Paper detail

Probing the CME Core--Prominence Relation Using Inner Coronal Observations

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 (MLSO) K-Coronagraph (K-Cor), while the corresponding prominence eruptions were examined using H$α$ data from the Global Oscillation Network Group (GONG) and 304 Å images from the Atmospheric Imaging Assembly (AIA). Our results show a strong spatial correspondence between H$α$ prominences and CME cores in white light, with an average image correlation of $\sim$0.7, while correlations between white light and AIA 304 Å are comparatively weaker ($\sim$0.5). Several events could be continuously traced into the Large Angle and Spectrometric Coronagraph Experiment (LASCO/C2) field of view, confirming the persistence of prominence material into the outer corona. We find back-extrapolating LASCO/C2 CME cores under constant-velocity, linear-trajectory assumptions can introduce large errors -- up to 40$^\circ$ in inferred position angle and $\sim$140 minutes in eruption time relative to their true values -- underscoring the importance of inner-coronal observations for accurately constraining CME dynamics. Overall, our findings suggest that in prominence-associated CMEs, the bright cores are predominantly composed of prominence material.