Slipping Magnetic Reconnection, Chromospheric Evaporation, Implosion, and Precursors in the 2014 September 10 X1.6-CLASS Solar Flare

Abstract

We investigate the occurrence of slipping magnetic reconnection, chromospheric evaporation, and coronal loop dynamics in the 2014 September 10 X-class flare. The slipping reconnection is found to be present throughout the flare from its early phase. Flare loops are seen to slip in opposite directions towards both ends of the ribbons. Velocities of 20-40 km s −1 are found within time windows where the slipping is well resolved. The warm coronal loops exhibit expanding and contracting motions that are interpreted as displacements due to the growing flux rope that subsequently erupts. This flux rope existed and erupted before the onset of apparent coronal implosion. This indicates that the energy release proceeds by slipping reconnection and not via coronal implosion. The slipping reconnection leads to changes in the geometry of the observed structures at the IRIS slit position, from flare loop top to the footpoints in the ribbons. This results in variations of the observed velocities of chromospheric evaporation in the early flare phase. Finally, it is found that the precursor signatures including localized EUV brightenings as well as non-thermal X-ray emission are signatures of the flare itself, progressing from the early phase towards the impulsive phase, with the tether-cutting being provided by the slipping reconnection. The dynamics of both the flare and outlying coronal loops is found to be consistent with the predictions of the standard solar flare model in 3D.

Expanding and Contracting Coronal Loops as Evidence of Vortex Flows Induced by Solar Eruptions

“…We note that hot magnetic flux ropes emitting in 131 Å are commonly observed during eruptive flares (e.g., Zhang et al 2012;Cheng et al 2014;Dudík et al 2014Dudík et al , 2016Li & Zhang 2015;Li et al 2016;Zhu et al 2016). In our case, the erupting structure is probably also a hot magnetic flux rope, as indicated by the occurrence of the eruption first in 131 Å band, followed by a writhed series of loops in 171 Å.…”

“…They exhibit a multitude of observed dynamic phenomena arising from release of energy stored within the pre-flare magnetic field (e.g., Fletcher et al 2011;Schmieder et al 2015). The destabilization of the magnetic field via the torus instability results in an eruption (e.g., Aulanier et al 2012;Zuccarello et al 2015Zuccarello et al , 2016, with the eruption driving other dynamic phenomena, such as slipping motion of flare loops and expansion/contraction behavior of the neighboring coronal loops (e.g., Janvier et al 2013;Dudík et al 2014Dudík et al , 2016. In this paper, we are concerned with the expansion/contraction behavior of closed coronal loops at the periphery of active regions with respect to the flare and/or eruption site.…”

Transition from eruptive to confined flares in the same active region

“…In particular, Savcheva et al (2015Savcheva et al ( , 2016 have shown that the flare ribbons often coincide with the photospheric signature of quasi-separatrix layers (QSLs, Démoulin et al 1996), i.e., thin layers characterized by a sharp gradient in the connectivity of the magnetic field. The brightening motions along the ribbons have been interpreted as the signatures of the slipping reconnection of the magnetic field lines through the QSL (Aulanier et al 2006;Janvier et al 2013;Dudík et al 2014Dudík et al , 2016.The morphology and evolution of flare ribbons can also give information on the overall topology of the system. Masson et al (2009) have shown that circular flare ribbons are associated with the presence of a null-point topology in the corona, while parallel ribbons moving away from each other have been interpreted as an indication of quasi-separator reconnection occurring higher in the corona (Aulanier et al 2012).…”

Flare Ribbons Approach Observed by the Interface Region Imaging Spectrograph and the Solar Dynamics Observatory

“…Priest & Démoulin (1995), Masson et al (2009) and Aulanier et al (2006) proposed that 3D slipping magnetic reconnection at a null point, separator or quasi-separatrix layers (QSLs) can account for the elongation motion. Recently, the apparent slipping motions of flare loops and ribbons during eruptive flares were investigated by and Dudík et al (2014Dudík et al ( , 2016. The slippage exhibited a quasi-periodic pattern with a period of 3−6 minutes and its speed reached several tens of km s −1 .…”