coma cluster of galaxies

Inside the Coma Cluster of Galaxies : Almost every object in the above photograph is a galaxy. The Coma Cluster of Galaxies pictured above is one of the densest clusters known - it contains thousands of galaxies. Each of these galaxies houses billions of stars - just as our own Milky Way Galaxy does. Although nearby when compared to most other clusters, light from the Coma Cluster still takes hundreds of millions of years to reach us. In fact, the Coma Cluster is so big it takes light millions of years just to go from one side to the other! The above mosaic of images of a small portion of Coma was taken in unprecedented detail in 2006 by the Hubble Space Telescope to investigate how galaxies in rich clusters form and evolve. Most galaxies in Coma and other clusters are ellipticals, although some imaged here are clearly spirals. The spiral galaxy on the upper left of the above image can also be found as one of the bluer galaxies on the upper left of this wider field image. In the background thousands of unrelated galaxies are visible far across the universe. via NASA

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The Invisible Galaxy

A new form of diffuse galaxy has been discovered inside the Coma Cluster. This place is made 99.99% of dark matter, totally invisible as it doesn’t interact with light.

The galaxy is known as Dragonfly 44 and was discovered by astronomers Pieter van Dokkum and his colleagues.

The way star systems orbit around the center of a galaxy is inexplicable with “normal” physics. To account for the velocity variations and patterns we need to add a new ingredient to the gravitational pot: dark matter.

Dragonfly 44 in particular has so few stars that were the dark matter to be taken away, the galaxy would fly apart the same way you’d go flying if the cord holding the swing to a swing set were severed.

(Image credit: NASA, JPL-CalTech and L. Jenkins

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NASA just spotted the biggest black hole scientists have ever seen

Examining images taken by NASA’s Hubble Space Telescope, astronomers discovered a black hole 21 billion times bigger than the sun — the biggest black hole known to humankind. The “supermassive” black hole is 300 million light years away from us and resides right in the middle of the Coma Cluster, part of the NGC 4889 galaxy, the Hubble Space Telescope’s official website explains. “The placid appearance of NGC 4889 can fool the unsuspecting observer,” reads the website.

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Spiral galaxy NGC 4911 in the Coma Cluster

A long-exposure Hubble Space Telescope image shows a majestic face-on spiral galaxy located deep within the Coma Cluster of galaxies, which lies 320 million light-years away in the northern constellation Coma Berenices.

The galaxy, known as NGC 4911, contains rich lanes of dust and gas near its centre. These are silhouetted against glowing newborn star clusters and iridescent pink clouds of hydrogen, the existence of which indicates ongoing star formation. Hubble has also captured the outer spiral arms of NGC 4911, along with thousands of other galaxies of varying sizes. The high resolution of Hubble’s cameras, paired with considerably long exposures, made it possible to observe these faint details.

NGC 4911 and other spirals near the centre of the cluster are being transformed by the gravitational tug of their neighbours. In the case of NGC 4911, wispy arcs of the galaxy’s outer spiral arms are being pulled and distorted by forces from a companion galaxy (NGC 4911A), to the upper right. The resultant stripped material will eventually be dispersed throughout the core of the Coma Cluster, where it will fuel the intergalactic populations of stars and star clusters.

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA). Acknowledgment: K. Cook (Lawrence Livermore National Laboratory, USA)

Anemic Spiral NGC 4921 from Hubble
Image Credit: Data - Hubble Legacy Archive, ESA, NASA; Processing - Roberto Colombari

How far away is spiral galaxy NGC 4921? Although presently estimated to be about 310 million light years distant, a more precise determination could be coupled with its known recession speed to help humanity better calibrate the expansion rate of the entire visible universe. Toward this goal, several images were taken by the Hubble Space Telescope in order to help identify key stellar distance markers known as Cepheid variable stars. Since NGC 4921 is a member of the Coma Cluster of Galaxies, refining its distance would also allow a better distance determination to one of the largest nearby clusters in the local universe. The magnificent spiral NGC 4921 has been informally dubbed anemic because of its low rate of star formation and low surface brightness. Visible in the above image are, from the center, a bright nucleus, a bright central bar, a prominent ring of dark dust, blue clusters of recently formed stars, several smaller companion galaxies, unrelated galaxies in the far distant universe, and unrelated stars in our Milky Way Galaxy.

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NGC 4911: Spiral Diving into a Dense Cluster 

Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA); Acknowledgment: K. Cook (LLNL) et al.

Explanation: Why are there faint rings around this spiral galaxy? Possibly because the galaxy, NGC 4911, is being pulled at by its neighbors as it falls into the enormous Coma Cluster of Galaxies. If NGC 4911 ends up like most of the galaxies in the central Coma cluster, it will become a yellowish elliptical galaxy, losing not only its outer layers, but dust, gas, and its cadre of surrounding satellite galaxies as well. Currently, however, this process is just beginning. Visible in the above deep image from the Hubble Space Telescope are NGC 4911’s bright nucleus, distorted spiral arms laced with dark dust, clusters of recently formed stars, unusual faint outer rings, dwarf companion galaxies, and even faint globular clusters of stars. Far in the distance many unassociated galaxies from the early universe are visible, some even through NGC 4911 itself. The Coma Cluster contains over 1,000 galaxies making it among the most massive objects known. NGC 4911 can be found to the lower left of the great cluster’s center.

Behemoth Black Hole Found in an Unlikely Place

Astronomers have uncovered a near-record breaking supermassive black hole, weighing 17 billion suns, in an unlikely place: in the center of a galaxy in a sparsely populated area of the universe. The observations, made by NASA’s Hubble Space Telescope and the Gemini Telescope in Hawaii, may indicate that these monster objects may be more common than once thought.

Until now, the biggest supermassive black holes – those roughly 10 billion times the mass of our sun – have been found at the cores of very large galaxies in regions of the universe packed with other large galaxies. In fact, the current record holder tips the scale at 21 billion suns and resides in the crowded Coma galaxy cluster that consists of over 1,000 galaxies.

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NGC 4676, or the Mice Galaxies, are two spiral galaxies in the constellation Coma Berenices. About 290 million light-years away, they began the process of colliding and merging. Their name refers to the long tails produced by tidal action—the relative difference between gravitational pulls on the near and far parts of each galaxy—known here as a galactic tide. Members of the Coma cluster, it is a possibility that both galaxies have experienced collision, and will continue colliding until they coalesce.

The sleeping giant NGC 4889 harbors a dark secret

The placid appearance of NGC 4889 can fool the unsuspecting observer. But the elliptical galaxy, pictured in this new image from the NASA/ESA Hubble Space Telescope, harbours a dark secret. At its heart lurks one of the most massive black holes ever discovered.

Located about 300 million light-years away in the Coma Cluster, the giant elliptical galaxy NGC 4889, the brightest and largest galaxy in this image, is home to a record-breaking supermassive black hole. Twenty-one billion times the mass of the Sun, this black hole has an event horizon – the surface at which even light cannot escape its gravitational grasp – with a diameter of approximately 130 billion kilometres. This is about 15 times the diameter of Neptune’s orbit from the Sun. By comparison, the supermassive black hole at the centre of our galaxy, the Milky Way, is believed to have a mass about four million times that of the Sun and an event horizon just one fifth the orbit of Mercury.

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