An estimate of the magnetic field strength associated with a solar coronal mass ejection from low frequency radio observations

TL;DR

This study estimates the magnetic field strength of a solar coronal mass ejection using low frequency radio observations, providing specific measurements at different frequencies and corresponding solar distances.

Contribution

It introduces a method to estimate magnetic field strengths in CMEs from ground-based low frequency radio data, with specific measurements at 80 and 40 MHz.

Findings

Magnetic field near the CME source is approximately 2.2 G at 80 MHz.

Magnetic field is approximately 1.4 G at 40 MHz.

Corresponding radial distances are about 1.9 and 2.2 solar radii.

Abstract

We report ground based, low frequency heliograph (80 MHz), spectral (85-35 MHz) and polarimeter (80 and 40 MHz) observations of drifting, non-thermal radio continuum associated with the `halo' coronal mass ejection (CME) that occurred in the solar atmosphere on 2013 March 15. The magnetic field strengths ($B$) near the radio source were estimated to be $B \approx 2.2 \pm 0.4$ G at 80 MHz and $B \approx 1.4 \pm 0.2$ G at 40 MHz. The corresponding radial distances ($r$) are $r \approx 1.9~R_{\odot}$ (80 MHz) and $r \approx 2.2~R_{\odot}$ (40 MHz).