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Properties of Accelerated Particles at the Sun from Gamma-Ray and Neutron Measurements

Properties of Accelerated Particles at the Sun from Gamma-Ray and Neutron Measurements Gerry Share and Ron Murphy. Application to SMM, Yohkoh, and RHESSI studies

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Properties of Accelerated Particles at the Sun from Gamma-Ray and Neutron Measurements

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  1. Properties of Accelerated Particles at the Sun from Gamma-Ray and Neutron Measurements Gerry Share and Ron Murphy

  2. Application to SMM, Yohkoh, and RHESSI studies We fit flare spectra with pl + pl*exp (bremsstrahlung), 0.5, 2.2 MeV, a – 4He lines, a solar Compton-scattered 2.2 MeV continuum, individual line template for p, a interactions on Ne, for p, a interactions on ambient composition (e.g. Asplund photospheric) , and a template for accelerated particle composition (coronal or SEP impulsive) on H and He. These nuclear line templates were calculated for the heliocentric angle of the flare and for various values of a/p and ion spectral index (assuming the same index for all accelerated particles).

  3. Fits to the 1989 October 19 flare showing the total fit, bremsstrahlung (dashed/dotted blue), direct interaction (i.e. accelerated p and a on ambient elements; dotted red), p and a on neon (dot/dash red),inverse interaction (i.e. heavy ions on ambient elements; dashed red), a-4He, and 0.511/2.223 MeV line components (dashed green) and Compton-scattered 2.2 MeV line and positronium continuum (dotted green).

  4. chi2 contour plots for spectral index and /p ratio. From Monte Carlo studies a dc2 = 3.8 has a 68% probability. Uses best fit coronal ambient abundances and coronal accelerated particles abundances. Upper plot: RHESSI 03 October 28 Lower plot: SMM 89 October 19, best fit pho-cor. Red (blue) curves show the indices and /p ratios consistent with photospheric He/O for Asplund 2004 abundances based on fits to the flux measured in the -4He fusion lines (dotted curves show the 1 sigma statistical uncertainties).

  5. Properties of flare-accelerated ions derived from gamma-ray spectra (some preliminary estimates) Flare Composition Heavy/p+a a/p ratio PL Index (~90% confidence) (~2-30 MeV) 03 Oct 28 Coronal 3.4 ± 0.8 0.12-0.45 3.4-4.4 89 Oct 19 Coronal 1.8 ± 0.6 0.14–0.30 3.6-4.2 88 Dec 16 Coronal 2.4 ± 0.4 0.14–0.22 3.4-4.0 81 Apr 27 Imp. SEP 2.0 ± 0.12 0.08-0.90 3.6-4.2

  6. 2005 January 20 Flare

  7. Chi2 contour map for the 2005 January 20 solar flare. Not sensitive to composition broad range of allowable indices and alpha/proton ratios.

  8. 2005 January 20 Time History

  9. 06:45:40 to 06:48:00 UT. Best fitting model (solid black curve); low-energy brems. (solid yellow), high-energy brems. (solid orange), nuclear line and cont. (solid blue), pion-decay (solid purple), 2223 MeV (dotted purple), solar 511 keV (dashed purple), solar-scattered N-capture (solid light green), He line (dashed light blue).

  10. Comparison of RHESSI pion-decay flux with SONG >11 MeV (Yushkov and Kurt) count rates normalized to the RHESSI fluxes. Agreement allows us to use RHESSI pion-decay gamma-ray data at later times.

  11. 2005 January 20 Time Histories of Different Flare Components. Inferred ion and electron spectra show variability.

  12. ~2-50 MeV protons ~50-500 MeV protons >2 MeV electrons ~2-500 MeV protons

  13. Spectral Episodes in the 2005 January 20 Solar Flare Time Interval Inferred Ion Spectral Index ~2-50 MeV ~50-500 MeV 06:44-06:45:40 <4.0 ~3.3 06:45:40-06:48 ~3.4 ~3.4 06:48-06:54 ~2.2 ~3.4 06:54-07:06 ~3.0 ~2.8 07:06-07:18 ~2.8 ~2.4 >8:00 ---- ~2.2 From 06:44-06:54 emission concentrated in Northern footpoint. Emission may be extended after that time.

  14. 2.2 MeV and pion emission observed for >3 hours and appears to fall faster than the NM proton flux >300 MeV (Allan Tylka, private comm.).

  15. Preliminary comparison of accelerated particles interacting at the Sun (RHESSI) and observed in space (Mewaldt, priv. comm. 2005) for the 2005 January 20 flare. Total number of protons >30 MeV: Solar flare: ~5 x 1032 Event integrated SEPs: 210 x 1032 Power-law spectral index: Solar flare; variable from ~2.2 to ~4.0 Event integrated SEPs: 2.15

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