Investigation of long-duration arcade flares

I. Morphology and physical parameters

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

Received: 12 April 2006
Accepted: 23 January 2007

Abstract

Aims.We present the analysis of the three well-observed long-duration arcade flares (LDAFs). We aim to find general properties of LDAFs. In this paper results concerning morphology and physical parameters in these flares are shown.

Methods.Yohkoh observations, Kitt Peak Vacuum Telescope (KPVT) magnetograms and GOES/SEM measurements are used to determine morphology and evolution of the analysed flares and physical parameters of their loop-top kernels (temperature, density, altitude).

Results.We found that: (1) a so-called arcade channel may exist in LDAFs; (2) the energy release in LDAFs occurs in several places simultaneously and the reconnection process is not uniform along the flaring arcade; (3) a presence of  MK hot plasma during the decay phase suggests that the reconnection occurs after the LDAF maximum.