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

Kunder, Andrea and Rich, R. M. and Koch, A. and Storm, Jesper and Nataf, D. M. and Propris, R. De and Walker, Alistair and Bono, G. and Johnson, Christian I. and Shen, Juntai and Li, Z.-y. (2016) Before the bar : kinematic detection of a spheroidal metal-poor bulge component. Astrophysical Journal Letters, 821 (2): L25. ISSN 2041-8205

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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 ($[\mathrm{Fe}/{\rm{H}}]\sim -1$ dex) halo–bulge population. The complete catalog of radial velocities for the BRAVA-RR stars is also published electronically.

Item Type:
Journal Article
Journal or Publication Title:
Astrophysical Journal Letters
Additional Information:
This is an author-created, un-copyedited version of an article accepted for publication/published in Astrophysical Journal Letters. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at doi:10.3847/2041-8205/821/2/L25
Uncontrolled Keywords:
?? galaxy: bulgegalaxy: evolutiongalaxy: formationgalaxy: halo galaxy: kinematics and dynamicsgalaxy: structurespace and planetary scienceastronomy and astrophysics ??
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Deposited On:
18 May 2016 14:22
Last Modified:
15 Jul 2024 00:14