Galaxy interactions in the Hickson Compact Group 88

TL;DR

This study reveals that galaxies in Hickson Compact Group 88 have experienced significant past interactions, contrary to previous beliefs, through deep imaging and H-alpha observations.

Contribution

First detailed imaging of HCG88 showing evidence of past galaxy interactions, including faint tails and isophote distortions, challenging prior assumptions.

Findings

Discovery of a faint extended tail from a group galaxy

Detection of isophote twisting and possible shells

Mapping of HII regions in all group galaxies

Abstract

I present observations of the Hickson Compact Group 88 (HCG88) obtained during the commissioning of a new 28-inch telescope at the Wise Observatory. This galaxy group was advertised to be non-interacting, or to be in a very early interaction stage, but this is not the case. The observations reported here were done using a "luminance" filter, essentially a very broad R filter, reaching a low surface brightness level of about 26 mag per square arcsec. Additional observations were obtained in a narrow spectral band approximately centered on the rest-frame H-alpha line from the group. Contrary to previous studies, my observations show that at least two of the major galaxies have had significant interactions in the past, although probably not between themselves. I report the discovery of a faint extended tail emerging from the brightest of the group galaxies, severe isophote twisting and possible outer shells around another galaxy, and map the HII regions in all the galaxies.