Author contributions D.J.M. is IS☉IS Principal Investigator (PI) and led the data analysis and writing of the study. E.R.C. is IS☉IS Deputy PI, helped develop EPI-Hi, and participated in the data analysis. C.M.S.C. helped develop EPI-Hi and participated in the data analysis. A.C.C. helped develop EPI-Hi and participated in the data analysis. A.J.D. helped develop EPI-Hi and participated in the data analysis. M.I.D. participated in the data analysis. J.G. participated in the data analysis. M.E.H. helped develop EPI-Lo and participated in the data analysis. C.J.J. produced Figs. 3, 4 and participated in the data analysis. S.M.K. participated in the data analysis. A.W.L. helped develop EPI-Hi and participated in the data analysis. R.A.L. helped develop EPI-Hi and participated in the data analysis. O.M. participated in the data analysis. W.H.M. participated in the data analysis. R.L.M. led the development of EPI-Lo and participated in the data analysis. R.A.M. helped develop EPI-Hi and participated in the data analysis. D.G.M. helped develop EPI-Lo and participated in the data analysis. A.P. participated in the data analysis. J.S.R. helped develop EPI-Hi and participated in the data analysis. E.C.R. participated in the data analysis. N.A.S. led the development of the IS☉IS Science Operations Center and participated in the data analysis. E.C.S. helped develop EPI-Hi and participated in the data analysis. J.R.S. led the development of the analysis tool, produced Figs. 1, 2, and participated in the data analysis. M.E.W. led the development of EPI-Hi and participated in the data analysis. S.D.B. is FIELDS PI and participated in the data analysis. J.C.K. is SWEAP PI and participated in the data analysis. A.W.C. helped develop SWEAP and participated in the data analysis. K.E.K. helped develop SWEAP and participated in the data analysis. R.J.M. helped develop FIELDS and participated in the data analysis. M.P. helped develop FIELDS and participated in the data analysis. M.L.S. helped develop SWEAP and participated in the data analysis. A.P.R. led the CME simulation work and participated in the data analysis.

The slow solar wind exhibits strong variability on timescales from minutes to days, likely related to magnetic reconnection processes in the extended solar corona. Higginson et al. (2017b) presented a numerical magnetohydrodynamic simulation which showed interchange magnetic reconnection is ubiquitous and most likely responsible for releasing much of the slow solar wind, in particular along topological features known as the Separatrix-Web (S-Web). Here, we continue our analysis, focusing on two specific aspects of structured slow solar wind variability. The first type is present in the slow solar wind found near the heliospheric current sheet, and the second we predict should be present everywhere S-Web slow solar wind is observed. For the first type, we examine the evolution of three-dimensional magnetic flux ropes formed at the top of the helmet streamer belt by reconnection in the heliospheric current sheet (HCS). For the second, we examine the simulated remote and in situ signatures of the large-scale torsional Alfvén wave (TAW) which propagates along an S-Web arc to high latitudes. We describe the similarities and differences between the reconnection-generated flux ropes in the HCS, which resemble the well-known "streamer blob" observations, and the similarly structured TAW. We discuss the implications of our results for the complexity of the HCS and surrounding plasma sheet, and the potential for particle acceleration, as well as the interchange reconnection scenarios which may generate TAWs in the solar corona. We discuss predictions from our simulation results for the dynamic slow solar wind in the extended corona and inner heliosphere.

In this paper, we present an analysis of the internal structure of a coronal mass ejection (CME) detected by in situ instruments on board 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 a low proton temperature and signatures of bidirectionality in the electron pitch angle distribution (PAD). These signatures are indicative of a CME embedded in the slow solar wind. Operating in conjunction with PSP was the STEREO A spacecraft, which enabled the remote observation of a streamer blowout 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, the details of which are described in Korreck et al. 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 configuration reveal a highly distorted structure consistent with the highly elongated “bubble” observed remotely. A double-ring substructure observed in the SECCHI-COR2 field 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 justification 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 serve as the main driver of the internal flux rope distortion detected in situ at PSP solar distance.

A major challenge in solar and heliospheric physics is understanding the origin and nature of the so-called slow solar wind. The Sun's atmosphere is divided into magnetically open regions, coronal holes, where the plasma streams out freely and fills the solar system, and closed regions, where the plasma is confined to coronal loops. The boundary between these regions extends outward as the heliospheric current sheet (HCS). Measurements of plasma composition strongly imply that much of the slow wind consists of plasma from the closed corona that escapes onto open field lines, presumably by field-line opening or by interchange reconnection. Both of these processes are expected to release closed-field plasma into the solar wind within and immediately adjacent to the HCS. Mysteriously, however, slow wind with closed-field plasma composition is often observed in-situ far from the HCS. We use high-resolution, three-dimensional, magnetohydrodynamic simulations to calculate the dynamics of a coronal hole whose geometry includes a narrow corridor flanked by closed field and which is driven by supergranule-like flows at the coronal-hole boundary. These dynamics produce giant arcs of closed-field plasma that originate at the open-closed boundary in the corona, but extend far from the HCS and span tens of degrees in latitude and longitude at Earth. We conclude that such structures can account for the long-puzzling slow-wind observations.