Authors: Carlos R. Braga (JHU/APL), Vamsee K. Jagarlamudi (JHU/APL), Angelos Vourlidas (JHU/APL), Guillermo Stenborg (JHU/APL), Nour Raouafi (JHU/APL)

While most spacecraft intercept coronal mass ejections (CMEs) from upstream to downstream approximately along its radial direction, Parker Solar Probe (PSP) usually probes them longitudinally due to its high tangential speed near perihelion. This resulted in few measurements of the CME upstream region up to late 2024. Here, we report one of the first cases in which PSP intercepts a CME from upstream to downstream below 32 solar radii. Our objective is to investigate the properties of the CME and its related outflows, and to evidence differences with the 1 au counterparts of CMEs. We used coronagraphs and heliospheric imagers from four viewpoints (including PSP/WISPR) to determine the CME size and position. Compared to previous CMEs, WISPR observations are relatively fainter in the inner field of view but still discernible in the outer camera, suggesting an encounter with PSP, as confirmed by magnetic field measurements and other in situ measurements. The region probed includes an upstream region, shock, ejecta, and its downstream outflows. The CME results in increased electron density for approximately 10 hours. PSP probes a region with increased magnetic field and signs of rotation, which lasts approximately 3 hours. According to our CME reconstruction with the Graduated Cylindrical Shell model, this corresponds to the toroidal portion. Right after, PSP probed a 6-hour region with relatively small magnetic field rotation. As this period corresponds to the CME “leg”, we interpret this result as an indication that the twisted flux rope is confined mainly to the CME front region. This finding contradicts some of the earlier diagrams, including twisted magnetic field up to the Sun, but it agrees with some 1 au measurements suggesting otherwise. Our result suggests that the lack of twist in CME legs is not exclusively a 1 au property. Moreover, the plasma beta parameter of this event is well above unity, indicating that some CMEs are dominated by the plasma thermal pressure since 32 solar radii.