Hubble Space Telescope proper motions of Large Magellanic Cloud star clusters

II. Kinematic structure of young and intermediate-age clusters

¹ Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany
² INAF – Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti 93/3, 40129 Bologna, Italy
³ Donostia International Physics Center (DIPC), Paseo Manuel de Lardizabal, 4, 20018 Donostia-San Sebastián, Guipuzkoa, Spain
⁴ IKERBASQUE, Basque Foundation for Science, 48013 Bilbao, Spain
⁵ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁶ atlanTTic, Universidade de Vigo, Escola de Enxeñaría de Telecomunicación, 36310 Vigo, Spain
⁷ Universidad de La Laguna, Avda. Astrofísico Fco. Sánchez, 38205 La Laguna, Tenerife, Spain
⁸ INAF – Osservatorio Astronomico d’ Abruzzo, Via M. Maggini, 64100 Teramo, Italy
⁹ INFN – Sezione di Pisa, Università di Pisa, Largo Pontecorvo 3, 56127 Pisa, Italy
¹⁰ Department of Physics, University of Surrey, Guildford GU2 7XH, UK
¹¹ INAF – Osservatorio Astronomico di Padova, Vicolo dell’Osservatorio 5, Padova 35122, Italy
¹² Vyoma GmbH, Karl-Theodor-Straße 55, 80803 Munich, Germany
¹³ Dipartimento di Fisica e Astronomia, Università degli Studi di Bologna, via Gobetti 93/2, 40129 Bologna, Italy
¹⁴ Lennard-Jones Laboratories, School of Chemical and Physical Sciences, Keele University, Keele ST5 5BG, UK
¹⁵ ESO, European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching bei München, Germany
¹⁶ Aix Marseille Université, CNRS, CNES, LAM, Marseille, France
¹⁷ INAF – Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy

^★ Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Received: 24 September 2025
Accepted: 17 November 2025

Abstract

In this paper, we explore the kinematic properties of a sample of 19 young (<1 Gyr) and intermediate-age (1–2.5 Gyr) massive star clusters within the Large Magellanic Cloud (LMC). We analysed the proper motions of the clusters, which have been measured based on multi-epoch Hubble Space Telescope (HST) observations. Additionally, from the HST data we inferred homogeneous and robust estimates for the distances, ages, and metallicities of the clusters. This collection of information, in combination with literature line-of-sight velocities, allowed us to investigate the full 3D dynamics of our sample of clusters within the frame of the LMC in a self-consistent way. While most young clusters orbit the LMC close to the stellar disc plane, NGC 1850 (∼100 Myr old) depicts a peculiar case. Depending on the exact distance from the disc, it follows either a highly inclined retrograde orbit or an eccentric orbit along the bar structure. The orbits of young clusters that formed north of the LMC centre show signs that might be connected to the resettling motion of the LMC bar structure. Based on the dynamic properties in combination with the positions of the clusters in the age-metallicity space, we find no clear-cut evidence of clusters in our sample that could have been stripped from the Small Magellanic Cloud (SMC) onto the LMC. Finally, we compared the kinematics of the intermediate-age clusters with a suite of simple numerical simulations of the Magellanic system to interpret the cluster motions. A possible interaction history of the LMC with the SMC, where the SMC had two past crossings of the LMC disc plane (about 300 and 900 Myr ago), in combination with the recent SMC pericentre passage, can qualitatively explain the observed kinematic structure of the clusters analysed in this work.