B. Joshi, Physical Research Laboratory, bhuwan@prl.res.in
  U. Kushwaha, Udaipur Solar Observatory, Physical Research Laboratory, Udaipur 313001, India, bhuwan@prl.res.in
  A. Veronig, Institute of Physics, University of Graz, Graz, Austria, astrid.veronig@uni-graz.at
  Y. Moon, School of Space Research, Kyung Hee University, Yongin, South Korea, moonyj@khu.ac.kr

We investigate evolutionary phases of an M6.2 solar flare and associated confined eruption of a flux rope which occurred in solar active region NOAA 10646 on 2004 July 14. The pre-flare phase is characterized by the spectacular large-scale contraction of overlying extreme ultraviolet (EUV) coronal loops during which the loop system was subjected to an altitude decrease of ~20 Mm, corresponding to 40% of its initial height, for an extended span of ~30 minutes. Such a large-scale contraction of coronal loops has been reported for the first time. This contraction phase is accompanied by sequential EUV brightenings associated with hard X-ray (HXR; up to 25 keV) and microwave (MW) sources from low-lying loops in the core region which together with X-ray spectra indicate strong localized heating in the source region before the filament activation. With the onset of the flare’s impulsive phase, we detect HXR and MW sources that exhibit intricate temporal and spatial evolution in relation to the fast rise of the prominence. Following the flare maximum, the filament eruption slowed down and subsequently became confined within the large overlying active region loops. HXR spectroscopy reveals high plasma temperature (~30 MK) and substantial non-thermal characteristics (δ ~5) during the impulsive phase of the flare. The time evolution of thermal energy exhibits a good correspondence with the variations in cumulative non-thermal energy, which suggests that the energy of accelerated particles is efficiently converted to hot flare plasma, implying an effective validation of the Neupert effect in terms of flare energetics