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Diagnostics of electron-heated solar flare models. III - Effects of tapered loop geometry and preheating

1992; IOP Publishing; Volume: 399; Linguagem: Inglês

10.1086/171964

1538-4357

A. G. Emslie, Peng Li, J. T. Mariska,

Geomagnetism and Paleomagnetism Studies

view Abstract Citations (53) References (15) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Diagnostics of Electron-heated Solar Flare Models. III. Effects of Tapered Loop Geometry and Preheating Emslie, A. G. ; Li, Peng ; Mariska, John T. Abstract A series of hydrodynamic numerical simulations of nonthermal electron-heated solar flare atmospheres and their corresponding soft X-ray Ca XIX emission-line profiles, under the conditions of tapered flare loop geometry and/or a preheated atmosphere, is presented. The degree of tapering is parameterized by the magnetic mirror ratio, while the preheated atmosphere is parameterized by the initial upper chromospheric pressure. In a tapered flare loop, it is found that the upward motion of evaporated material is faster compared with the case where the flare loop is uniform. This is due to the diverging nozzle seen by the upflowing material. In the case where the flare atmosphere is preheated and the flare geometry is uniform, the response of the atmosphere to the electron collisional heating is slow. The upward velocity of the hydrodynamic gas is reduced due not only to the large coronal column depth, but also to the increased inertia of the overlying material. It is concluded that the only possible electron-heated scenario in which the predicted Ca XIX line profiles agree with the BCS observations is when the impulsive flare starts in a preheated dense corona. Publication: The Astrophysical Journal Pub Date: November 1992 DOI: 10.1086/171964 Bibcode: 1992ApJ...399..714E Keywords: High Temperature Plasmas; Hydrodynamic Equations; Nonthermal Radiation; Solar Electrons; Solar Flares; Hot Electrons; Metallicity; Solar Corona; Stellar Models; Solar Physics; MAGNETOHYDRODYNAMICS: MHD; METHODS: NUMERICAL; SUN: CORONA; SUN: FLARES full text sources ADS |