A&A 440, 67-71 (2005)
Can rotation curves reveal the opacity of spiral galaxies?A. Misiriotis
University of Crete, Physics Department, PO Box 2208, 710 03 Heraklion, Crete, Greece
(Received 16 August 2004 / Accepted 21 April 2005)
The observed anti-correlation between the inclination and the slope of the innermost part of the rotation curve can be attributed to dust extinction. However, the implied central face-on opacity of for the most luminous galaxies is embarrassingly high compared with studies of edge-on galaxies, which yield central face-on opacities equal to at most in the optical band. I show that the controversy can be resolved by adopting a model that includes the velocity dispersion of the emitters. Through the use of such a model, I reproduce the correlation between galaxy inclination and the slope of its inner rotation curve without having to resort to excessively high optical depth.
Key words: dust, extinction -- galaxies: kinematics and dynamics -- galaxies: spiral
© ESO 2005