Bridge over troubled gas: clusters and associations under the SMC and LMC tidal stresses

TL;DR

This study uses photometry of star clusters in the LMC-SMC Bridge to analyze their properties, ages, and the structure's evolution into a potential tidal dwarf galaxy under tidal stresses.

Contribution

It provides the first detailed characterization of star clusters in the Bridge, revealing their ages, sizes, and the Bridge's connection to tidal dwarf galaxy formation.

Findings

Clusters are larger than Galactic counterparts of similar age.

Clusters range from a few Myr to 200 Myr in age.

The Bridge connects the LMC and SMC and may evolve into a tidal dwarf galaxy.

Abstract

We obtained SOAR telescope B and V photometry of 14 star clusters and 2 associations in the Bridge tidal structure connecting the LMC and SMC. These objects are used to study the formation and evolution of star clusters and associations under tidal stresses from the Clouds. Typical star clusters in the Bridge are not richly populated and have in general relatively large diameters (~30-35 pc), being larger than Galactic counterparts of similar age. Ages and other fundamental parameters are determined with field-star decontaminated photometry. A self-consistent approach is used to derive parameters for the most-populated sample cluster NGC 796 and two young CMD templates built with the remaining Bridge clusters. We find that the clusters are not coeval in the Bridge. They range from approximately a few Myr (still related to optical HII regions and WISE and Spitzer dust emission measurements) to about 100-200 Myr. The derived distance moduli for the Bridge objects suggests that the Bridge is a structure connecting the LMC far-side in the East to the foreground of the SMC to the West. Most of the present clusters are part of the tidal dwarf candidate D 1, which is associated with an H I overdensity. We find further evidence that the studied part of the Bridge is evolving into a tidal dwarf galaxy, decoupling from the Bridge.