Kavli Affiliate: Huawei Zhang
| First 5 Authors: Weixiang Sun, Yang Huang, Han Shen, Chun Wang, Huawei Zhang
| Summary:
We present a comprehensive study of the kinematic properties of the different
Galactic disk populations, as defined by the chemical abundance ratios and
stellar ages, across a large disk volume (4.5 $leq$ R $leq$ 15.0 kpc and
$|Z|$ $leq$ 3.0 kpc), by using the LAMOST-Gaia red clump sample stars. We
determine the median velocities for various spatial and population bins,
finding large-scale bulk motions, such as the wave-like behavior in radial
velocity, the north-south discrepancy in azimuthal velocity and the warp signal
in vertical velocity, and the amplitudes and spatial-dependences of those bulk
motions show significant variations for different mono-age and mono-abundance
populations. The global spatial behaviors of the velocity dispersions clearly
show a signal of spiral arms and, a signal of the disk perturbation event
within 4 Gyr, as well as the disk flaring in the outer region (i.e., $R ge 12$
kpc) mostly for young or alpha-poor stellar populations. Our detailed
measurements of age/[$alpha$/Fe]-velocity dispersion relations for different
disk volumes indicate that young/$alpha$-poor populations are likely
originated from dynamically heated by both giant molecular clouds and spiral
arms, while old/$alpha$-enhanced populations require an obvious contribution
from other heating mechanisms such as merger and accretion, or born in the
chaotic mergers of gas-rich systems and/or turbulent interstellar medium.
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