Latest Active galactic nucleus Stories

2010-04-01 15:40:00

If our eyes could see radio waves, the nearby galaxy Centaurus A (Cen A) would be one of the biggest and brightest objects in the sky, nearly 20 times the apparent size of a full moon. What we can't see when looking at the galaxy in visible light is that it lies nestled between a pair of giant radio-emitting gas plumes ejected by its supersized black hole. Each plume is nearly a million light-years long. NASA's Fermi Gamma-Ray Space Telescope maps gamma rays, radiation that typically packs...

2010-03-25 06:55:00

Up to now, primitive black holes, which occupy the cores of active galaxies and were around as far back as the early days of the universe, only existed in astronomer's models. Researchers have now found two such gravitational monsters, however, which revealed themselves as brightly glowing quasars. Their light originates from a time when the universe was barely one billion years old - and we can see them now exactly as they appeared 12.7 billion years ago (Nature, March 18, 2010). A quasar is...

2010-03-17 13:20:00

Quasars are active and very powerful black holes at the center of distant galaxies. The black holes are extremely massive weighing between 100 million and 10 billion solar masses and rotating around the super massive black hole is a disc of gas and dust. The inner ring of the disc moves faster than the outer rings. The movement causes the material in the rings to rub against each other, heating it and causing it to emit light. Near to the black hole it becomes so hot that X-ray radiation is...

2009-12-11 06:47:07

An international team of scientists has observed four super-massive black holes at the center of galaxies, which may provide new information on how these central black hole systems operate. Their findings are published in December's first issue of the journal Astronomy and Astrophysics. These super-massive black holes at the center of galaxies are called active galactic nuclei. For the first time, the team observed a quasar with an active galactic nucleus, as part of the group of four, which...

2009-12-10 12:16:47

This composite image of data from three different telescopes shows an ongoing collision between two galaxies, NGC 6872 and IC 4970. X-ray data from NASA's Chandra X-ray Observatory is shown in purple, while Spitzer Space Telescope's infrared data is red and optical data from ESO's Very Large Telescope (VLT) is colored red, green and blue. Astronomers think that supermassive black holes exist at the center of most galaxies. Not only do the galaxies and black holes seem to co-exist, they are...

2009-12-09 14:50:00

A galaxy located billions of light-years away is commanding the attention of NASA's Fermi Gamma-ray Space Telescope and astronomers around the globe. Thanks to a series of flares that began September 15, the galaxy is now the brightest source in the gamma-ray sky -- more than ten times brighter than it was in the summer. Astronomers identify the object as 3C 454.3, an active galaxy located 7.2 billion light-years away in the constellation Pegasus. But even among active galaxies, it's...

2009-07-14 15:45:00

Back in June 1991, just before the launch of NASA's Compton Gamma-Ray Observatory, astronomers knew of gamma rays from exactly one galaxy beyond our own. To their surprise and delight, the satellite captured similar emissions from dozens of other galaxies. Now its successor, the Fermi Gamma-ray Space Telescope, is filling in the picture with new finds of its own."Compton showed us that two classes of active galaxies emitted gamma rays -- blazars and radio galaxies," said Luigi Foschini at...

2009-05-27 15:51:07

The European Space Agency says data from its XMM-Newton space observatory has allowed astronomers to closely study a supermassive black hole. The black hole is located at the core of a distant active galaxy known as 1H0707-495. It was observed during four 48-hour-long orbits of XMM-Newton around Earth, starting in January 2008. We can now start to map out the region immediately around the black hole, said Andrew Fabian of the University of Cambridge, who led the observations and analysis....

2009-05-27 13:00:00

Using new data from ESA's XMM-Newton spaceborne observatory, astronomers have probed closer than ever to a supermassive black hole lying deep at the core of a distant active galaxy. The galaxy "“ known as 1H0707-495 "“ was observed during four 48-hr-long orbits of XMM-Newton around Earth, starting in January 2008. The black hole at its center was thought to be partially obscured from view by intervening clouds of gas and dust, but these current observations have revealed the...

2009-05-14 17:20:00

Activity from a supermassive black hole is responsible for the intriguing appearance of this galaxy, 3C305, located about 600 million light years away from Earth. The structures in red and light blue are X-ray and optical images from the Chandra X-ray Observatory and Hubble Space Telescope respectively. The optical data is from oxygen emission only, and therefore the full extent of the galaxy is not seen. Radio data are shown in darker blue and are from the National Science Foundation's Very...

Latest Active galactic nucleus Reference Libraries

2004-10-19 04:45:42

Seyfert Galaxy -- Seyfert galaxies are spiral or irregular galaxies containing an extremely bright nucleus, most likely caused by a supermassive black hole, that can sometimes outshine the surrounding galaxy. The light from the central nucleus varies in less than a year, which implies that the emitting region must be less than one light year across. They are named for the astronomer Carl Seyfert, who studied them extensively in the 1940s. They are a subclass of active galactic nuclei....

2004-10-19 04:45:42

Quasar -- A quasar (from quasi-stellar radio source) is an astronomical object that looks like a star in optical telescopes (i.e. it is a point source), but has a very high redshift. The general consensus is that this high redshift is cosmological, the result of Hubble's law and that their redshift indicates that they are typically very distant from Earth; we observe them as they were several billions of years ago. Since we can see them despite their distance, they must emit more...

2004-10-19 04:45:41

Active Galaxy -- An active galaxy is a galaxy where a significant fraction of the energy output is not emitted from normal stellar populations or 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. Frequently, the abbreviation AGN (Active Galactic Nuclei) is used, since most of the active galaxies emit most of their radiation from a narrow region in their...

2004-10-19 04:45:40

Circinus Galaxy -- Resembling a swirling witch's cauldron of glowing vapors, the black hole-powered core of a nearby active galaxy appears in this colorful NASA Hubble Space Telescope image. The galaxy lies 13 million light-years away in the southern constellation Circinus. This galaxy is designated a type 2 Seyfert, a class of mostly spiral galaxies that have compact centers and are believed to contain massive black holes. Seyfert galaxies are themselves part of a larger class of objects...

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Word of the Day
  • The unit of magnetic flux density in the International System of Units, equal to the magnitude of the magnetic field vector necessary to produce a force of one newton on a charge of one coulomb moving perpendicular to the direction of the magnetic field vector with a velocity of one meter per second. It is equivalent to one weber per square meter.
This word is named for Nikola Tesla, the inventor, engineer, and futurist.