Gamma-ray bursts: are we safe?September 17, 2003For a few seconds every day, Earth is bombarded by gamma rays created by cataclysmic explosions in distant galaxies. Such explosions, similar to supernovae, are known as 'gamma-ray bursts' or GRBs. Astronomers using ESA's X-ray observatory, XMM-Newton, are trying to understand the cause of these extraordinary explosions from the X-rays given out for a day or two after the initial burst. Danger to life? However, the violence of the process begs the question, what happens to the space surrounding a GRB? A few years ago, some astronomers thought that a GRB might wipe out all life in its host galaxy. That now seems to be a pessimistic view because the latest evidence shows that GRBs focus their energy along two narrow beams, like a lighthouse might do on Earth, rather than exploding in all directions like a bomb. That does not mean that GRBs are not dangerous. Some theories suggest that anything caught in the beam, out to a distance of around 200 light years, will be vaporised. Have there been GRBs in our own galaxy? Although none of the recently detected GRBs seem powerful enough, events in the distant past are another question. "There are a lot of supernova remnants in our galaxy, so I suspect that most probably there have been several GRBs as well," says ESA astronomer Norbert Schartel. While astronomers have yet to detect a really close GRB, they may already have picked up the most distant ones. ESA's gamma-ray observatory, Integral, continues to collect invaluable data about GRBs on a daily basis, but last year XMM-Newton recorded the fading afterglow of X-rays that accompanied one GRB. When Schartel and collaborators analysed the results, they found that the X-rays contained the 'fingerprints' of gas that was glowing like the X-ray equivalent of a 'neon' strip light. Using these data and the discovery of visible explosions of some GRBs by NASA/ESA's Hubble Space Telescope, astronomers have pieced together a picture of what happens. However, we do know that ESA's scientific study of these fascinating - and frightening - cosmic events will continue for many years to come. | |||||||||||||||||||||
Science Research Departments
Earth Science Alternative Energy | Anthropology and Archaeology | Earthquakes and Volcanoes | Environment and Nature News | Global Warming | High-Energy and Particle Physics | Ozone Hole | Scientists Slow Light | Tsunami Space Science Astronomy and Space News | Black Holes | Chandra X-Ray Observatory | Extrasolar Planets | Hubble Telescope | International Space Station | Jupiter Galileo Mission | Jupiter Cassini Mission Flyby | Mars Exploration | Mars Odyssey 2001 | Mars Global Surveyor | Mars Polar Lander | Mars Climate Orbiter | Mars Pathfinder | Meteors and Asteroids | Mir Space Station | NEAR Asteroid Probe Mission | Pluto Planet Debate | Search for Extraterrestrial Life | Space Shuttle Program | Space Shuttle Mission: STS-102 | Space Weather Life Science Animal News | Biotechnology and Genetics | Brain Research | Human Cloning | Dinosaur and Fossil Discoveries | Endangered Species | Gene Therapy | Genetically Modified Food | Stem Cell Research | Whales and Whaling |
|||||||||||||||||||||
|
|||||||||||||||||||||
|
|||||||||||||||||||||