Niembro, T. ; Reeves, K. K. ; Seaton, D. B. ; Hess, P. ; Berghmans, D. ; Andretta, V.

Poster presented at Solar Orbiter 8, Belfast on 2022-09-12

Abstract: P120 In the early hours of 2021 April 25, the Solar Probe Cup on-board Parker Solar Probe (PSP) registered the passage of a solar wind structure characterized by a clear and constant He+2/proton density ratio above 6% during three hours. The alpha contribution remained present but faint and intermittent within a twelve-hour window. Solar Orbiter (SolO) and PSP were in nearly perfect quadrature, allowing for an optimal observing configuration in which the material impacting PSP was in the SolO plane of sky and visible off the limb. In this work, we report the helium-enriched plasma structure from the Sun to PSP combining multi-spacecraft remote sensing and in situ measurements. We identify an erupting prominence as the likely source, behind the Sun relative to the Earth, but visible to multiple instruments on both the Solar-Terrestrial Relations Observatory-A (STA) and SolO. The associated CME was also observed by coronagraphs and heliospheric imagers from both spacecraft before reaching PSP at 46 Rs, 8 hours after the spacecraft registered a crossing of the heliospheric current sheet. Except for the extraordinary alpha ratio enhancement, the CME showed ordinary plasma signatures and a complex magnetic field with an overall enhancement. The PSP/WISPR images show a structure entering the field of view a few hours before the in situ crossing followed by repetitive transient structures that may be the result of flying through the CME body. We believe this to be the first example of a CME being imaged by PSP/WISPR directly before and during being detected in situ. This study highlights the potential of combining PSP in situ measurements in the inner heliosphere with simultaneous remote-sensing observations in (near) quadrature from other spacecraft.

Keyword(s): Solar Orbiter ; EUI
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