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Explanation: How old is this galaxy? The galaxy on the left, I Zwicky 18, was once thought to be one of the youngest galaxies on record since its bright stars indicated an age of only 500 million years. The galaxy was also intriguing because it resembled galaxies forming in the very early universe, but mysterious since it is so nearby -- only 59 million light years away -- and surrounded by galaxies that are significantly older. Recent images of I Zwicky 18 by the Hubble Space Telescope have helped resolve this mystery, discovering a population of old faint stars intermixed with the bright star population. Therefore I Zwicky 18 is now thought to be just as old as its neighbors, roughly 10 billion years old, but with an intense episode of relative new star formation. Possibly the trigger for this recent episode of bright star formation is the changing gravitational influence of I Zwicky 18's smaller companion galaxy, visible at the upper right.
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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: star formation
Publications with words: star formation
See also:
- NGC 1893 and the Tadpoles of IC 410
- Star Factory Messier 17
- APOD: 2023 August 28 Á Star Formation in the Pacman Nebula
- APOD: 2023 July 10 Á Stars, Dust and Nebula in NGC 6559
- NGC 1333: Stellar Nursery in Perseus
- APOD: 2023 March 21 Á Dark Nebulae and Star Formation in Taurus
- The Tadpole Nebula in Gas and Dust