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Gamma-Ray Bursts

News
  1. Magnetic Field of a Gamma-Ray Burst Measured for the First Time (ScienceDaily.com)
      "A specialized camera on a telescope operated by U.K. astronomers from Liverpool has made the first measurement of magnetic fields in the afterglow of a gamma-ray burst (GRB)." 12-09

  2. Most Distant Object Seen Without Optical Aid (ScienceDaily.com)
      "A powerful stellar explosion detected March 19 by NASA's Swift satellite has shattered the record for the most distant object that could be seen with the naked eye."

      "A redshift is a measure of the distance to an object. A redshift of 0.94 translates into a distance of 7.5 billion light years, meaning the explosion took place 7.5 billion years ago, a time when the universe was less than half its current age and Earth had yet to form. This is more than halfway across the visible universe."

      " 'No other known object or type of explosion could be seen by the naked eye at such an immense distance,' said Swift science team member Stephen Holland of Goddard." 12-09

Papers
  1. Gamma-Ray Bursts (Wikipedia.org)
      "Gamma-ray bursts (GRBs) are the most luminous events known in the universe since the Big Bang. They are flashes of gamma rays coming from seemingly random places in deep space at random times. GRBs last from milliseconds to many minutes, and are often followed by 'afterglow' emission at longer wavelengths (X-ray, UV, optical, IR, and radio). Gamma-ray bursts are detected by orbiting satellites about two to three times a week, as of 2007, though their actual rate of occurrence is much higher."
      "One line of research has investigated the consequences of Earth being hit by a beam of gamma rays from a nearby (about 500 light years) gamma ray burst. This is motivated by the efforts to explain mass extinctions on Earth and estimate the probability of extraterrestrial life. The consensus seems to be that the damage that a gamma ray burst could do would be limited by its very short duration, and the fact that it would only cover half the Earth (the other half would be in its shadow). A sufficiently close gamma ray burst could do serious damage to atmospheric chemistry, perhaps instantly wiping out half the ozone layer, and causing nitrogen-oxygen recombination, generating acidic nitrogen oxides. These effects would diffuse across to the other side of the Earth and result in long-term climate and atmospheric changes, resulting in a mass extinction. The damage from a gamma ray burst would probably be significantly greater than a supernova at the same distance." 10-07

   
   


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