High-Frequency Oscillations in a Solar Active Region observed with the Rapid Dual Imager

摘要

High-cadence, synchronized, multiwavelength optical observations of a solaractive region (NOAA 10794) are presented. The data were obtained with the DunnSolar Telescope at the National Solar Observatory/Sacramento Peak using a newlydeveloped camera system : the Rapid Dual Imager. Wavelet analysis is undertakento search for intensity related oscillatory signatures, and periodicitiesranging from 20 to 370 s are found with significance levels exceeding 95%.Observations in the H-alpha blue wing show more penumbral oscillatory phenomenawhen compared to simultaneous G-band observations. The H-alpha oscillations areinterpreted as the signatures of plasma motions with a mean velocity of 20km/s. The strong oscillatory power over H-alpha blue-wing and G-band penumbralbright grains is an indication of the Evershed flow with frequencies higherthan previously reported.