Browsing by Subject "m-giants"
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Item The Bulge Radial Velocity Assay (BRAVA). II. Complete Sample And Data Release(2012-03) Kunder, Andrea; Koch, Andreas; Rich, R. Michael; de Propris, Roberto; Howard, Christian D.; Stubbs, Scott A.; Johnson, Christian I.; Shen, Juntai T.; Wang, Yougang G.; Robin, Annie C.; Kormendy, John; Soto, Mario; Frinchaboy, Peter; Reitzel, David B.; Zhao, HongSheng; Origlia, Livia; Kormendy, JohnWe present new radial velocity measurements from the Bulge Radial Velocity Assay, a large-scale spectroscopic survey of M-type giants in the Galactic bulge/bar region. The sample of similar to 4500 new radial velocities, mostly in the region -10 degrees < l < +10 degrees and b approximate to -6 degrees, more than doubles the existent published data set. Our new data extend our rotation curve and velocity dispersion profile to +20 degrees, which is similar to 2.8 kpc from the Galactic center. The new data confirm the cylindrical rotation observed at -6 degrees and -8 degrees and are an excellent fit to the Shen et al. N-body bar model. We measure the strength of the TiO epsilon molecular band as a first step toward a metallicity ranking of the stellar sample, from which we confirm the presence of a vertical abundance gradient. Our survey finds no strong evidence of previously unknown kinematic streams. We also publish our complete catalog of radial velocities, photometry, TiO band strengths, and spectra, which is available at the Infrared Science Archive as well as at UCLA.Item Kinematics At the Edge of the Galactic Bulge: Evidence for Cylindrical Rotation(2009-09) Howard, Christian D.; Rich, R. Michael; Clarkson, Will; Mallery, Ryan; Kormendy, John; De Propris, Roberto; Robin, Anne C.; Fux, Roger; Reitzel, David B.; Zhao, HongSheng; Kuijken, Konrad; Koch, Andreas; Kormendy, JohnWe present new results from BRAVA, a large-scale radial velocity survey of the Galactic bulge, using M giant stars selected from the Two Micron All Sky Survey catalog as targets for the Cerro Tololo Inter-American Observatory 4 m Hydra multi-object spectrograph. The purpose of this survey is to construct a new generation of self-consistent bar models that conform to these observations. We report the dynamics for fields at the edge of the Galactic bulge at latitudes b = -8 degrees and compare to the dynamics at b = -4 degrees. We find that the rotation curve V (r) is the same at b = -8 degrees as at b = -4 degrees. That is, the Galactic boxy bulge rotates cylindrically, as do boxy bulges of other galaxies. The summed line-of-sight velocity distribution at b = -8 degrees is Gaussian, and the binned longitude-velocity plot shows no evidence for either a (disk) population with cold dynamics or for a (classical bulge) population with hot dynamics. The observed kinematics are well modeled by an edge-on N-body bar, in agreement with published structural evidence. Our kinematic observations indicate that the Galactic bulge is a prototypical product of secular evolution in galaxy disks, in contrast with stellar population results that are most easily understood if major mergers were the dominant Formation process.