Mewaldt, R. A. and Leske, R. A. and Stone, E. C. and Barghouty, A. F. and Labrador, A. W. and Cohen, C. M. S. and Cummings, A. C. and Davis, A. J. and von-Rosenvinge, T. T. and Wiedenbeck, M. E. (2009) STEREO Observations of Energetic Neutral Hydrogen Atoms During the 2006 December 5 Solar Flare. Astrophysical Journal Letters, 693 (1). L11-L15. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20090918-091120378
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We report the discovery of energetic neutral hydrogen atoms (ENAs) emitted during the X9 solar event of 2006 December 5. Beginning ~1 hr following the onset of this E79 flare, the Low Energy Telescopes (LETs) on both the STEREO A and B spacecraft observed a sudden burst of 1.6-15 MeV protons beginning hours before the onset of the main solar energetic particle event at Earth. More than 70% of these particles arrived from a longitude within ±10° of the Sun, consistent with the measurement resolution. The derived emission profile at the Sun had onset and peak times remarkably similar to the GOES soft X-ray profile and continued for more than an hour. The observed arrival directions and energy spectrum argue strongly that the particle events < 5 MeV were due to ENAs. To our knowledge, this is the first reported observation of ENA emission from a solar flare/coronal mass ejection. Possible origins for the production of ENAs in a large solar event are considered. We conclude that the observed ENAs were most likely produced in the high corona and that charge-transfer reactions between accelerated protons and partially stripped coronal ions are an important source of ENAs in solar events.
|Additional Information:||© 2009. The American Astronomical Society. Received 2008 November 14; accepted 2009 January 21; published 2009 February 11. This work was supported by NASA at Caltech and JPL under subcontract SA2715-26309 from the University of California, Berkeley, under NASA contract NAS5-03131. The work at Marshall Space Flight Center was supported by the TEI Program of NASA’s Office of Chief Engineer. We thank NOAA for GOES X-ray data, Mike Kaiser for STEREO/WAVES data, Chris Russell for STEREO magnetic field data, and the RHESSI team for γ-ray data. We also appreciate discussions with Eric Christian, Sam Krucker, Bob Lin, Ron Murphy, and Gerry Share.|
|Group:||Space Radiation Laboratory|
|Subject Keywords:||Sun: corona; Sun: coronal mass ejections (CMEs); Sun: flares; Sun: particle emission; Sun: X-rays, gamma rays|
|Official Citation:||STEREO Observations of Energetic Neutral Hydrogen Atoms During the 2006 December 5 Solar Flare R. A. Mewaldt, R. A. Leske, E. C. Stone, A. F. Barghouty, A. W. Labrador, C. M. S. Cohen, A. C. Cummings, A. J. Davis, T. T. von Rosenvinge, and M. E. Wiedenbeck 2009 ApJ 693 L11-L15 doi: 10.1088/0004-637X/693/1/L11|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||22 Sep 2009 17:09|
|Last Modified:||26 Dec 2012 11:24|
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