Kinematic complexity around NGC419: resolving the proper motion of the cluster, the Small Magellanic Cloud and the Magellanic Bridge

Abstract

We present $Hubble$ $Space$ $Telescope$ proper motions in the direction of the star cluster NGC419 in the Small Magellanic Cloud. Because of the high precision of our measurements, for the first time it is possible to resolve the complex kinematics of the stellar populations located in the field, even along the tangential direction. In fact, the proper motions we measured allow us to separate cluster stars, which move on average with (${\mu }_{\alpha }\cos {\delta }^{\mathrm{NGC}419},{\mu }_{\delta }^{\mathrm{NGC}419}$) = ($+0.878\pm 0.055$, $-1.246\pm 0.048$) mas yr${}^{-1}$, from those of the Small Magellanic Cloud and those belonging to a third kinematic feature that we recognise as part of the Magellanic Bridge. Resolving such a kinematic complexity enables the construction of decontaminated colour-magnitude diagrams, as well as the measurement of the absolute proper motion of the three separate components. Our study therefore sets the first steps towards the possibility of dynamically investigating the Magellanic system by exploiting the resolved kinematics of its stellar clusters.

9 pages, 9 figures, accepted for publication in MNRAS

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Cited by in corpus (5)

• Hubble Space Telescope survey of Magellanic Cloud star clusters. Photometry and astrometry of 113 clusters and early results
• Expanding the time domain of multiple populations: evidences of nitrogen variations in the ~1.5 Gyr old star cluster NGC 1783
• Blue Stragglers as tracers of the dynamical state of two clusters in the Small Magellanic Cloud: NGC 339 and NGC 419
• Extended Main-Sequence Turnoff and Red Clump in intermediate-age star clusters: A study of NGC 419
• Hubble Space Telescope proper motions of Large Magellanic Cloud star clusters -- II. Kinematic structure of young and intermediate-age clusters