Comprehensive Observations of a Solar Minimum CME with STEREO

TL;DR

This study presents a detailed kinematic analysis of a solar minimum CME observed by STEREO, combining imaging and in situ data from multiple spacecraft to improve understanding of CME behavior and space weather prediction.

Contribution

First comprehensive analysis of a CME using combined imaging and in situ data from STEREO, revealing insights into its angular extent and multi-perspective observations.

Findings

CME was observed differently from various viewpoints.

Continuous coverage enhances confidence in kinematic assessments.

Evidence suggests the CME had a narrow angular extent.

Abstract

We perform the first kinematic analysis of a CME observed by both imaging and in situ instruments on board STEREO, namely the SECCHI, PLASTIC, and IMPACT experiments. Launched on 2008 February 4, the CME is tracked continuously from initiation to 1 AU using the SECCHI imagers on both STEREO spacecraft, and is then detected by the PLASTIC and IMPACT particle and field detectors on board STEREO-B. The CME is also detected in situ by ACE and SOHO/CELIAS at Earth's L1 Lagrangian point. The CME hits STEREO-B, ACE, and SOHO on 2008 February 7, but misses STEREO-A entirely. This event provides a good example of just how different the same event can look when viewed from different perspectives. We also demonstrate many ways in which the comprehensive and continuous coverage of this CME by STEREO improves confidence in our assessment of its kinematic behavior, with potential ramifications for space weather forecasting. The observations provide several lines of evidence in favor of the observable part of the CME being narrow in angular extent, a determination crucial for deciding how best to convert observed CME elongation angles from Sun-center to actual Sun-center distances.