1999/02/17 by Ortwin E. Gerhard, Gerhard, Ortwin E.
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9902247
15 pages, LaTeX, 5 figures, Fig.4 degraded. Invited review, to appear in `Galaxy Dynamics', ASP Conf.Ser., eds. D.Merritt, M.Valluri, J.Sellwood
arxiv created 1999/02/17 · arxiv updated 2009/12/01
Our Galaxy is a barred spiral. Recent work based on the COBE NIR data implies a small bulge-bar and a disk with a short scale-length. The corotation radius of the bar is in the range 3-4.5 kpc. The stellar density distribution beyond the end of the bar appears to be perturbed strongly by the Galaxy's spiral arms. Gas flow calculations in corresponding potentials provide a qualitative explanation of many features observed in HI and CO lv-diagrams. These include the 3-kpc-arm and the apparent four-armed spiral structure between corotation and the solar radius. The mass of NIR-luminous matter is constrained by the terminal velocity curve, the Oort limit, and the bulge microlensing observations, and this implies that the Milky Way has a near-maximum disk and a dark halo with a large core radius of ~ 15 kpc. However, we are still some way from a detailed quantitative model for the large-scale dynamics of the Galaxy. I summarize a number of uncertainties as well as how future work might resolve them.