Rotation of a Stealth CME on 2012 October 5 Observed in the Inner Heliosphere

TL;DR

This study documents the continuous rotation and tilt increase of a stealth CME observed from the Sun to L1, emphasizing the importance of heliospheric imaging for understanding CME evolution and space weather impacts.

Contribution

It provides the first detailed observation of CME rotation using combined coronagraphic and heliospheric imaging, bridging near-Sun and in-situ measurements.

Findings

CME exhibited a continuous tilt increase up to 58 solar radii.

Tilt further increased at L1 based on flux rope fitting.

Heliospheric Imager observations are crucial for CME tracking.

Abstract

Coronal Mass Ejections (CMEs) are subject to changes in their direction of propagation, tilt, and other properties. This is because CMEs interact with the ambient solar wind and other large-scale magnetic field structures. In this work, we report on the observations of the 2012 October 5 stealth CME using coronagraphic and heliospheric images. We find clear evidence of a continuous rotation of the CME, i.e., an increase in the tilt angle, estimated using the Graduated Cylindrical Shell (GCS) reconstruction at different heliocentric distances, up to 58 solar radii. We find a further increase in the tilt at L1 estimated from the toroidal and cylindrical flux rope fitting on the in situ observations of IMF and solar wind parameters. This study highlights the importance of observations of Heliospheric Imager (HI), onboard the Solar TErrestrial RElations Observatory (STEREO). In particular, the GCS reconstruction of CMEs in HI field-of-view promises to bridge the gap between the near-Sun and in-situ observations at the L1. The changes in the CME tilt has significant implications for the space weather impact of stealth CMEs.