Coma Cluster
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- This article is about the cluster of galaxies named the Coma Cluster. For the star cluster, see Coma star cluster.
Map of the central part of the Coma Cluster |
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| Observation data (Epoch J2000) |
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|---|---|
| Constellation(s): | Coma Berenices |
| Right ascension: | 12h 59m 49s[1] |
| Declination: | +27° 58′ 50″[1] |
| Number of galaxies: | 484[1] |
| Brightest member: | |
| Other designations | |
| Abell 1656[1] | |
| See also: Galaxy groups and clusters, List of galaxy clusters |
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The Coma Cluster (Abell 1656) is a large cluster that contains over 1000 identified galaxies[citation needed].
The cluster's mean distance from Earth is 99 Mpc (321 million light years)[2] . Its 10 brightest spiral galaxies have apparent magnitudes of 12-14 that are observable with amateur telescopes larger than 20 cm[citation needed]. The central region is dominated by two giant elliptical galaxies: NGC 4874 and NGC 4889[3]. The cluster is within a few degrees of the north galactic pole on the sky.
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[edit] Intracluster gas
The galaxies in this cluster are surrounded by very hot intracluster gas that produces significant X-ray emission[citation needed]. This ionized gas also shifts the microwave spectrum of the cosmic microwave background radiation, an effect called Sunyaev-Zel'dovich effect[4]. The mass of the intracluster gas is much higher than the mass of all the galaxies in the cluster[citation needed].
[edit] Cluster members
As is usual for clusters of this richness, the galaxies are overwhelmingly elliptical and S0 galaxies, with only a few spirals of younger age, and many of them probably near the outskirts of the cluster.
The full extent of the cluster was not understood until it was more thoroughly studied in the 1950s by astronomers at Mount Palomar Observatory[citation needed], although many of the individual galaxies in the cluster had been identified previously[citation needed].
[edit] See also
- Fornax Cluster - another nearby cluster of galaxies
- Virgo Cluster - another nearby cluster of galaxies
[edit] External links
[edit] References
- ^ a b c d NASA/IPAC Extragalactic Database. Results for Abell 1656. Retrieved on September 19, 2006.
- ^ Colless, M. (2001). "Coma Cluster". Encyclopedia of Astronomy and Astrophysics. Ed. P Murdin. Bristol Institute of Physics publishing. Retrieved on 2006-10-08.
- ^ Conselice, Christopher J., Gallagher, John S., III (1998). "Galaxy aggregates in the Coma cluster". Monthly Notices of the Royal Astronomical Society 297: L34-L38.
- ^ M. De Petris, L. D'Alba, L. Lamagna, F. Melchiorri, A. Orlando, E. Palladino, Y. Rephaeli, S. Colafrancesco, E. Kreysa, M. Signore (2002). "MITO Measurements of the Sunyaev-Zeldovich Effect in the Coma Cluster of Galaxies". Astrophysical Journal 574: L119-L122.
- The dynamical state of the Coma cluster with XMM-Newton
- Very Small Array observations of the Sunyaev-Zel'dovich effect in nearby galaxy clusters
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