1 US Government, Department of Commerce, NOAA, Space Environment Center,325 Broadway, MS: R/E/SE, Boulder, Colorado, USA 80303

2 Astronomical Institute, 251 65 ONDREJOV, Czech Republic

A theory-based scaling law derived by Hawley et al.(1995) and Metcalf and Fisher (1996) relates the flaring loop length to the rise time, decay time and the loop top temperature. The latter authors also measured the loop lengths of a number of flares (19) occurring in 1992 and 1993 that were imaged by the Yohkoh SXT experiment. Using the Metcalf and Fisher data Garcia (1998) found an empirically strong correlation between the loop lengths and the decay times, a weaker correlation with the rise times (in soft X-rays), but essentially no correlation with the flare temperature. The present work is intended to further quantify this important relationship by enlarging the number and variety of measured flare loops using more recent data collected during the current solar cycle by the SXT experiment, augmented where available, with loop imagery obtained from the SOHO EIT and TRACE experiments. These findings have potential application to studies of flare dynamics, e.g., volumetric heating, cooling, density and temperature structure. However, the main significance lies in the utility of a proxy relationship between the temporal X-ray light curves and the spatial dimension of coronal features that are not amenable to direct observation, viz., active stars and the vast reservoir of spatially unresolved X-ray observations of the solar corona.

References:

Garcia, H.A. 1998, ApJ, 504,1051.

Hawey, S.L.,et al. 1995, ApJ, 453, 464.

Metcalf, T.R. and Fisher, G.H. 1996, ApJ, 462, 977.