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Issue A&A
Volume 465, Number 3, April III 2007
Page(s) 1035 - 1040
Section The Sun
DOI http://dx.doi.org/10.1051/0004-6361:20065424



A&A 465, 1035-1040 (2007)
DOI: 10.1051/0004-6361:20065424

Investigation of long-duration arcade flares

II. Energy release
S. Kolomanski

Instytut Astronomiczny Uniwersytetu Wroclawskiego, Kopernika 11, 51-622 Wroclaw, Poland
    e-mail: kolomans@astro.uni.wroc.pl

(Received 12 April 2006 / Accepted 20 December 2006)

Abstract
Aims.We analyse three well-observed long-duration arcade flares (LDAFs) to find their general properties. Results concerning energy release in LDAFs (energy balance and diagnostic diagrams) are shown.
Methods.Yohkoh observations and Kitt Peak Vacuum Telescope magnetograms are used to determine physical parameters of flare loop-top kernels (temperature, density, altitude). Using these parameters the energy release is studied in detail.
Results.We found that: (1) the energy release in LDAFs occurs during their whole decay phase; (2) the kernel heating ($E_{\rm H}$) is of the order of 0.01-1 erg cm-3 s-1; (3) the kernels usually cannot be distinguished in SXT images when $E_{\rm H}$ is drops below a particular value. This value depends on the altitude of the kernels.


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



© ESO 2007

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