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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 ... It has been later not...

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...

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 ...

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 ...

galaxy - Types of galaxies | astronomy | Britannica.com


Some of the features of this revised scheme are subject to argument ... Finally, astronomers have found that a few ellipticals do in fact have small numbers of luminous O ... The normal spirals have arms that emanate from the nucleus, while barred ...... It was discovered that galaxies and galaxy clusters tend to fall in position ...

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 .

Hubble Views a Galaxy Fit to Burst | NASA


Jul 25, 2016 ... Discovered by John Herschel in 1835, NGC 3125 is a great ... Some of these clumps of stars are notable — one of the most ..... But studies of the nearby universe have turned up only a few of these unusual ..... This is demonstrated by the striking face-on spiral galaxy NGC 6814, whose luminous nucleus ...

Hubble Spies the Barred Spiral Galaxy NGC 4394 | NASA


May 6, 2016 ... Discovered in 1784 by the German–British astronomer William ... NGC 4394 is the archetypal barred spiral galaxy, with bright spiral arms ... The presence of both tells us that stars have been forming in this galaxy throughout its history. ..... spiral galaxy NGC 6814, whose luminous nucleus and spectacular ...

NASA's Hubble Looks to the Final Frontier | NASA


Jul 21, 2016 ... But Hubble's powerful vision has carried us into the true "final frontier." ... Some are distorted like a funhouse mirror through a "space warp" ... called a nuclear ring, is extremely unusual in galaxies without a bar at their center, ...... face-on spiral galaxy NGC 6814, whose luminous nucleus...

Galaxies and the Universe - Host Galaxies of Active Nuclei


Some relation between galaxy and AGN properties might be expected, ... Seyfert galaxies are, almost by definition, mostly in spirals and S0s (Simkin et al 1980 ... A few dwarf systems (like the SMC or even fainter) have Seyfert nuclei, down to .... that the brightest AGN come in unusually luminous galaxies, and the probability ...

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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.

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.

Galaxy Growth Examined Like Rings of a Tree | NASA


Oct 31, 2013 ... The discovery may also solve a mystery of elderly galaxies. .... "It's still a mystery how certain molecules get excited in the cores of galaxies," Pearson said. ..... "We saw spiral arms extending far outside this galaxy, which no one had ..... of some nearby luminous galaxies that host active galact...