Volume 442, Number 2, November I 2005
|Page(s)||455 - 459|
|Published online||07 October 2005|
The large asymmetric HI envelope of the isolated galaxy NGC 864 (CIG 96)
Instituto de Astrofísica de Andalucía, CSIC, Apdo. 3004, 18080 Granada, Spain e-mail: email@example.com
2 Observatoire de Marseille, 2 Place le Verrier, 13248 Marseille Cedex 4, France
3 Department of Astronomy, University of Alabama, AL 35487, USA
4 Department of Astronomy, University of Massachussetts, Amherst, MA 01003, USA
Accepted: 23 June 2005
We present an HI synthesis imaging study of NGC 864 (CIG 96), a spiral galaxy well isolated from similarly sized companions, yet presenting an intriguing asymmetry in its integral HI spectrum. The asymmetry in the HI profile is associated with a strong kinematical perturbation in the gaseous envelope of the galaxy, where at one side the decay of the rotation curve is faster than Keplerian. We detect a small (M(HI) = 5 106 ) galaxy with a faint optical counterpart at ~80 kpc projected distance from NGC 864. This galaxy is probably not massive enough to have caused the perturbations in NGC 864. We discuss alternatives, such as the accretion of a gaseous companion at a radial velocity lower than the maximum.
Key words: galaxies: spiral / galaxies: structure / galaxies: kinematics and dynamics / galaxies: evolution / radio lines: galaxies
© ESO, 2005
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