Observation of All Pre- and Post-reconnection Structures Involved in Three-dimensional Reconnection Geometries in Solar Eruptions

Abstract

We report on observations of the two newly-identified reconnection geometries involving erupting flux ropes. In 3D, a flux rope can reconnect either with a surrounding coronal arcade (recently named "ar-rf" reconnection) or with itself ("rr-rf" reconnection), and both kinds of reconnection create a new flux rope field line and a flare loop. For the first time, we identify all four constituents of both reconnections in a solar eruptive event, the filament eruption of 2011 June 07 observed by SDO/AIA. The ar-rf reconnection manifests itself as shift of one leg of the filament by more than 25 northward. At its previous location, a flare arcade is formed, while the new location of the filament leg previously corresponded to a footpoint of a coronal loop in 171Å. In addition, the evolution of the flare ribbon hooks is also consistent with the occurrence of ar-rf reconnection as predicted by MHD simulations. Specifically, the growing hook sweeps footpoints of preeruptive coronal arcades, and these locations become inside the hook. Furthermore, the rr-rf reconnection occurs during the peak phase above the flare arcade, in an apparently X-type geometry involving a pair of converging bright filament strands in the erupting filament. A new flare loop forms near the leg of one of the strands, while a bright blob, representing a remnant of the same strand, is seen ascending into the erupting filament. All together, these observations vindicate recent predictions of the 3D standard solar flare model.

Observations of a prominence eruption and loop contraction

“…9 shows that, at the same time, loops expand or contract at different locations of the coronal configuration. This is in agreement with previous results obtained for other eruptions (Dudík et al 2016(Dudík et al , 2017(Dudík et al , 2019. This evolution variety could be interpreted in the context of the vortex model derived from MHD simulations (Zuccarello et al 2017).…”

“…Observations reveal another aspect of eruptions with contracting and expanding loops that were observed during eruptive solar flares (Veronig et al 2006;Joshi et al 2007;Liu et al 2009aLiu et al , 2012Simões et al 2013;Kushwaha et al 2014;Petrie 2016;Dudík et al 2016Dudík et al , 2017Dudík et al , 2019, and references cited therein). Liu et al (2009a) and Joshi et al (2009) found that the coronal loop contraction is associated with the converging motion of the conjugate hard X-ray (HXR) footpoints and the downward motion of the HXR loop top sources.…”

Filament Eruption Driving EUV Loop Contraction then Expansion above a Stable Filament

“…We conclude that the lateral drift of the filament foot is accomplished via interchange reconnection with encountered southern magnetic loops. These observations are globally consistence with the previously reported observations of such lateral drift of the foot of an erupted prominence/filament (Hori 2000;van Driel-Gesztelyi et al 2014;Dudík et al 2019;Lörinčík et al 2019;Zemanová et al 2019). Another part of the erupted filament drains to the end region of the J-shaped flare ribbon in the west (towards polarity P 0 in Figure 3), which is near the periphery of the flux rope leg.…”

“…These vortex flows drive the coronal loops and as a result of this the contraction/expansion in loops observed, depending where the loops are in the vortex. The careful analysis of the contraction/expansion of loops in some studied eruptions filament support the conclusion of the MHD simulations (Dudík et al 2017(Dudík et al , 2019Devi et al 2021).…”

“…This phenomenon is reported with various space borne observations in flare loops with the shrinkage of individual loops while the global loop system expand upwards as further flare loops are formed (Forbes & Acton 1996;Li & Gan 2006;Sui et al 2004;Zhou et al 2008;Joshi et al 2009). Moreover, since the launch of SDO in 2010, observational evidences of coronal loop contraction and expansion, not associated to flare loops, are increasing (Sun et al 2012;Gosain 2012;Liu et al 2012;Zhou et al 2013;Simões et al 2013;Shen et al 2014;Dudík et al 2017;Wang et al 2018;Dudík et al 2019;Devi et al 2021). This is a consequence of SDO continuous high temporal and spatial resolution observations.…”