Latest Gamma ray Stories

2010-02-11 07:20:00

Instruments scanning outer space for cataclysmic explosions called gamma-ray bursts are detecting intense flashes of gamma-ray energy right here in the friendly skies of Earth. These terrestrial gamma-ray flashes, or TGFs, blast through thunderstorms close to the altitude where commercial airliners fly. In fact, they could be too close for comfort. In a recent study,* scientists estimated that airline passengers could be exposed to 400 chest X-rays worth of radiation by being near the origin...

2010-01-30 07:30:00

High-energy bursts of gamma rays typically occur far out in space, perhaps near black holes or other high-energy cosmic phenomena. So imagine scientists' surprise in the mid-1990s when they found these powerful gamma ray flashes happening right here on Earth, in the skies overhead. They're called Terrestrial Gamma-ray Flashes, or TGFs, and very little is known about them. They seem to have a connection with lightning, but TGFs themselves are something entirely different. "In fact," says Doug...

2009-12-07 15:51:44

Scientists say incidents are likely rare and more research is needed New information about lightning-emitted X-rays, gamma rays and high-energy electrons during thunderstorms is prompting scientists to raise concerns about the potential for airline passengers and crews to be exposed to harmful levels of radiation. Scientists at the Florida Institute of Technology, University of California, Santa Cruz and the University of Florida have estimated that airplane passengers could be exposed to a...

2009-10-28 13:25:00

During its first year of operations, NASA's Fermi Gamma Ray Space Telescope mapped the extreme sky with unprecedented resolution and sensitivity. It captured more than 1,000 discrete sources of gamma rays -- the highest-energy form of light. Capping these achievements was a measurement that provided rare experimental evidence about the very structure of space and time, unified as space-time in Einstein's theories. "Physicists would like to replace Einstein's vision of gravity -- as expressed...

2009-10-03 11:13:58

Quite a few distant galaxies turn out to be cosmic delivery rooms. Large numbers of massive stars are born in the hearts of these starburst galaxies, and later explode as supernovae. In the remnants they leave behind, particles are accelerated to very high energies. Astrophysicists have now used the H.E.S.S. telescopes to make detailed measurements of the gamma rays from the NGC 253 galaxy. As predicted, these high-energy rays originate from the region of maximum supernova activity close to...

2009-07-28 15:01:15

NASA's Fermi Gamma-ray Space Telescope is making some exciting discoveries about cosmic rays and the Large Area Telescope aboard Fermi is the tool in this investigation. Scientists in the Naval Research Laboratory's (NRL's) Space Science Division were instrumental in the design and development of the Large Area Telescope (LAT).Cosmic rays are electrons, positrons, and atomic nuclei that move at nearly the speed of light. Astronomers believe that the high-energy cosmic rays originate from...

2009-07-23 09:33:53

A team of researchers working with data from ESA's Integral gamma-ray observatory has disproved theories that some form of dark matter explains mysterious radiation in the Milky Way. That this radiation exists has been known since the 1970s, and several theories have been proposed to explain it. Integral's unprecedented spectral and spatial resolution showed that it strongly peaks towards the center of the Galaxy, with an asymmetry along the Galactic disc. Several researchers have...

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...

2009-07-09 06:20:00

A team of astrophysicists has solved a mystery that led some scientists to speculate that the distribution of certain gamma rays in our Milky Way galaxy was evidence of a form of undetectable "dark matter" believed to make up much of the mass of the universe. In two separate scientific papers, the most recent of which appears in the July 10 issue of the journal Physical Review Letters, the astrophysicists show that this distribution of gamma rays can be explained by the way "antimatter...

2009-07-02 13:35:00

High-resolution radio, gamma-ray observations reveal site of relativistic particle acceleration in galaxy M 87An international collaboration of 390 scientists reports the discovery of an outburst of very-high-energy (VHE) gamma radiation from the giant radio galaxy Messier 87 (M 87), accompanied by a strong rise of the radio flux measured from the direct vicinity of its super-massive black hole.The combined results give first experimental evidence that particles are accelerated to extremely...

Latest Gamma ray Reference Libraries

2004-10-19 04:45:43

Gamma-Ray Astronomy -- Gamma-ray astronomy is the astronomical study of gamma rays. Long before experiments could detect gamma rays emitted by cosmic sources, scientists had known that the universe should be producing these photons. Work by Feenberg and Primakoff in 1948, Hayakawa and Hutchinson in 1952, and, especially, Morrison in 1958 had led scientists to believe that a number of different processes which were occurring in the universe would result in gamma-ray emission. These...

2004-10-19 04:45:41

Hypernova -- A hypernova is a theoretical type of supernova produced when exceptionally large stars collapse at the end of their lifespan. In a hypernova, the core of the star collapses directly into a black hole and two extremely energetic jets of plasma are emitted from its rotational poles at nearly light speed. These jets emit intense gamma rays, and are a candidate explanation for gamma ray bursts. Theorists have come up with several plausible explanations for hypernovae. It may...

2004-10-19 04:45:41

Electromagnetic Spectrum -- The electromagnetic spectrum describes the various types of electromagnetic radiation based on their wavelengths. Radio, representing wavelengths from a few feet to well over a mile, is at one end of the spectrum. Gamma ray radiation is at the other end: the wavelength of the harder types is so short, in the subatomic range, that we do not have instruments capable of directly measuring it. While the above classification scheme is generally accurate, in...

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Word of the Day
  • 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.'