Work

Evidence of a Metal-rich Galactic Bar from the Vertex Deviation of the Velocity Ellipsoid

Year: 2007

Type: article

Abstract: We combine radial velocities, proper motions, and low-resolution abundances for a sample of 315 K and M giants in the Baade's window ( l , b ) = (0.9°, -4°) Galactic bulge field. The velocity ellipsoid of stars with [Fe/H] > -0.5 dex shows a vertex deviation in the plot of radial versus transverse velocity, consistent with that expected from a population with orbits supporting a bar. We demonstrate that the significance of this vertex deviation, using nonparametric rank correlation statistic, is >99%. The velocity ellipsoid for the metal-poor ([FeH] < -0.5) part of the population shows no vertex deviation and is consistent with an isotropic, oblate rotating population. We find no evidence of kinematic subgroups, but there is a mild tendency for the vertical velocity dispersion σ b to decrease with increasing metallicity.

Source: The Astrophysical Journal

DOI: 10.1086/521098

Authors: M. Soto, R. M. Rich, K. Kuijken

Institutions: Leiden University, Leiden Observatory, University of California, Los Angeles

Language: English

Topic: Stellar, planetary, and galactic studies

Subfield: Astronomy and Astrophysics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: bronze

Funders: Space Telescope Science Institute, Leids Kerkhoven-Bosscha Fonds

OpenAlex ID: W2066588711

FWCI: 1.981

Cites: 26

Cited by: 68

Related to: 10