2010/01/25 by A. Spagna, M. G. Lattanzi, P. Re Fiorentin +1 · 55 citations
Physics and Astronomy · #Astrophysics and Star Formation Studies #Context (archaeology) #Galactic halo #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Halo #Kinematics #Rotation (mathematics) #Stars #Stellar, planetary, and galactic studies #Thick disk #Thin disk #astro-ph.GA
paper · pdf · doi:10.1051/0004-6361/200913538
published in Astronomy and Astrophysics 510, L4 (EDP Sciences) · 5 pages, 6 figures, 3 tables. Accepted for pubblication in Astronomy and Astrophysics Letters, in press. Version with enlarged figures
openalex publication_date 2010/01/25 · arxiv created 2010/01/30 · arxiv updated 2015/05/18 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We analyze a new kinematic survey that includes accurate proper motions derived from SDSS DR7 positions, combined with multi-epoch measurements from the GSC-II database. By means of the SDSS spectro-photometric data (effective temperature, surface gravity, metallicity, and radial velocities), we estimate photometric parallaxes for a sample of 27 000 FGK (sub)dwarfs with [Fe/H] < -0.5, which we adopted as tracers of the seven-dimensional space distribution (kinematic phase distribution plus chemical abundance) of the thick disk and inner halo within a few kiloparsecs of the Sun. We find evidence of a kinematics-metallicity correlation, km s<sup>-1<sup/> dex<sup>-1<sup/>, amongst thick disk stars located between one and three kiloparsecs from the plane and with abundance -1 < [Fe/H] < -0.5, while no significant correlation is present for [Fe/H] -0.5. In addition, we estimate a shallow vertical rotation velocity gradient, km s<sup>-1<sup/> kpc<sup>-1<sup/>, for the thick disk between 1 kpc <i><<i/> |<i>z<i/>| < 3 kpc, and a low prograde rotation, 37 <i>±<i/> 3 km s<sup>-1<sup/> for the inner halo up to 4 kpc. Finally, we briefly discuss the implications of these findings for the thick disk formation scenarios in the context of CDM hierarchical galaxy formation mechanisms and of secular evolutionary processes in galactic disks.