HR: 16:00h
AN: SH24A-01    [Abstracts]
TI: RHESSI Observations of Gamma-Ray Lines From Solar Flares
AU: * Shih, A Y
EM: ayshih@ssl.berkeley.edu
AF: Department of Physics and Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720 United States
AU: Smith, D M
EM: dsmith@scipp.ucsc.edu
AF: Department of Physics and Santa Cruz Institute for Particle Physics, University of California, Santa Cruz, Santa Cruz, CA 95064 United States
AU: Lin, R P
EM: rlin@ssl.berkeley.edu
AF: Department of Physics and Space Sciences Laboratory, University of California, Berkeley, Berkeley, CA 94720 United States
AU: Share, G H
EM: gerald.share@nrl.navy.mil
AF: E. O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, DC 20375 United States
AU: Murphy, R J
EM: ronald.murphy@nrl.navy.mil
AF: E. O. Hulburt Center for Space Research, Naval Research Laboratory, Washington, DC 20375 United States
AU: Schwartz, R A
EM: richard.schwartz@gsfc.nasa.gov
AF: NASA Goddard Space Flight Center, Greenbelt Road, Greenbelt, MD 20771 United States
AB: The Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) has detected nuclear gamma-ray line emission from several large solar flares, including four of the X-class solar flares of October-November 2003. Collisions of accelerated ions with the ambient solar medium produce nuclear de-excitation lines, and these lines are spectrally resolved by RHESSI. The fluxes and shapes of these lines depend on the acceleration spectrum and the composition of the accelerated and ambient populations. Several of these flares exhibit changes in the relative fluxes over time, which in some of the flares is consistent with variations of the ambient abundances according to first-ionization potentials (FIP). Also, since these lines are produced by both accelerated protons and accelerated alpha particles, a detailed study of the line shapes constrains the alpha/proton ratio in these flares. We present the latest results from RHESSI on line-ratio variability and constraints on the alpha/proton ratio.
DE: 7514 Energetic particles (2114)
DE: 7519 Flares
DE: 7529 Photosphere
DE: 7554 X rays, gamma rays, and neutrinos
SC: SPA-Solar and Heliospheric Physics [SH]
MN: 2004 AGU Fall Meeting