Not to be confused with Coma Star Cluster.

The Coma Cluster (Abell 1656) is a large cluster of galaxies that contains over 1,000 identified galaxies.[1][2] Along with the Leo Cluster (Abell 1367), it is one of the two major clusters comprising the Coma Supercluster.[3] It is located in and takes its name from the constellation Coma Berenices. It is one of the first galaxy clusters that was remarked upon in the astronomy literature, being visually noted by William Herschel in 1785[4][5] and photographically surveyed by Max Wolf in 1901.[6][7]

The cluster's mean distance from Earth is 99 Mpc (321 million light years).[2][8][9] Its ten brightest spiral galaxies have apparent magnitudes of 12–14 that are observable with amateur telescopes larger than 20 cm.[10] The central region is dominated by two supergiant elliptical galaxies: NGC 4874 and NGC 4889.[11] The cluster is within a few degrees of the north galactic pole on the sky. Most of the galaxies that inhabit the central portion of the Coma Cluster are ellipticals. Both dwarf and giant ellipticals are found in abundance in the Coma Cluster.[12]

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. Some of the galaxies in the Coma Cluster have also been identified as ultra diffuse galaxies.

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.[13][14][15]

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).[16][17]

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.[18] This X-ray observation was performed by balloon, but the source was not detected in the sounding rocket flight launched by the X-ray astronomy group at the Naval Research Laboratory on November 25, 1964.[19] A strong X-ray source was observed by the X-ray observatory satellite Uhuru close to the center of the Coma cluster and this source was suggested to be designated Coma X-1.[20] The Coma cluster contains about 800 galaxies within a 100 × 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 × 1044 ergs/s.[20] 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.[20] The Uhuru observations indicated a source strength of no greater than ~10−3 photons cm−2s−1keV−1 at 25 keV,[20] which disagrees with the earlier observations[18] claiming a source strength of ~10−2 photons cm−2s−1keV−1 at 25 keV, and a size of 5°.

See also

References

  1. ^ "Chandra/Field Guide to X-ray Sources". Coma Cluster. Archived April 21, 2008 at the Wayback Machine. Retrieved 2008-06-16.
  2. ^ "NASA / Focus on the Coma Cluster". Archived 2008-05-30 at the Wayback Machine. Retrieved 2008-06-16.
  3. ^ "The Coma Supercluster"
  4. ^ "From Messier to Abell: 200 Years of Science with Galaxy Clusters - A.Biviano". ned.ipac.caltech.edu. Retrieved 2026-02-16.
  5. ^ Herschel, William (1785). "On the Construction of the Heavens.". Philosophical Transactions of the Royal Society of London. 75: 213–266. Series I. Bibcode:1785RSPT...75..213H
  6. ^ Wolf, Max (1901). "Ein merkwürdiger Haufen von Nebelflecken" (in German). Astronomische Nachrichten. 155 (6–8): 127–128. Bibcode:1901AN....155..127W. doi:10.1002/asna.19011550608
  7. ^ Wolf, Max (1902). "Die Nebelflecken am Pol der Milchstrasse" (in German). Publikationen des Astrophysikalischen Instituts Koenigstuhl-Heidelberg. 1: 125–176. Bibcode:1902PAIKH...1..125W
  8. ^ "2MASS Atlas Image Gallery: Galaxy Groups and Clusters". Infrared Processing and Analysis Center. Retrieved 2010-05-02.
  9. ^ Colless, M (2001). "Coma Cluster". Encyclopedia of Astronomy and Astrophysics. P Murdin (ed.). Bristol Institute of Physics publishing. Retrieved 2006-10-08.[dead link]
  10. ^ Singapore Science Centre. "ScienceNet – Astronomy & Space Science – Observatories/ Telescopes – Question No. 13490". Archived 2005-11-11 at the Wayback Machine. Retrieved 2012-02-25.
  11. ^ Conselice, Christopher J., Gallagher, John S., III (1998). "Galaxy aggregates in the Coma cluster". Monthly Notices of the Royal Astronomical Society. 297 (2): L34–L38. arXiv:astro-ph/9801160. Bibcode:1998MNRAS.297L..34C. doi:10.1046/j.1365-8711.1998.01717.x. S2CID 14908115
  12. ^ Newswise: Hubble's Sweeping View of the Coma Cluster of Galaxies Retrieved on June 11, 2008.
  13. ^ Zwicky, Fritz (October 1937). "On the Masses of Nebulae and of Clusters of Nebulae". Astrophysical Journal. 86 (3): 217–246. Bibcode:1937ApJ....86..217Z. doi:10.1086/143864
  14. ^ Shapley, Harlow (July 1934). "A Photometric Investigation of Wolf's Cluster of Nebulae in Coma". Harvard College Observatory Bulletin. 896: 3–12. Bibcode:1934BHarO.896....3S
  15. ^ Wallenquist, Å. (1933). "On the space distribution of the nebulae in the Coma Cluster". Annalen V.d. Bosscha-Sterrenwacht (Miscellaneous Papers (Observatorium Bosscha)). 4 (6): 73–77. France: Bandoeng : Gebrs. Kleijne. Bibcode:1933AnBos...4...73W
  16. ^ Zwicky, F. (1933). "Die Rotverschiebung von extragalaktischen Nebeln" [The red shift of extragalactic neubulae] (in German). Helvetica Physica Acta. 6: 110–127. Bibcode:1933AcHPh...6..110Z From p 125: "Um, wie beobachtet, einen mittleren Dopplereffekt von 1000 km/sek oder mehr zu erhalten, müsste also die mittlere Dichte im Comasystem mindestens 400 mal grösser sein als die auf Grund von Beobachtungen an leuchtender Materie abgeleitete. Falls sich dies bewahrheiten sollte, würde sich also das überraschende Resultat ergeben, dass dunkle Materie in sehr viel grösserer Dichte vorhanden ist als leuchtende Materie." (In order to obtain an average Doppler effect of 1000 km/s or more, as observed, the average density in the Coma system would thus have to be at least 400 times greater than that derived on the basis of observations of luminous matter. If this were to be verified, the surprising result would then follow that dark matter is present in very much greater density than luminous matter.)
  17. ^ de Swart, J. G.; Bertone, G.; van Dongen, J. (2017). "How dark matter came to matter". Nature Astronomy. 1 (59): 0059. arXiv:1703.00013. Bibcode:2017NatAs...1E..59D. doi:10.1038/s41550-017-0059. S2CID 119092226
  18. ^ Boldt E, McDonald FB, Riegler G, Serlemitsos P (1966). "Extended source of energetic cosmic X rays". Phys. Rev. Lett.. 17 (8): 447–50. Bibcode:1966PhRvL..17..447B. doi:10.1103/PhysRevLett.17.447
  19. ^ Friedman H, Byram ET (January 1967). "X-rays from the Coma cluster of galaxies". Astrophysical Journal. 147 (1): 399–401. Bibcode:1967ApJ...147..368.. doi:10.1086/149022. S2CID 4286878
  20. ^ Gursky H, Kellogg E, Murray S, Leong C, Tananbaum H, Giacconi R (Aug 1971). "A strong X-ray source in the Coma cluster observed by Uhuru". Astrophysical Journal. 167 (8): L81–4. Bibcode:1971ApJ...167L..81G. doi:10.1086/180765