| Issue |
A&A
Volume 416, Number 2, March III 2004
|
|
|---|---|---|
| Page(s) | 507 - 514 | |
| Section | Extragalactic astronomy | |
| DOI | https://doi.org/10.1051/0004-6361:20034475 | |
| Published online | 27 February 2004 | |
Minor-axis velocity gradients in disk galaxies
*,**
1
Dipartimento di Astronomia, Università di Padova, vicolo dell'Osservatorio 2, 35122 Padova, Italy
2
European Southern Observatory, 3107 Alonso de Cordova, Santiago, Chile
3
Vatican Observatory, University of Arizona, Tucson, AZ 85721, USA
Corresponding author: L. Coccato, coccato@pd.astro.it
Received:
8
October
2003
Accepted:
25
November
2003
We present the ionized-gas kinematics and photometry of a sample of 4
spiral galaxies which are characterized by a zero-velocity plateau
along the major axis and a velocity gradient along the minor axis,
respectively. By combining these new kinematical data with those
available in the literature for the ionized-gas component of the S0s
and spirals listed in the Revised Shapley-Ames Catalog of Bright
Galaxies we realized that about 
of unbarred galaxies show a
remarkable gas velocity gradient along the optical minor axis. This
fraction rises to about 
if we include unbarred galaxies with
an irregular velocity profile along the minor axis. This phenomenon is
observed all along the Hubble sequence of disk galaxies, and it is
particularly frequent in early-type spirals. Since minor-axis
velocity gradients are unexpected if the gas is moving onto circular
orbits in a disk coplanar to the stellar one, we conclude that
non-circular and off-plane gas motions are not rare in the inner
regions of disk galaxies.
Key words: galaxies: kinematics and dynamics / galaxies: elliptical and lenticular, cD / galaxies: spiral / galaxies: structure
Based on observations carried out at the European Southern Observatory in La Silla (Chile) (ESO 69.B-0706 and 70.B-0338), with the Multiple Mirror Telescope which is a joint facility of the Smithsonian Institution and the University of Arizona, and with the Italian Telescopio Nazionale Galileo (AOT-5, 3-18) at the Observatorio del Roque de los Muchachos in La Palma (Spain).
© ESO, 2004
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