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Seyfert galaxy - Wikipedia


Seyfert galaxies are one of the two largest groups of active galaxies, along with quasars. ... In 1943, Carl Keenan Seyfert discovered more galaxies similar to NGC 1068 and reported that ... At the ...



The universe started expanding at some time in the past; the universe has an age . b. ..... That some spirals have unusually luminous nuclei was discovered by: a.

Active Galaxies - Imagine the Universe! - NASA


Most large galaxies have ~10<sup>11</sup> Mo of stars, ~10<sup>9-10</sup> Mo of interstellar gas, and ... while the more luminous quasi-stellar objects, like quasars, exhibit accretion onto a ... lines from normal stars, Seyfert galaxy nuclei have strong emission lines . ... the jets of some blazars: Stronger than X-ray, optical, radio emission combined.

Galaxies - Astronomy Notes


Jun 2, 2007 ... When the universe was younger, some galaxies produced a lot ... A peculiar group of galaxies are extremely luminous but very compact. ... an ``active galaxy'' to be a galaxy with a very luminous nucleus. ... Later, some other blue star-like objects at large redshifts were discovered to have no radio emission ...

A galaxy with two hearts - Phys.org


Jan 9, 2014 ... This new Hubble image shows the spiral galaxy Messier 83, otherwise ... number of supernova explosions, and is thought to have a double nucleus lurking at its core. ... Located some 15 million light-years away in the constellation of Hydra ... However, Messier 83's centre is mysterious and unusual; the ...

Hubble sequence - University of Oregon


Some galaxies have spiral or pinwheel arms. .... It has a bright nucleus, an unusually large central bulge, and a prominent dust lane in its ... Most representatives of this class consist of grainy, highly irregular assemblages of luminous areas.

Active galactic nuclei - D.E. Osterbrock - NED


Many of the most luminous radio galaxies are morphologically classified as ... In many cases these spectra are earlier in spectral type than normal spirals, ... Only one `Seyfert 2 QSO' has been reported, E 0449-184, originally discovered as .... definition of a very low-luminosity Seyfert 1.8 nucleus with unusually narrow lines .

John Kormendy: Monsters in Galactic Nuclei


Jul 15, 2000 ... Soon after quasars were discovered in 1963, astronomers proposed .... but it does not rule out some other concentration of underluminous matter. ... An unusual aspect of this image is that foreground stars have been removed. .... type between spirals and ellipticals in Edwin Hubble's classification scheme.

Structure of the M33 nucleus - SAO/NASA Astrophysics Data System


Interest in the M33 nucleus recently has been stimulated by the discovery that it .... scaled-down versions of M3 l's nucleus, a luminous globular cluster, or some .... have seen that globular clusters and some Local Group spiral-galaxy nuclei are similar. ... The M31 nucleus, with a 190 km s~1, is clearly a dynamically unusual ...

Lecture 24: Nuclear Activity in Galaxies, QSOs - University of Arizona


Some galaxies have been observed to have very unusual activiy in the their ... we discovered that some ordinary looking galaxies has infrared outputs 10 to 100 ... These galaxies were dubbed "Ultra-luminous Infrared Galaxies" or ULIRGS for short. .... and infrared) nuclei which look like stars superposed on spiral galaxies.

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Chapter 17 - Astronomy


More recently, astronomers have discovered objects that fit none of Hubble's categories, ... the spiral arms come from the ends of a bar through the nucleus rather than from the nucleus itself. 4. ..... Some irregulars are seen to be pairs of galaxies in collision. ... An active galaxy is a galaxy with an unusually luminous nucleus...

galaxy - Types of galaxies | astronomy | Britannica.com


Apr 13, 2016 ... The normal spirals have arms that emanate from the nucleus, while ... Some S0 systems have a hint of structure in the envelope, either .... Q: Quasars, or QSOs, small, extremely luminous objects, many of which are strong radio sources. ..... It was discovered that galaxies and galaxy clusters tend to fall in ...

Active Galaxies - Teach Astronomy


The placid exteriors of some galaxies conceal events of great violence. ... The most luminous of these objects give off the same amount of energy as 1 trillion suns. ... can get pulled in (just like a comet getting pulled into the sun), but as it spirals to ... discovered in 1908 by Edward Fath, who discovered intense emission lines ...