Analysis of CME Interactions in Solar Corona Combining Coronagraphic Observations with Wide-field Imagers from Solar Orbiter and Parker Solar Probe

Abstract Accurately determining the trajectory of coronal mass ejections (CMEs) is vital for space weather forecasting and assessing their potential impact on Earth. CMEs often deviate from a radial path, due to local pressure gradients or interactions with other CMEs. Combining coronagraphic and heliospheric observations offers deeper insights into these phenomena, enhancing future space weather prediction capabilities. On 2023 September 24, a sequence of four CMEs was observed by several spacecraft within 10 hr. This study provides a detailed analysis of these CMEs, with three-dimensional trajectories determined using a Graduated Cylindrical Shell forward-modeling technique. For the first time, this approach integrates quasi-simultaneous coronagraph data from STEREO-A and Solar and Heliospheric Observatory as well as heliospheric imaging from both Solar Orbiter and Parker Solar Probe. This multi-instrument, multi-viewpoint method allowed us to identify several indications of interaction between the second and third CMEs. This study aims to examine the consequences of interaction in low corona between two CMEs originating from closely spaced source regions on the propagation of both. In particular, the analysis revealed a southward deflection of approximately 15° in latitude for CME3 from its source region, as well as an acceleration of CME2. Following the acceleration, the two CMEs appear to propagate as a single entity at a uniform speed of approximately 750 km s −1 . Various interpretations are proposed to explain observations and indications of CME interactions.