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Topic: Seyfert galaxy

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	Seyfert galaxy - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-06)
		They are named after the astronomer Carl Seyfert, who studied them extensively in the 1940s.
		These emission lines exhibit strong Doppler broadening, which implies velocities from 500 to 4000 km/s, and are believed to originate near an accretion disk surrounding the central fl hole.
		This effect was first discovered by Antonucci and Miller in the Type 2 Seyfert NGC 1068.
	en.wikipedia.org /wiki/Seyfert_galaxy (414 words)

	Active galaxy - Wikipedia, the free encyclopedia (Site not responding. Last check: 2007-10-06)
		An active galaxy is a galaxy where a significant fraction of the energy output is not emitted by the normal components of a galaxy: stars, dust and interstellar gas.
		This energy, depending on the active galaxy type, can be emitted across most of the electromagnetic spectrum, as infrared, radio waves, UV, X-ray and gamma rays.
		Seyferts, quasars and blazars are the main types of AGNs that emit high-energy radiation (X-rays).
	en.wikipedia.org /wiki/Active_galaxy (727 words)

	Seyfert galaxy
		Seyfert galaxies, named after Carl Seyfert (1911-1960), who first defined them as a group of similar objects in 1943, are nearly all spiral galaxies or barred spirals.
		Although the visual luminosity of Seyferts is not unusual for spirals, their total luminosity, including radio wave, X-ray, and, most significantly, infrared emission, is roughly 100 times normal.
		Taken as a whole, Seyferts display many of the properties of quasars and almost certainly produce the bulk of their energy output in the same way — through the gravitational influence of a supermassive fl hole at the heart of an active galactic nucleus.
	www.daviddarling.info /encyclopedia/S/Seyfert_galaxy.html (315 words)

	Seyfert Galaxies (Site not responding. Last check: 2007-10-06)
		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.
		Consequently, observations of Seyfert galaxies and quasars were a goal of one of the major observational programs for HUT on Astro-1.
		One of the brightest and best-studied Seyfert galaxies is NGC 4151.
	praxis.pha.jhu.edu /papers/papers/afdscirev_b/node9.html (749 words)

	Galaxies
		Approximately 10% of the brightest galaxies in the sky are Seyferts.
		Seyferts are thought to be spiral galaxies with a quasar-like center.
		B L Lacertae objects are active galaxies characterized by rapid (days) luminosity variations and a lack of emission lines in their spectra.
	hyperphysics.phy-astr.gsu.edu /hbase/astro/galax.html (423 words)

	Seyfert Galaxy NGC 7742 - Wikipedia, the free encyclopedia
		Seyfert Galaxy NGC 7742 imaged by the Hubble Space Telescope.
		The Seyfert Galaxy NGC 7742 (also known as Galaxy NGC 7742 or NGC 7742) is the designation for a Type 2 Seyfert galaxy and a spiral galaxy that lies approximately 22 mega-parsecs (72 million light-years) away from Earth in the Pegasus constellation.
		This galaxy shows evidence of highly ionized atoms because of the spectrum of its intensely luminous nucleus.
	en.wikipedia.org /wiki/NGC_7742 (124 words)

	Seyfert galaxy -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-10-06)
		Seyfert galaxies are (Flying downward in a helical path with a large radius) spiral or (Merchandise that has imperfections; usually sold at a reduced price without the brand name) irregular (Click link for more info and facts about galaxies) galaxies containing an extremely bright nucleus,
		The light from the central nucleus varies in less than a year, which implies that the emitting region must be less than one (The distance that light travels in a vacuum in 1 year; 5.88 trillion miles or 9.46 trillion kilometers) light year across.
		They are named for the (A physicist who studies astronomy) astronomer (Click link for more info and facts about Carl Seyfert) Carl Seyfert, who studied them extensively in the (The decade from 1940 to 1949) 1940s.
	www.absoluteastronomy.com /encyclopedia/S/Se/Seyfert_galaxy.htm (378 words)

	Seyfert Galaxy Observations May Trigger New Debates
		Seyfert galaxies and astronomers have always been a little bit like the proverbial blind man and the elephant.
		The characteristic trait of a Seyfert galaxy is a blisteringly bright fountain of energetic emissions from the central fl hole.
		Seyfert 1 galaxies are oriented so that the opening of the torus points toward Earth, allowing a direct view of activity in the galactic nucleus.
	unisci.com /stories/20012/0612011.htm (1001 words)

	Seyfert Galaxies
		Seyfert galaxies are named for Carl K. Seyfert who in 1943, described them as their central regions having peculiar spectra with notable emission lines.
		Seyfert lists 12 galaxies which he states "probably belong to this unusual class of objects": NGC 1068 (M 77), NGC 1275 (Perseus A), NGC 2782, NGC 3077 (in the M81 group), NGC 3227, NGC 3516, NGC 4051, NGC 4151, NGC 4258 (M 106), NGC 5548, NGC 6814, and NGC 7469.
		Seyfert 2 galaxies show only one set of emission lines which are comparatively narrow and originate from low-density ionized gas (electron density 10^3 to 10^6 electrons per cm^3) with widths corresponding to several 100 km/s as indicated from the line width, which is somewhat broader than the emission lines from non-active galactic nuclei.
	www.seds.org /~spider/spider/ScholarX/seyferts.html (1084 words)

	Headlines@Hopkins: Johns Hopkins University News Releases
		Seyfert galaxies and astronomers have always been a little bit like the proverbial blind men and the elephant.
		Astronomers aren't blind, but they are limited to observing galaxies from Earth or its vicinity, and for an object as big as a galaxy, that amounts to a single tightly restricted perspective.
		Astronomers first came to think of Seyfert galaxies as one type of galaxy seen from different views in 1983, when Tran's future mentor, Joseph Miller of the University of California-Santa Cruz and his student Robert Antonucci, now at the University of California-Santa Barbara, proposed what would become known as the unified model of Seyfert galaxies.
	www.jhu.edu /news_info/news/home01/jun01/seyfert.html (1013 words)

	Seyfert Galaxy (Site not responding. Last check: 2007-10-06)
		A Seyfert galaxy is any of a class of galaxies known to have active nuclei.
		The nuclear spectra of Seyfert galaxies show broad emission lines, which are indicative of a central concentration of hot gas that is expanding at speeds of up to thousands of kilometres per second.
		Galaxies of this type appear normal in ordinary photographs but are extremely strong sources of infrared radiation.
	abyss.uoregon.edu /~js/glossary/seyfert_galaxy.html (122 words)

	www.herts.ac.uk/astro_ub/aS_ub.html (Site not responding. Last check: 2007-10-06)
		The Schwarzchild radius demarks the distance of the event horizon from the centre of the fl hole, which is known as the singularity and is where the escape velocity is greater then the speed of light.
		They are elliptical galaxies surrounded by thin shells of stars which are thought to have been ejected during a galaxy merger.
		Any galaxy in which a central bulge of older stars is surrounded by a flattened galactic disc containing a spiral pattern of young, hot stars.
	www.herts.ac.uk /astro_ub/aS_ub.html (3109 words)

	NGC 1566 - A Seyfert galaxy in Dorado
		NGC 1566 - A Seyfert galaxy in Dorado
		NGC 1566 is an active galaxy of the Seyfert type.
		Seyfert galaxies contain gas clouds that move at about 10.000 km per second.
	astrosurf.com /antilhue/ngc_1566.htm (87 words)

	Gene Smith's Astronomy Tutorial - Active Galaxies
		This was a surprise because galaxies had been thought to be collections of billions of stars along with bits of hydrogen gas and dust.
		Seyfert galaxies are divided into two classes, based upon the widths of their spectral emission features.
		The Seyfert 1 galaxy above has hydrogen emission features with very large widths, indicating that the gas in the galaxy's central regions is moving with velocities of several thousand km/sec (Seyfert 1 galaxies show velocities up to almost 0.1c).
	cassfos02.ucsd.edu /public/tutorial/AGN.html (914 words)

	Seyfert galaxy -- Encyclopædia Britannica
		Such galaxies were named for the American astronomer Carl K. Seyfert, who first called attention to them in 1944.
		In 1943 Carl Seyfert identified a type of galaxy that is spiral in form and has a small, extremely bright nucleus and abnormal spectral features.
		Also includes an introduction to the different classes of galaxies and the mechanisms by which their light is emitted.
	www.britannica.com /eb/article-9067008 (973 words)

	Hubble Space Telescope, Markarian 315, Seyfert galaxy (Site not responding. Last check: 2007-10-06)
		A NASA Hubble Space Telescope image of the core of the Seyfert galaxy Markarian 315 reveals two nuclei located approximately 6,000 light-years apart.
		The fainter companion is considered to be the core of a galaxy in the process of merging with Markarian 315.
		The image helps confirm that galaxy mergers may be one mechanism for driving gas deep into the heart of a galaxy, according to astronomers.
	www.laughtergenealogy.com /bin/hubble/html/markarian315.html (166 words)

	NGC 1566, Seyfert galaxy (Site not responding. Last check: 2007-10-06)
		NGC 1566 is the brightest member of a nearby group of galaxies in Dorado and is at a distance of about 50 million light years.
		This striking galaxy is also of interest because it has a very luminous nucleus which has many of the characteristics of a quasar, though it is much less energetic.
		Galaxies of this type are known as Seyfert galaxies, after Carl Seyfert who first recognised their peculiar nature in 1943.
	www.aao.gov.au /images/captions/aat054.html (230 words)

	Seyfert Galaxies (Site not responding. Last check: 2007-10-06)
		Seyfert Galaxies are spiral galaxies with unusually bright, tiny cores that fluctuate in brightness.
		Approximately 2% of all spiral galaxies are Seyfert galaxies.
		The heart of our own galaxy is believed by some astronomers to contain a supermassive (although quiet) fl hole and suggests that all spirals erupt now and then.
	www.astro.umd.edu /education/astro/actgal/seyfert.html (279 words)

	Inclined Gas Disks in the Lenticular Seyfert Galaxy NGC 5252
		This simple model of two inclined rotating disks, superposed along the line of sight, describes well the seemingly complex kinematics observed in the optical emission lines and the H I 21-cm radio maps.
		The large misalignment between the second disk and the stellar disk suggests that the gas distribution, and possibly the nuclear activity, in NGC 5252 may have resulted from a galaxy merger event.
		The absence of significant radial motions, together with the well-defined ionization cones, strongly suggests that the gas is photoionized by a compact nuclear source rather than being ionized in silt by shock waves in a large-scale outflow.
	casa.colorado.edu /Publications/preprints/1999/janapr/375.shtml (360 words)

	The Seyfert Galaxy
		W Hz Classification of this object as a Seyfert 2 galaxy is based on its known properties and the properties of the various AGN classes discussed by Woltjer (1990).
		The presence of the 3727 [OII] line is typical of PN and of many AGN types, including Seyfert galaxies.
		However in PN, the excitation is produced by a central star, with an approximately fl-body continuum, in a relatively narrow range of wavelengths.
	www.atnf.csiro.au /pasa/16_2/beer/paper/node4.html (299 words)

	APOD Search Results for "seyfert galaxies"
		Alternatively, the fl holes in the center of Seyfert Type II galaxies might be obscured by a surrounding torus.
		The thin disk galaxy is oriented nearly edge-on, however, and shrouded in dark dust.
		Seyferts are thought to have fl holes in their centers.
	antwrp.gsfc.nasa.gov /cgi-bin/apod/apod_search?seyfert%2Bgalaxies (1576 words)

	Bill Keel's Publication List
		The Stellar Population in the Wolf-Rayet Knot in NGC 5430, Astron.
		Galaxy Cluster Formation from the Large-Scale Structure: A Case Study of the Abell 2125 Complex at z=0.247, Q. Daniel Wang, Frazer Owen, Michael Ledlow, and William Keel, in Outskirts of Galaxy Clusters: Intense Life in the Suburbs, IAU Coll.
		Escape of Lyman alpha from the ISM in the starburst galaxy Mkn 357, W.C. Keel, BAAS 33, 1373 (49.06), 2001.
	www.astr.ua.edu /keel/publist.html (5471 words)

	Year 3 Observatory lab projects (Site not responding. Last check: 2007-10-06)
		Galaxies are the basic building blocks of the Universe.
		The different kinds of galaxies (spiral, elliptical etc.) have a wide range of populations of stars of varying age, temperature and chemical composition.
		The redshift will have to be corrected for the Earth's motion around our Galactic centre to find the radial velocity of the galaxy with respect to our galaxy, and thus the distance may be estimated using an appropriate value of the Hubble constant.
	www.sr.bham.ac.uk /observatory/obslab/projects/seyfert.htm (333 words)

	FOS Spectroscopy of the Seyfert 1 Galaxy NGC 5548 (Site not responding. Last check: 2007-10-06)
		FOS Spectroscopy of the Seyfert 1 Galaxy NGC 5548
		Ultraviolet spectra of the Seyfert 1 galaxy NGC 5548 have been obtained with the Faint Object Spectrograph (FOS) on the Hubble Space Telescope.
		Relative to the other UV narrow lines, C IV is much stronger in NGC 5548 than in Seyfert 2 galaxies observed with IUE, which indicates that the average ionization parameter is higher in the narrow-line region (NLR) of NGC 5548.
	www.aas.org /publications/baas/v25n2/aas182/abshtml/S404.html (213 words)

	Seyfert Galaxies (Site not responding. Last check: 2007-10-06)
		Seyfert galaxies are usually (but not always) spirals with very bright (almost starlike) nuclei, They exhibit a strong continuum from IR through X-ray regions of the spectrum, with emission lines that are sometimes variable (Here are spectra of Seyfert and other active galaxies - see the following description).
		The adjacent right image shows a Hubble Space Telescope view of the Seyfert galaxy NGC7742, which is about 72 million light years away, in the constellation Pegasus (Ref).
		The central region is about 3000 light years across, and as for most Seyferts is very bright at visible wavelengths.
	csep10.phys.utk.edu /astr162/lect/active/seyfert.html (151 words)

	Messier Object 77
		M77 is one of the first recognized spiral galaxies, and listed by Lord Rosse as one of 14 "spiral nebulae" discovered to 1850.
		It classifies M77 as a Seyfert galaxy of type II (type I Seyfert galaxies exhibit an even larger expansion velocity of several 1000 km/sec); it is the nearest and brightest representative of this class of active galaxies.
		Galaxy, jet, and obscuring disk in NGC 1068 and The hidden nucleus of NGC 1068 revealed by polarization, from Bill Keel's Quasars and Active Galactic Nuclei series (University of Alabama)
	www.seds.org /messier/m/m077.html (1122 words)

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