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New class of gamma rays discovered in Milky Way

Gamma Rays
Impression of the line of sight straight down a gas jet produced by a black hole, which may be the source of gamma-ray glows  

March 23, 2000
Web posted at: 11:46 AM EST (1646 GMT)


In this story:

Many could reside in Gould Belt

Final curtain for gamma ray hunter?

RELATED STORIES, SITES icon



GREENBELT, Maryland (CNN) -- Astronomers have detected a new class of gamma rays coming from a mysterious source or sources within our own galaxy.

Gamma rays are invisible to the eye, but are the most powerful form of light, far exceeding visible light, ultraviolet radiation and X-rays.

There are 271 known sources of gamma rays in the universe, which before this discovery were thought to originate in the distant reaches of the universe, far beyond the Milky Way. Those distant sources emit gamma rays in sudden bursts.

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See a NASA QuickTime animation showing how black holes could emit gamma rays

 

But research published in the journal Nature this week by NASA astrophysicist Neil Gehrels and colleagues suggests the 170 of the gamma ray sources are located within our Milky Way galaxy.

Many could reside in Gould Belt

"These are objects we've never seen before," Gehrels said. "We can't make out what they are yet, but we know they're strange and, boy, there's a lot of them. These are very different than the famous gamma-ray burst sources, because the gamma rays shine continuously instead of coming in a flash like the gamma-ray bursts."

Many of these nearby sources seem to originate from a region in the Milky Way called the Gould Belt, an area containing massive stars and gas clouds.

Sources
In this image, the bright areas are gamma ray sources detected by the Compton observatory are overlaid on a map of the entire celestial sphere that has been projected on a flat, two-dimensional plane. In reality, the gamma sources surround us.  

Other gamma ray sources in our galaxy are closer to the Earth and considered a new class of objects, said Gehrels, who works for NASA's Goddard Space flight Center in Greenbelt, Maryland.

Scientists are still struggling to understand what types of objects emit these gamma rays. Potential candidates include black holes, massive stars, neutron stars and clusters of pulsars. But more research is required to determine the sources, the astronomers said.

Final curtain for gamma ray hunter?

Gamma rays are about 100 million times more powerful than visible light, but they pose no danger to terrestrial life.

Discovery of the gamma ray sources is based on data collected from the orbiting Compton Gamma Ray Observatory. After nearly a decade in space, the observatory has lost two of its three gyroscopes needed to keep it properly aligned in orbit.

NASA will hold a meeting Thursday to determine the fate of the satellite. The space agency is considering taking the 35,000-pound spacecraft out of orbit in a controlled re-entry into the Pacific Ocean, off the coast of Hawaii.

Much of it would burn up in the atmosphere, but pieces could survive re-entry and fall to Earth. NASA will announce its decision Friday.



RELATED STORIES:
Huge NASA telescope may be headed for fiery descent to splash landing
January 14, 2000
Gamma ray finding may open new window on universe
November 25, 1999
NASA announces missions to seek planets, study gamma rays
October 15, 1999
Chandra observation deepens mystery of 'superstar'
October 12, 1999

RELATED SITES:
CGRO Public Relations
Gamma-ray Generation
NASA: Structure and Evolution of the Universe

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