The VISCACHA survey -- III. Star clusters counterpart of the Magellanic Bridge and Counter-Bridge in 8D

TL;DR

This study identifies star clusters in the outskirts of the SMC that serve as stellar counterparts to the Magellanic Bridge and Counter-Bridge, providing observational evidence for these tidal structures and informing models of their interaction history.

Contribution

The paper presents the first observational confirmation of the stellar counterpart of the Magellanic Bridge and Counter-Bridge using star clusters with 6D phase-space data, ages, and metallicities.

Findings

Five clusters belong to the Magellanic Bridge.

One cluster belongs to the Counter-Bridge.

The existence of the tidal counterpart is confirmed through star clusters.

Abstract

Context. The interactions between the SMC and LMC created the Magellanic Bridge, a stream of gas and stars pulled out of the SMC towards the LMC about 150 Myr ago. The tidal counterpart of this structure, which should include a trailing arm, has been predicted by models but no compelling observational evidence has confirmed the Counter-Bridge so far. Aims. The main goal of this work is to find the stellar counterpart of the Magellanic Bridge and Counter-Bridge. We use star clusters in the SMC outskirts as they provide 6D phase-space vector, age and metallicity that help characterise the outskirts of the SMC. Methods. Distances, ages and photometric metallicities are derived from fitting isochrones to the colour-magnitude diagrams from the VISCACHA survey. Radial velocities and spectroscopic metallicities are derived from the spectroscopic follow-up using GMOS in the CaII triplet region. Results. Among the seven clusters analysed in this work, five belong to the Magellanic Bridge and one belongs to the Counter-Bridge and the other to the transition region. Conclusions. The existence of the tidal counterpart of the Magellanic Bridge is evidenced by star clusters. The stellar component of the Magellanic Bridge and Counter-Bridge are confirmed in the SMC outskirts. These results are an important constraint for models that seek to reconstruct the history of the orbit and interactions between LMC-SMC and constrain their future interaction including with the Milky Way.