Magnetic reconnection between a solar filament and nearby coronal loops

Abstract

Magnetic reconnection, the rearrangement of magnetic field topology, is a fundamental physical process in magnetized plasma systems all over the universe 1,2 . Its process is difficult to be directly observed. Coronal structures, such as coronal loops and filament spines, often sketch the magnetic field geometry and its changes in the solar corona 3 . Here we show a highly suggestive observation of magnetic reconnection between an erupting solar filament and its nearby coronal loops, resulting in changes in connection of the filament. X-type structures form when the erupting filament encounters the loops. The filament becomes straight, and bright current sheets form at the interfaces with the loops. Many plasmoids appear in these current sheets and propagate bi-directionally. The filament disconnects from the current sheets, which gradually disperse and disappear, reconnects to the loops, and becomes redirected to the loop footpoints. This evolution of the filament and the loops suggests successive magnetic reconnection predicted by theories 1 but rarely detected with such clarity in observations. Our results on the formation, evolution, and disappearance of current sheets, confirm three-dimensional magnetic reconnection theory and have implications for the evolution of dissipation regions and the release of magnetic energy for reconnection in many magnetized plasma systems.Magnetic reconnection 1,2 is considered to play an essential role in the rapid release of the magnetic energy and its conversion to other forms (thermal, kinetic and particle) in magnetized plasma systems (such as accretion disks, solar and stellar coronae, planetary magnetospheres, and laboratory plasmas) throughout the universe. It shows the reconfiguration of the magnetic field geometry. In solar physics, numerous theoretical studies of the magnetic reconnection have been undertaken to explain flares 5 , filament eruptions 6 , et al. In two dimensional (2D) models, reconnection occurs at an X-point where anti-parallel magnetic field lines converge and reconnect 1,5,6 . So far, many observations of magnetic reconnection signatures, e.g., cusp-shaped post-flare loops 7 , loop-top hard X-ray source 3,8 , reconnection inflows 3,9 and outflows 3,10,11 , flare supra-arcades downflows 12,13 , current sheets, and plasmoid ejections 11 , have been reported by using remote sensing data. However, to directly observe the details of magnetic reconnection process is difficult, because of the small spatial scale and the fast temporal evolution of the process.A solar filament is a relatively cool and dense plasma structure in the corona suspended above a magnetic polarity inversion line (PIL), with ends rooted in regions with opposite magnetic polarity. Its spine, a narrow ribbon-like structure through the full filament, consists of horizontal and parallel threads 14 when viewed from above. In the region around a filament, the plasma-beta, i.e., the ratio of thermal to magnetic energy density, is below unity. Because of the high electric conductivity, the...

A Complex Solar Coronal Jet with Two Phases

“…The length of region p1 is around6.0 10 cm 8 . We calculate the mean magnetic energy release rate during the time of magnetic cancellation to be ( ) 2.8 0.1 10 27 erg s −1 , which is similar to the change of magnetic energy in a reconnection event described by Li et al (2016). Following the calculation of the plasma density and temperature by Liu et al (2016), the average electron number density is about 10 9 cm −3…”

Quasi-periodic pulsations with periods that change depending on whether the pulsations have thermal or nonthermal components

“…Thus, it is possible that the QPPs are produced by periodic magnetic reconnection in this flare. Based on the standard flare model, magnetic reconnection could simultaneously accelerate the bidirectional electron beams (Aschwanden et al 1995;Su et al 2013;Li et al 2016). The downward beam produces the microwave emission peak in its trajectory propagation, it also produces one peak of the HXR emission when it is injected into the chromosphere, and this process will heat the local plasmas to produce one peak in the EUV/UV emission.…”

Magnetic Reconnection at the Earliest Stage of Solar Flux Emergence

“…As one of the most important mechanisms of energy release, magnetic reconnection plays an important role in the energization of the space and astrophysical plasmas (e.g., Priest & Forbes 2000;Deng et al 2004;Gosling et al 2005;Phan et al 2006;Zhang et al 2012). Magnetic reconnection is also believed to be the key process that drives both large-scale solar eruptions and smallscale jets (e.g., Sun et al 2015;Chen et al 2015;Sterling et al 2015;Chen et al 2016;Xue et al 2016;Li et al 2016;Wyper et al 2017;Ni et al 2017). In the past decade, due to high-resolution observations by advanced telescopes such as the Solar Optical Telescope (SOT, Tsuneta et al 2008) on board the Hinode spacecraft, the Interface Region Imaging Spectrograph (IRIS, De Pontieu et al 2014) and the New Vacuum Solar Telescope (NVST, Liu et al 2014), small-scale reconnection in the partially ionized lower solar atmosphere has received a lot of attention (e.g., Shibata et al 2007;Katsukawa et al 2007;Tian et al 2014a;Peter et al 2014;Yang et al 2015).…”