the galaxy enabled the determination of fairly well-behaved rotation curves for the galaxies. However, two of the compact group galaxies which are the most massive members in M51–like pairs, HCG 91a and HCG 96a, have very asymmetric rotation curves, with one arm rising and the other one falling, indicating, most probably, a recent perturbation by the small close companions.
author:
- 'C. Mendes de Oliveira , P. Amram , H. Plana'
- 'C. Balkowski'
title: |
    Dynamical effects of interactions and the\
    Tully-Fisher relation for Hickson compact groups 
---

Introduction
============

The influence of environmental effects on the internal dynamics and matter distribution of compact group galaxies has not yet been clearly established, mostly due to lack of reliable kinematic data. A recent study of the internal kinematics of 30 galaxies by Nishiura et al. (2000, hereafter N2000) found that asymmetric and peculiar rotation curves are more frequently seen in the Hickson Compact Groups (HCG) spiral galaxies than in field or cluster spirals and the dynamical properties of the galaxies do not seem to correlate with any group or galaxy parameter. An older but very influential study is that by Rubin et al. (1991, hereafter R1991), who analyzed rotation curves 