I Zwicky 18
| Galaxy data for I Zwicky 18 |
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|---|---|
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| HST image of I Zwicky 18 (bottom left) | |
| AladinLite | |
| Constellation | Big Bear |
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Position equinox : J2000.0 , epoch : J2000.0 |
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| Right ascension | 09 h 34.0 m |
| declination | + 55 ° 14.4 ′ |
| Appearance | |
| Brightness (visual) | 16.0 mag |
| Angular expansion | 0.3 ′ × 0.2 ′ |
| Physical data | |
| Radial velocity | (751 ± 2) km / s |
| distance | approx. 59 million ly / approx. 18 million pc |
| history | |
| discovery | Fritz Zwicky |
| Discovery date | 1930 |
| Catalog names | |
| UGCA 166 • PGC 27182 • Mrk 116 • I Zw 18 | |
I Zwicky 18 ( I Zw 18 ), after Fritz Zwicky , is a dwarf galaxy about 59 million light years away.
For a long time it was assumed that galaxy formation ended only a few billion years after the Big Bang . At the end of 2004, based on images from the Hubble telescope, it was certain that I Zwicky 18 was only 500 million years old - in contrast to the Milky Way , for example , which is already 12 billion years old.
However, due to new evaluations of images from the Hubble telescope in 2007, faint, red stars were discovered in I Zwicky 18, which indicate that the galaxy is significantly older than previously assumed, namely between 1 and 10 billion years.
In addition, the distance from I Zwicky 18 to the Milky Way has been corrected to 59 million light years by recent measurements on Cepheids .
The galaxy has been rather unproductive for most of the time since it was formed and only started forming most of its stars that exist today relatively late. The reason for the late formation of stars is currently unknown.
Web links
- Astronews: "The baby galaxy is older than expected.
- n-tv: "But not a cosmic baby"
- Hubble Finds 'Dorian Gray' Galaxy
- Hubble Finds Mature Galaxy Masquerading as Toddler (photo left)
- Hubble Uncovers a Baby Galaxy in a Grown-Up Universe
- Astronomers claim first 'dark galaxy' find
Individual evidence
- ↑ a b NASA / IPAC Extragalactic Database . In: Results for I Between 18 . Retrieved March 15, 2007.
- ↑ Hubble Uncovers a Baby Galaxy in a Grown-Up Universe. In: hubblesite.org. December 1, 2004, accessed February 20, 2019 .