High resolution observations of motions and structure of prominence threads
Hα profiles and filtergrams were obtained of quiescent prominences at the National Solar Observatory, Sunspot, NM, with spatial resolution better than 1.6 arcseconds. The Hα profiles of individual threads are often Gaussian, but may show marked asymmetries, particularly near the prominence edges. Filtergrams, taken at ± 0.7 Å (± 30 km/sec) in Hα (with a 0.18 Å passband) show high speed knots and threads at the prominence edges, that persist with no perceptible change for at least 10 minutes. This result implies plasma motions (along essentially horizontal magnetic fields) over distances as large as 18000 km, i.e. much larger than typical thicknesses (5000 km) of Hα filaments. These motions may be associated with thread formation or decay, but continuous observations of this prominence over 6 hours show that the large-scale form of the prominence remained unchanged.