Ha Velocity Fields and Galaxy Interaction in the Quartet of Galaxies NGC
  7769, 7770, 7771 and 7771A
  The quartet of galaxies NGC 7769, 7770, 7771 and 7771A is a system of
interacting galaxies. Close interaction between galaxies caused characteristic
morphological features: tidal arms and bars, as well as an induced star
formation. In this study, we performed the Fabry-Perot scanning interferometry
of the system in Ha line and studied the velocity fields of the galaxies. We
found that the rotation curve of NGC 7769 is weakly distorted. The rotation
curve of NGC 7771 is strongly distorted with the tidal arms caused by direct
flyby of NGC 7769 and flyby of a smaller neighbor NGC 7770. The rotation curve
of NGC 7770 is significantly skewed because of the interaction with the much
massive NGC 7771. The rotation curves and morphological disturbances suggest
that the NGC 7769 and NGC 7771 have passed the first pericenter stage, however,
probably the second encounter has not happened yet. Profiles of surface
brightness of NGC 7769 have a characteristic break, and profiles of color
indices have a minimum at a radius of intensive star formation induced by the
interaction with NGC 7771.
