A type of spiral galaxy that has a bright nucleus and whose spectrum shows emission lines. Historically, N galaxies and Seyfert galaxies were defined by different astronomers on the basis of different information, and the difference between them is not always clear cut.
An energetic galaxy with an exceptionally bright core that emits non-thermal radiation. Carl Seyfert first observed these peculiar galaxies in the early 1940s. The majority of Seyfert galaxies have a spiral structure and vary in brightness over several months. This indicates a small energy source (perhaps a black hole) at the nucleus that is responsible for the non-thermal radiation. Seyfert galaxy luminosity varies between one-tenth and ten times the luminosity of our galaxy.
A spiral galaxy whose nucleus shows bright spectral emission lines in all wavelengths; a class of galaxies first described by C. Seyfert.
class of spiral galaxy that exhibits intense, irregular, electromagnetic radiations within a small active nucleus.
a spiral galaxy with a compact, very bright nucleus that produces a non-thermal continuous spectrum with broad (fat) emission lines on top.
a class of nearby galaxy that has an extremely bright central region that often obscure the much dimmer stars in the surrounding disk
A galaxy belonging to the class of those with active galactic nuclei; one whose nucleus shows bright emission lines; one of a class of galaxies first described by C. Seyfert.
A galaxy that appears to be a normal spiral galaxy, but whose core fluctuates in brightness. It is believed that these fluctuations are caused by powerful eruptions in the core of the galaxy.
a galaxy (usually a spiral) with a very bright nucleus and strong spectral emission lines; the first was discovered in 1943 by Carl Seyfert
A spiral galaxy with an extremely active, bright core with strong radio emission lines. M77 in Cetus is a Seyfert galaxy.
A spiral galaxy with a very compact, highly luminous nucleus.
Type of active galaxy that exhibits intense energetic activity from a small region within the nucleus of an otherwise normal-looking spiral galaxy.
A type of spiral galaxy exhibiting a bright nucleus and with a spectrum that shows broad emission lines.
A Seyfert galaxy is an active spiral galaxy. Its nucleus (center) has bright emission lines, including visible wavelengths. The brightness varies over relatively short time periods (less than a year). They may have massive black holes at their centers. Seyfert galaxies were first described by Carl Seyfert in 1943.
galaxy, usually a spiral or disturbed system, whose nucleus shows strong emission lines which are too broad and of ionization too high to be produced by the galaxy's stellar population. Often, we see a bright starlike nucleus associated with this. In type 1 Seyferts, some of the emission lines, those that an be produced at high densities, are still broader, while in type 2 nuclei, all the linewidths are comparable. Seyfert nuclei are strong X-ray sources, and many show significant radio emission.
A spiral-type galaxy having an unusually bright, compact nucleus, and that seems to have properties midway between normal galaxies and the most violent of the active galaxies.
A galaxy characterized by a moderately bright, compact active galactic nucleus, presumably powered by a black hole.
Seyfert galaxies are spiral or irregular galaxies containing an extremely bright nucleus, most likely caused by a supermassive black hole, that can sometimes outshine the surrounding galaxy. The light from the central nucleus varies in less than a year, which implies that the emitting region must be less than one light year across. They are named after the astronomer Carl Seyfert, who studied them extensively in the 1940s.