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News Release 181 of 325

March 6, 2003 09:00 AM (EST)

News Release Number: STScI-2003-07

Hubble Resolves a Blaze of Stars in a Galaxy's Core

A Hubble Heritage Release

March 6, 2003: The central region of the small galaxy NGC 1705 blazes with the light of thousands of young and old stars in this image, taken by NASA's Hubble Space Telescope. At 17 million light-years away, the individual stars of the dwarf irregular galaxy NGC 1705 are out of range of all but the sharp eyes of Hubble. NGC 1705 is classified as a dwarf irregular because it is small and lacks any regular structure.

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Q & A: Understanding the Discovery

  1. 1. Why did astronomers use the Hubble telescope to observe this galaxy?

  2. NGC 1705 is an ideal laboratory to conduct investigations on star formation history. Young, blue, hot stars are strongly concentrated toward the galaxy's center, while older, red, cooler stars are more spread out. This galaxy has been forming new stars throughout its lifetime. A burst of star-formation activity took place as recently as 26 to 31 million years ago. This "starburst" is responsible for many of the young stars on the outskirts of the galaxy's core, as well as the central giant star cluster.

    Many astronomers now believe that dwarf galaxies, like NGC 1705, were the first systems to collapse and start forming stars in the early universe. They represent the building blocks from which more massive objects (spiral and elliptical galaxies) were later formed through mergers and accretion. Nearby small galaxies are thought to be the leftovers of the galaxy-formation process.

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Image Credit: NASA, ESA, and The Hubble Heritage Team (STScI/AURA)

Acknowledgment: M. Tosi (INAF, Osservatorio Astronomico di Bologna)