SCG0018-4854: a young and dynamic compact group I. Kinematical analysis

TL;DR

This study analyzes the kinematics and interactions of galaxies in the compact group SCG0018-4854, revealing recent interactions, peculiar galaxy kinematics, and a young dynamical age of 0.2-0.7 Gyr.

Contribution

It provides detailed spectroscopic and photometric evidence of galaxy interactions and revises the classification of NGC 92, highlighting the group's youth and dynamical state.

Findings

Irregular gas and stellar velocity curves in member galaxies

Detection of a bar in NGC 92

Galactic-scale outflow in NGC 89

Abstract

Compact groups of galaxies are in particular good laboratories for studying galaxy interactions and their effects on the evolution of galaxies due to their high density and low velocity dispersion. SCG0018-4854 is a remarkably high galaxy density and low velocity dispersion group with evidence of a recent interaction. We obtained VLT FORS2 optical observations and we present spectroscopic and photometric evidence of how dramatically galaxy interactions have affected each of the four member galaxies. We found peculiar kinematics for each galaxy and evidence of recent star formation. In particular, the gas and stellar radial velocity curves of two galaxies are irregular with a level of asymmetry similar to that of other interacting galaxies. We discovered the presence of a bar for NGC 92 therefore revising a previous morphological classification and we obtained spectroscopic confirmation of a galactic-scale outflow of NGC 89. Peculiar kinematics and dynamic consideration lead to a rough estimate of the age of the latest interaction: 0.2-0.7 Gyr, suggesting that SCG0018-4854 is a young and dynamical group.