rich clusters
large galaxy clusters with unusually high population densities
rich-field telescope ...
Rich Clusters
Clusters with a particularly large number of galaxies.
Richardson-Lucy Method ...
rich cluster: A cluster containing over 1000 galaxies, mostly elliptical, scattered over a volume about 3 Mpc in diameter.
rift valley: A long, straight, deep valley produced by the separation of crustal plates.
This rich cluster of galaxies is located about 1°30' SW of b Coronae Borealis (see finder chart below). About 1.5 billion light years distant, it occupies area of the sky almost 1° across! ...
A rich cluster is seen in the Coma constellation---the Coma Cluster. It has thousands of galaxies (mostly ellipticals and S0 spirals) in a large, spherically-shaped cluster about 300 million light years from us.
A rich cluster of galaxies identified in the Abell Catalog of Rich Clusters of Galaxies, which was the first comprehensive catalogue of clusters of galaxies and, in its extended form, is still the largest.
As many as 10% of rich clusters have been found to contain strong far-IR sources.
Another unexpected discovery is that for some (but not all) moderately rich clusters, clusters with a few dozen galaxies, the dark matter fraction is higher -- around 90%.
Gravitational mass measurements have also been performed for elliptical galaxies, small groups, and rich clusters of galaxies.
The first of these are the S0 galaxies, which are usually found in rich clusters of galaxies. They resemble spirals but have no spiral arms, possibly because their interstellar matter is stripped away as they move through intracluster gas.
The original paper by Abell is entitled "The distribution of rich clusters of galaxies", Astrophysical Journal Supplement Series, 3, 211 (1958).
The open star cluster M46 is a very rich cluster with more than 500 stars.
Just about 50 stars belong to M47. This open star cluster is a good object for binoculars and be seen with the naked eye as a misty patch under very good conditions.
More recent studies have further refined Butcher and Oemler's initial measurements, showing that the fraction of blue galaxies in rich clusters rises from approximately 3% for nearby (z<0.1) clusters, to 25% at z 0.5 and reaching 70% by z ~ 1.
The accompanying image shows the latest battleground in the quest to determine H0, the barred spiral galaxy NGC 1365 in the Fornax Cluster, another rich cluster of galaxies like the Virgo Cluster, lying about 15 Mpc away.
A 1994 census ("The structure of the Universe traced by rich clusters of galaxies.", see References) lists a total of 27 supervoids with a distance of up to 740 Mpc; a selection is given below:
# Name Distance (Mpc) Diameter (Mpc)
1 ...
The astronomers conclude that this group of early galaxies will develop into a rich cluster of galaxies, such as those seen in the nearby present-day Universe.
M11, the Wild Duck Cluster is a very rich cluster located towards the centre of the Milky Way.
Professor Kroupa summarises the results of the research team: "In this picture we can elegantly combine the observational and theoretical results and understand why later forming, more metal-rich clusters experienced stronger force fields.
Nearly every object in this picture is a galaxy - only a few of the objects are stars located in our own galaxy. This is clearly a rich cluster. Image credit: Omar Lopez-Cruz & Ian Shelton/NOAO/AURA/NSF.
Unlike spiral galaxies, elliptical galaxies are generally yellow-red in color, do not have spiral arms, and contain little interstellar dust or gas. They are generally found in rich clusters of galaxies.
The IGM is thought to exist at a density of 10 to 100 times the average density of the universe (10 to 100 hydrogen atoms per cubic meter). It reaches densities as high as 1000 times the average density of the universe in rich clusters of galaxies.
 See also: Cluster, Clusters, Galaxies, Galaxy, Universe
|
