Structure of the Galaxies in the NGC 80 Group

TL;DR

This study analyzes the structure and stellar populations of 13 large disk galaxies in the NGC 80 group, revealing common two-tiered disks and suggesting minor mergers and tidal interactions as key transformation mechanisms.

Contribution

It provides detailed structural and population analysis of NGC 80 group galaxies, highlighting the prevalence of two-tiered disks and the role of gravitational interactions in galaxy evolution.

Findings

Most luminous galaxies have two-tiered stellar disks.

Dwarf S0 galaxies are close companions to giants.

Minor mergers and tidal interactions likely transform spirals into lenticulars.

Abstract

BV-bands photometric data obtained at the 6-m telescope of the Special Astrophysical Observatory are used to analyze the structure of 13 large disk galaxies in the NGC 80 group. Nine of the 13 galaxies under consideration are classified by us as lenticular galaxies. The stellar populations in the galaxies are very different, from old ones with ages of T>10 Gyrs (IC 1541) to relatively young, with the ages of T<2-3 Gyr (IC 1548, NGC 85). In one case, current star formation is known (UCM 0018+2216). In most of the galaxies, more precisely in all of them more luminous than M(B) -18, two-tiered (`antitruncated') stellar disks are detected, whose radial surface brightness profiles can be fitted by two exponential segments with different scalelengths -- shorter near the center and longer at the periphery. All dwarf S0 galaxies with single-scalelength exponential disks are close companions to giant galaxies. Except for this fact, no dependence of the properties of S0 galaxies on distance from the center of the group is found. Morphological traces of minor merger are found in the lenticular galaxy NGC 85. Basing on the last two points, we conclude that the most probable mechanisms for the transformation of spirals into lenticular galaxies in groups are gravitational ones, namely, minor mergers and tidal interactions.