The VMC survey: XVII. Proper motions of the Small Magellanic Cloud and the Milky Way globular cluster 47 Tucanae

In this study we use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motions of different stellar populations in a tile of 1.5 deg2 in size in the direction of the Galactic globular cluster 47 Tuc. We obtain the proper motion of...

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Bibliographic Details
Published in:Astronomy and astrophysics (Berlin) 2016-02, Vol.586, p.A77
Main Authors: Cioni, Maria-Rosa L, Bekki, Kenji, Girardi, Leo, de Grijs, Richard, Irwin, Mike J, Ivanov, Valentin D, Marconi, Marcella, Oliveira, Joana M, Piatti, Andres E, Ripepi, Vincenzo, van Loon, Jacco Th
Format: Article
Language:English
Subjects:
Astronomy
Calibration
Galaxies
Globular clusters
Magellanic clouds
Milky Way Galaxy
Spatial distribution
Stars
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Summary:In this study we use multi-epoch near-infrared observations from the VISTA survey of the Magellanic Cloud system (VMC) to measure the proper motions of different stellar populations in a tile of 1.5 deg2 in size in the direction of the Galactic globular cluster 47 Tuc. We obtain the proper motion of the cluster itself, of the Small Magellanic Cloud (SMC), and of the field Milky Way stars. Stars of the three main stellar components are selected according to their spatial distributions and their distributions in colour-magnitude diagrams. Their average coordinate displacement is computed from the difference between multiple Ks-band observations for stars as faint as Ks = 19 mag. Proper motions are derived from the slope of the best-fitting line among ten VMC epochs over a time baseline of ~1 yr. Background galaxies are used to calibrate the absolute astrometric reference frame. Systematic uncertainties associated with the astrometric reference system are 0.18 mas yr-1. Thanks to the proper motion we detect 47 Tuc stars beyond its tidal radius.
ISSN:0004-6361
1432-0746
DOI:10.1051/0004-6361/201527004