, S. R.; Beaton, R.; Shetrone, M. D.
Referencia bibliográfica
American Astronomical Society, AAS Meeting #221, #242.01
Fecha de publicación:
1
2013
Número de citas
0
Número de citas referidas
0
Descripción
As a system currently in the state of merging with the Milky Way -- and
therefore a prototype for substructures that participate in the
hierarchical build-up of our galaxy -- the structure of the Sagittarius
(Sgr) dSph system is of particular interest. The APOGEE survey is
ideally suited for the study of Sgr stars because of its ability to
sample numerous stars over a large field of view; its high spectral
resolution, which allows precision abundances and kinematics to be
measured in these stars; and its infrared sensitivity, which allows
these dust-extinguished fields to be explored more easily. Initial
APOGEE observations of Sgr have provided accurate radial velocities,
stellar parameters, and chemical abundances of over 200 confirmed Sgr
members in the dwarf galaxy’s central 2.5 degrees. The < 1 km/s
precision RVs have verified with strong significance the existence of a
dynamical cold point in the center of the Sgr dSph. We explore various
explanations for this phenomenon in terms of the distribution of both
dark matter and stellar populations. The data also shows evidence of a
metallicity gradient over the same radial range, demonstrating that the
velocity dispersion variations span, and may be related to, differences
in the distributions and dynamics of multiple stellar populations within
the satellite.