Propagating and Stationary Bright Knots in the Quiet Sun

Zhang, Jun; Hou, Yijun; Fang, Y.; Chen, F.; Li, Ting; Yan, Xiaoli; Ding, Tao; Song, Zhiping; Xiang, Yanjuan; Liu, Zhong

doi:10.3847/2041-8213/aca97b

Cited by 4 publications

(3 citation statements)

References 50 publications

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“…The interaction between the fibrils is inevitable and common (e.g., Yang et al 2015;Ding et al 2022;Yan et al 2022). However, based on 10 yr (from 2012 October 1 to 2022 September 30) highresolution chromospheric data from the NVST, we detect fewer than 15 events with explicit X-type reconnection between the fibrils (Zhang et al 2023). Such rare examples indicate that the occurrence of magnetic reconnection should satisfy several physical conditions, e.g., enlarged MFDs at the footpoints of atmospheric structures, enhanced nonpotentiality and complexity of magnetic fields, antiparallel magnetic field lines, etc.…”

Section: Discussionmentioning

confidence: 76%

The Evolution of Photospheric Magnetic Fields at the Footpoints of Reconnected Structures in the Solar Atmosphere

Ding,

Zhang,

Fang

et al. 2024

ApJ

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Magnetic reconnection is believed to play an important role in the release and conversion of energy among magnetized plasma systems. So far, we have been unable to understand under what conditions magnetic reconnection can take place. Based on observations from the New Vacuum Solar Telescope and the Solar Dynamics Observatory (SDO), we study 16 magnetic reconnection events, and each event has a clear X-type configuration consisting of two sets of atmospheric structures. We focus on 38 footpoints that are relevant to these structures and can be clearly determined. By using SDO/Helioseismic and Magnetic Imager line-of-sight magnetograms, we track the field evolution of these footpoints. Prior to the occurrence of magnetic reconnection, the associated fields at the footpoints underwent convergence and shear motions, and thus became enhanced and complex. During the converging period, the rates of increase of the mean magnetic flux densities (MFDs) at these footpoints are 0.03–0.25 hr−1. While the unsigned mean MFDs are 70–300 G, magnetic reconnection in the solar atmosphere takes place. Subsequently, the photospheric fields of these footpoints diffuse and weaken, with rates of decrease of the MFDs from 0.03 to 0.18 hr−1. These results suggest that, due to the photospheric dynamical evolution at the footpoints, the footpoint MFDs increase from a small value to a large one, and the corresponding atmospheric magnetic fields become complicated and nonpotential; then reconnection happens and it releases the accumulated magnetic field energy. Our study supports the conjecture that magnetic reconnection releases free magnetic energy stored in the nonpotential fields.

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Section: Discussionmentioning

confidence: 76%

The Evolution of Photospheric Magnetic Fields at the Footpoints of Reconnected Structures in the Solar Atmosphere

Ding,

Zhang,

Fang

et al. 2024

ApJ

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“…During this process, magnetic energy is released into thermal and kinetic energy of the plasmas (Phan et al 2020;Fleishman et al 2023). In the solar atmosphere, kinds of activities and phenomena, e.g., flares (Fleishman et al 2020;Collier et al 2024), jets (Shibata et al 1992;Sterling et al 2024), brightenings (Berghmans et al 2021;Zhang et al 2023), and coronal mass ejections (CMEs; Green et al 2018;O'Kane et al 2021), are associated with this mechanism. The observational signatures of inflows and outflows (Reeves et al 2020;Yan et al 2022) are thought to be a direct consequence of the reconnection process.…”

Section: Introductionmentioning

confidence: 99%

Dynamical Evolution of Newly Formed Structures After Magnetic Reconnection

Ding,

Zhang

2024

ApJL

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Although extensive research on magnetic reconnection, e.g., current sheets, inflows/outflows, and plasma ejections, has been done, the dynamical evolution of newly formed structures during and after the reconnection between two sets of atmospheric structures is rarely studied. Here we investigate five reconnection events based on observations from the Solar Dynamics Observatory and the New Vacuum Solar Telescope. In each event, two independent atmospheric structures are involved. While they meet, a plasma sheet is detected. After exchanging topological connectivity, new structures are formed in the outflow regions. For each new structure, it is composed of a part of one original structure and that of the other one. In this Letter, for the first time, we find that there are two types of evolution patterns of the new structures. The first type is that the new structures move away from the reconnection position as a whole and then undergo a to-and-fro motion (an oscillation). The second is that the new structures display a “throwing whip” movement. We suggest that the evolution patterns are relevant to the topological configuration of the original structures and the position of the reconnection site.

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“…In the solar atmosphere, MHD waves are ubiquitously observed (e.g., Tian et al 2012;. They can heat the quiet corona, e.g., the corona outside active regions (ARs; Tomczyk et al 2007;McIntosh et al 2011;Zhang et al 2023). However, the observed wave power is generally 2 orders of magnitude too weak to power the AR corona (see reviews in Withbroe & Noyes 1977; Arregui 2015and references therein).…”

Section: Introductionmentioning

confidence: 99%

Heating of Quiescent Coronal Loops Caused by Nearby Eruptions Observed with the Solar Dynamics Observatory and the Solar Upper Transition Region Imager

Chen

Song

et al. 2023

ApJ

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How structures, e.g., magnetic loops, in the upper atmosphere, i.e., the transition region and corona, are heated and sustained is one of the major unresolved issues in solar and stellar physics. Various theoretical and observational studies on the heating of coronal loops have been undertaken. The heating of quiescent loops caused by eruptions, however, is rarely observed. In this study, employing data from the Solar Dynamics Observatory (SDO) and Solar Upper Transition Region Imager (SUTRI), we report the heating of quiescent loops associated with nearby eruptions. In active regions (ARs) 13092 and 13093, a long filament and a short filament, and their overlying loops, were observed on 2022 September 4. In AR 13093, a warm channel erupted toward the northeast, whose material moved along its axis toward the northwest under the long filament, turned to the west above the long filament, and divided into two branches falling to the solar surface. Subsequently, the short filament erupted toward the southeast. Associated with these two eruptions, the quiescent loops overlying the long filament appeared in SDO/Atmospheric Imaging Assembly (AIA) high-temperature images, indicating the heating of loops. During the heating, the signature of magnetic reconnection between loops is identified, including the inflowing motions of loops, and the formation of X-type structures and newly reconnected loops. The heated loops then cooled down. They appeared sequentially in AIA and SUTRI lower-temperature images. All the results suggest that the quiescent loops are heated by reconnection between loops caused by the nearby warm channel and filament eruptions.

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Propagating and Stationary Bright Knots in the Quiet Sun

Cited by 4 publications

References 50 publications

The Evolution of Photospheric Magnetic Fields at the Footpoints of Reconnected Structures in the Solar Atmosphere

The Evolution of Photospheric Magnetic Fields at the Footpoints of Reconnected Structures in the Solar Atmosphere

Dynamical Evolution of Newly Formed Structures After Magnetic Reconnection

Heating of Quiescent Coronal Loops Caused by Nearby Eruptions Observed with the Solar Dynamics Observatory and the Solar Upper Transition Region Imager

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