VLA STEREOSCOPY OF SOLAR ACTIVE REGIONS .2. ALTITUDE, RELATIVE MOTION, AND CENTER-TO-LIMB DARKENING OF 20 CENTIMETER EMISSION

A newly developed method of stereoscopic correlation is applied to sol ar radio maps at a wavelength of 20 cm. On the basis of stereoscopic c orrelations..between radio maps obtained on 6 different days we establ ish the presence of 66 radio source components associated with 22 acti ve regions. We find the following statistical results for active regio n source structures at 20 cm: 1. The observed lifetime is consistent w ith an exponential distribution having an e-folding time scale of > 18 days. 2. The average altitude of 20 cm sources is 25 +/- 15 Mm; 90% o f the sources are found in heights < 40 Mm. 3. The average diameter of discrete source structures is 48 +/- 15 Mm, implying a vertical/horiz ontal aspect ratio of q(A) almost-equal-to 0.5. 4. No significant sour ce motion has been found with respect to the standard differential rot ation rate of OMEGA = 13.45-degrees - 3-degrees sin 2 B. 5. We find a statistical limb darkening, which can be described by the relation T(B )(alpha)/T(B)(0) = 0.4 +/- 0.6 cos2 alpha for sources with T(B) > 0.5 MK.6. The degree of source polarization is 15% +/- 10% and is independ ent of source location. 7. Bright sources (greater-than-or-equal-to 0. 5 MK), or equivalently, long-lived sources (greater-than-or-similar-to 5 days) show a systematic variation of their altitude as function of the center-limb distance. We investigated a number of homogeneous and inhomogeneous active region models and found that inhomogeneous (both temperature and density) models are required to reproduce all observat ional constraints.