Refractive radio scintillation in the solar wind

Abstract

The strong radio source 3C279 has been observed with the Very Large Array radio interferometer when the source was at a solar elongation of 0.9 deg. The visibilities were measured with a time resolution of 6.67 s. Convincing evidence of slow variations in the flux has been interpreted as refractive scintillation caused by large-scale density inhomogeneities in the solar wind. Furthermore, it was found that the angular size of the scatter-broadened image of 3C279 fluctuates in a correlated fashion with the flux. This effect, which had been predicted theoretically, is verified here for the first time.