Engineering topics
Publications and source records attributed to Dwivedi, B. N..
We present new calculations for several solar ions in the temperature range 10(exp 5) is less than T is less than 10(exp 6) K and discuss their diagnostic applications with the help of available observational data. In particular, we rediscuss the plasma density and temperature in the source region of the solar wind. We also study the variation of relative elemental abundances in the solar atmosphere and compare them with previous studies.
Morphological features of two-ribbon flares have been studied, using simultaneous ISEE-3 hard X-ray records and high-resolution Big Bear H-alpha movies for more than 20 events. Long-lasting and complex hard X-ray bursts are almost invariably found associated with flares of the two-ribbon type. At least three events are found, namely March 31, 1979, April 10, 1980, and July 1, 1980, where the occurrence of individual spikes in hard X-ray radiation coincides with suddenly enhanced H-alpha emission covering the sunspot penumbra. There definitely exist important (greater than or equal to 1 B) two-ribbon flares without significant hard X-ray emission.
It is noted that recent gamma-ray observations of solar flares have provided a better means for estimating the heating of the solar atmosphere by energetic protons. This type of heating has been suggested as the explanation of the continuum emission of the white-light flare. The effects on the photosphere of high-energy particles capable of producing the intense gamma-ray emission observed in the flare of July 11, 1978, are analyzed. A simple energy-balance argument is used, and hydrogen ionization is taken into account. It is found that energy deposition increases with height for the inferred proton spectra and is not strongly dependent upon the assumed angle of incidence. At the top of the photosphere, the computed energy inputs fall in the range 10-100 ergs/cu cm-s.