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Session 26 - Solar Flares II.
Oral session, Monday, June 10
Recent results based on hard X-ray and gamma-ray observations of solar flares have suggested that the energy content in accelerated protons may rival that of accelerated electrons. However, simply having a large energy content in accelerated protons is not sufficient to ensure an important role for protons in driving the response of the atmosphere to flare energy input: a viable model must also deposit a large fraction of the particle energy at the top of the chromosphere, to account for the large increase in soft X-ray emission measure that characterizes the main phase of a flare. While hard X-ray-producing electrons indeed deposit a sufficient amount of energy at the appropriate depths in the atmosphere, we show that only protons with a characteristic energy of order 1 MeV do likewise. Since protons of this energy do not have a signature in hard X-rays, we conclude that a substantial fraction of the flare energy budget must indeed reside in deka-keV electrons. In order to complete the global energetic picture, observational diagnostics for MeV protons are required; suitable observations are discussed.
This work was supported by the NASA Office of Space Science and by the NSF International Programs Division.
Program listing for Monday