Solar Prominence Bubble and Plumes Caused By an Eruptive Magnetic Flux Rope

Prominence bubbles and plumes often form near the lower prominence–corona boundary. They are believed to play an important role in mass supply and evolution of solar prominences. However, how they form is still an open question. In this Letter we present a unique high-resolution Hα observation of a quiescent prominence by the New Vacuum Solar Telescope. Two noteworthy bubble–plume events are studied in detail. The two events are almost identical, except that an erupting mini filament appeared below the prominence–bubble interface in the second event, unlike the first one or any of the reported bubble observations. Analysis of the Hα and extreme-ultraviolet data indicates that the rising magnetic flux rope (MFR) in the mini filament is the cause of bubble expansion and that the interaction between the prominence and MFR results in plume formation. These observations provided clear evidence that emerging MFR may be a common trigger of bubbles and suggested a new mechanism of plumes in addition to Rayleigh–Taylor instability and reconnection.

Dynamics of moving knots in a solar prominence observed by New Vacuum Solar Telescope

<p>In this report, we present a prominence observed by New Vacuum Solar Telescope (NVST) in Hα wavelength.  We use morphological approach to identify the rising or descending knots in the prominence. The rising knots are often found on the top of the prominence, while more knots are seen to descend from anywhere of the prominence.</p><p>The optical flow, referring to the apparent proper motion of a feature across the image plane, may be used to determine the velocity field from two images. The technique of local correlation tracking (LCT) optical flow has been widely used in the solar research. The Demon algorithm, which has been  used to match medical image, performs image-to-image matching by determining the optical flow between two images. We have examined the performance of the two methods applying the Hα images, and we noted that the Demon algorithm outperforms traditional LCT  methods.</p><p>The result of Demon optical flow allows us to estimate the velocity and acceleration of the moving knots. The descending speed of the knots near the solar surface is higher than that far away from the solar surface. This indicate that most of knots are more possible to descend across the horizontal magnetic field.</p>