Chandra/47 Tuc
Credit: NASA/CfA/J.Grindlay et al.

Swarm of Stars

Globular clusters are spherical distributions of hundreds of thousands of stars; these clusters are found on the outskirts of galaxies and form a "halo" around the Galactic center. Because large numbers of stars are packed into a relatively small region of space, stellar densities are large. The stars in globulars have ages of billions of years and thus are some of the oldest objects in the Galaxy (and maybe the Universe). Studies of stars in globular clusters provide evidence for astronomers on important topics such as stellar evolution and the age of the universe. TheChandra X-ray observatory has recently obtained the best X-ray image of a globular cluster. The Chandra image (of the globular cluster, 47 Tucanae) is shown above. Chandra finds more than 100 bright X-ray sources; nearly all these sources are binary systems in which a collapsed star (a neutron star or white dwarf) pulls matter off a sun-like companion star; X-rays are emitted by the matter as it gets heated to enormous temperatures (of millions of degrees) as it crashes onto the surface of the compact object. The image on the right show a zoomed image of the center of the cluster; the colors represent the energy of the X-rays emitted by the stars (red-low energy, blue-high energy). By understanding how these binary systems form astronomers gain a deeper understanding about the interaction of stars in this stellar swarm.

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Page Author: Dr. Michael F. Corcoran
Last modified June 2, 2001