The height distribution of non-thermal X-ray sources in impulsive solar flares

Fletcher, L. (1996) The height distribution of non-thermal X-ray sources in impulsive solar flares. Astronomy and Astrophysics, 310, pp. 661-671.

Abstract

In this paper we use numerical simulations to accurately model the evolution of non-thermal electron distributions in coronal loops, from which we calculate electron bremsstrahlung height versus energy distributions. The results are compared with results of the Yohkoh satellite and it is found that a model taking into account the full complexity of electron transport can explain what is observed, for quite reasonable loop parameters. We test three loop models, the first with no field convergence, the second with field convergence occurring rapidly and only in the chromosphere and the third where field convergence occurs slowly in the corona. We demonstrate the effects of varying parameters of the loop (such as density, length and field strength), and of the beam (spectral index, pitch angle distribution) and outline parameter regimes in which best agreement with the data can be found. Broadly, densities between 2x10^10 and 3x10^11^cm^-3 and coronal half-lengths L=~1.3-2.7x10^9 cm give qualitatively acceptable results. Finally we discuss possible tests to distinguish between the various models which can explain the height distribution.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: UNSPECIFIED
• Authors: Fletcher, L.
• Subjects: Q Science > QB Astronomy; Q Science > QC Physics
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Research Group: Astronomy and Astrophysics
• Journal Name: Astronomy and Astrophysics
• Publisher: EDP Sciences
• ISSN: 0004-6361
• ISSN (Online): 1432-0746
• Copyright Holders: Copyright © 1996 European Southern Observatory
• First Published: First published in Astronomy and Astrophysics 310:661-671
• Publisher Policy: Reproduced in accordance with the copyright policy of the publisher