active galaxy
The different features of an active galactic nucleus (AGN), and how our viewing angle determines what type of AGN we observe. The extreme luminosity of an AGN is powered by a supermassive black hole at the center.
Active Galaxy
A galaxy that is a source of excess radiation, usually radio waves, X rays, gamma rays or some combination
Active Galaxy Nucleus (AGN) ...
Active Galaxy
Accretion is extremely efficient at converting infalling mass (in the form of gas) into energy (in the form of electromagnetic radiation).
Active galaxy- a galaxy under-going a violent outburst in its central regions ...
Active Galaxy - A galaxy whose nucleus is unusually bright and small. Seyfert galaxies, BL Lacertae objects, and quasars are examples of active galaxies ...
active galaxy
a galaxy emitting unusually large amounts of energy from a compact central source
active optics ...
ACTIVE GALAXY - Galaxy characterized by certain properties: (1) high luminosity, (2) nonthermal spectra (unlike the sum of many stellar spectra), (3) luminosity in a region of the spectrum other than optical (e.g., radio, UV, Infrared), ...
Active Galaxy
Any galaxy which is emitting large quantities of non-thermal radiation.
(b) Active galactic nuclei are very luminous (1043-1046 ergs s-1). Their energy output is in two forms: nonthermal continuum and thermal emission line.
ACTIVE GALAXY
An active galaxy is a galaxy that produces huge amounts of energy; they produce more energy than the total energy emitted from all of the stars in the nebula.
Active Galaxy: Active Galaxies are galaxies characterized by certain properties: (1) High Luminosity, (2) Nonthermal Spectra that do not look like the sum of many stellar spectra, ...
active galaxy
A galaxy whose center emits large amounts of excess energy, often in the from of radio emission. Active galaxies are suspected of having massive black holes in their centers into which matter is flowing.
albedo ...
Active Galaxy
A galaxy possessing an active galactic nucleus at its center.
Afterglow ...
active galaxy A galaxy which shows explosive activity and can emit large amounts of energy, especially from its central regions.
active galaxy, active galactic nucleus, AGN
radio wavelengths, radiowaves
bremsstrahlung radiation ...
An active galaxy is a formation that is emitting a significant amount of its energy from a source other than stars, dust and gas. Most such galaxies are powered by a compact region at the core, usually thought to be a supermassive black hole.
Types of active galaxy
It is convenient to divide AGN into two classes, conventionally called radio-quiet and radio-loud.
One type of active galaxy is the Seyfert galaxy, named after Carl Seyfert who was the first to discover the peculiar spectra of these types of galaxies.
[ Top of Page ]
12. Active Galaxy Nucleus (AGN)
The central energy source of an active galaxy.
[ Top of Page ]
13. Active Optics
Optical elements whose position or shape is continuously controlled by computers.
A diagram of an active galaxy, showing the primary components.
Seyfert Galaxies
Of the two types of Active Galactic Nuclei (AGN) which emit gamma-rays, Seyfert galaxies are the low-energy gamma sources.
The different types of radio-loud active galaxies are linked by unified models (see active galaxy).
holes, you might remember that the radio galaxy M87 (Figure 7) is likely to have a huge black hole in its core, and there are many galaxies with visible disks in their cores, jets, and the things described in the above model for an active galaxy.
It is now believed, largely because of the work of Sir Martin Rees and Roger Blandford, that the nucleus of an active galaxy supplies the basic energy that powers the radio emission, ...
Galaxy collision may also lead to the formation of an active galaxy. An active galaxy is a galaxy that radiates unusual large amount of energy in the form of infrared, ultraviolet and X-rays; always from the nucleus of the galaxy.
A particular type of active galaxy that emits more light at radio wavelengths than at visible wavelengths, also known as a radio-luminous galaxy or radio-loud galaxy. Radio galaxies are driven by non-thermal emission.
Somewhere inside each object there must be a system responsible for the tremendous amounts of energy released; because they share so many basic characteristics, it is generally thought that in each of the different varieties of active galaxy this ...
A composite image of the active galaxy NGC 4261, showing jets of radio-emitting particles spurting from the core of the galaxy.
Below is a NASA Hubble Space Telescope image of a spiral-shaped disk of hot gas in the core of active galaxy M87. Hubble measurements show the disk is rotating very rapidly. Scientists believe it contains a massive black hole at its hub.
The Circinus Galaxy is a spiral active galaxy 15 million light-years distant, discovered in 1975. It is interesting for the tumultuous gas motions occurring in it, most of them forming two discernible rings.
An example of an object at different wavebands is the active galaxy, Centaurus A (or NGC 5128). The Cool Cosmos Cen A site provides images from radio to X-ray with a description of the processes involved for producing the different types of emission.
From it pours a variable jet at nearly the speed of light, making M 87 an "active galaxy" and the core an "active galactic nucleus," or "AGN.
Centaurus A is eleven million light years from Earth, and is the fifth brightest galaxy in the sky as well as the closest active galaxy to us.
The combined efforts of all these instruments and astronomers gave an unprecedented insight into the core of an active galaxy. Right in the middle of the campaign the source went into outburst.
A Hubble Space Telescope image of a spiral-shaped disk of hot gas in the core of active galaxy M87. The disk is rotating so rapidly it contains a massive black hole at its hub. (Courtesy of NASA)
(28K GIF) ...
Carl K. Seyfert
1911-1960
American
discovered the first active galaxy, part of a group now called Seyfert galaxies ...
Lacerta had no bright stars or significant deep sky objects apart from 14th magnitude star-like object BL Lac, a prototype of an unusal kind of active galaxy whose nucleus varies in brightness by a few magnitudes over several days.
 See also: Galaxy, Galaxies, Black Hole, Light, Universe
|
