The VMC survey

LIV. The internal kinematics of the Large Magellanic Cloud with new VISTA observations

¹ Institut für Physik und Astronomie, Universität Potsdam, Haus 28, Karl-Liebknecht-Str. 24/25, D-14476 Golm (Potsdam), Germany
² Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, D-14482 Potsdam, Germany
³ International Centre for Radio Astronomy Research, The University of Western Australia, 35 Stirling Highway, Crawley, Western Australia 6009 Australia
⁴ Lennard-Jones Laboratories, Keele University, Keele ST5, 5BG, UK
⁵ School of Mathematical and Physical Sciences, Macquarie University, Balaclava Road, Sydney, NSW, 2109 Australia
⁶ Astrophysics and Space Technologies Research Centre, Macquarie University, Balaclava Road, Sydney, NSW, 2109 Australia
⁷ International Space Science Institute–Beijing, 1 Nanertiao, Zhongguancun, Hai Dian District, Beijing, 100190 China
⁸ European Southern Observatory, Karl-Schwarzschild-Str. 2, D-85748 Garching bei München, Germany
⁹ Koninklijke Sterrenwacht van België, Ringlaan 3, B–1180 Brussels, Belgium
¹⁰ Department of Physics, University of Surrey, Guildford GU2, 7XH UK

^⋆ Corresponding author: svijayasree@aip.de

Received: 25 November 2024
Accepted: 8 July 2025

Abstract

Context. The study of the internal kinematics of galaxies provides insights into their past evolution, current dynamics, and future trajectory. The Large Magellanic Cloud (LMC), as the largest and one of the nearest satellite galaxies of the Milky Way (MW), presents unique opportunities to investigate these phenomena in great detail.

Aims. We aim to investigate the internal kinematics of the LMC by deriving precise stellar proper motions using data from the VISTA survey of the Magellanic Clouds system (VMC). The main objective is to refine the LMC’s dynamical parameters using improved proper motion measurements exploiting the additional epochs of observations from the VMC survey.

Methods. We utilised high-precision proper motion measurements from the VMC survey, leveraging an extended time baseline from approximately 2 to 10 years. This extension significantly enhanced the precision of the proper motion data, reducing uncertainties from 6 mas yr⁻¹ in prior studies using the VMC dataset to 1.5 mas yr⁻¹. Using this data, we derived geometrical and kinematic parameters, and generated velocity maps and rotation curves in the LMC disc plane and the sky plane, for both young and old stellar populations. Finally, we compared a suite of dynamical models that simulate the interaction of the LMC with the MW and Small Magellanic Cloud (SMC), against the observations.

Results. The tangential rotation curve reveals an asymmetric drift between young and old stars, while the radial velocity curve for the young population shows an increasing trend within the inner bar region, suggesting non-circular orbits. The internal rotation map confirms the clockwise rotation around the dynamical centre of the LMC, which is consistent with previous predictions. A significant residual motion was detected towards the north-east of the LMC, directed away from the centre. This feature observed in the inner disc region is kinematically connected with a substructure identified in the periphery known as Eastern Substructure 1. This motion of the LMC sources suggests a possible tidal influence from the MW, combined with the effects of the recent close pericentre passage of the SMC ∼150 Myr ago.