Before the bar: kinematic detection of a spheroidal metal-poor bulge component

Journal Article · Wed Apr 20 04:00:00 EDT 2016 · Astrophysical Journal Letters

DOI:https://doi.org/10.3847/2041-8205/821/2/L25· OSTI ID:22869095

Kunder, Andrea; Storm, J. ^[1]; Rich, R. M. ^[2]; Koch, A. ^[3]; Nataf, D. M. ^[4]; Propris, R. De ^[5]; Walker, A. R. ^[6]; Bono, G. ^[7]; Johnson, C. I. ^[8]; Shen, Juntai; Li, Z. -Y. ^[9]

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1. Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, D-14482 Potsdam (Germany)
2. Department of Physics and Astronomy, University of California, Los Angeles, Los Angeles, CA 90095-1562 (United States)
3. Physics Department, Lancaster University, Lancaster LA1 4YB (United Kingdom)
4. Research School of Astronomy and Astrophysics, The Australian National University, Canberra, ACT 2611 (Australia)
5. Finnish Centre for Astronomy with ESO, University of Turku, 2150 Turku (Finland)
6. Cerro Tololo Inter-American Observatory, National Optical Astronomy Observatory, Casilla 603, La Serena (Chile)
7. Dipartimento di Fisica, Universita di Roma Tor Vergata, via Della Ricerca Scientifica 1, I-00133 Roma (Italy)
8. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States)
9. Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China)

We present 947 radial velocities of RR Lyrae variable stars in four fields located toward the Galactic bulge, observed within the data from the ongoing Bulge RR Lyrae Radial Velocity Assay (BRAVA-RR). We show that these RR Lyrae stars (RRLs) exhibit hot kinematics and null or negligible rotation and are therefore members of a separate population from the bar/pseudobulge that currently dominates the mass and luminosity of the inner Galaxy. Our RRLs predate these structures and have metallicities, kinematics, and spatial distribution that are consistent with a “classical” bulge, although we cannot yet completely rule out the possibility that they are the metal-poor tail of a more metal-rich ([Fe/H]∼−1 dex) halo–bulge population. The complete catalog of radial velocities for the BRAVA-RR stars is also published electronically.

• OSTI ID: 22869095
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 2 Vol. 821; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CATALOGS
DETECTION
GALAXIES
LUMINOSITY
MASS
METALLICITY
RADIAL VELOCITY
ROTATION
SPATIAL DISTRIBUTION
VARIABLE STARS