From the 2Mass Image Gallery
One of the brightest Milky Way globular star clusters, 47 Tucanae, is seen near the Small Magellanic Cloud in the sky. It is 4.6 kpc (15000 light years) from us and 7.3 kpc (23800 light years) from the Galactic Center and likely contains about 1 million stars. Its optical half-light radius is 2.79", or only 3.7 pc; the stars in globular clusters, such as 47 Tuc, are clearly densely packed. This cluster is known to be typically metal-rich, relative to many other globular clusters. Globular clusters formed early in the Galaxy's history and, therefore, must have been chemically enriched by massive short-lived stars. In the near-IR, globular cluster stars look very homogeneous, as can be seen in this image, with very little in the way of color or population gradients, particularly in the central regions. The near-IR light is dominated by the old red giants and asymptotic giant branch stars in the cluster.
This image is a three-band composites constructed from 2MASS Atlas Images. As infrared images they must be mapped into false colors: J light (1.2 µm) into blue, H light (1.6 µm) in green, and Ks light (2.2 µm) into red. The Atlas Images are produced in the 2MASS Production Processing System. For all images, north is up and east is to the left. This mage mosaic is by E. Kopan (IPAC).
The text is based on accompanying on-line materials.
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Last Modified On: Friday, December 15, 2000