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Session 1 - Chromosphere, Corona, Flares.
Display session, Friday, June 27
Ballroom B, Chair: Charles Kankelborg
This analysis of a solar flare's macro thermodynamic-spatial structure is based on the RTV model of the dynamics of quies cent solar coronal forms (Rosner,Tucker and Vaiana,1978) and full disk soft X-ray measurements by the GOES two-channel soft X-ray sensor. The RTV model provides a relationship between maximum (loop top) temperature, T_m, and the semi- loop length, L. In order to reconstruct the flare's thermo- dynamic macro structure utilizing the RTV law one must know or be able to solve for T_m and the internal pressure, p (the latter assumed spatially constant at fixed times). From the GOES dual X-ray measurement one can derive the spatially averaged temperature, T_av, and the emission measure, EM, at any point during the flare. Treating these two derived parameters as measurements one can solve for the unknowns p and T_m if the loop length L can be independently specified. The constant crossection A can be deduced from L utilizing the theoretical relationship of the ratio L/A to T_m and EM (Sylwester,1988). Once the flare's L and A are specified one can numerically integrate over the full semi-length to compute density, X-ray emission, and the differentials of of volume, thermal energy and emission measure for equal increments of temperature; compare the computed T_av and EM with their observed (derived) values; and recover T_m and p by linearized iterative solutions. As noted everything depends on the availability of an independently obtained L. Fortunately L bears a robust physical relationship with the flare's rise and decay times and peak temperature. Metcalf and Fisher (1996) and predecessors (Fisher and Hawley, 1990; Hawley et al.,1995) have developed algorithms which permit the loop length to be estimated from X-ray light curves. These data are used to initiate a solution which not only yields T_m and p but collaterally determines L as well. Fourteen cases are discussed comparing thermodynamic results with Yohkoh SXT measured loop data.
Fisher, G.H. amp; Hawley, S.L. 1990, ApJ, 357, 243 Hawley, S.L., et al. 1995, ApJ, 453, 464 Metcalf, T.R. amp; Fisher, G.H. 1996, ApJ, 462, 977 Rosner, R., Tucker, W.H. amp; Vaiana, G.S. 1978, ApJ, 220, 643 Sylwester, J. 1988, Adv. Space Res. Vol.8, No.11, 55
Program listing for Friday