Analysis of the Internal structure of the Streamer Blow Out Observed by the Parker Solar Probe during the First Solar Encounter

We present an analysis of the internal structure of a coronal mass ejection (CME) detected by in situ instruments onboard the Parker Solar Probe (PSP) spacecraft during its first solar encounter. On 2018 November 11 at 23:53 UT, the FIELDS magnetometer measured an increase in strength of the magnetic field as well as a coherent change in the field direction. The SWEAP instrument simultaneously detected the low proton temperature and signatures of bi-directionality in the electron pitch angle distribution (PAD). These signatures are indicative of a CME embedded in the slow solar wind. In conjunction with PSP was the STEREO A spacecraft, which enabled the remote observation of a streamer blow-out by the SECCHI suite of instruments. The source at the Sun of the slow and well-structured flux-rope was identified in an overlying streamer.

Our detailed inspection of the internal transient structure magnetic properties suggests high complexity in deviations from an ideal flux rope 3D topology. Reconstructions of the magnetic field conguration reveal a highly distorted structure consistent with the highly elongated `bubble' observed remotely. A double-ring substructure observed in the SECCHI-COR2 eld of view (FOV) is suggestive of a double internal flux rope. Furthermore, we describe a scenario in which mixed topology of a closed flux rope is combined with the magnetically open structure, which helps explain the flux dropout observed in the measurements of the electron PAD. Our justication for this is the plethora of structures observed by the EUV imager (SECCHI-EUVI) in the hours preceding the streamer blowout evacuation. Finally, taking advantage of the unique observations from PSP, we explore the first stages of the effects of coupling with the solar wind and the evolutionary processes in the magnetic structure. We found evidence of bifurcated current sheets in the structure boundaries suggestive of magnetic reconnection. Our analysis of the internal force imbalance indicates that internal Lorentz forces continue to dominate the evolution of the structure in the COR2 FOV and serves as the main driver of the internal flux rope distortion as detected in situ at PSP solar distance.