V.L.A. Observations of Solar-Active Regions. I. The Slowly Varying Component,
Abstract
Very Large Array (V.L.A.) synthesis maps of the total intensity and the circular polarization of the active region AR 2032 at 6 cm wavelength are presented and compared with H alpha photographs and Zeeman effect magnetograms of the same region with second-of-arc accuracy. The maps indicate that the radio emission is dominated by a small (approx. 30 inches), bright (10 to the 6th power K), circularly polarized (40% to 100%) source whose detailed morphological features are correlated with the chromospheric plage seen as bright regions on the H alpha photographs. The large brightness temperatures of the radio features indicate that they are the coronal counterparts of the chromospheric plage. The regions of enhanced emission at 6 cm wavelength exhibited substantial structural changes on a time scale of one day, and these changes were correlated with similar changes in the chromospheric plage. Weak or undetectable radio emission was found in the regions directly overlying sunspots; but two small (approx. 10 inches), bright (approx. 10 to the 6th power K) radio sources were found at the outer edges of one sunspot where the magnetic field gradient is large. Although the degree of circular polarization varied from 40% to 100% in different regions of the dominant, plage-associated source, the entire source had one magnetic polarity and the general magnetic structure was correlated with the longitudinal magnetic field seen on magnetograms of the lower lying photosphere.
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 01, 1980
- Accession Number
- ADA091722
Entities
People
- Kenneth R. Lang
- Marcello Felli
- Robert F. Willson
Organizations
- Tufts University