AAS 200th meeting, Albuquerque, NM, June 2002
Session 68. Flares
Display, Thursday, June 6, 2002, 9:20am-4:00pm, SW Exhibit Hall

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[68.01] Directionality of Solar Flare Accelerated Protons and \alpha Particles from \gamma-Ray Line Measurements

G. H. Share, R. J. Murphy (Naval Research Laboratory), J. Kiener, N. de Sereville (Univ. of Paris-South)

The energies and widths of \gamma-ray lines emitted by ambient nuclei excited by flare-accelerated protons and \alpha particles provide information on the ions directionality and spectra, and on the characteristics of the interaction region. We have measured the energies and widths of strong lines from de-excitations of 12C, 16O, and 20Ne in solar flares as a function of heliocentric angle. The line energies from all three nuclei exhibit ~1% redshifts for flares at small heliocentric angles, but are not shifted near the limb. The lines have widths of ~3% FWHM. We compare the 12C line measurements for flares at five different heliocentric angles with calculations for different interacting-particle distributions. A downward isotropic distribution (or one with a small upward component) provides a good fit to the line measurements. An angular distribution derived for particles that undergo significant pitch angle scattering by MHD turbulence in coronal magnetic loops provides comparably good fits. This work was partially supported by NASA DPR 18995.

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The author(s) of this abstract have provided an email address for comments about the abstract: share@gamma.nrl.navy.mil

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.