Propagation of Interplanetary Shocks in the Heliosphere

TL;DR

This paper investigates the properties and shapes of interplanetary shocks in the Heliosphere using spacecraft data, revealing how different drivers and shock orientations influence their structure and behavior.

Contribution

It provides a detailed analysis of two interplanetary shock events, highlighting the variations in shock parameters and shapes using multiple measurement techniques.

Findings

Shock parameters are consistent during the May 07 event.

The shock surface is tilted similarly to the Parker spiral.

The April 23 shock shows a twisted shape due to a fast-reverse shock.

Abstract

Interplanetary shocks are one of the crucial dynamic processes in the Heliosphere. They accelerate particles into a high energy, generate plasma waves, and could potentially trigger geomagnetic storms in the terrestrial magnetosphere disturbing significantly our technological infrastructures. In this study, two IP shock events are selected to study the temporal variations of the shock parameters using magnetometer and ion plasma measurements of the STEREO$-$A and B, the Wind, Cluster fleet, and the ACE spacecraft. The shock normal vectors are determined using the minimum variance analysis (MVA) and the magnetic coplanarity methods (CP). During the May 07 event, the shock parameters and the shock normal direction are consistent. The shock surface appears to be tilted almost the same degree as the Parker spiral, and the driver could be a CIR. During the April 23 event, the shock parameters do not change significantly except for the shock $\theta_{Bn}$ angle, however, the shape of the IP shock appears to be twisted along the transverse direction to the Sun-Earth line as well. The driver of this rippled shock is SIRs/CIRs as well. Being a fast-reverse shock caused this irregularity in shape.