Temperature Distributions and Energy Scaling Law of Solar Coronal Loops Obtained with YOHKOH
Abstract
We derived the temperature distributions along the 16 steady loops observed with the Yohkoh Soft Xray Telescope. We have found that the temperature and emission measure (pressure) are the highest around the loop top, and decrease towards the footpoints. Some of the loops have a plateau in the temperature distribution at around the loop top (``trapezoidal'' temperature distribution). The other loops, on the other hand, have a sharp peak in the temperature distributions (``triangular'' temperature distribution). This triangular temperature distribution suggests that the energy input is concentrated at the peak. We have estimated the thermal conductive fluxes downward to the footpoints from the gradients of the temperature distributions. The flux ranges from 1 times 10(7) to 2 times 10(8) [erg s(1) cm(2) ]. We derived the total energy loss {cal L}_T, which is the sum of the conductive and radiative losses: {cal L}_T= 2 times 10(7) 3 times 10(8) [erg s(1) cm(2) ]. We discovered a good correlation between the total energy loss and the gas pressure p_g for the steady loops: {cal L}_T = 1.2 times 10(7) p_g({0.99+/) 0.12}. The correlation is consistent with the theoretical energy scaling law for the steady loops: {cal L}_T = 4.0  5.1 times 10(3) * (p_g * T_m(1/2) ), where T_m is the maximum temperature (T_m ~ 6 times 10(6) [K] for all the loops analyzed here). } % % Key word %
 Publication:

Publications of the Astronomical Society of Japan
 Pub Date:
 June 1996
 DOI:
 10.1093/pasj/48.3.535
 Bibcode:
 1996PASJ...48..535K
 Keywords:

 MAGNETOHYDRODYNAMICS;
 SUN: ACTIVITY;
 SUN: CORONA;
 SUN: XRAYS