http://arxiv.org/abs/2205.09227
We investigate the kinemato-chemical distribution of a sample of Red Giant Branch (RGB) stars from the LAMOST survey crossed matched with Gaia DR2 proper motions, and present the time tagging for the well-known ridge structures (diagonal distributions in the $R, V_{\phi}$ plane) in the range of Galactocentric distance R = 8 to 18 kpc. We detect six long-lived ridge structures, including five ridges apparent in the radial velocity distribution and one ridge apparent in the vertical velocity. Based on an analysis of the evolution of the angular momentum distribution, we find that four ridges are relatively stationary, while another is evolving with time, which is confirmed by the difference analysis at different populations and supporting that there might be two kinds of dynamical origins with possible coupling mechanisms. Furthermore, ridge features are also vividly present in the chemical properties ([Fe/H], [$\alpha$/Fe]), in particular for the mass distribution (M). The comparison between the north and south hemispheres of the Galaxy does not show a clear asymmetry in the phase space location even though the amplitude (e.g., vertical velocity) is asymmetrical. Moreover, we find that diagonal ridge structures may affect the shape of the rotation curve, which is manifested as fluctuations and undulations on top of a smooth profile.
P. Yang, H. Wang, Z. Luo, et. al.
Fri, 20 May 22
56/65
Comments: 10 pages, 13 figures
You must be logged in to post a comment.