A Comprehensive Kinematic Model of the Large Magellanic Cloud Disk from Star Clusters and Field Stars using Gaia DR3: Tracing the Disk Characteristics, Rotation, Bar, and Outliers

Abstract

The internal kinematics of the Large Magellanic Cloud (LMC) disk have been modeled by several studies using different tracers with varying coverage, resulting in a range of parameters. Here, we model the LMC disk using 1705 star clusters and field stars, based on a robust Markov Chain Monte Carlo method, using Gaia DR3 data. The dependency of the model parameters on the age, coverage, and strength of the clusters are also presented. This is the first comprehensive 2D kinematic study using star clusters. Red clump (RC) stars and young main-sequence stars are also modeled for comparison. The clusters and field stars are found to have distinctly different kinematic centers, disk inclination, position angle of the line of nodes, and scale radius. We also note a significant radial variation of the disk parameters. Clusters and young stars are found to have a large residual proper motion and a relatively large velocity dispersion when compared to the RC field population, which could be due to perturbation from the bar and spiral arms. We trace the presence of the large residual proper motion and noncircular motion among clusters likely to be due to the bar and detect a decrease in the scale radius as a result of the possible evolution of the bar. The kinematically deviant clusters point to a spatiotemporal disturbance in the LMC disk, matching with the expected impact factor and time of the recent collision between the LMC and the Small Magellanic Cloud.

Keywords

• Magellanic Clouds
• Large Magellanic Cloud
• Galaxy interactions
• Star clusters
• Galaxy kinematics
• Galaxy evolution