Residual velocities of Small Magellanic Cloud star clusters

Abstract

We analyzed the largest Small Magellanic Cloud (SMC) cluster sample (32) with proper motions and radial velocity measurements, from which we obtained their space velocity components. By adopting as a reference the recent best-fitted rotating disc of SMC star clusters as a function of the position angle, we computed their residual velocity vectors, and compared their magnitudes ($\Delta$V) with that of a cluster with residual velocity components equal to the velocity dispersions along the three independent SMC rotating disc axes of motion ($\Delta$V = 60 km/s). We found that clusters that belong to SMC tidally induced structures have $\Delta$V > 50 km/s, which suggests that space velocities of clusters in the process of escaping the rotating disc kinematics, are measurably different. Studied clusters pertaining to a northern branch of the Magellanic Bridge, the main Magellanic Bridge, the Counter-Bridge and the West halo give support to these findings. NGC 121, the oldest known SMC cluster, does not belong to any SMC tidal feature, and has $\Delta$V = 64 km/s, slightly above the boundary between bound and kinematically perturbed clusters.

7 pages, 4 figures. Accepted for publication in MNRAS

References in corpus (19)

• Detection of a 63 Degree Cold Stellar Stream in the Sloan Digital Sky Survey
• Age Determination of Six Intermediate-age SMC Star Clusters with HST/ACS
• A 22 Degree Tidal Tail for Palomar 5
• The VMC Survey. XXV. The 3D structure of the Small Magellanic Cloud from Classical Cepheids
• Stellar Population Models and Individual Element Abundances I: Sensitivity of Stellar Evolution Models
• Revealing the tidal scars of the Small Magellanic Cloud
• The eye of Gaia on globular clusters structure: tidal tails
• Kinematics of the Palomar 5 stellar stream from RR Lyrae stars
• The VMC survey -- XLI. Stellar proper motions within the Small Magellanic Cloud
• The VISCACHA survey -- III. Star clusters counterpart of the Magellanic Bridge and Counter-Bridge in 8D
• Gaia view of a stellar sub-structure in front of the Small Magellanic Cloud
• Using Gaia DR2 to detect extratidal structures around the Galactic globular cluster NGC362
• Discovery of Extended Tidal Tails around the Globular Cluster Palomar 13
• Two kinematically distinct old globular cluster populations in the Large Magellanic Cloud
• The kinematics of Small Magellanic Cloud star clusters
• Gaia Early Data Release 3: Structure and properties of the Magellanic Clouds
• Short period variability in the globular cluster NGC 419 and the SMC field
• Bruck 88 : a young star cluster with an old age resemblance in the outskirts of the Small Magellanic Cloud
• On the structure of Small Magellanic Cloud star clusters

Cited by in corpus (1)

• Probing the farthest star clusters to the Small Magellanic Cloud