| 其他摘要 | The solar filaments (or prominences) have a wide range of spatiotemporal distribution characteristics. They usually form in different regions of the Sun and with a spatial scale of several hundred megameters. The life span of filaments is about a few minutes to several weeks. Because some large-scale and intense explosive activities are produced by the eruption of filaments, such as flares and coronal mass ejections, which often have an impact on the near-Earth space weather. Therefore, solar filaments have always received much attention. The filament eruptions can not only drive some hot plasmas to propagate toward the higher atmosphere and may contribute to the coronal heating or the acceleration of the solar winds, but also release a large amount of nonpotential magnetic energy stored in the eruption source region into interplanetary space. The filaments are supported by the highly non-potential magnetic structures which originate from below the photosphere. Therefore, studying on the mechanism of filament formation can help further understand the source of the solar magnetic field and the dynamo theorem. Although there are many magnetic reconnection mechanisms related to the formation and eruption of multi-scale filaments in the active regions, the relevant details are still not very clear. By using the high spatiotemporal resolution and multibands observational data from the New Vacuum Solar Telescope (NVST) of Yunnan Observatories and the Solar Dynamics Observatory(SDO), we studied the formation and evolution of multi-scale filaments in the active regions, as well as the detailed evolution of magnetic reconnection during the filament formation and eruption. Our purpose is to reveal the similarities and differences in the formation and eruption mechanisms of multi-scale filaments in the active regions, as well as the significance of some associated energy release processes in solving some basic problems in solar physics. The main contents of our study are as follows: Using the high resolution observational data from the SDO/AIA、HMI and the NVST to study the formation process of a U-shaped filament in a solar active region. It was found that a successive reconnection can occur between a filament and its nearby chromospheric fibrils, resulting in the formation of a U-shaped filament. The observational evidence for successive reconnection is as follows: The associated brightening and magnetic cancellation were observed. The changes in appearance of the CF at the reconnection site. The changes in the topology of the filament and chromospheric fibrils were characterized by the formation and accumulation of some new magnetic loops at the reconnection site,as well as plasmas propagated along the formed magnetic loops from the reconnection site. While the successive reconnection can provide a part of the materials for the formation of the U-shaped filament. This study demonstrated that the formation of the U-shaped filament was led by the successive reconnection that occurred between the filament and its nearby chromospheric fibrils. This study revealed a rare formation mechanism of a U-shaped filament, which is caused by successive magnetic reconnection, and part of the materials of the U-shaped filament can come from the material injection during the successive reconnection process. Using the high resolution observational data from the SDO/AIA、HMI and the NVST to study the interaction process between two nearby filaments and the associated successive partial eruptions in a solar active region. It was found that when the eruptive right part of a larger filament collided with its nearby smaller filament, a reconnection can occur between them. This filament interaction resulted in a rightward motion of the smaller filament at first, and then its activation and eruption. When the smaller filament erupted rapidly and disturbed the overlying magnetic fields of the left part of the larger filament, it resulted in the left part of the larger filament also erupting successively. In this study, the right part of the larger filament collided with the small filament at a relatively smaller contact angle, and the two filaments have opposite signs of magnetic helicity. Therefore, when they collided with each other, a magnetic reconnection can occur between them and lead to a bounce interaction. This is the first interaction episode discovered in observations. This study demonstrated that the successive eruptions of filaments occurred with in a relatively short time and were caused by the filament interaction,they were sympathetic filament eruptions with certain linkages. The left and right parts of a filament erupted separately and showed obvious rotational motions during its eruption process, indicating the filament was composed of several magnetic flux ropes with different twists. This study advances the understanding of solar sympathetic filament eruption activities and provides a good reference value for studying the continuous eruption activities of other asters. Based on the relevant observational data from the SDO/AIA, HMI, and NVST, the intermittent eruptions of a minifilament triggered by a two-step magnetic reconnection within a fan-spine configuration in a solar activity region were studied. We found that the first-step magnetic reconnection occurred between the small-scale magnetic loop under the fan-spine structure and its nearby inner part of the fan-spine structure, resulting in the reconstruction of the inner part of the fan-spine structure and gradually approached the outer part of the fan-spine structure, then the reconnection occurred between them at the null point, namely the second-step reconnection occurred. This caused the minifilament to erupt partially due to its overlying fields being weakened. Subsequently, this two-step reconnection process occurred again and triggered the minifilament to erupt completely. The observational evidence for the null point reconnection is as follows: The changes in topology structure of the inner spine and outer spine of the fan-spine structure, the bright outer spine, as well as the generation of circular flare and remote brightening. Especially during the null point magnetic reconnection that triggers the second eruption of the minifilament, some plasmoids propagated from the reconnection site were observed. This study demonstrated that the two-step reconnection is the main mechanism that triggers the minifilament eruptions. In which the null point reconnection plays a direct role, but the dynamical evolution of the inner spine and outer spine of the fan-spine structure that is driven by the first-step reconnection might be a precursor for the subsequent null point reconnection. This study provides a detailed analysis of the inner and outer spine of the fan-spine structure before and during null point magnetic reconnection. Meanwhile, this study explains the triggering mechanism of null point magnetic reconnection before the minifilament eruption. Therefore, our study reveals the causality of the null point magnetic reconnection and the associated minifilament eruptions. |
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