The shape and dynamics of coronal mass ejections (CMEs) varies significantly based on the instrument and wavelength used. This has led to significant debate about the proper definitions of CME/shock fronts, pile-up/compression regions, and cores observed in projection in optically thin vs. optically thin emission. As part of our work on advanced characterization of solar eruptions, we have performed observational analysis of the evolving shape and kinematics of a large-scale CME that occurred on May 7, 2021 on the eastern limb of the Sun as seen from the Earth. This is a rare eruption, because it was observed continuously by space- and ground-based instruments: consecutively by the Atmospheric Imaging Assembly (AIA) telescope suite on the Solar Dynamics Observatory (SDO) satellite, the ground-based COronal Solar Magnetism Observatory (COSMO) K-coronagraph (K-Cor) on Mauna Loa in Hawaiii, and the C2 and C3 telescopes of the Large Angle Solar Coronagraph (LASCO) on the Solar and Heliospheric Observatory (SoHO) satellite. Currently, the vast majority of eruptive events are only observable in AIA and LASCO, with a gap between the fields of view of these instruments.
Applying the Wavetrack software successfully to three separate types of observations in this study boosts our confidence in its functionality and applicability. Its use allows us to directly overlay feature masks from separate instruments. It also allows us to provide answers to two important questions: 1. How does the CME shape evolve from the lower to the outer corona? 2. Is there a correspondence between the EUV wave and the CME front? Examination of the multi-instrument results suggests a strong correspondence between the CME features seen in the three instruments, shown in the figure below. This has not been reported previously. This study is being written up and will be submitted to a refereed journal shortly.
A sequence of eight composite images, showing a Wavetrack-tracked CME that occurred 07/05/2021 off the eastern solar limb. AIA pixel masks are shown in yellow, K-Cor pixel masks are in gray, and SOHO/LASCO C2 masks are in red, overlaid on AIA 193-angstrom images of the Sun as background (orange hue).