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Latest Accretion disc Stories

Study Discovers How Massive Black Holes Grow So Rapidly
2012-03-25 04:42:56

Black holes that grow to masses billions of times greater than that of our sun most likely reached those sizes by consuming objects from multiple locations at the same time, researchers from the UK and Australia claim in a new study set for publication in the journal Monthly Notices of the Royal Astronomical Society. In a Friday press release, officials with the University of Leicester, who conducted the study along with colleagues from Australia's Monash University, compared the process...

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2011-06-06 11:25:00

Active galactic nuclei By studying the X-rays emitted when superheated gases plunge into distant and massive black holes, astrophysicists at the Georgia Institute of Technology have provided an important test of a long-standing theory that describes the extreme physics occurring when matter spirals into these massive objects. Matter falling into black holes emits tremendous amounts of energy which can escape as visible light, ultraviolet light and X-rays. This energy can also drive outflows...

c41a4acf60021c99dad0f0e13a905306
2011-05-23 07:35:00

Two UK astronomers have found that the giant black holes in the center of galaxies are on average spinning faster than at any time in the history of the Universe. Dr Alejo Martinez-Sansigre of the University of Portsmouth and Prof. Steve Rawlings of the University of Oxford made the new discovery by using radio, optical and X-ray data. They publish their findings in the journal Monthly Notices of the Royal Astronomical Society. There is strong evidence that every galaxy has a black hole in...

41028d63be6ea184415eb01a29e398b4
2011-02-06 08:06:32

Astrophysicists use computer simulations to gain new insights on star formation The first stars in the universe were not as solitary as previously thought. In fact, they could have formed alongside numerous companions when the gas disks that surrounded them broke up during formation, giving birth to sibling stars in the fragments. These are the findings of studies performed with the aid of computer simulations by researchers at Heidelberg University's Centre for Astronomy together with...

c2b6a5ac876bca939f643a62437d01141
2010-06-24 13:05:00

Using two of the world's largest telescopes, an international team of astronomers have found evidence of a collision between galaxies driving intense activity in a highly luminous quasar. The scientists, led by Montserrat Villar Martin of the Instituto de Astrofisica de Andalucía-CSIC in Spain, used the Very Large Telescope (VLT) in Chile and the Gran Telescopio Canarias (GTC) on La Palma in the Canary Islands, to study activity from the quasar SDSS J0123+00. They publish...

f393a68a6788f855120c1e57995dce021
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...

5f6ac73d290c41a77e176c3f2545c489
2009-12-10 12:53:53

Studies of one of the galaxy's most active black-hole binaries reveal a dramatic change that will help scientists better understand how these systems expel fast-moving particle jets. Binary systems where a normal star is paired with a black hole often produce large swings in X-ray emission and blast jets of gas at speeds exceeding one-third that of light. What fuels this activity is gas pulled from the normal star, which spirals toward the black hole and piles up in a dense accretion disk....

7b4f6c3b406163fc29513bb1e00852181
2009-11-16 11:40:00

The constellation of Orion is a hotbed of massive star formation, most prominently in the Great Nebula that sits in Orion's sword.  The glowing gas of the Nebula is powered by a group of young massive stars, but behind it is a cluster of younger stars and clumps of gas. Still gathering together under gravity's pull, these gas clumps will eventually ignite into stars. The youthful cluster cannot be seen with traditional telescopes because of the surrounding gas and dust, but a new...

821102b6d8840b85f1350b0a15bc25fa1
2009-03-25 16:25:00

New results from NASA's Chandra X-ray Observatory have made a major advance in explaining how a special class of black holes may shut off the high-speed jets they produce. These results suggest that these black holes have a mechanism for regulating the rate at which they grow. Black holes come in many sizes: the supermassive ones, including those in quasars, which weigh in at millions to billions of times the mass of the Sun, and the much smaller stellar-mass black holes which have measured...

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2008-09-17 14:20:00

XMM-Newton has uncovered a well-tuned periodic signal from a super-massive black hole lodged at the centre of a galaxy, ending a long quest for such an object. The discovery provides scientists with a clearer picture on black hole accretion processes and an excellent tool to study active galactic nuclei (AGNs). These periodic signals originating from the black hole are emitted in X-rays, which are blocked out by the Earth's atmosphere. So the team used data from ESA's orbiting X-ray...


Latest Accretion disc Reference Libraries

8_2c71772f2c3a31994d5208d4518632494
2004-10-19 04:45:44

Cosmogony -- Cosmogony is the study of the origins of celestial objects. It is most commonly used to refer to the study of the origin of the solar system. Currently, the most widely accepted theory is that the solar system was formed roughly 5 billion years ago with the collapse of a nebula of gas and dust, likely caused by shock waves generated by a nearby supernova. The solar system would have formed as a member of a star cluster, now long-since dispersed throughout the Milky Way over...

6_1446abbc556d86191d7944d6c5cf68052
2004-10-19 04:45:43

X-ray Burster -- X-ray bursters are a class of binary stars which are luminous in X-rays. They contain a neutron star and a low-mass companion star. The companion fills its Roche lobe and therefore the neutron star is accreting matter from it. The inflowing gas forms an accretion disk around the neutron star. Sometimes X-ray bursters show a sudden increase in their X-ray luminosity, called X-ray burst. All properties of the X-ray bursts can be explained assuming that they result from...

6_c7a74d948ad4cfdc1dd54ceada2509fb2
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....

6_c74ddf89e1e986e7de2e5e2451d6b60b2
2004-10-19 04:45:41

Microquasar -- Microquasars are smaller cousins of quasars. They are named after quasars, as they have some common characteristics: strong and variable radio emission often seen as radio jets, and an accretion disk surrounding a black hole. In quasars, the black hole is supermassive (millions of solar masses) as in microquasars, the black hole mass is a few solar masses. In microquasars, the accreted mass comes from a normal star and the accretion disk is very luminous in optical regions...

6_75b9b62fd255ef9e172fae83099783a52
2004-10-19 04:45:41

Accretion Disk -- An accretion disk is a structure formed by material falling into a gravitational source. Conservation of angular momentum requires that, as a large cloud of material collapses inward, any small rotation it may have will increase. Centrifugal force causes the rotating cloud to collapse into a disk, and tidal effects will tend to align this disk's rotation with the rotation of the gravitational source in the center. Friction between the particles of the disk generates heat...

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Word of the Day
cacodemon
  • An evil spirit; a devil.
  • A nightmare.
  • In astrology, the twelfth house of a scheme or figure of the heavens: so called from its signifying dreadful things, such as secret enemies, great losses, imprisonment, etc.
'Cacodemon' comes from a Greek term meaning 'evil genius.'
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