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

Astronomy and Astrophysics (Impact Factor: 5.08). 07/2007; DOI: 10.1051/0004-6361:20077142
Source: arXiv

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. Comment: 9 pages, 9 figures

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