class of galaxies
Factsheet
Named after Carl Keenan Seyfert
Named after Carl Keenan Seyfert
Wikipedia
en.wikipedia.org › wiki › Seyfert_galaxy
Seyfert galaxy - Wikipedia
November 5, 2025 - They have quasar-like nuclei (very luminous sources of electromagnetic radiation that are outside of our own galaxy) with very high surface brightnesses whose spectra reveal strong, high-ionisation emission lines, but unlike quasars, their host galaxies are clearly detectable. Seyfert galaxies account for about 10% of all galaxies and are some of the most intensely studied objects in astronomy, as they are thought to be powered by the same phenomena that occur in quasars, although they are closer and less luminous than quasars.
Caltech
ned.ipac.caltech.edu › level5 › Glossary › Essay_seyfert.html
Seyfert galaxies
A Seyfert galaxy has a quasar-like nucleus, but the host galaxy is clearly detectable. The original definition of the class (Seyfert 1943) was primarily morphological, i.e., these are galaxies with high surface brightness nuclei, and subsequent spectroscopy revealed unusual emission-line ...
Videos
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Teach Astronomy - Seyfert Galaxies
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Merriam-Webster
merriam-webster.com › dictionary › Seyfert galaxy
SEYFERT GALAXY Definition & Meaning - Merriam-Webster
The meaning of SEYFERT GALAXY is any of a class of spiral galaxies that have small compact bright nuclei characterized by variability in light intensity, emission of radio waves, and spectra —called also Seyfert.
Encyclopedia Britannica
britannica.com › science › astronomy
Seyfert galaxy | Active Nucleus, Supermassive Black Hole & Quasar | Britannica
July 20, 1998 - Seyfert galaxy, any of a class of galaxies known to have active nuclei. Such galaxies were named for the American astronomer Carl K. Seyfert, who first called attention to them in 1944.
Open Learning
open.edu › openlearn › science-maths-technology › introduction-active-galaxies › content-section-3.2
Introduction to active galaxies: 3.2 Seyfert galaxies | OpenLearn - Open University
In 1943 the American astronomer Carl Seyfert (1911-1960) drew attention to a handful of spiral galaxies that had unusually bright point-like nuclei. Figure 12 shows NGC 4051, one of the first Seyfert galaxies to be identified. Subsequently, it has been found that compared to normal galaxies, Seyfert galaxies show an excess of radiation in the far infrared and at other wavelengths.
Dictionary.com
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SEYFERT GALAXY Definition & Meaning | Dictionary.com
Seyfert galaxy definition: one of a group of spiral galaxies with compact, bright nuclei having characteristically broad emission lines suggestive of very hot gases in violent motion at the center.. See examples of SEYFERT GALAXY used in a sentence.
Oxford Reference
oxfordreference.com › display › 10.1093 › oi › authority.20110803100458314
Seyfert galaxy - Oxford Reference
A type of galaxy with a small, bright nucleus which shows broad, strong emission lines in its spectrum. The first galaxies of this type were described in 1943 by C. K. Seyfert. Nearly all known Seyfert galaxies are spirals or barred spirals, ...
Caltech
ned.ipac.caltech.edu › level5 › March01 › Weedman › Weed2.html
Seyfert Galaxies - D. W. Weedman
A Seyfert galaxy, however, can ... distinguished from a star. Consequently, the morphological definition of a Seyfert galaxy is the presence of an unresolved, very bright nucleus....
ScienceDirect
sciencedirect.com › topics › physics-and-astronomy › seyfert-galaxies
Seyfert Galaxies - an overview | ScienceDirect Topics
Seyfert galaxies are apparently otherwise normal galaxies that have abnormally bright central cores.1 Seyfert (1943) identified a handful of these among nearby bright galaxies. Spectroscopy of their cores shows an unusually blue spectrum with strong, broad emission lines.
Universe Guide
universeguide.com › home › space facts › seyfert galaxy
What is a Seyfert Galaxy? - Universe Guide
August 11, 2025 - A Seyfert Galaxy is a galaxy whose luminosity changes over time. There are two types of Seyfert Galaxies. Carl Seyfert, an American Astronomer, discovered them, and this galaxy group is named after him.
David Darling
daviddarling.info › encyclopedia › S › Seyfert_galaxy.html
Seyfert galaxy
A Seyfert galaxy is galaxy with a small, intensely bright nucleus which shows strong, broad emission lines. Seyfert galaxies, named after Carl Seyfert (1911–1960), who first defined them as a group of similar objects in 1943, are nearly all ...
Utk
csep10.phys.utk.edu › OJTA2dev › ojta › c2c › activegalaxies › agn › seyfert_tl.html
Seyfert Galaxies
Seyfert galaxies are usually spirals with very bright but very small nuclei. They are named for American astronomer Carl Seyfert, who first studied their properties in the early 1940s (see the right panel). Seyfert's are the most commonly observed active galaxies, with about 1 in 100 spirals ...
Seds
spider.seds.org › spider › ScholarX › seyferts.html
Seyfert Galaxies
Seyfert who in 1943, described them as their central regions having peculiar spectra with notable emission lines. "Normal" (spiral) galaxies often have emission nebulae in their spiral arms, as have irregulars throughout; these regions, of course, show the corresponding emission lines in their ...
University of Oregon
pages.uoregon.edu › soper › ActiveGalxy › seyfert.html
Seyfert Galaxies
Seen with visible light, these are fairly ordinary spiral galaxies.
Collins Dictionary
collinsdictionary.com › dictionary › english › seyfert-galaxy
SEYFERT GALAXY definition and meaning | Collins English Dictionary
one of a group of spiral galaxies with compact, bright nuclei having characteristically broad emission lines suggestive of very hot gases in violent motion at the center · Word origin [1965–70; named after Carl K. Seyfert (1911–60), American ...
Study.com
study.com › science courses › astronomy 101: intro to astronomy
Seyfert Galaxies & Double-Lobed Radio Galaxies - Lesson | Study.com
March 16, 2015 - A Seyfert galaxy is a spiral galaxy with spiral arms that has a small, bright, point-like nucleus that changes in brightness. Learn more about Seyfert galaxies, double-lobed radio galaxies and active galaxies.
Space Telescope Science Institute
archive.stsci.edu › hut › papers › afdscirev_b › node9.html
Seyfert Galaxies
Seyfert galaxies have been among the most intensively studied objects in astronomy, primarily because they are thought to be nearby, low-luminosity versions of the same phenomenon observed in quasars. A massive black hole in the nucleus of a galaxy, accreting gas from its surrounding environment, ...