H$\alpha$ velocity widths of giant extragalactic \hii regions
J. R. Roy, R. Arsenault, G. Joncas;
ApJ, 1986, 300, 624
ABSTRACT:Velocity dispersions have been deduced from H-alpha profiles obtained with a Fabry-Perot interferometer spectrometer in 47 giant H II
regions observed in 16 nearby spiral and irregular Magellanic galaxies.
The
velocity width W is found to be related to the size of the H II region; the relation
is significantly different from the prediction of
self-gravitation.
The mean of the three largest velocity widths of H II regions in a galaxy is
closely related to the absolute blue magnitude of the present galaxy.
The
shape of the relation log D-log W is dependent on the adopted distances to the
galaxies.
Analysis of detailed velocity maps of two galactic H II regions shows that the
internal relationship between the velocity width and linear size is the same as
for giant extragalactic regions.
A turbulent energy cascade is
suggested as the most viable mechanism explaining both the relationship between
velocity dispersion and size and that between velocity dispersion and the
absolute magnitude of the parent galaxy.
KEYWORDS: astronomical spectroscopy, h alpha line, h ii regions, nebulae, data correlation, diameters, regression analysis, spectral line width, turbulence
PERSOKEY:turbulence, ,
CODE: roy86