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Seyfert galaxy
(redirected from Seyfert galaxies)

   Also found in: Encyclopedia, Wikipedia 0.03 sec.
Sey·fert galaxy  (sfrt, s-)
n.
A spiral galaxy with a small, compact, bright nucleus that exhibits variable light intensity and radio-wave emission.

[After Carl Keenan Seyfert (1911-1960), American astronomer.]

Seyfert galaxy [ˈsaɪfət]
n
(Astronomy & Space / Celestial Objects) any of a class of spiral galaxies having a very bright nucleus, possibly corresponding to an active period in the lives of all spiral galaxies
[named after Carl K. Seyfert (died 1960), US astronomer]

Seyfert galaxy  (sfrt, s-)
A spiral galaxy with a small, compact, bright nucleus that exhibits variable light intensity and radio-wave emission. Seyfert galaxies are active galaxies and are thought to contain a black hole in their galactic nucleus. The nuclei of Seyfert galaxies generate an emission spectrum characteristic of hot, ionized clouds of gas, shooting out from the accretion disk around the black hole. The observations during the 1940s of American astronomer Carl Seyfert (1911-60), after whom the galaxies are named, demonstrated that these jets of gas are expelled from the nucleus at speeds up to millions of miles per hour. See also blazarquasar


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Since then, astronomers have come to suspect that supermassive black holes cause the turmoil in the center of Seyfert galaxies.
Scientists have generally agreed that radiation pouring out of active galactic nuclei (AGNs) - quasars, Seyfert galaxies, and other compact sources - accounts for at least half the low-energy portion of the X-ray background.
For years, astronomers have suspected that relatively small black holes fuel the energetic activity found at the core of M51 and several other galaxies, called LINERs (for low-ionization narrow emission-line region), just as larger black holes may power the more luminous cores of Seyfert galaxies.
 
 
 
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