Ha Velocity Fields and Galaxy Interaction in the Quartet of Galaxies NGC 7769, 7770, 7771 and 7771A

TL;DR

This study investigates the velocity fields of the interacting galaxy quartet NGC 7769, 7770, 7771, and 7771A using Fabry-Perot interferometry, revealing how interactions distort their rotation curves and induce star formation.

Contribution

It provides detailed velocity field analysis of the galaxy quartet, highlighting the effects of interactions on their rotation curves and morphological features, which was not previously documented.

Findings

NGC 7769's rotation curve is weakly distorted.

NGC 7771's rotation curve is strongly distorted by tidal interactions.

Star formation is induced at a specific radius in NGC 7769.

Abstract

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.