Deflected propagation of a coronal mass ejection from the corona to interplanetary space

TL;DR

This study provides evidence that a coronal mass ejection (CME) can undergo significant deflection in interplanetary space, influenced by solar wind interactions, affecting its likelihood of impacting Earth.

Contribution

It demonstrates for the first time that CMEs can be deflected in interplanetary space, not just in the corona, and identifies solar wind interaction as a key cause.

Findings

CME was deflected more than 20 degrees westward in interplanetary space.

Deflection affects the probability of CME hitting Earth.

Interaction with solar wind causes the interplanetary deflection.

Abstract

Among various factors affecting the space weather effects of a coronal mass ejection (CME), its propagation trajectory in the interplanetary space is an important one determining whether and when the CME will hit the Earth. Many direct observations have revealed that a CME may not propagate along a straight trajectory in the corona, but whether or not a CME also experiences a deflected propagation in the interplanetary space is a question, which has never been fully answered. Here by investigating the propagation process of an isolated CME from the corona to interplanetary space during 2008 September 12 -- 19, we present solid evidence that the CME was deflected not only in the corona but also in the interplanetary space. The deflection angle in the interplanetary space is more than 20 degrees toward the west, resulting a significant change in the probability the CME encounters the Earth. A further modeling and simulation-based analysis suggest that the cause of the deflection in the interplanetary space is the interaction between the CME and the solar wind, which is different from that happening in the corona.