Bibcode
Wilhelm, R.; Beers, T. C.; Allende Prieto, C.; Newberg, H.; Yanny, B.
Referencia bibliográfica
American Astronomical Society Meeting 203, #112.01; Bulletin of the American Astronomical Society, Vol. 35, p.1383
Fecha de publicación:
12
2003
Número de citas
0
Número de citas referidas
0
Descripción
Recent results from the Sloan Digital Sky Survey (SDSS) and the 2MASS
All-Sky Survey have clearly revealed the extent of the spatial
distribution of stars affiliated with the tidal debris tail of the
Sagittarius Dwarf Galaxy (Sgr). Although these surveys help to constrain
the shape of the Sgr orbit, kinematics of the tidal tail stars are
crucial in order to fully characterize the structure and dynamics of
this component of our Galactic halo, and to allow a better determination
of the shape of the Milky Way dark matter halo.
We present kinematic results for a sample of horizontal-branch stars
from the SDSS-DR1 spectroscopic data. SDSS photometry and spectroscopy
were used to determine the stellar parameters (Teff, log g,
[Fe/H]) and subsequent luminosity classification. Distances and radial
velocities for a sample of blue horizontal-branch stars were analyzed in
the direction of the leading Northern tidal arm located at (b,l) ˜
(350, 50) and the trailing southern arc at (b, l) ˜ (157, -58).
There exists clear evidence of kinematic substructure in both
directions. The data match quite well the distribution of carbon stars
and model predictions of Ibata et. al (2001 ApJ 551, 2941). This
includes the velocity dispersion in the northern arm, where we find
σ = 55 km/s, and evidence for a bi-modal distribution in the
southern arc field, with the dominant component having a very small
velocity dispersion, σ = 30 km/s. These results are consistent
with a more spherical dark matter halo (qm = 0.9) as found by
Ibata et. al.
Partial support has been received for this work from NSF grants AST
00-98508 and AST 00-98549.