Coronal and Chromospheric Dynamics of a Coronal Hole Bright Point

Abstract Data from the Atmospheric Imaging Assembly (AIA) and the Helioseismic Magnetic Imager on board the Solar Dynamics Observatory and from the Interface Region Imaging Spectograph, are used to study the evolution at different atmospheric layers of a bright point (BP) in a coronal hole near the network that displays high variability over a period of ∼60 minutes. During this IRIS/AIA interval, there is significant wavelet power in three ranges: ∼6–6.5 minutes (AIA EUV and UV), ∼9–10 minutes (AIA EUV and UV; magnetic field density), and ∼16–17 minutes (EUV). The Mg ii k chromospheric flux is modulated by the variations in the BP area and exhibits peak power in the ranges ∼9–10 and 16–17 minutes. The BP is characterized by a complex magnetic structure with a dominant negative-polarity footpoint and three positive-polarity footpoints connected by short extrapolated magnetic field lines. The Mg ii k intensity tends to be localized at the footpoints, whereas the coronal emission predominantly occurs at the loop tops. The BP region is mainly redshifted, but the footpoints present Doppler velocities in the ranges −17 to 14 km s −1 (negative polarity) and −12 to 8 km s −1 (positive polarity). For ∼6 minutes, the negative-polarity footpoint shows an upflow, while the positive-polarity footpoints are redshifted. The velocities along the field lines connecting the footpoints, which could serve as a proxy for a low-lying loop, show a gradual variation in orientation and value, suggesting possible plasma propagation along a loop.