The kinematics of Small Magellanic Cloud star clusters

Abstract

We report results of proper motions of 25 known Small Magellanic Cloud (SMC) clusters (ages ~ 1 - 10 Gyr old) derived from Gaia EDR3 data sets. When these mean proper motions are gathered with existent radial velocity measurements to compose the clusters' velocity vectors, we found the parameter values of a rotation disk that best resemble their observed motions, namely: central coordinates and distance, inclination and position angle of the line-of-node, proper motion in right ascension and declination and systemic velocity, rotation velocity and velocity dispersion. The SMC cluster rotation disk seems to be at some level kinematically synchronized with the rotation of field red giants recently modeled using DR2 data sets. Such a rotation disk is seen in the sky as a tilted edge-on disk, with a velocity dispersion perpendicular to it twice as big as that in the plane of the disk. Because the direction perpendicular to the disk is nearly aligned with the Magellanic Bridge, we interpret the larger velocity dispersion as a consequence of the SMC velocity stretching caused by the tidal interaction with the Large Magellanic Cloud. Rotation alone would not seem sufficient to explain the observed kinematic behaviors in the SMC.

5 pages, 5 figures. Accepted for publication in Astronomy & Astrophysics

References in corpus (10)

• The Gaia mission
• Ca II Triplet Spectroscopy of Small Magellanic Cloud Red Giants. III. Abundances and Velocities for a Sample of 14 Clusters
• The VMC survey -- XLI. Stellar proper motions within the Small Magellanic Cloud
• Star cluster formation history along the minor axis of the Large Magellanic Cloud
• Deciphering the Kinematic Structure of the Small Magellanic Cloud through its Red Giant Population
• Two kinematically distinct old globular cluster populations in the Large Magellanic Cloud
• Stellar cluster candidates discovered in the Magellanic System
• Detection of a diffuse extended halo-like structure around 47 Tuc
• Towards a comprehensive knowledge of the open cluster Haffner 9
• On the structure of Small Magellanic Cloud star clusters

Cited by in corpus (10)

• Hubble Space Telescope survey of Magellanic Cloud star clusters. Photometry and astrometry of 113 clusters and early results
• The VISCACHA survey -- IV. The SMC West Halo in 8D
• Ca II Triplet Spectroscopy of Small Magellanic Cloud Red Giants. V. Abundances and Velocities for 12 Massive Clusters
• Hubble Space Telescope survey of Magellanic Cloud star clusters. UV-dim stars in young clusters
• The VISCACHA survey -- VIII. Chemical evolution history of Small Magellanic Cloud West Halo cluster
• Residual velocities of Small Magellanic Cloud star clusters
• The Small Magellanic Cloud through the lens of the James Webb Space Telescope : binaries and mass function within the galaxy outskirts
• Revisiting a detached stellar structure in the outer northeastern region of the Small Magellanic Cloud
• Probing the farthest star clusters to the Small Magellanic Cloud
• The Delegate Survey: KOALA/AAOmega-IFU spectroscopy of three nearby dwarf galaxies