The merging process of chromospheric fibrils into a filament

Fang, Y.; Zhang, J.; Song, Zhiping; Hou, Yijun; Li, Tao

doi:10.1051/0004-6361/202142723

Cited by 4 publications

(5 citation statements)

References 41 publications

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“…However, numerical simulations and high-resolution observations have found that filament materials are usually in a cyclic state, which is characterized by the dynamic balance between the drainage of filament materials back to the chromosphere and the formation of filament materials transferred from the low atmosphere to the corona (Engvold 1976;Berger et al 2008;Chae et al 2008;Xia et al 2016). Three models have been proposed to explain the formation of filament materials: injection model (Chae et al 2001), levitation model (Poland & Mariska 1986;Lites 2005;Fang et al 2022), and evaporation-condensation model (Antiochos et al 2000;Kaneko & Yokoyama 2017). About the drainage of filament materials, observational results have displayed that filament materials fall back to the lower chromosphere either along the barbs (Dai et al 2021) or the footpoints (Seaton et al 2011;Bi et al 2014).…”

Section: Summary and Discussionmentioning

confidence: 99%

Interactions between Filament Fibrils and a Network Field

Song

Zhang

Fang

2023

ApJ

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Filaments are common structures in the solar atmosphere, and usually interact with their surrounding magnetic fields. However, interactions between filaments and network fields are rare. Here, we report interactions between filament fibrils and a nearby network field in the quiet Sun by employing observations from the New Vacuum Solar Telescope (NVST) and Solar Dynamics Observatory. NVST Hα images show that several filament fibrils separated from the main body of the filament, and moved sideward. While a fibril met the network field, the movement of the fibril segment corresponding to the network field slowed down. Subsequently, weak extremely ultraviolet brightenings appeared near the interface of the filament and the network field, and then the fibril materials began to converge toward the network field. Meanwhile, continuous redshift signal enhancements appeared in the corresponding Dopplergrams, accompanying the convergences of the fibril materials. About 10 and 35 minutes later, two other similar processes occurred again. These observations imply that the network field blocks movements of the filament fibrils and weak magnetic reconnections between the blocked fibrils and the network field take place. We suggest that new field lines developed due to the magnetic reconnections, along which fibril materials fell down into the lower solar atmosphere. These results provide a new picture of filament material drainage.

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Section: Summary and Discussionmentioning

confidence: 99%

Interactions between Filament Fibrils and a Network Field

Song

Zhang

Fang

2023

ApJ

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“…To determine which physical mechanism triggering these propagating knots, we examine all the NVST Hα observations over the past decade. The examples (Yang et al 2015;Fang et al 2022) of unambiguous magnetic reconnection between chromospheric fibrils are no more than 15, implying that magnetic reconnection between fibrils is difficult to occur (or at least difficult to be detected). Besides, all the examples show that magnetic reconnection occurs between fibrils with oppositepolarity fields.…”

Section: Summary and Discussionmentioning

confidence: 99%

Propagating and Stationary Bright Knots in the Quiet Sun

Zhang

Hou

Fang

et al. 2022

ApJL

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The question of what heats the solar chromosphere and corona remains one of the most important puzzles in solar physics and astrophysics. Up to now, two mechanisms are considered to work in heating the chromosphere and corona: magnetic reconnection and wave (turbulent flow) dissipation. But it is still not understood which mechanism is dominant. To solve the heating problem, one important topic at this stage is that we should understand how much energy is contributing from the two mechanisms respectively to the heating. In the quiet Sun, the thermal energy signal is observed as brightenings. Here we report two kinds of bright knots with a total of 3605 in the chromosphere of the quiet Sun, using the data from the New Vacuum Solar Telescope at Yunnan Observatories. The first kind of 1537 bright knots, which is first detected in chromospheric fibrils where waves and their dissipation are ubiquitous, propagates along these fibrils with velocities from 5 to 69 km s−1. The second kind of 2068 knots keeps stationary, and always appears at the footpoints of these fibrils where network magnetic fields exist, suggesting that magnetic reconnection locally produces these stationary knots. Based on the observations of thousands of bright knots, we display the different distribution patterns of the two kinds of bright knots in the quiet Sun, and deduce that half of the energy for heating the chromosphere is supplied by wave dissipation, and the other half by magnetic reconnection.

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“…For explaining the source of filament material, three types of models are proposed. They are the levitation model (Poland et al 1986;Zhao et al 2017;Fang et al 2022), injection model (An et al 1988;Chae 2003;Liu et al 2005;Wang et al 2019), and evaporation-condensation model (Antiochos et al 2000;Li et al 2019;Yang et al 2021;Zhao & Keppens 2022). In the levitation model, cool chromospheric plasma can be carried by the rising magnetic field and lifted to the corona to form filament (Fang et al 2022).…”

Section: Introductionmentioning

confidence: 99%

“…They are the levitation model (Poland et al 1986;Zhao et al 2017;Fang et al 2022), injection model (An et al 1988;Chae 2003;Liu et al 2005;Wang et al 2019), and evaporation-condensation model (Antiochos et al 2000;Li et al 2019;Yang et al 2021;Zhao & Keppens 2022). In the levitation model, cool chromospheric plasma can be carried by the rising magnetic field and lifted to the corona to form filament (Fang et al 2022). As for the injection model, filament material can be fed by magnetic reconnection in the form of jets or surge (Liu et al 2005;Wang et al 2019).…”

Section: Introductionmentioning

confidence: 99%

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The Formation of a U-shaped Filament Due to the Successive Magnetic Reconnection between a Filament and Its Nearby Chromospheric Fibrils

Yan

Xue

et al. 2023

ApJ

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Although magnetic reconnection plays a key role in the formation of a solar filament, the detailed formation process is still ambiguous. Combining the observational data from the New Vacuum Solar Telescope and the Solar Dynamics Observatory, we analyzed the formation of a U-shaped filament via successive magnetic reconnection in the AR NOAA 11598 on 2012 October 25. The successive reconnection occurred between a filament (F) and its nearby chromospheric fibrils (CF). The associated brightening and magnetic cancellation were observed. The changes in appearance of the CF at the reconnection site were accompanied by the formation and accumulation of some new magnetic loops, as well as plasmas propagated along the formed magnetic loops from the reconnection site, indicating the changes in the topology of the F and CF. These can provide comprehensive observational evidence for successive reconnection. After the reconnection, a longer U-shaped filament was formed. During the formation of the U-shaped filament, two major magnetic energy releases took place. While in the two energy release processes, the injected plasma from the reconnection site can provide part of the material for the formation of the U-shaped filament. Therefore, we conclude that the successive reconnection results in both the dynamical evolution and the subsequent formation associated with the U-shaped filament. And the results of nonlinear force-free field extrapolation demonstrated that the magnetic topology of the F was changed significantly; this is consistent with the observational results and further confirms the formation of the U-shaped filament.

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The merging process of chromospheric fibrils into a filament

Cited by 4 publications

References 41 publications

Interactions between Filament Fibrils and a Network Field

Interactions between Filament Fibrils and a Network Field

Propagating and Stationary Bright Knots in the Quiet Sun

The Formation of a U-shaped Filament Due to the Successive Magnetic Reconnection between a Filament and Its Nearby Chromospheric Fibrils

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