Round-trip Slipping Motion of the Circular Flare Ribbon Evidenced in a Fan-spine Jet

Abstract

A solar jet on 2014 July 31, which was accompanied by a GOES C1.3 flare and a mini-filament eruption at the jet base, was studied by using observations taken by the New Vacuum Solar Telescope and the Solar Dynamic Observatory. Magnetic field extrapolation revealed that the jet was confined in a fan-spine magnetic system that hosts a null point at the height of about 9 Mm from the solar surface. An inner flare ribbon surrounded by an outer circular ribbon and a remote ribbon were observed to be associated with the eruption, in which the inner and remote ribbons respectively located at the footprints of the inner and outer spines, while the circular one manifested the footprint of the fan structure. It is interesting that the circular ribbon's west part showed an interesting round-trip slipping motion, while the inner ribbon and the circular ribbon's east part displayed a northward slipping motion. Our analysis results indicate that the slipping motions of the inner and the circular flare ribbons reflected the slipping magnetic reconnection process in the fan quasi-separatrix layer, while the remote ribbon was associated with the magnetic reconnection at the null point. In addition, the filament eruption was probably triggered by the magnetic cancellation around its south end, which further drove the slipping reconnection in the fan quasiseparatrix layer and the reconnection at the null point.

Observation and modelling of solar jets

“…They found that the initiation of the jet is due to the magnetic reconnection near a set of two 3D magnetic nullpoints, and the jet itself evolves from a flux rope near the nullpoints through changing the flux rope’s magnetic field lines from an anchored to an open topology. In addition, the generation of flare ribbons is found to be attributed to reconnections at a 3D nullpoint and a quasi-separatrix layer, consistent with a previous data-constrained simulation of circular flares [50] and the observations of confined fan–spine jets [55].…”

“…By contrast, a two-sided-loop jet appears as a pair of plasma beams ejecting in opposite directions from the eruption source region [44][45][46][47][48][49]. Recently, high-resolution observations combined with extrapolated three-dimensional (3D) coronal magnetic fields revealed the fan-spine topology magnetic system of straight anemone jets [50], which consists of a coronal nullpoint, a dome-like fan that represents the [51][52][53][54][55][56][57][58][59][60]. A fan-spine topology often arises when a parasitic magnetic polarity emerges (or carries) into a pre-existing magnetic field region with opposite polarity, and a jet occurring within it can lead to three flare ribbons as a result of the low-altitude impact of the particle beams accelerated through the nullpoint magnetic reconnection; namely, an inner bright patch surrounded by a circular ribbon relevant to the inner spine and the dome-like fan structure, and a remote elongated bright ribbon associated with the outer spine.…”

“…Roy [21] confirmed this finding and further proposed that significant magnetic flux change over a short time interval is also important for producing surges. Subsequent studies based on high-resolution observations revealed that evolving satellite sunspots are liable to launch recurrent jets through continuous collisions with the main sunspots [55,[88][89][90][91][92][93][94]. In quiet-Sun and coronal hole regions, small opposite-polarity magnetic elements can be recognized as the most conspicuous photospheric progenitor for many lower-energy, smallscale coronal jets.…”

“…Liu et al [240] observed a jet-associated bubble-like CME whose bright core was evolved from the jet. Solar jets in or around active regions in association with fan-spine magnetic systems are often confined [55]. However, a few studies found that some broad CMEs are evolved from fan-spine eruptions [251].…”

Development of a solar circular flare М6.4 according to observations in the Нα line

“…Ñïàëàõîâ³ ïåòë³ êîâçàþòü ó ïðîòèëåaeíèõ íàïðÿìêàõ äî ê³í ö³â ñòð³÷îê. Ö³êàâèé ôàêò êîâçàííÿ ó ñòð³÷ö³ ñïàëàõó áàëà C1.3 31 ëèïíÿ 2014 ðîêó ñïî÷àòêó íà ï³âí³÷, à ïîò³ì íà ï³âäåíü âèÿâëåíî â ðîáîò³ [41]. Ó ðîáîò³ [19] ïîâ³äîìëÿºòüñÿ ïðî ñïîñòåðåaeåííÿ òðè âàëîãî âåëèêîìàñøòàáíîãî êîâçíîãî ïåðåç'ºäíàííÿ ó ñïàëàõó M6.5 â àê -òèâí³é îáëàñò³ NOAA 12371.…”