View Full Version : Sombrero Galaxy speed.

2009-Oct-03, 03:33 AM
Does anyone know how fast the outer ring of the Sombrero Galaxy orbits the central bulge?

2009-Oct-03, 09:52 PM
This paper (http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1989A%26A...215..243W&data_type=PDF _HIGH&whole_paper=YES&type=PRINTER&filetype=.pdf) uses the starlight to derive a rotation-curve semiamplitude (that is, typical orbital velocity) which is nearly constant at 300 km/s from projected radii 1-2.5 arcminutes. That agrees well with the H-alpha gas measurements by Rubin et al. (http://articles.adsabs.harvard.edu/cgi-bin/nph-iarticle_query?1985ApJ...289...81R&data_type=PDF_H IGH&whole_paper=YES&type=PRINTER&filetype=.pdf), whose data extend to 3 arcminutes on the eastern side of the disk.