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[54.10] Observations of Doppler Shift Oscillations with the Bragg Crystal Spectrometer on Yohkoh

J. T. Mariska (Naval Research Laboratory)

Oscillations in solar coronal loops appear to be a common phenomenon. Transverse and longitudinal oscillations have been observed with both the TRACE and EIT imaging experiments. Damped Doppler shift oscillations have been observed in emission lines from ions formed at flare temperatures with the SUMER experiment on SOHO. These observations provide valuable diagnostic information on coronal conditions and may help refine our understanding of coronal heating mechanisms. We have initiated a study of the time dependence of Doppler shifts measured during flares with the Bragg Crystal Spectrometer on Yohkoh. In this presentation, we report some initial results on Doppler shifts as a function of time measured in the emission lines of \ion{S}{15} and \ion{Ca}{19}. For some flares, both lines exhibit damped Doppler shift oscillations with amplitudes of a few km~s^-1 and periods and decay times of a few minutes.

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Bulletin of the American Astronomical Society, 36 #2
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