Probing the CME core–prominence relation using observations of the inner corona

Abstract

Coronal mass ejections (CMEs) often exhibit a three-part structure consisting of a bright inner core, an outer leading edge, and an intervening dark cavity. While the core has traditionally been attributed to prominence material, an alternative interpretation suggests it may arise from the projection effects of a twisted flux rope. We focused on limb CME events to reassess the connection between CME cores and their associated prominences in the inner corona. The CME cores were analyzed using white-light observations from the Mauna Loa Solar Observatory K-Coronagraph, while the corresponding prominence eruptions were examined using Hα data from the Global Oscillation Network Group and 304 Å images from the Atmospheric Imaging Assembly (AIA). Our results show a strong spatial correspondence between Hα prominences and CME cores in white light, with an average image correlation of ∼0.7, while correlations between white light and AIA 304 Å are comparatively weaker (∼0.5). Several events could be continuously traced into the field of view of the Large Angle and Spectrometric Coronagraph Experiment (LASCO/C2), confirming the persistence of prominence material into the outer corona. We find back-extrapolating LASCO/C2 CME cores under assumptions of constant velocity and a linear trajectory can introduce large errors—up to ∼40° in inferred position angle and ∼140 minutes in eruption time relative to their true values—underscoring the importance of observations of the inner corona for accurately constraining CME dynamics. Overall, our findings suggest that in prominence-associated CMEs, the bright cores are predominantly composed of prominence material.