Prominence Motions Observed at High Cadences in Temperatures from 10 000 to 250 000 K
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We report here for the first time observations of prominence velocities over a wide range of temperatures and with a high time cadence. Our study of ultraviolet movies of prominences reveals that multi-thermal features with speeds of 5–70 km s−1 perpendicular to the line of sight are common in the prominences which showed traceable motions. These speeds are noticeably higher than the typical speeds of 5–20 km s−1 observed in Hα data from `quiet' prominences and are more typical of `activated' prominences in which speeds of up to 40 km s−1 have been reported. The observations were performed using five separate datasets taken by the Solar and Heliospheric Observatory's Coronal Diagnostic Spectrometer (SOHO/CDS) in its wide slit overlappogram mode in lines from He i, O v, and Mg ix and a separate prominence observation taken with both the Transition Region and Coronal Explorer (TRACE) in its 1216 and 1600 Å bands and in Hα by the Swedish Vacuum Solar Telescope (SVST) at La Palma. The movies were taken with cadences >1 image per minute and were made simultaneously or near-simultaneously in spectral lines formed at two or more temperatures. We traced motion that lasted for 3 to 20 min and went distances up to 105 km. Most, but not all, of these were chiefly horizontal. In many cases we were able to observe the same motions over temperature ranges from 20 000 to 250 000 K or 10 000 to 100 000 K. Observations are compared with model predictions.
KeywordsModel Prediction Spectral Line Transition Region Time Observation High Time
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