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Astron. Astrophys. 364, 859-872 (2000)

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Location of the source of soft X-ray non-thermal line broadenings in a solar flare

N.D.R. Ranns, S.A. Matthews, L.K. Harra and J.L. Culhane

University College London, Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK

Received 17 July 2000 / Accepted 25 October 2000


We determine the location of the source of the non-thermal Soft X-ray line broadenings in an M1.7 two-ribbon solar flare using multi-wavelength observations. Using a combination of the Yohkoh Soft X-ray Telescope (SXT), Hard X-ray Telescope (HXT), Bragg Crystal Spectrometer (BCS) and the Transition Region and Coronal Explorer (TRACE), we find the source of the non-thermal broadenings, at their peak value, to be located in and above the SXR flare loops, not at the flare loop footpoints. After eliminating the footpoints as a potential source we discuss the likelihood that the source of non-thermally broadened emission lines is either evaporating chromospheric plasma or plasma above the Soft X-ray flare loop that is associated with the flare energy release.

Key words: Sun: flares – Sun: X-rays, gamma rays

Send offprint requests to: N.D.R. Ranns

Correspondence to: ndrr@mssl.ucl.ac.uk

© European Southern Observatory (ESO) 2000

Online publication: January 29, 2001