A Pocketful of Stars

Many colorful stars are packed close together in this Hubble Space Telescope image of the globular cluster NGC 1805. This tight grouping of thousands of stars is located near the edge of the Large Magellanic Cloud, a satellite galaxy of our own Milky Way. The stars orbit close to one another, like bees swarming around a hive. In the dense center of one of these clusters, stars are 100 to 1,000 times closer together than the nearest stars are to our Sun. The striking difference in star colors shows in this image: blue stars, shining brightest in near-ultraviolet light, and red stars, illuminated in red and near-infrared. Usually, globular clusters contain stars that are born at the same time; however, NGC 1805 is unusual as it appears to host two different populations of stars with ages millions of years apart. Observing such clusters of stars can help astronomers understand how stars evolve, and what factors determine whether they end their lives as white dwarfs, or explode as supernovae.