Coma Cluster

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, although many of the individual galaxies in the cluster had been identified previously.{{cite journal | author-link1 = Fritz Zwicky | doi-access = free | author-link1 = Harlow Shapley

Dark matter

The Coma Cluster is one of the first places where observed gravitational anomalies were considered to be indicative of unobserved mass. In 1933 Fritz Zwicky showed that the galaxies of the Coma Cluster were moving too fast for the cluster to be bound together by the visible matter of its galaxies. Though the idea of dark matter would not be accepted for another fifty years, Zwicky wrote that the galaxies must be held together by "dunkle Materie" (dark matter).

About 90% of the mass of the Coma cluster is believed to be in the form of dark matter.

X-ray source

An extended X-ray source centered at 1300+28 in the direction of the Coma cluster of galaxies was reported before August 1966.{{ cite journal | doi-access = free The Coma cluster contains about 800 galaxies within a 100 x 100 arc-min area of the celestial sphere. The source near the center at RA (1950) 12h56m ± 2m Dec 28°6' ± 12' has a luminosity Lx = 2.6 x 1044 ergs/s. As the source is extended, with a size of about 45', this argues against the possibility that a single galaxy is responsible for the emission. The Uhuru observations indicated a source strength of no greater than ~10−3 photons cm−2s−1keV−1 at 25 keV, which disagrees with the earlier observations claiming a source strength of ~10−2 photons cm−2s−1keV−1 at 25 keV, and a size of 5°.

Gallery

File:Clusters within clusters - Coma Cluster.jpg|Thousands of globular clusters lying at the core of a galaxy cluster File:The Coma Galaxy Cluster as seen by Hubble Heic0813a.jpg|A large portion of the Coma Cluster seen by Hubble's Advanced Camera for Surveys File:Hubble close-up on the Coma Cluster.jpg|Hubble close-up on the Coma Cluster File:NGC 4911.jpg|A face-on view of a spiral galaxy (NGC 4911) located deep within the Coma Cluster File:Comacl zentrum600.png|Map of the central part of the Coma Cluster.

References

References

1. "The Coma Supercluster".
2. "2MASS Atlas Image Gallery: Galaxy Groups and Clusters". Infrared Processing and Analysis Center.
3. Colless, M. (August 2017). "Coma Cluster". Bristol Institute of Physics publishing }}{{dead link.
4. [http://newswise.com/articles/view/541574/ Newswise: Hubble's Sweeping View of the Coma Cluster of Galaxies] Retrieved on June 11, 2008.
5. "Wading through water".
6. Cramer, William J.. (Jan 2019). "Spectacular Hubble Space Telescope Observations of the Coma Galaxy D100 and Star Formation in Its Ram Pressure–stripped Tail". The Astrophysical Journal.
7. (1933). "Die Rotverschiebung von extragalaktischen Nebeln". Helvetica Physica Acta.
8. (2017). "How dark matter came to matter". Nature Astronomy.
9. "Clusters within clusters".
10. "Hubble close-up on the Coma Cluster". ESA/Hubble Picture of the Week.