Hα, hard X-ray, and microwave emissions in the impulsive phase of solar flares

The observational relationship between the location of flare sites in active regions and three other observables, viz., Hα line width, hard X-ray burst parameters, and peak microwave fluxes has been studied. Results suggested that the strength of the magnetic field plays a role in governing the magnitudes of these emissions. Qualitative relationships are derived on the assumption of proportionality between the spectral maximum frequency of the associated microwave burst and the field strength in the microwave source. The relationship inferred between the power in thick target electrons (derived from the hard X-ray burst) and the column density of second-level hydrogen atoms (derived from the Hα line widths) is compared with calculations by Brown (1973) and Canfield (1974). The line widths observed for two white light flares suggest that a criterion for detectable continuum emission in disk flares is an Hα line width >approximately 20 A. (Auth.)