Abell 2218
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| Observation data (Epoch J2000) |
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| Constellation(s): | Draco |
| Right ascension: | 16h 35m 54s[1] |
| Declination: | +66° 13′ 00″[1] |
| Number of galaxies: | ~250 |
| Brightest member: | |
| Other designations | |
| See also: Galaxy groups and clusters, List of galaxy clusters |
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Abell 2218 is a cluster of galaxies about 3 billion light-years away in the constellation Draco. Acting as a powerful lens, magnifying all galaxies lying behind the cluster core. The lensed galaxies are all stretched along the cluster's center and some of them are multiply imaged. Those multiple images usually appear as a pair of images with a third — generally fainter — counter image, as is the case for the very distant object.
Abell 2218 was used as a gravitational lens to discover the most distant known object in the universe as of 2004. It (the object) is seen as it would have been 750 million years after the Big Bang.
The color of the lensed galaxies is a function of their distances and types. The orange arc is an elliptical galaxy at moderate redshift (z=0.7). The blue arcs are star-forming galaxies at intermediate redshift (z=1-2.5). The encircled very red pair is the newly discovered star-forming galaxy at about redshift 7.
The lensed galaxies are particularly numerous, as we are looking in between two mass clumps, in a saddle region where the magnification is quite large.
[edit] External Links
[edit] References
- ^ a b NASA/IPAC Extragalactic Database. Results for Abell 2218. Retrieved on 2006-09-18.
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