OSCILLATING LIGHT WALL ABOVE A SUNSPOT LIGHT BRIDGE

摘要

With the high tempo-spatial Interface Region Imaging Spectrograph 1330 angstrom images, we find that many bright structures are rooted in the light bridge of NOAA 12192, forming a 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 alpha and the Solar Dynamics Observatory 171 and 131 angstrom images are also used to study the light-wall properties. In 1330, 171, and 131 angstrom, the top of the wall has a higher emission, while in the H alpha line, the wall-top emission is very low. The wall body corresponds to bright areas in 1330 angstrom 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(-1), and 3.9 minutes, respectively. We interpret the oscillations of the light wall as the leakage of 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 angstrom images, we find that the wall top in the upward motion phase is significantly brighter than in the downward phase. This kind of oscillation may be powered by the energy released due to intermittent impulsive magnetic reconnection.