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Titolo:
PROTONS IN FLARES
Autore:
SIMNETT GM;
Indirizzi:
UNIV BIRMINGHAM,SCH PHYS & SPACE RES BIRMINGHAM B15 2TT W MIDLANDS ENGLAND
Titolo Testata:
Space science reviews
fascicolo: 3-4, volume: 73, anno: 1995,
pagine: 387 - 432
SICI:
0038-6308(1995)73:3-4<387:PIF>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
HARD X-RAY; LOOP RADIATIVE HYDRODYNAMICS; SOLAR-FLARES; IMPULSIVE PHASE; CHROMOSPHERIC EVAPORATION; PARTICLE-ACCELERATION; ENERGETIC PARTICLES; LINEAR-POLARIZATION; ION-ACCELERATION; 2-RIBBON FLARES;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
120
Recensione:
Indirizzi per estratti:
Citazione:
G.M. Simnett, "PROTONS IN FLARES", Space science reviews, 73(3-4), 1995, pp. 387-432

Abstract

This work addresses the role of non-thermal protons as a means of transporting energy in stellar atmospheres. The most dramatic transient visible phenomena are flares, the best studied of which are from the Sun. It is believed that energetic particles take a fundamental part in flare development, but it is controversial as to whether protons or electrons play the dominant role. This review is aimed at helping resolve the controversy. We start by outlining acceleration mechanisms for energetic particles, on the premise that the acceleration site is in the corona. The propagation of a proton beam through the atmosphere is discussed, together with the radiation signatures it would produce. Chromospheric evaporation is expected as the beam reaches the dense part of the atmosphere. Direct observational evidence for energetic protonsis reviewed, from gamma-ray production involving energies > 30 MeV toH alpha polarization, which is significant at energies less than or similar to 100 keV. Proton beams can be detected in the corona via slowly-drifting type III bursts, while they can be directly sampled by spacecraft and, at energies > 1 GeV, by detectors on the Earth. A number of key flare observations and energy arguments are debated from the viewpoint of protons versus electrons. The conclusion is that primary non-thermal protons are much more important, in terms of total energy, than non-thermal electrons in flares, and that the bulk of the energetic electrons are secondary.

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Documento generato il 03/12/20 alle ore 15:37:48