The Larson-Tinsley Effect in the UV: Interacting vs. `Normal' Spiral Galaxies

TL;DR

This study compares UV-optical colors of interacting galaxy pairs and normal spirals, revealing higher star formation rates and extinctions in interacting galaxies, with significant variation among individual cases.

Contribution

It provides new insights into the UV color dispersion and star formation activity differences between interacting and normal spiral galaxies.

Findings

Interacting galaxies show larger UV color dispersion than normal spirals.

Higher star formation rates are observed in interacting galaxies.

Star formation in interacting galaxies is often more centrally concentrated.

Abstract

We compare the UV-optical colors of a well-defined set of optically-selected pre-merger interacting galaxy pairs with those of normal spirals. The shorter wavelength colors show a larger dispersion for the interacting galaxies than for the spirals. This result can best be explained by higher star formation rates on average in the interacting galaxies, combined with higher extinctions on average. This is consistent with earlier studies, that found that the star formation in interacting galaxies tends to be more centrally concentrated than in normal spirals, perhaps due to gas being driven into the center by the interaction. As noted in earlier studies, there is a large variation from galaxy to galaxy in the implied star formation rates of the interacting galaxies, with some galaxies having enhanced rates but others being fairly quiescent.