Current Star Formation in the Outer Rings among Early-Type Disk Galaxies

TL;DR

This study investigates star formation in outer rings of early-type disk galaxies using ultraviolet data, revealing that about half of pure rings and nearly all pseudorings exhibit recent star formation activity.

Contribution

It provides the first comprehensive analysis of current star formation in outer rings of early-type disk galaxies using GALEX ultraviolet data.

Findings

Approximately 50% of pure rings show recent star formation.

Almost all pseudorings exhibit current star formation.

Young stellar populations are less than 200 Myr old.

Abstract

By using the ARRAKIS, the atlas of stellar rings in galaxies (Comeron et al. 2014) based on data of the S4G survey, we have compiled a list of early-type, S0-Sb, disk galaxies with outer stellar ring-like features (`pure' rings, R, or pseudorings, R'). Current star formation signatures within these features were searched for through the NUV-maps of the galaxies provided by the ultraviolet space telescope GALEX. We have found that current star formation, with the mean age of the young stellar population less than 200 Myr, is present in about a half of all `pure' rings; and within the pseudorings it is observed almost always.