Coronal magnetic field value radial distributions obtained by using the information on fast halo coronal mass ejections

TL;DR

This study extends the radial profiling of coronal magnetic fields using fast halo CMEs, reaching farther into the corona and suggesting improvements for magnetic field estimation accuracy.

Contribution

It applies a method to determine magnetic field distributions along the Sun-Earth line using 3D CME data, extending the radial range beyond previous studies.

Findings

Magnetic field profiles extend up to 43 solar radii.

Develops a technique to select CMEs in slow solar wind.

Suggests improving magnetic field estimation accuracy.

Abstract

Based on the method of finding coronal magnetic field value radial profiles B(R) described in (Gopalswamy and Yashiro, 2011), and applied for the directions close to the sky plane, we determined magnetic field value radial distributions along the directions close to the Sun-Earth axis. For this purpose, by using the method in (Xue, Wang, and Dou, 2005), from the SOHO/LASCO data, we found 3D characteristics for fast halo coronal mass ejections (HCMEs) and for the HCME-related shocks. Through these data, we managed to obtain the B(R) distributions as far as 43 solar radii from the Sun center, which is approximately by a factor of 2 farther, than those in (Gopalswamy and Yashiro, 2011). We drew a conclusion that, to improve the accuracy of the Gopalswamy-Yashiro method to find the coronal magnetic field, one should develop a technique to detect the CME sites that move in the slow and in the fast solar wind. We propose a technique to select the CMEs, whose central (paraxial) part moves, indeed, in the slow wind.