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Astron. Astrophys. 321, 409-423 (1997)


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Hickson 96: a physical compact group *

L. Verdes-Montenegro 1, A. del Olmo ** 1, J. Perea 1, E. Athanassoula 2, I. Márquez 1 and R. Augarde 2

1 Instituto de Astrofísica de Andalucía, CSIC, Apdo. 3004, E-18080 Granada, Spain
2 Observatoire de Marseille, 2 Place le Verrier, F-13248 Marseille Cedex 4, France

Received 23 August 1996 / Accepted 22 October 1996

Abstract

We analyze the morphology and dynamics of the galaxies of the Hickson 96 compact group by means of deep CCD images in the B, V and R photometric bands and long-slit spectroscopy.

The four galaxies of this spiral rich group show signs of gravitational interaction. Two long tails come out from the contact region of the close pair H96ac. It is also there where both galaxies, bi-symmetrical in their inner parts, loose one of their arms. Moreover, both the photometric and kinematical center of H96a are displaced relative to the center of the disk.

H96b, a giant elliptical galaxy, shows significant deviations from a [FORMULA] law at the inner parts and small rotation along its major axis. We find at the centre of the galaxy an elongated component which is kinematically decoupled. A wide faint plume seems to emerge from this galaxy. H96d, the smallest galaxy of the group, seems to be influenced by the bigger members, as indicated by three prominent knots of recent bursts of star formation in its blue disk, and by hints of optical bridges joining H96d with H96a and b.

Finally the group has a low velocity dispersion (160 km s-1) and is well isolated - no galaxies with comparable magnitude to H96a or H96b are found in its neighborhood. All these results lead us to conclude that Hickson 96 constitutes a real physical system.

Key words: galaxies: clusters: Hickson 96 – galaxies: interactions – galaxies: kinematics and dynamics – galaxies: evolution – galaxies: structure

* Based partially on data obtained at the Observatoire de Haute Provence, France
** Visiting Astronomer German-Spanish Astronomical Center, Calar Alto, operated by the Max-Planck-Institute for Astronomy, Heidelberg, jointly with the Spanish National Commission for Astronomy

Send offprint requests to: L. Verdes-Montenegro

© European Southern Observatory (ESO) 1997

Online publication: June 30, 1998

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