Coronal Magnetic Structures Observing Campaign. III. Coronal Plasma and Magnetic Field Diagnostics Derived from Multiwaveband Active Region Observations
Abstract
Simultaneous soft X-ray, microwave, and photospheric magnetic field observations were taken during the Coronal Magnetic Structures Observing Campaign (CoMStOC '87). The plasma electron temperature and emission measures determined from the X-ray data are used to predict the free-free emission expected at 20 and 6 cm. Comparing these predictions with the microwave observations, it is found that the predicted 20 cm brightness temperatures are higher than the observed, requiring cool absorbing material between the hot X-ray plasma and the observer. The model that is most consistent with all the observations and minimizes the required coronal fields indicates that this 20 cm emission is either free-free or a combination of free-free and fourth harmonic cyclotron emanating from the X-ray plasma with an electron temperature of approximately 3.1 x 106 K and an emission measure of approximately 1.3 x 1029/cm5. The observed 20 cm polarization requires a field strength of greater than or equal to 150 G. In addition, the 6 cm emission is free-free, emanating from cooler plasma with an electron temperature of approximately 1.5 x 106 K and an emission measure of approximately 3-6 x 1029/cm5. This model is consistent with the rather unusual combination of high 20 cm and low 6 cm polarization as well as the low extrapolated coronal fields.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 1994
- DOI:
- 10.1086/174781
- Bibcode:
- 1994ApJ...434..786S
- Keywords:
-
- Brightness Temperature;
- Circular Polarization;
- Electron Energy;
- Magnetic Field Configurations;
- Magnetic Signatures;
- Radio Astronomy;
- Solar Corona;
- Stellar Models;
- X Ray Astronomy;
- X Ray Spectra;
- Calcium;
- Iron;
- Magnesium;
- Neon;
- Oxygen;
- Radio Interferometers;
- Solar Maximum Mission;
- Spectrometers;
- Very Large Array (Vla);
- X Ray Telescopes;
- Solar Physics;
- POLARIZATION;
- SUN: CORONA;
- SUN: MAGNETIC FIELDS;
- SUN: RADIO RADIATION