Dynamical Phenomena in Sunspots.
Final rept. 1 Mar-31 Jul 82,
ROCHESTER UNIV NY DEPT OF MECHANICAL ENGINEERING
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Observations were taken of a sunspot on August 18 and 21, 1980 with high spatial and temporal resolution, in spectral lines formed in the photosphere and chromosphere. The data has been reduced and the results of the analysis are given in this report. A typical moving magnetic feature MMF was observed in velocity, intensity, and magnetic field. New information included an observed downflow of 400ms centered in the feature. The lifetime of the MMF is dependent on the type of observation and needs to be defined clearly. The umbral flashes and umbral oscillations are the same feature with different amplitudes. The flash seems due to saturation of the film. With high resolution it is shown that the umbral oscillations exhibit a characteristic Z pattern when the Calcium II H profiles is plotted in a time series. Five-minute oscillations were clearly detected in the sunspot photosphere. They are the passive response of the umbra to the global p-mode oscillations of the quiet photosphere. The particular modes observed depend on the geometry of the sunspot at different depths. The observations can be used as a probe of sunspot structure below the visible surface. Author