1,395 research outputs found
Keck Studies of M31's Stellar Halo
We present Keck 10-meter/LRIS spectra of candidate red giants in the halo of
M31, located at a projected radius of R=19kpc on the minor axis. These
spectroscopic targets have been selected using a combination of UBRI-based and
morphological screening to eliminate background galaxies. Radial velocity
measurements are used to separate M31 halo giants from foreground Milky Way
dwarf stars, M31 disk stars, and residual background galaxies. The metallicity
of each M31 halo giant is measured using standard photometric and spectroscopic
techniques, the latter based on the strength of the CaII triplet. The various
[Fe/H] estimates are in rough agreement with one another. The data reveal a
large spread (>2dex) in [Fe/H] in M31's halo; there is no strong radial [Fe/H]
gradient. LRIS and HIRES spectra are also presented for red giants in five
dwarf spheroidal satellites of M31: AndI, AndIII, AndV, AndVI, and AndVII.
There appears to be a significant metallicity spread in AndVI and possibly in
AndI. The new radial velocity data on these outer dwarfs are used to constrain
the total mass of M31: the best estimate is under 10^(12)Msun, somewhat less
than the best estimate for the Milky Way.Comment: 12 pages, 7 figures, Proceedings of SPIE Conference: Discoveries and
Research Prospects with 8-10 Meter Class Telescopes (Munich March 2000
The Strategic Process: In Theory and Practice
Rather than a function delegated to the military in a time of emergency, the formulation and execution of national strategy has come to be recognized as a blend of military and political factors—the work of soldiers and statesmen together
Mahan on the Use of the Sea
Inasmuch as trade overseas has traditionally played a significant part in the U.S. economy, the size of its Navy is an accurate indicator of the economic and political status Americans feel their country must occupy
The National Higher Strategic Direction of War
I am approaching the subject from two sides. First, I inÂtend to schematize it - see what the situation looks like in the abstract. Second, I intend to examine three cases - the United States, Great Britain and Germany - and see what was actually done to deal with such a situation in its concrete form
Naval Command Course: Seapower in the Mediterranean
The discussion arranges itself in three parts: (1) an examination of straÂtegic significance; (2) a discussion of free world and related interests; and (3) the application of seapower, or, to put it in other terms, the strategic exploitation of the Mediterranean situation
The Cause of War
The jump-off had better be a look at the extent to which the subject of war and its causes has been cluttered up by partial explanations - all of them laid on weak foundations - and built with strong conviction
Kinematics and Composition of the Galactic Bulge: Recent Progress
We present recent results from a Keck study of the composition of the
Galactic bulge, as well as results from the bulge Bulge Radial Velocity Assay
(BRAVA). Culminating a 10 year investigation, Fulbright, McWilliam, & Rich
(2006, 2007) solved the problem of deriving the iron abundance in the Galactic
bulge, and find enhanced alpha element abundances, consistent with the earlier
work of McWilliam & Rich (1994). We also report on a radial velocity survey of
{\sl 2MASS}-selected M giant stars in the Galactic bulge, observed with the
CTIO 4m Hydra multi-object spectrograph. This program is to test dynamical
models of the bulge and to search for and map any dynamically cold substructure
in the Galactic bulge. We show initial results on fields at and . We construct a longitude-velocity plot for
the bulge stars and the model data, and find that contrary to previous studies,
the bulge does not rotate as a solid body; from the
rotation curve has a slope of and flattens considerably
at greater and reaches a maximum rotation of
(heliocentric) or (Galactocentric). This rotation is
slower than that predicted by the dynamical model of Zhao (1996).Comment: 6 pages, 6 figures, contributed paper at IAU Symposium 245 "Formation
and Evolution of Galactic Bulges
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