A comparison of the height distributions of solar flare hard X-rays in thick target and thermal models

Abstract

view Abstract Citations (53) References (46) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS A comparison of the height distributions of solar flare hard X-rays in thick target and thermal models Emslie, A. G. Abstract Using recent observations of solar hard X-ray bursts having a spatial resolution of a few arcsec, a computation is made of the theoretically predicted spatial variation of hard X-ray flux versus height in both thick target nonthermal and thermal models of solar hard X-ray bursts. The work on the thick target model revises previous results in this area by adopting a more realistic model for the flaring atmospheric structure and also by taking into account energy loss and scattering processes in the evolution of the nonthermal electron beam which have previously been neglected. It is noted that in the so-called 'thermal' model currently in vogue there is a substantial nonthermal bremsstrahlung component at all photon energies; it is further demonstrated that this nonthermal component results in a hard X-ray flux versus height distribution whose maximum brightness per unit length is, similarly to the thick target model, located in the chromosphere and not in the thermal source itself. The characteristics of the hard X-ray height distributions in both thick target and thermal models are summarized and compared. Publication: The Astrophysical Journal Pub Date: April 1981 DOI: 10.1086/158846 Bibcode: 1981ApJ...245..711E Keywords: Atmospheric Models; Bremsstrahlung; Solar Atmosphere; Solar Flares; Solar X-Rays; Spatial Distribution; Chromosphere; Electron Beams; Energy Dissipation; Height; Nonthermal Radiation; Temperature Distribution; X Ray Scattering; Astrophysics full text sources ADS |