Physical Processes in the “Feet” of Solar Prominences
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Spectrograms of hydrogen Hα and helium D3 were obtained with a large non-eclipsing coronagraph on November 21, 2012 and July 20, 2015 for a study of the velocities of the plasma in prominences at the Abastumani Astrophysical Observatory. An analysis of this data yielded the following major results: an asymmetry is observed in the time variations in the Doppler velocities and half widths of the Hα prominences. This asymmetry appears in roughly 40% of the 227 spectrograms that were studied. This kind of asymmetry is observed in 70% of the 320 D3 spectrograms that were studied. In the “feet” of the Hα prominences, the Doppler velocities vary over a range of approximately -9 to -15 km/s, and in the “feet” of the D3 prominences, from -8 to -18 km/s. For the Hα prominences the period of the oscillations in the velocity varies over 3-5 min and the period of the oscillations in the half width ranges from 5 to 12 min. For the D3 prominences the period of the oscillations in the Doppler velocities varies over 7-10 min, and the period of the oscillations in the half width ranges from 5-10 min.
Keywordssun: prominences: “feet” of prominences
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