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

TL;DR

This study uses high-cadence, multiwavelength optical observations with the Rapid Dual Imager to detect and analyze high-frequency oscillations in a solar active region, revealing new insights into plasma motions and flows.

Contribution

It introduces the Rapid Dual Imager system and applies wavelet analysis to identify significant high-frequency oscillations in a solar active region.

Findings

Detected oscillations with periods from 20 to 370 seconds.

H-alpha blue wing shows more penumbral oscillations than G-band.

Oscillations indicate plasma motions at about 20 km/s and suggest enhanced Evershed flow.

Abstract

High-cadence, synchronized, multiwavelength optical observations of a solar active region (NOAA 10794) are presented. The data were obtained with the Dunn Solar Telescope at the National Solar Observatory/Sacramento Peak using a newly developed camera system : the Rapid Dual Imager. Wavelet analysis is undertaken to search for intensity related oscillatory signatures, and periodicities ranging from 20 to 370 s are found with significance levels exceeding 95%. Observations in the H-alpha blue wing show more penumbral oscillatory phenomena when compared to simultaneous G-band observations. The H-alpha oscillations are interpreted as the signatures of plasma motions with a mean velocity of 20 km/s. The strong oscillatory power over H-alpha blue-wing and G-band penumbral bright grains is an indication of the Evershed flow with frequencies higher than previously reported.