English

Before the Bar: Kinematic Detection of A Spheroidal Metal-Poor Bulge Component

Astrophysics of Galaxies 2016-04-27 v1 Solar and Stellar Astrophysics

Abstract

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 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 RR Lyrae stars 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.

Keywords

Cite

@article{arxiv.1603.06578,
  title  = {Before the Bar: Kinematic Detection of A Spheroidal Metal-Poor Bulge Component},
  author = {Andrea Kunder and R. M. Rich and J. Storm and D. M. Nataf and R. De Propris and A. R. Walker and G. Bono and C. I. Johnson and J. Shen and Z. Y. Li},
  journal= {arXiv preprint arXiv:1603.06578},
  year   = {2016}
}

Comments

accepted to ApJL