Accession Number:

ADA605063

Title:

Measurement of Accelerated Particles at the Sun

Descriptive Note:

Journal article

Corporate Author:

NAVAL RESEARCH LAB WASHINGTON DC E O HULBURT CENTER FOR SPACE RESEARCH

Personal Author(s):

Report Date:

2000-01-01

Pagination or Media Count:

6.0

Abstract:

Solar -ray lines and continua provide information on flare-accelerated particles that interact at the Sun. We primarily discuss observations of flare spectra made by the OSSE experiment on CGRO and the gamma-ray spectrometer on SMM. Continuum -ray spectra reflect the MeV electron population. These spectra show various shapes above 0.1 MeV single power laws, broken power-laws both hardening and softening 0.1 to 0.3 MeV, and spectra that harden 1 MeV. The spectra and directionality of accelerated protons and particles are revealed in the narrow lines from excited ambient nuclei and -4He fusion. These measurements imply power-law spectral indices between -3 and -5 for energies 5 MeVnucleon, evidence for both broad angular distributions and directionality in the interactions, and high accelerated p ratios 0.5 in many flares. The presence of accelerated 3He is revealed in weak line features suggesting 3He4He ratios of 0.1 or greater. Strongly Doppler-broadened lines reveal the composition and directionality of heavy accelerated ions. Fe appears to be enhanced by about the same ratio found in impulsive SEPs. We present some preliminary results on flares that individually were not detected at energies 1 MeV their summed spectra exhibit hardening 1 MeV that may be due to nuclear radiation. There appears to be equipartition of energy between accelerated electrons and ions in flares with strong line emission.

Subject Categories:

  • Astrophysics
  • Nuclear Physics and Elementary Particle Physics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE