@article{Liu:2024:1538-4357/ad1e56,
author = {Liu, YD and Zhu, B and Ran, H and Hu, H and Liu, M and Zhao, X and Wang, R and Stevens, ML and Bale, SD},
doi = {1538-4357/ad1e56},
journal = {Astrophysical Journal},
title = {Direct In Situ Measurements of a Fast Coronal Mass Ejection and Associated Structures in the Corona},
url = {http://dx.doi.org/10.3847/1538-4357/ad1e56},
volume = {963},
year = {2024}
}

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TY  - JOUR
AB  - We report on the first direct in situ measurements of a fast coronal mass ejection (CME) and shock in the corona, which occurred on 2022 September 5. In situ measurements from the Parker Solar Probe spacecraft near perihelion suggest two shocks, with the second one decayed, which is consistent with more than one eruption in coronagraph images. Despite a flank crossing, the measurements indicate unique features of the young ejecta: a plasma much hotter than the ambient medium, suggestive of a hot solar source, and a large plasma β implying a highly non-force-free state and the importance of thermal pressure gradient for CME acceleration and expansion. Reconstruction of the global coronal magnetic fields shows a long-duration change in the heliospheric current sheet (HCS), and the observed field polarity reversals agree with a more warped HCS configuration. Reconnection signatures are observed inside an HCS crossing as deep as the sonic critical point. As the reconnection occurs in the sub-Alfvénic wind, the reconnected flux sunward of the reconnection site can close back to the Sun, which helps balance magnetic flux in the heliosphere. The nature of the sub-Alfvénic wind after the HCS crossing as a low Mach-number boundary layer (LMBL) leads to in situ measurements of the near subsonic plasma at a surprisingly large distance. Specifically, an LMBL may provide favorable conditions for the crossings of the sonic critical point in addition to the Alfvén surface.
AU  - Liu,YD
AU  - Zhu,B
AU  - Ran,H
AU  - Hu,H
AU  - Liu,M
AU  - Zhao,X
AU  - Wang,R
AU  - Stevens,ML
AU  - Bale,SD
DO  - 1538-4357/ad1e56
PY  - 2024///
SN  - 0004-637X
TI  - Direct In Situ Measurements of a Fast Coronal Mass Ejection and Associated Structures in the Corona
T2  - Astrophysical Journal
UR  - http://dx.doi.org/10.3847/1538-4357/ad1e56
VL  - 963
ER  - 

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