Metric Radio Observations of the Evolution of a "Halo" Coronal Mass Ejection Close to the Sun

Abstract

We report direct imaging observations of the propagation of a diffuse thermal radio enhancement in close temporal and spatial association with a "halo" coronal mass ejection from the solar atmosphere, in the metric wavelength regime. The speed and acceleration of the latter in the low corona were estimated in an independent manner from the displacement of the associated radio features, and the average values are 1136 ± 73 km s-1 and 157 ± 121 m s-2, respectively. The brightness temperature and electron density of the enhancement were found to be ≈1.92 × 105 K and 2.81 × 107 cm-3 at a distance of 2.7 R☉ from the center of the Sun. We also computed the magnetic field strength of the enhancement at the above height, and the value is ≈0.86 G. The mass of the radio enhancement increased by a factor of ~2 during our observing period.