Probing the farthest star clusters to the Small Magellanic Cloud

¹ Instituto Interdisciplinario de Ciencias Básicas (ICB), CONICET-UNCuyo, Padre J. Contreras 1300, M5502JMA Mendoza, Argentina
² Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Godoy Cruz 2290, C1425FQB Buenos Aires, Argentina

^⋆ Corresponding author: andres.piatti@fcen.uncu.edu.ar

Received: 18 June 2025
Accepted: 19 August 2025

Abstract

The Small Magellanic Cloud (SMC) has been tidally shaped by the interaction with the Large Magellanic Cloud (LMC). The scope of such an interaction was recently studied with regard to different astrophysical properties of its star cluster population, which point to star clusters placed, remarkably, outside the known extension of the galaxy. In this paper, we report results for three of the recently identified most external SMC star clusters, OGLE-CL-SMC0133, OGLE-CL-SMC0237, and Lindsay 116, using deep GEMINI GMOS imaging. Once we confidently cleaned their color-magnitude diagrams from field star contamination, we estimated their fundamental parameters by applying likelihood techniques. We also derived their structural parameters from normalized star-number-density radial profiles. Based on Gaia astrometric data, complemented by kinematics information available in the literature, we computed the 3D components of their space velocities. With similar ages (∼2.2 Gyr) and moderately metal-poor overall abundances ([Fe/H] = –1.0 to –0.7 dex), OGLE-CL-SMC0237 is placed 2.6 kpc from the SMC center and shares its disk rotation; OGLE-CL-SMC0133 is located 7.6 kpc from the galaxy center and exhibits a kinematics marginally similar to the SMC rotation disk, while Lindsay 116, placed 15.7 kpc from the center of the SMC, is facing strong perturbations of its orbital motion with respect to an ordered rotational trajectory. Furthermore, its internal dynamical evolution would seem to be accelerated – it seems kinematically older – in comparison with star clusters in the outskirts of relatively isolated galaxies. These outcomes lead to conclude that Lindsay 116 is subject to LMC tides.