Fine Scale Radio Studies of the Sun.

Abstract

Abstract : Very Large Array (V.L.A.) synthesis maps at 6 cm wavelength are presented for six different active regions on seven different days scattered over a one and a half year period. In every case the active region has been resolved into one or more small (approx. 20-in.), bright (approx 1000000 K) highly circularly polarized (30% to 100%) sources which dominate active region emission at 6 cm wavelength. Although each small bright source and each active region has one dominant magnetic polarity, several active regions contained a few small bright sources with opposite senses of circular polarization. Comparisons of the syntheses maps of total intensity with H alpha photographs of the same active regions indicate that the enhanced 6 cm emission is well correlated with the chromospheric plage seen as bright regions on the H alpha photographs, and that there is often no similar enhanced 6 cm emission in the regions which directly overlay sunspots. The large brightness temperatures of the regions of enhanced 6 cm emission indicate an origin in the coronal atmosphere above active regions whereas comparisons of the synthesis maps of circular polarizaiton with magnetograms of the underlying photosphere indicate that these maps act as coronal magnetograms. We also present observations of solar flares using the Owens Valley interferometer at 2.8 wavelength.