Dec 6 2007
From The Space Library
NASA announced that images about the Japanese Hinode satellite, collected by NASA-funded telescopes, had provided new information about the Sun’s magnetic field and the origins of solar wind. Hinode’s high-resolution x-ray telescope had revealed a record number of x-ray jets—up to 240—in the corona at the Sun’s poles, contrary to previous research that had detected only a few such jets daily. Based on observation of these solar jets, a team led by solar physicist Jonathan W. Cirtain, of NASA’s MSFC, concluded that a magnetic reconnection occurring in the low solar corona was forming Alfvén waves and bursts of energized plasma in the x-ray jets. Alfvén waves form when convective motions and sound waves push magnetic fields around, or otherwise allow magnetic fields to change shape or to reconnect. Previously, researchers had been unable to observe Alfvén waves because of the limited resolution of available instruments. Yet, in their search to identify the forces responsible for the formation of solar winds, scientists had long considered Alfvén waves the leading candidate. Alfvén waves are capable of transferring energy from the Sun’s surface up through its atmosphere (corona) and into the solar wind. Cirtain explained that the team’s observations had revealed a clear relationship between magnetic reconnection and the formation of Alfvén waves in the x-ray jets, and that “the large number of jets, coupled with the high speeds of the outflowing plasma, lends further credence to the idea that x-ray jets are a driving force in the creation of the fast solar wind.” The team published its findings in the 7 December issue of the journal Science, a special issue focusing on Hinode.
NASA, “Spacecraft Reveals New Insights About the Origin of Solar Wind,” news release 07-264, 6 December 2007, http://www.nasa.gov/home/hqnews/2007/dec/HQ_07264_Hinode_Waves.html (accessed 20 October 2010); Jonathan W. Cirtain et al., “Evidence for Alfvén Waves in Solar X-ray Jets,” Science 318, no. 5856 (7 December 2007): 1580-1582, http://www.sciencemag.org/content/318/5856/1580.abstract (DOI 10.1126/science.318.5856. 1571; accessed 1 December 2010).
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