The VISCACHA Survey XV: Tracing the 3D Structure and Chemical Evolution of the Outskirts of the Large Magellanic Cloud from Star Clusters

Abstract The Large Magellanic Cloud (LMC) is the Milky Way’s most massive satellite. Its interactions with the Small Magellanic Cloud are expected to leave imprints on its structure and evolution. In this work, we use the LMC outer star cluster population to seek possible evidence imprinted in the LMC stellar population by presenting the ages, metallicities, and distances of 85 stellar clusters in the LMC outskirts, determined using statistical isochrone fitting applied to high-quality photometric data from the VISCACHA Survey. From the distances, we analyze their 3D distribution, which allows us to observe the counterpart of the southwestern warp previously inferred from red clump stars, as well as determine that eastern clusters are closer to us than the LMC’s disk. From the ages and metallicities, we observe an overall homogeneous chemical evolution with two main exceptions: first, a metallicity dip is present in the northeast around 1 Gyr ago; second, the clusters’ ages are more dispersed in the north of the galaxy, while in the remainder of the galaxy’s periphery, we observe a positive azimuthal age gradient along the east–south–west direction. Furthermore, clusters older than 1.5 Gyr tend to be closer to the LMC plane. Such features can be connected to the past interactions between the Magellanic Clouds, particularly their more recent close encounters that are expected to have occurred between 1 and 2 Gyr and 250 Myr ago, which distort the external structure, trigger star formation, and potentially lead to the infall of metal-poor material into the LMC.