2004/05/20 by A. V. Zasov, А. В. Хоперсков, Zasov, A. V. +5
Chemistry · Physics and Astronomy · #Astrophysics (astro-ph) #Astrophysics and Star Formation Studies #FOS: Physical sciences #Galaxies: Formation, Evolution, Phenomena #Spectroscopy and Laser Applications #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/0405400
10 pages, 6 figures inside, Oral talk was presented in International Workshop "Progress in Study of Astrophysical Disks: Collective and Stochastic Phenomena and Computational Tools", Volgograd, September 9-11, 2003
arxiv created 2004/05/20 · openalex publication_date 2004/05/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
We propose that the lower bound of the stellar radial velocity dispersion cr of an equilibrium stellar disk is determined by the gravitational stability condition. We compared the estimates of stellar velocity dispersion at radii r>(1.5 - 2)R0 (where R0 is the photometric radial scalelength of a disk), found in the literature, with the minimal values of cr necessary for the disk to be in a stable state, using the results of numerical simulations of 3D collisional disks. This approach enables to estimate an upper limit of the local surface density and (if R0 is known) a total masses of a disk and a dark halo. We argue that the old stellar disks of spiral galaxies with active star formation usually have the velocity dispersions which are close to the expected marginal values. A rough values of disk-to-total mass ratios (within the fixed radius) are found for about twenty spiral galaxies. Unlike spirals, the disks of the ``red'' Sa--S0 galaxies are evidently ``overheated'': their radial dispersion of velocities at r ~ 2 R0 exceeds significantly the marginal values for gravitational stability.