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Kinematics and composition of the Galactic bulge: recent progress

Published online by Cambridge University Press:  01 July 2007

R. Michael Rich ,
Christian Howard ,
David B. Reitzel ,
HongSheng Zhao  and
Roberto de Propris
R. Michael Rich
Affiliation:
Department of Physics and Astronomy, UCLA, Los Angeles CA, 90095-1547, U.S.A. email: rmr@astro.ucla.edu; howard@astro.ucla.edu; reitzel@astro.ucla.edu
Christian Howard
Affiliation:
Department of Physics and Astronomy, UCLA, Los Angeles CA, 90095-1547, U.S.A. email: rmr@astro.ucla.edu; howard@astro.ucla.edu; reitzel@astro.ucla.edu
David B. Reitzel
Affiliation:
Department of Physics and Astronomy, UCLA, Los Angeles CA, 90095-1547, U.S.A. email: rmr@astro.ucla.edu; howard@astro.ucla.edu; reitzel@astro.ucla.edu
HongSheng Zhao
Affiliation:
SUPA, School of Physics and Astronomy, University of St Andrews, KY16 9SS, Fife, U.K. email: hz4@st-andrews.ac.uk
Roberto de Propris
Affiliation:
Cerro Tololo Inter-American Observatory, Casilla 603, La Serena, Chile email: rdepropris@ctio.noao.edu
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Abstract

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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 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 −10° < l < + 10° and b = −4°. 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 −5° < l < + 5° the rotation curve has a slope of ≈ 100 km s−1 and flattens considerably at greater l and reaches a maximum rotation of 45 km s−1 (heliocentric) or ~ 70 km s−1 (Galactocentric). This rotation is slower than that predicted by the dynamical model of Zhao (1996).

Keywords

Galaxy: bulgeGalaxy: abundancesGalaxy: kinematics and dynamicsGalaxy: formationgalaxies: bulges
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 3 , Symposium S245: Formation and Evolution of Galaxy Bulges , July 2007 , pp. 333 - 338
Copyright
Copyright © International Astronomical Union 2008

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