HXR emission from an activated flux rope and subsequent evolution of an eruptive long duration solar flare

Abstract

In this paper, we present a comprehensive study of the evolutionary phases of a major M6.6 long duration event (LDE) with special emphasize on its pre-flare phase. The event occurred in NOAA 12371 on 2015 June 22. A remarkable aspect of the event was an active pre-flare phase lasting for about an hour during which a hot EUV coronal channel was in build-up stage and displayed co-spatial hard X-ray (HXR) emission up to energies of 25 keV. As such, this is the first evidence of HXR coronal channel. The coronal magnetic field configuration based on NLFFF modeling clearly exhibited a magnetic flux rope (MFR) oriented along the polarity inversion line (PIL) and co-spatial with the coronal channel. We observed significant changes in the AR's photospheric magnetic field during an extended period of $\approx$42 hours in the form of rotation of sunspots, moving magnetic features, and flux cancellation along the PIL. Prior to the flare onset, the MFR underwent a slow rise phase ($\approx$14 km s${}^{-1}$) for $\approx$12 min which we attribute to the faster build-up and activation of the MFR by tether-cutting reconnection occurring at multiple locations along the MFR itself. The sudden transition in the kinematic evolution of the MFR from the phase of slow to fast rise ($\approx$109 km s${}^{-1}$ with acceleration $\approx$110 m s${}^{-2}$) precisely divides the pre-flare and impulsive phase of the flare, which points toward the feedback process between the early dynamics of the eruption and the strength of the flare magnetic reconnection.

Accepted for publication in The Astrophysical Journal

References in corpus (11)

• Nonlinear force-free modeling of the solar coronal magnetic field
• Direct Observations of Tether-cutting Reconnection During a Major Solar Event From 2014 February 24 to 25
• Solar Magnetic Flux Ropes
• Formation and eruption of a flux rope from the sigmoid active region NOAA 11719 and associated M6.5 flare: A multi-wavelength study
• Triggering Mechanism for the Filament Eruption on 2005 September 13 in Active Region NOAA 10808
• Witnessing a Large-scale Slipping Magnetic Reconnection along a Dimming Channel during a Solar Flare
• Acceleration phases of a solar filament during its eruption
• Pre-eruption processes: heating, particle acceleration and the formation of a hot channel before the 2012 October 20 M9.0 limb flare
• Signatures of magnetic reconnection in solar eruptive flares: A multi-wavelength perspective
• Trigger of successive filament eruptions observed by SDO and STEREO
• Introduction to the physics of solar eruptions and their space weather impact

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