CORONAL MAGNETIC-STRUCTURES OBSERVING CAMPAIGN .2. MAGNETIC AND PLASMA PROPERTIES OF A SOLAR ACTIVE REGION

Simultaneous soft X-ray, microwave, and photospheric magnetic field observations were taken during the Coronal Magnetic Structures Observing Campaign (CoMStOC). The plasma electron temperatures and emission measures determined from the X-ray data are used to predict the intensity and structure of the thermal bremsstrahlung emission at 20 and 6 cm. Comparing these predictions with the microwave observations, it is found that the 20 cm structure is very similar to that expected from the X-rays, but a substantial amount of the 6 cm emission was resolved out. The predicted 20 cm brightness temperatures are higher than the observed, requiring cool absorbing material (T(e) less-than-or-equal-to 500,000 K) between the hot X-ray plasma and the observer. The absorption mechanism in the cool plasma at 20 cm is most likely thermal bremsstrahlung, requiring coronal magnetic fields as high as 150 G. ''Coronal Magnetograms,'' made by extrapolating the photospheric longitudinal field using the Sakurai code, show that appropriate values of the total field are reached at heights of 6000-10,000 km above the photosphere (at many but not all locations). The model proposed to explain the full set of observations requires polarization inversion of the 20 cm emission high in the solar atmosphere where the longitudinal component of the magnetic field reverses direction (where the magnetic field is transverse to the line of sight). Such a reversal is found with the magnetic field extrapolation code. At 6 cm, the polarization modes must be strongly coupled so that no polarization inversion is observed. These results require a density approximately 10(8) cm-3 at the location of the field reversal.