Ultraviolet spectral diagnostics of solar flares and heating events
Thesis/Dissertation
·
OSTI ID:5412806
Heating processes in the outer solar atmosphere manifest themselves in continuous and discrete phenomena ranging from the largest solar flares down to the smallest events discernible with present instruments. This thesis addresses two such phenomena as seen in ultraviolet observations of the solar transition zone: data obtained with the Solar Maximum Mission (SMM) satellite are found to reveal the presence of frequent and rapid brightenings in ultraviolet line emission in active regions, and observations obtained with the NRL Slitless Spectroheliograph on Skylab are analyzed to determine the role of the helium resonance lines in the energy balance of a large class M flare. SMM observations with high spatial and temporal resolution at small bright sites in active regions show significant increases in intensity in spectral lines of Si IV and O IV on short time scales. Intensity increases of 20 - 100% are common and typically last 40 - 60s. These characteristics suggest that topological dissipation of energy stored in the magnetic field is occurring more frequently and on smaller spatial scales than previously observed. Such events may constitute a large fraction of the energy budget of the outer solar atmosphere.
- Research Organization:
- Colorado Univ., Boulder (USA)
- OSTI ID:
- 5412806
- Country of Publication:
- United States
- Language:
- English
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