Astrophysical properties of binary star clusters in the Small Magellanic Cloud

TL;DR

This study investigates the properties and evolution of binary star clusters in the Small Magellanic Cloud by imaging, analyzing their structures, ages, and interactions to understand their formation and dynamics.

Contribution

It provides detailed observational analysis of seven binary clusters, including age, metallicity, and structural parameters, highlighting cases of interaction and possible chance alignments.

Findings

Some clusters show signs of interaction through disturbed density profiles.

Age differences suggest some pairs are chance alignments or formed sequentially.

Distances and age gaps help understand their physical connection or independence.

Abstract

To study the evolution of binary star clusters we have imaged 7 systems in the Small Magellanic Cloud with SOAR 4-m telescope using B and V filters. The sample contains pairs with well-separated components (d < 30 pc) as well as systems that apparently merged, as evidenced by their unusual structures. By employing isochrone fittings to their CMDs we have determined reddening, age and metallicity and by fitting King models to their radial stellar density profile we have estimated core radius. Disturbances of the density profile are interpreted as an evidence of interaction. Circunstances as distances between components and their age difference are addressed in terms of the timescales involved to access the physical connection of the system. In two cases the age difference is above 50 Myr, which suggests chance alignment, capture or sequential star formation.