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News Release 175 of 325

January 6, 2004 09:30 AM (EST)

News Release Number: STScI-2004-02

Too Fast, Too Furious: A Galaxy's Fatal Plunge

An American Astronomical Society Meeting Release

January 6, 2004: Trailing 200,000-light-year-long streamers of seething gas, a galaxy that was once like our Milky Way is being shredded as it plunges at 4.5 million miles per hour through the heart of a distant cluster of galaxies. In this unusually violent collision with ambient cluster gas, the galaxy is stripped down to its skeletal spiral arms as it is eviscerated of fresh hydrogen for making new stars.

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Q & A: Understanding the Discovery

  1. 1. What is unique about this galaxy?

  2. This galaxy has a strange shape reminiscent of the wake around a boat sailing across a lake. The analogy is apt because the galaxy is plowing through hot gas in the center of a galaxy cluster

  3. 2. What will happen to the galaxy?

  4. The galaxy will be stripped of the hydrogen gas needed to make successive generations of stars. In that sense the galaxy will grow old prematurely. It will be left with aging stars, but no bright blue, new star clusters.

  5. 3. What telescope viewed the galaxy?

  6. To analyze the galaxy astronomers made a variety of diagnostic observations from telescopes that record the galaxy's appearance in X-ray, optical, and radio light. The observations discovered bright star clusters on the galaxy's leading edge; the galaxy has a tail of gas; and the galaxy is surrounded by its own gas, which is leaking from it.

  7. 4. Is it unusual to find this type of galaxy in the universe?

  8. Though such "distressed" galaxies have been seen before, this one's demise is unusually swift and violent. That's because the galaxy belongs to a cluster of galaxies that slammed into another cluster about 100 million years ago.

  9. 5. What does this tell us about galaxy evolution?

  10. Views of the early universe show that spiral galaxies were once much more abundant in rich clusters of galaxies. But they seem to have been vanishing over cosmic time. This result helps explain why.

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Credit: NASA, W. Keel (U Alabama), F. Owen (NRAO), M. Ledlow (Gemini Obs.), and D. Wang (U Mass.)