Young Stellar Populations in the Collisional Ring Galaxy NGC 922

TL;DR

This study analyzes young star clusters in the collisional ring galaxy NGC 922, revealing their ages, spatial distribution, and potential origins, and compares them with distant ring galaxies to understand their formation processes.

Contribution

It provides detailed analysis of star cluster properties in NGC 922 and compares them with distant ring galaxies, highlighting similarities and potential progenitors for faint fuzzy clusters.

Findings

69% of clusters are younger than 7 Myr

Clusters are mainly located in the ring and bar regions

Similar masses and sizes to distant ring galaxy complexes

Abstract

We studied the star cluster population properties in the nearby collisional ring galaxy NGC 922 using HST/WFPC2 photometry and population synthesis modeling. We found that 69% of the detected clusters are younger than 7 Myr, and that most of them are located in the ring or along the bar, consistent with the strong Halpha emission. The images also show a tidal plume pointing toward the companion. Its stellar age is consistent with pre-existing stars that were probably stripped off during the passage of the companion. We compared the star-forming complexes observed in NGC 922 with those of a distant ring galaxy from the GOODS field. It indicates very similar masses and sizes, suggesting similar origins. Finally, we found clusters that are excellent progenitor candidates for faint fuzzy clusters.