2024/12/10 by Sun, Weixiang, Shen, Han, Jiang, Biwei +1 · 1 citation
#Astrophysics of Galaxies (astro-ph.GA) #FOS: Physical sciences
paper · doi:10.48550/arxiv.2412.07089
Using nearly 230,000 red clump (RC) stars selected from LAMOST and Gaia, we conduct a comprehensive analysis of the stellar age-velocity dispersion relations (AVRs) for various disk populations, within 5.0 ≤ R ≤ 15.0 kpc and |Z| ≤ 3.0 kpc. The AVRs of the whole RC sample stars are accurately described as σv = σv,0 (τ + 0.1)^βv, with βR, βϕ and βZ displaying a global exponential decreasing trend with R, which may point to the difference in spatial distributions of various disk heating mechanisms. The measurements of β - R for various disks suggest that the thin disk exhibits a radial dependence, with a global exponential decreasing trend in βR - R and βZ - R, while βϕ remains a nearly constant value (around 0.20∼0.25) within 8.5 ≤ R ≤ 11.5 kpc. The thick disk displays a global increasing trend in βR - R, βϕ - R and βZ - R. These results indicate that the thin disk stars are likely heated by long-term heating from GMCs and spiral arms, while thick disk stars are likely heated by some violent heating process from merger and accretion, and/or formed by the inside-out and upside-down star formation scenarios, and/or born in the chaotic mergers of gas-rich systems and/or turbulent ISM. Our results also suggest that the disk perturbation by a recent minor merger from Sagittarius may have occurred within 3.0 Gyr.