Arthur Allen Hoag (January 28, 1921 - July 17, 1999) was an American astronomer most famous for his discovery of Hoag's Object, a type of ring galaxy, in 1950. He worked at the Naval Ordnance Laboratory, was director of the stellar division of Kitt Peak National Observatory and later the director of Lowell Observatory from 1977-1986. He was also one of the founders of the dark-sky movement.
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👉 Arthur Hoag in the context of Ring galaxy
A ring galaxy is a type of galaxy that includes a large annular structure. The galactic center may be relatively separate from the ring structure, or present a continuous disc shape. Hoag's Object, discovered by Arthur Hoag in 1950, is an example of a ring galaxy. The ring contains many massive, relatively young blue stars, which are extremely bright. The central region contains relatively little luminous matter. Some astronomers believe that ring galaxies are formed when a smaller galaxy passes through the center of a larger galaxy. Because most of a galaxy consists of empty space, this "collision" rarely results in any actual collisions between stars. However, the gravitational disruptions caused by such an event could cause a wave of star formation to move through the larger galaxy. Other astronomers think that rings are formed around some galaxies when external accretion takes place. Star formation would then take place in the accreted material because of the shocks and compressions of the accreted material.
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Arthur Hoag in the context of Nicholas U. Mayall Telescope
The Nicholas U. Mayall Telescope, also known as the Mayall 4-meter Telescope, is a four-meter (158 inches) reflector telescope located at the Kitt Peak National Observatory in Arizona and named after Nicholas U. Mayall. It saw first light on February 27, 1973, and was the second-largest telescope in the world at that time. Initial observers included David Crawford, Nicholas Mayall, and Arthur Hoag. It was dedicated on June 20, 1973 after Mayall's retirement as director. The mirror has an f/2.7 hyperboloidal shape. It is made from a two-foot (61 cm (24 in)) thick fused quartz disk that is supported in an advanced-design mirror cell. The prime focus has a field of view six times larger than that of the Hale reflector. It is host to the Dark Energy Spectroscopic Instrument. The identical Víctor M. Blanco Telescope was later built at Cerro Tololo Inter-American Observatory, in Chile.
Arthur Hoag in the context of Hoag's Object
Hoag's Object is an unusual ring galaxy in the constellation of Serpens Caput. It is named after Arthur Hoag, who discovered it in 1950 and identified it as either a planetary nebula or a peculiar galaxy. The galaxy has a D25 isophotal diameter of 45.41 kiloparsecs (148,000 light-years).