Yongyuan Xiang

New Vacuum Solar Telescope Observations of a Flux Rope Tracked by a Filament Activation

One main goal of the New Vacuum Solar Telescope (NVST) which is located at the Fuxian Solar Observatory is to image the Sun at high resolution. Based on the high spatial and temporal resolution NVST Ha data and combined with the simultaneous observations from the Solar Dynamics Observatory for the first time, we investigate a flux rope tracked by filament activation. The filament material is initially located at one end of the flux rope and fills in a section of the rope; the filament is then activated by magnetic field cancellation. The activated filament rises and flows along helical threads, tracking the twisted flux rope structure. The length of the flux rope is about 75 Mm, the average width of its individual threads is 1.11 Mm, and the estimated twist is 1 pi. The flux rope appears as a dark structure in Ha images, a partial dark and partial bright structure in 304 angstrom, and as a bright structure in 171 angstrom and 131 angstrom images. During this process, the overlying coronal loops are quite steady since the filament is confined within the flux rope and does not erupt successfully. It seems that, for the event in this study, the filament is located and confined within the flux rope threads, instead of being suspended in the dips of twisted magnetic flux.

THE FORMATION AND MAGNETIC STRUCTURES OF ACTIVE-REGION FILAMENTS OBSERVED BY NVST, SDO, AND HINODE

To better understand the properties of solar active-region filaments, we present a detailed study on the formation and magnetic structures of two active-region filaments in active region NOAA 11884 during a period of four days. It is found that the shearing motion of the opposite magnetic polarities and the rotation of the small sunspots with negative polarity play an important role in the formation of two active-region filaments. During the formation of these two active-region filaments, one foot of the filaments was rooted in a small sunspot with negative polarity. The small sunspot rotated not only around another small sunspot with negative polarity, but also around the center of its umbra. By analyzing the nonlinear force-free field extrapolation using the vector magnetic fields in the photosphere, twisted structures were found in the two active-region filaments prior to their eruptions. These results imply that the magnetic fields were dragged by the shearing motion between opposite magnetic polarities and became more horizontal. The sunspot rotation twisted the horizontal magnetic fields and finally formed the twisted active-region filaments.

OSCILLATING LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

With the high tempo-spatial \emph{Interface Region Imaging Spectrograph} 1330 {\AA} images, we find that many bright structures are rooted in the light bridge of NOAA 12192, forming a \emph{light wall}. The light wall is brighter than the surrounding areas, and the wall top is much brighter than the wall body. The New Vacuum Solar Telescope H

Fine Structures and Overlying Loops of Confined Solar Flares

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Observing the release of twist by magnetic reconnection in a solar filament eruption

and the \emph{Solar Dynamics Observatory} 171 {\AA} and 131 {\AA} images are also used to study the light wall properties. In 1330 {\AA}, 171 {\AA}, and 131 {\AA}, the top of the wall has a higher emission, while in the H

MAGNETIC RECONNECTION BETWEEN SMALL-SCALE LOOPS OBSERVED WITH THE NEW VACUUM SOLAR TELESCOPE

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PARTIAL ERUPTION OF A FILAMENT WITH TWISTING NON-UNIFORM FIELDS

line, the wall top emission is very low. The wall body corresponds to bright areas in 1330 {\AA} and dark areas in the other lines. The top of the light wall moves upward and downward successively, performing oscillations in height. The deprojected mean height, amplitude, oscillation velocity, and the dominant period are determined to be 3.6 Mm, 0.9 Mm, 15.4 km s

THE EVOLUTION OF THE ELECTRIC CURRENT DURING THE FORMATION AND ERUPTION OF ACTIVE-REGION FILAMENTS

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Interaction of Two Active Region Filaments Observed by NVST and SDO

, and 3.9 min, respectively. We interpret the oscillations of the light wall as the leakage of \emph{p}-modes from below the photosphere. The constant brightness enhancement of the wall top implies the existence of some kind of atmospheric heating, e.g., via the persistent small-scale reconnection or the magneto-acoustic waves. In another series of 1330 {\AA} images, we find that the wall top in the upward motion phase is significantly brighter than in the downward phase. This kind of oscillations may be powered by the energy released due to intermittent impulsive magnetic reconnection.

OSCILLATION OF NEWLY FORMED LOOPS AFTER MAGNETIC RECONNECTION IN THE SOLAR CHROMOSPHERE

Using the H