The Closest View of a Fast Coronal Mass Ejection: How Faulty Assumptions Near Perihelion Lead to Unrealistic Interpretations of PSP/WISPR Observations

Abstract

We report on the closest view of a coronal mass ejection (CME) observed by the Parker Solar Probe (PSP)/ Wide-field Imager for Parker Solar PRobe (WISPR) instrument on 2022 September 5, when PSP was traversing from a distance of 15.3 to 13.5 R _⊙ from the Sun. The CME leading edge and an arc-shaped concave-up structure near the core were tracked in the WISPR field of view using the polar coordinate system for the first time. Using the impact distance on the Thomson surface, we measured the average speeds of the CME leading edge and concave-up structure as ≈2500 ± 270 km s ^−1 and ≈400 ± 70 km s ^−1 with a deceleration of ≈20 m s ^−2 for the latter. The use of the plane-of-sky approach yielded an unrealistic speed of more than 3 times this estimate. We also used single viewpoint STEREO/COR-2A images to fit the Graduated Cylindrical Shell (GCS) model to the CME while incorporating the source region location from Extreme-Ultraviolet Imager of Solar Orbiter and estimated a 3D speed of ≈2700 km s ^−1 . We conclude that this CME exhibits the highest speed during the ascending phase of solar cycle 25. This places it in the category of extreme-speed CMEs, which account for only 0.15% of all CMEs listed in the CDAW CME catalog.

Keywords

• Solar coronal mass ejections
• Solar magnetic reconnection
• Solar corona
• Solar coronal transients