SIMBAD references

Observed parameters for 208 small flares with GOES classification B5 to C2 are discussed using data from the broad-band detectors on the Geostationary Operational Environmental Satellites (GOES) and the Bragg Crystal Spectrometer (BCS) on the Yohkoh solar flare spacecraft. Peak temperatures derived from He-like sulfur spectra are in the range 8±2x10⁶K and are similar to those derived from the ratio of the 1-8A and 0.5-4A GOES channels, but a little less than those from He-like calcium spectra, showing that even these small flares are non-isothermal. The absence of He-like iron emission shows that the temperatures are less than 14x10⁶K. There is a slight positive correlation between temperature and emission measure from the calcium and sulfur data. Differences in this distribution and that derived for larger flares in a separate study can be reconciled in terms of the fact that temperatures were measured from He-like iron spectra for the larger flares. The emission measure of the flares in our sample are correlated with GOES class. A detailed study of a subset of 20 flares shows that the temperatures generally reach peak flux slightly before (up to 30s) or coincident with the light curve maximum. It is found that even small flux enhancements which are frequently present are associated with temperature enhancements.