HR: 0800h
AN: SH41B-1128    [Abstracts]
TI: What RHESSI Annihilation-Radiation Observations Tell Us About The Flaring Solar Atmosphere
AU: * Share, G H
EM: gerald.share@nrl.navy.mil
AF: University of Maryland, Dept. of Astronomy, College Park, Md 20742 United States
AU: * Share, G H
EM: gerald.share@nrl.navy.mil
AF: Naval Research Laboratory, E.O. Hulburt Center for Space Research, Washington, DC 20375 United States
AU: Murphy, R J
EM: ronald.murphy@nrl.navy.mil
AF: Naval Research Laboratory, E.O. Hulburt Center for Space Research, Washington, DC 20375 United States
AU: Smith, D M
SH41B-1128 AF: University of California at Santa Cruz, Inst. for Particle Physics, Santa Cruz, CA 95064 United States
AU: Shih, A Y
SH41B-1128 AF: University of California at Berkeley, Space Science Laboratory, Berkeley, CA 94720 United States
AU: Lin, R P
SH41B-1128 AF: University of California at Berkeley, Space Science Laboratory, Berkeley, CA 94720 United States
AU: Schwartz, R A
SH41B-1128 AF: Goddard Space Flight Center, Code 682, Greenbelt, MD 20771 United States
AB: The electron-positron annihilation line and continuum below the line provide information on the density, temperature, and ionization state of the medium in which the positrons annihilate. The positrons originate from radioactive decay of nuclei and from pions created when flare-accelerated ions interact deep in the solar atmosphere and photosphere. The width of line has been found to be highly variable from flare-flare and during individual flares; during the 2003 October 28 flare the line width changed from ~ 6 keV to 1 keV in 2 - 3 minutes. This suggests that the temperature in the high density region where the line formed changed rapidly from ≥ 2 ×10⁵ K to < 10⁴ K. There is evidence that this change might be associated with cooling of small regions near the photosphere late in the flare. We review RHESSI observations of annihilation radiation in five solar flares and implications for the state of the flaring solar atmosphere. This work was supported by NASA DPR 10049 and NNG04ED181.
DE: 7507 Chromosphere
DE: 7519 Flares
DE: 7522 Helioseismology
DE: 7554 X-rays, gamma rays, and neutrinos
SC: SPA-Solar and Heliospheric Physics [SH]
MN: Fall Meeting 2005