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Latest Accretion disc Stories

3cc2030f54079dabcad067e9b656f86e1
2008-07-24 09:27:26

For the first time, a team of international researchers has found a way to view the accretion disks surrounding black holes and verify that their true electromagnetic spectra match what astronomers have long predicted they would be. Their work will be published in the July 24 issue of the science journal Nature. A black hole and its bright accretion disk have been thought to form a quasar, the powerful light source at the center of some distant galaxies. Using a polarizing filter, the...

85bb198156ff425d84985c03c585ebc71
2008-04-07 07:05:00

XMM-Newton has been surprised by a rare type of galaxy, from which it has detected a higher number of X-rays than thought possible. The observation gives new insight into the powerful processes shaping galaxies during their formation and evolution. Scientists working with XMM-Newton were looking into the furthest reaches of the universe, at celestial objects called quasars. These are vast cosmic engines that pump energy into their surroundings. It is thought an enormous black hole drives...

f66c637d01070ee03818f1fed5634e4d1
2008-01-10 08:15:56

Observations of the interacting binary star using telescopes at Kitt Peak National Observatory and NASA's Spitzer Space Telescope suggest that the disks of hot gas that accumulate around a wide variety of astronomical objects"”from degenerate stars in energetic binary systems to supermassive black holes at the hearts of active galaxies"”are likely to be much larger than previously believed. The target of this specific investigation, named WZ Sagittae (WZ Sge), is an interacting...

4700dca2c7607e31a2c8d10cb89939351
2007-05-23 15:55:00

Cambridge, MA -- Astronomers are hunting an elusive target: rogue black holes that have been ejected from the centers of their home galaxies. Some doubted that the quarry could be spotted, since a black hole must be gobbling matter from an accretion disk in order for that matter to shine. And if a black hole is ripped from the core of its home galaxy and sent hurling into the outskirts, the thinking goes, then its accretion disk might be left behind. New calculations by theorist Avi Loeb...

ddb1a8688407e7a924a126060127e68d1
2006-11-20 15:35:00

Cambridge, MA - The existence of black holes is perhaps the most fascinating prediction of Einstein's General Theory of Relativity. When any mass, such as a star, becomes more compact than a certain limit, its own gravity becomes so strong that the object collapses to a singular point, a black hole. In the popular mind, this immense gravity well is a place where strange things happen. And now, a Center for Astrophysics-led team has measured a stellar-mass black hole spinning so rapidly -...

c7350b425443d9deb0c300ea413947c41
2006-07-25 12:25:00

Cambridge, MA - In the distant, young universe, quasars shine with a brilliance unmatched by anything in the local cosmos. Although they appear starlike in optical telescopes, quasars are actually the bright centers of galaxies located billions of light-years from Earth. The seething core of a quasar currently is pictured as containing a disk of hot gas spiraling into a supermassive black hole. Some of that gas is forcefully ejected outward in two opposing jets at nearly the speed of light....

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2006-07-07 09:44:46

Thanks to data from ESA's XMM-Newton satellite, a team of scientists taking a closer look at an object discovered over 25 years ago have found that it is like none other known in our galaxy. The object is in the heart of supernova remnant RCW103, the gaseous remains of a star that exploded about 2 000 years ago. Taken at face value, RCW103 and its central source would appear to be a textbook example of what is left behind after a supernova explosion: a bubble of ejected material and a neutron...

c613fdf595cc7bab98037d27030398ac1
2006-06-21 15:55:00

Up to one quarter of the light brightening the universe comes from the massive crush of matter succumbing to the extreme gravity of black holes. Scientists have long understood that amount of light means black holes have the colossal appetite to ingest whole stars and huge amounts of gas. But a critical question has always remained: how they can continue to devour so much? For the first time, a team of scientists with NASA's Chandra X-ray Observatory led by Jon Miller has uncovered the...

9c06f81f1725452847c8a70ffceac7bf1
2005-11-18 05:30:00

Berkeley -- Astrophysicists at the University of California, Berkeley, and Lawrence Livermore National Laboratory (LLNL) have exploded one of two competing theories about how stars form inside immense clouds of interstellar gas. Using supercomputer simulations that take into account the turbulence within a cloud collapsing to form a star, the researchers conclude that the "competitive accretion" model cannot explain what astronomers observe of star-forming regions studied to date. That...

2005-06-06 23:20:36

ITHACA, N.Y. - The office that astronomer Lei Hao shares with her fellow research associates on the first floor of the Space Sciences Building at Cornell University is tidy and organized. But Hao has been thinking a lot lately about dust. Actually, she's recently found a great deal of it. And she's thrilled. The dust in question is between 0.88 billion and 2.4 billion light years away from Hao's office, in galaxies scientists classify as active galactic nuclei (AGNs). By confirming that the...


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
grass-comber
  • A landsman who is making his first voyage at sea; a novice who enters naval service from rural life.
According to the OED, a grass-comber is also 'a sailor's term for one who has been a farm-labourer.'