EUV and HXR Signatures of Electron Acceleration During the Failed Eruption of a Filament

Abstract

We search for EUV brightenings in TRACE 171 Å images and HXR bursts observed during failed eruptions. We expect that if an eruption is confined due to interaction with overlying magnetic structures then we should observe effects connected with reconnection between magnetic structures and acceleration of particles. We utilized TRACE observations of three well observed failed eruptions. EUV images were compared to HXR spatial distribution reconstructed from Yohkoh/HXT and RHESSI data. The EUV light curves of a selected area were compared to height profiles of eruption, HXR emission and HXR photon spectral index of power-law fit to HXR data. We have found that EUV brightenings are closely related to the eruption velocity decrease, to HXR bursts and to episodes of hardening of HXR spectra. The EUV brightened areas are observed far from the flaring structure, in footpoints of large systems of loops observed 30-60 minutes after the maximum of a flare. These are not `post-flare' loops that are also observed but at significantly lower heights. The high lying systems of loops are observed at heights equal to height, at which eruption was observed to stop. We observed HXR source spatially correlated with EUV brightening only once. For other EUV brightened areas we estimated the expected brightness of HXR sources. We find that EUV brightenings are produced due to interaction between the erupting structure with overlying loops. The interaction is strong enough to heat the system of high loops. These loops cool down and are visible in EUV range about 30-60 minutes later. The estimated brightness of HXR sources associated with EUV brightenings shows that they are too weak to be detected with present instruments. However, next generation instruments will have enough dynamic range and sensitivity to enable such observations.

A&A accepted

References in corpus (5)

• Combined STEREO/RHESSI study of CME acceleration and particle acceleration in solar flares
• A Comparative Study Between Eruptive X-class Flares Associated with Coronal Mass Ejections and Confined X-class Flares
• Eruption of magnetic flux ropes during flux emergence
• A Time Series of Filament Eruptions Observed by Three Eyes from Space: From Failed to Successful Eruptions
• Failed Eruption of a Filament as a Driver for Vertical Oscillations of Coronal Loops

Cited by in corpus (7)

• Confined Flares in Solar Active Region 12192 from 2014 October 18 to 29
• Helical Kink Instability in a Confined Solar Eruption
• Large-scale contraction and subsequent disruption of coronal loops during various phases of the M6.2 flare associated with the confined flux rope eruption
• A Model for Confined Solar Eruptions Including External Reconnection
• Magnetic structure of solar flare regions producing hard X-ray pulsations
• Multi-wavelength Observation of a Failed Eruption from a Helical Kink-unstable Prominence
• The deformation of an erupting magnetic flux rope in a confined solar flare