A DYNAMICAL SIGNATURE OF MULTIPLE STELLAR POPULATIONS IN 47 TUCANAE

Based on the width of its main sequence, and an actual observed split when viewed through particular filters, it is widely accepted that 47 Tucanae contains multiple stellar populations. In this contribution, we divide the main sequence of 47 Tuc into four color groups, which presumably represent st...

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Bibliographic Details
Published in:Astrophysical journal. Letters 2013-07, Vol.771 (1), p.1-5
Main Authors: Richer, Harvey B, Heyl, Jeremy, Anderson, Jay, Kalirai, Jason S, Shara, Michael M, Dotter, Aaron, Fahlman, Gregory G, Rich, R Michael
Format: Article
Language:English
Subjects:
ANISOTROPY
ASTRONOMY
ASTROPHYSICS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHEMICAL COMPOSITION
Color
Frames
HERTZSPRUNG-RUSSELL DIAGRAM
Kinematics
MAGELLANIC CLOUDS
MAIN SEQUENCE STARS
OPTICAL FILTERS
PROPER MOTION
RED GIANT STARS
Signatures
Stars
Stellar populations
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Summary:Based on the width of its main sequence, and an actual observed split when viewed through particular filters, it is widely accepted that 47 Tucanae contains multiple stellar populations. In this contribution, we divide the main sequence of 47 Tuc into four color groups, which presumably represent stars of various chemical compositions. The kinematic properties of each of these groups are explored via proper motions, and a strong signal emerges of differing proper-motion anisotropies with differing main-sequence color; the bluest main-sequence stars exhibit the largest proper-motion anisotropy which becomes undetectable for the reddest stars. In addition, the bluest stars are also the most centrally concentrated. A similar analysis for Small Magellanic Cloud stars, which are located in the background of 47 Tuc on our frames, yields none of the anisotropy exhibited by the 47 Tuc stars. We discuss implications of these results for possible formation scenarios of the various populations.
ISSN:2041-8205
2041-8213
DOI:10.1088/2041-8205/771/1/L15