The Study of Galactic Disk Kinematics with SCUSS and SDSS Data

Abstract

We derive chemical and kinematics properties of G and K dwarfs from the SCUSS and SDSS data. We aim to characterize and explore the properties of the Galactic disk in order to understand their origins and evolutions. A kinematics approach is used to separate Galactic stellar populations into the likely thin disk and thick disk sample. Then, we explore rotational velocity gradients with metallicity of the Galactic disks to provide constraints on the various formation models. We identify a negative gradient of the rotational velocity of the thin disk stars with [Fe/H], −18.2 ± 2.3 km s−1 dex−1. For the thick disk, we identify a positive gradient of the rotational velocity with [Fe/H], 41.7 ± 6.1 km s−1 dex−1. The eccentricity does not change with metallicity for the thin disk sample. Thick disk stars exhibit a trend of orbital eccentricity with metallicity (−0.13 dex−1). The thin disk shows a negative metallicity gradient with Galactocentric radial distance R, while the thick disk shows a flat radial metallicity gradient. Our results suggest that radial migration may play an important role in the formation and evolution of the thin disk.