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Дата изменения: Sun Aug 17 20:38:45 2003
Дата индексирования: Mon Feb 4 11:20:00 2013
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Поисковые слова: milky way
Blue Stagglers in Globular Clusters
Astronomy Picture of the Day
    


Blue Stagglers in Globular Clusters
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Blue Stagglers in Globular Clusters
Credit & Copyright: M. Shara (STScI), R.A. Safer (Villanova), M. Livio (STScI), WFPC2, HST, NASA
Explanation: This old dog is doing new tricks. On the left is ancient globular cluster 47 Tucanae which formed many billions of years ago. On the right is a closeup of its dense stellar center by the Hubble Space Telescope, released last week. Circled are mysterious stars called "blue stragglers." Stars as bright and blue as blue stragglers live short lives, much shorter than the age of the host globular cluster itself. But this contradicts evidence that globular cluster stars formed all at once. Although this problem has been known for almost 50 years, a mass and spin rate for a blue straggler was first published last Saturday. This new information indicates that BSS 19 was rejuvenated by two orbiting stars slowly coalescing , and not by a dramatic collision.

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
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NASA Official: Jay Norris. Specific rights apply.
A service of: LHEA at NASA / GSFC
& Michigan Tech. U.

Based on Astronomy Picture Of the Day

Publications with keywords: globular cluster - blue stragglers
Publications with words: globular cluster - blue stragglers
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