250407 - ACO 1656 "Coma" galaxy cluster
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click image to enlarge
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ASTRO:
type=Galaxy cluster const=Coma Berenices mag=N/A dist=321 M ly size=~5 M ly IMAGE: location=EB Driveway BrtlCls=4 moon=79% WxGb exposure=CMOS OSC: 99x180s (5.0h), G100 EQUIPMENT: camera=ZWO ASI2600MC-Pro optics=ES102 w24mmEP 1.7x (afoc prjctn), F=1238mm, f/12.1 filter=Optolong L-Pro LPS mount=Celestron AVX guiding=Orion 60x240mm, ZWO ASi224MC SOFTWARE: acquisition=Stellarium, NINA, PHD2 processing=PixInsight (RCAstro), Photoshop (RCAstro), LrC |
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The Coma Cluster, formally catalogued as ACO 1656, is a large cluster of galaxies that contains over 1,000 identified galaxies. Together with the Leo Cluster (ACO 1367), the Coma is one of two (2) major clusters comprising the Coma Supercluster. It is located in, and takes its name from the constellation "Coma Berenices".
The Abell-Corwin-Olowin catalogue lists approximately 4,000 galaxy clusters with at least 30 members having a red shift of z = 0.2 or greater. The initial effort to study and find large galaxy clusters across the universe focused on the northern hemisphere, and was largely compiled in 1958 by American astronomer Dr. George O. Abell of CalTech University using photographic plates from the Palomar Observatory Sky Survey ("POSS") beginning immediately after that project was completed, also in 1958. Using a simple magnifying glass, Dr. Abell spent countless hours studying mylar photographic sheets containing wide-field, black & white images of the sky. He identified appx 1250 clusters, many of which serve today as the basis for monumental (and on-going) studies into the structure of the universe. Then after Dr. Abell's death in 1987, his contemporaries Harold Corwin and Ronald Olowin extended the catalogue to the southern hemisphere. Today, the proper designation for galaxy clusters referenced in this catalogue is ACO, (e.g. - "ACO 1656") in recognition of all 3 of these renowned astronomical scientists.
The mean distance of cluster No. 1656 from Earth is appx 321 million light years. Its ten brightest galaxies have apparent magnitudes ranging between 12–14. The central region is dominated by two (2) supergiant elliptical galaxies: NGC 4874 and NGC 4889. The cluster is located within a few degrees of the north galactic pole.
Both dwarf and giant ellipticals are found in abundance in the Coma Cluster. As is usual for clusters of this richness, the galaxies are overwhelmingly classified as 'elliptical', and of the type 'S0'. Only a few are classified as spiral galaxies, being younger in age and existing near the outer edges of the cluster. Although many of the individual galaxies in the cluster were identified prior to Dr. Abell's efforts, the full extent of the cluster was not understood until it was more thoroughly studied in the 1950s by the ACO team at Mount Palomar Observatory.
The Coma Cluster is one of the first places where observed gravitational anomalies were considered to indicate the presence of unobserved mass. In 1933 Swiss Astronomer Fritz Zwicky showed that the galaxies of the Coma Cluster were moving too fast for the cluster to be bound together only by gravitational forces generated by the visible matter of its galaxies themselves. 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). Today, the existence of dark matter is widely accepted by the scientific community. About 90% of the mass of the Coma cluster is believed to be in the form of dark matter.
Unlike many of the ACO catalogue's entries that are not observable with common amateur astronomical telescopes, this one IS quite observable using equipment of 20 cm (appx 8 inches) and larger. Imaging is possible with smaller, but still moderately sized equipment of 100mm (appx 4 inches) and larger. The Coma Cluster is one of the most awe inspiring segments of sky to amateur astronomers today. Once it is seen, it always leaves one with a sense of the true expanse of the universe.
The Abell-Corwin-Olowin catalogue lists approximately 4,000 galaxy clusters with at least 30 members having a red shift of z = 0.2 or greater. The initial effort to study and find large galaxy clusters across the universe focused on the northern hemisphere, and was largely compiled in 1958 by American astronomer Dr. George O. Abell of CalTech University using photographic plates from the Palomar Observatory Sky Survey ("POSS") beginning immediately after that project was completed, also in 1958. Using a simple magnifying glass, Dr. Abell spent countless hours studying mylar photographic sheets containing wide-field, black & white images of the sky. He identified appx 1250 clusters, many of which serve today as the basis for monumental (and on-going) studies into the structure of the universe. Then after Dr. Abell's death in 1987, his contemporaries Harold Corwin and Ronald Olowin extended the catalogue to the southern hemisphere. Today, the proper designation for galaxy clusters referenced in this catalogue is ACO, (e.g. - "ACO 1656") in recognition of all 3 of these renowned astronomical scientists.
The mean distance of cluster No. 1656 from Earth is appx 321 million light years. Its ten brightest galaxies have apparent magnitudes ranging between 12–14. The central region is dominated by two (2) supergiant elliptical galaxies: NGC 4874 and NGC 4889. The cluster is located within a few degrees of the north galactic pole.
Both dwarf and giant ellipticals are found in abundance in the Coma Cluster. As is usual for clusters of this richness, the galaxies are overwhelmingly classified as 'elliptical', and of the type 'S0'. Only a few are classified as spiral galaxies, being younger in age and existing near the outer edges of the cluster. Although many of the individual galaxies in the cluster were identified prior to Dr. Abell's efforts, the full extent of the cluster was not understood until it was more thoroughly studied in the 1950s by the ACO team at Mount Palomar Observatory.
The Coma Cluster is one of the first places where observed gravitational anomalies were considered to indicate the presence of unobserved mass. In 1933 Swiss Astronomer Fritz Zwicky showed that the galaxies of the Coma Cluster were moving too fast for the cluster to be bound together only by gravitational forces generated by the visible matter of its galaxies themselves. 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). Today, the existence of dark matter is widely accepted by the scientific community. About 90% of the mass of the Coma cluster is believed to be in the form of dark matter.
Unlike many of the ACO catalogue's entries that are not observable with common amateur astronomical telescopes, this one IS quite observable using equipment of 20 cm (appx 8 inches) and larger. Imaging is possible with smaller, but still moderately sized equipment of 100mm (appx 4 inches) and larger. The Coma Cluster is one of the most awe inspiring segments of sky to amateur astronomers today. Once it is seen, it always leaves one with a sense of the true expanse of the universe.