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Galaxy Morphological Types
A galaxy is a system of stars, stellar remnants, interstellar gas, dust, dark matter, bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar System. Galaxies, averaging an estimated 100 million stars, range in size from dwarfs with less than a hundred million stars, to the largest galaxies known – supergiants with one hundred trillion stars, each orbiting its galaxy's center of mass. Most of the mass in a typical galaxy is in the form of dark matter, with only a few percent of that mass visible in the form of stars and nebulae. Supermassive black holes are a common feature at the centres of galaxies. Galaxies are categorized according to their visual morphology as elliptical, spiral, or irregular. Many are thought to have supermassive black holes at their centers. The Milky Way's central black hole, known as Sagittarius A*, has a mass four million times greater than the Sun. As of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 4414
NGC 4414 is an unbarred spiral galaxy about 62 million light-years away in the constellation Coma Berenices. It is a flocculent spiral galaxy, with short segments of spiral structure but without the dramatic well-defined spiral arms of a grand design spiral. In 1974 a supernova, SN 1974G, was observed and was the only supernova in this galaxy to be recorded until 7 June 2013 when SN 2013df was discovered at magnitude 14 and 1 January 2021 when SN 2021J was discovered at magnitude 12. It was imaged by the Hubble Space Telescope in 1995, as part of the HST's main mission to determine the distance to galaxies, and again in 1999 as part of the Hubble Heritage project. It has been part of an ongoing effort to study its Cepheid variable stars. The outer arms appear blue due to the continuing formation of young stars and include a possible luminous blue variable with an absolute magnitude of −10. NGC 4414 is also a very isolated galaxy without signs of past interactions with othe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
