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   Stellar Flare Blasts Exoplanet    
      
   June 28, 2012: An international team of astronomers using data from NASA's   
   Hubble Space Telescope has made an unparalleled observation, detecting   
   significant changes in the atmosphere of a planet located beyond our solar   
   system.    
      
   The scientists conclude the atmospheric variations occurred in response to a   
   powerful eruption on the planet's host star, an event observed by NASA's Swift   
   satellite.  The stellar flare, which hit the planet like 3 million X-flares   
   from our own sun, blasted material from the planet's atmosphere at a rate of   
   at least 1,000 tons per second.    
      
   http://tinyurl.com/7lcrkv8   
      
   This artist's rendering illustrates the evaporation of HD 189733b's atmosphere   
   in response to a powerful eruption from its host star. NASA's Hubble Space   
   Telescope detected the escaping gases and NASA's Swift satellite caught the   
   stellar flare. (Credit: NASA's Goddard Space Flight Center)    
      
   "The multiwavelength coverage by Hubble and Swift has given us an   
   unprecedented view of the interaction between a flare on an active star and   
   the atmosphere of a giant planet," said lead researcher Alain Lecavelier des   
   Etangs at the Paris Institute of Astrophysics (IAP), part of the French   
   National Scientific Research Center located at Pierre and Marie Curie   
   University in Paris.   
      
   The exoplanet is HD 189733b, a gas giant similar to Jupiter, but about 14   
   percent larger and more massive. The planet circles its star at a distance of   
   only 3 million miles, or about 30 times closer than Earth's distance from the   
   sun, and completes an orbit every 2.2 days. Its star, named HD 189733A, is   
   about 80 percent the size and mass of our sun.    
      
   Astronomers classify the planet as a "hot Jupiter." Previous Hubble   
   observations show that the planet's deep atmosphere reaches a temperature of   
   about 1,900 degrees Fahrenheit (1,030 C).    
      
   http://www.nasa.gov/multimedia/videogallery/index.html?media_id=147396961   
      
   A movie from the Goddard Space Flight Center explores the planet-blasting   
   stellar flare. Play itHD 189733b periodically passes across, or transits, its   
   parent star, and these events give astronomers an opportunity to probe its   
   atmosphere and environment. In a previous study, a group led by Lecavelier des   
   Etangs used Hubble to show that hydrogen gas was escaping from the planet's   
   upper atmosphere. The finding made HD 189733b only the second-known   
   "evaporating" exoplanet at the time.    
      
   The system is just 63 light-years away, so close that its star can be seen   
   with binoculars near the famous Dumbbell Nebula. This makes HD 189733b an   
   ideal target for studying the processes that drive atmospheric escape.   
      
   "Astronomers have been debating the details of atmospheric evaporation for   
   years, and studying HD 189733b is our best opportunity for understanding the   
   process," said Vincent Bourrier, a doctoral student at IAP and a team member   
   on the new study.    
      
   In April 2010, the researchers observed a single transit using Hubble's Space   
   Telescope Imaging Spectrograph (STIS), but they detected no trace of the   
   planet's atmosphere. Follow-up observations in September 2011 showed a   
   surprising reversal, with striking evidence that a plume of gas was streaming   
   away from the exoplanet at 300,000 mph. At least 1,000 tons of gas were   
   leaving the planet's atmosphere every second.   
      
   This turn of events was explained by data from Swift's X-ray Telescope. On   
   Sept. 7, 2011, just eight hours before Hubble was scheduled to observe the   
   transit, Swift was monitoring the star when it unleashed a powerful flare.   
      
   "The planet's close proximity to the star means it was struck by a blast of   
   X-rays tens of thousands of times stronger than the Earth suffers even during   
   an X-class solar flare, the strongest category," said co-author Peter   
   Wheatley, a physicist at the University of Warwick in England. After   
   accounting for the planet's enormous size, the team notes that HD 189733b   
   encountered about 3 million times as many X-rays as Earth receives from a   
   solar flare at the threshold of the X class.    
      
   These findings will appear in an upcoming issue of the journal Astronomy &   
   Astrophysics.    
      
      
   Production editor: Dr. Tony Phillips | Credit: Science@NASA   
      
   More Information    
   Hubble is a project of international cooperation between NASA and the European   
   Space Agency. Swift is operated in collaboration with several U.S.   
   institutions and partners in the United Kingdom, Italy, Germany and Japan.   
   NASA's Goddard Space Flight Center in Greenbelt, Md., manages both missions.   
      
   For more information about Swift, visit:   
      
   http://www.nasa.gov/swift   
      
   For more information about Hubble, visit:   
      
   http://www.nasa.gov/hubble   
      
      
   Regards,   
      
   Roger    
   --- timEd/386 1.10.y2k+   
    * Origin: NCS BBS - Houma, LA - (1:3828/7)