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HubbleSite Hubble Uncovers Largest Known Population of Star Clusters


Space Telescope Science

Ten years ago, astronomer John Blakeslee spotted dots of light peppered throughout images of a giant cluster of galaxies, called Abell 1689. Each dot was not one star, but hundreds of thousands of stars crowded together in groupings called globular clusters. Blakeslee counted 500 such clusters, the brightest members of a teeming population of globular clusters.

Now, a new Hubble census of globular clusters in Abell 1689 reveals that an estimated 160,000 such groupings are huddled near the galaxy cluster's core. The Hubble observations break the record for the farthest and the most globular clusters ever seen. Globular clusters are the homesteaders of galaxies, containing some of the oldest surviving stars in the universe. These stellar relics are important to study because they help reveal the story of galaxy formation in the early universe. By comparison, only 150 globular clusters orbit the Milky Way galaxy.

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