Temporal variations of solar flare spectral properties: Hard x-ray fluxes and Fe XXV, Ca XIX, and wideband soft x-ray fluxes, temperatures, and emission measures

We present fluxes, temperatures, and emission measures for nine solar hares, using data from both the Fe XXV and Ca XIX channels of the Bragg Crystal Spectrometer (BCS) experiment on the Yohkoh satellite and from the wide-band soft X-ray spectrometers on the GOES spacecraft. We also present hard X-ray fluxes from the Hard X-ray Telescope (HXT) on Yohkoh and the BATSE spectrometer on the Compton Gamma-Ray Observatory (CGRO). All events occurred during 1992 and ranged in size from GOES class C5 to M2. Three of the events occurred near the solar limb. For each flare we give two sets of plots. The first set shows flax, electron temperature, and emission measures for Fe XXV, Ca XIX, and GOES as functions of time. The second set of plots gives log electron temperature as functions of log (emission measure)(1/2) for these three wavelength ranges; we refer to these plots as E-1/2-T diagrams. Hard X-ray flux information is included in both sets of plots. Our observations indicate that (1) cooler plasmas are located along the legs of, or are evenly distributed along, the flaring loops, while hotter plasmas are concentrated near the loop tops, (2) peaks in temperature in each of the wavelength bands are closely associated with hard X-ray enhancements, and (3) the emission from both relatively hot and relatively cool flaring plasmas emanates from the same loop or from closely related loops.