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Lithium-6 from Solar Flares  

Reuven Ramaty   Submitted: 2000-03-27 19:01

By introducing a hitherto ignored Li-6 producing process, due to accelerated He-3 reactions with He-4, we show that accelerated particle interactions in solar flares produce much more Li-6 than Li-7. By normalizing our calculations to gamma-ray data we demonstrate that the Li-6 produced in solar flares, combined with photospheric Li-7, can account for the recently determined solar wind lithium isotopic ratio, obtained from measurements in lunar soil, provided that the bulk of the flare produced lithium is evacuated by the solar wind. Further research in this area could provide unique information on a variety of problems, including solar atmospheric transport and mixing, solar convection and the lithium depletion issue, and solar wind and solar particle acceleration.

Authors: R. Ramaty, V. Tatischeff, J. P. Thibaud, B. Kozlovsky, N. Mandzhavidze

Publication Status: ApJ Letters, 2000, in press
Last Modified: 2000-03-27 19:01
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High Energy Processes in Solar Flares  

Reuven Ramaty   Submitted: 1999-12-24 04:05

We review the highlights of the high energy processes in solar flares. Particle acceleration is an essential ingredient of the flare energy release process. Among all cosmic high energy sources, flares are unique in that both the accelerated particle and the radiations that they produce are observed. In this paper we emphasize the radiations, gyrosynchrotron emission, bremsstrahlung and gamma ray lines. These provide information on flare models, magnetic fields, energy content in the accelerated particles and abundances. The abundances are not only critical for constraining the acceleration mechanisms, but also provide unique information on solar atmospheric dynamics and mixing, solar wind acceleration, and Galactic chemical evolution.

Authors: Reuven Ramaty and Natalie Mandzhavidze

Publication Status: Cosmic Explosions, AIP, S. Holt and W. Zhang eds., in press
Last Modified: 1999-12-24 04:05
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Gamma Rays from Solar Flares  

Reuven Ramaty   Submitted: 1999-11-04 17:05

Gamma-ray emission is the most direct diagnostic of energetic ions and relativistic electrons in solar flares. Analysis of solar flare gamma-ray data has shown: (i) ion acceleration is a major consequence of flare energy release, as the total flare energy in accelerated particles appears to be equipartitioned between greater than about 1 MeV/nucleon ions and greater than 20 keV electrons and amounts to an important fraction of the total energy release; (ii) there are flares for which over 50% of the energy is in α particles and heavier ions; (iii) in both impulsive and gradual flares, the particles that interact at the Sun and produce gamma rays are always accelerated by the same mechanism that operates in impulsive flares, probably stochastic acceleration through gyroreso- gyroresonant wave particle interaction; (iv) gamma-ray spectroscopy can provide new information on solar abundances, for example the site of the FIP bias onset and the photospheric He-3 abundance. We propose a new technique for the investigation of mass motion and mixing in the solar atmosphere, the observatio- observations of gamma-ray lines from long term radioactivity produced by flare accelerated particles.

Authors: Reuven Ramaty and Natalie Mandzhavidze

Publication Status: In press, Highly Energetic Physical Processes and Mechanisms in Astrophysical Plasmas, IAU, P.C.H. Martens and S.Tsuruta, eds.
Last Modified: 1999-11-04 17:05
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Lithium-6 from Solar Flares
High Energy Processes in Solar Flares
Gamma Rays from Solar Flares

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