The Dynamic Evolution of Solar Wind Streams Following Interchange Reconnection

Abstract

Interchange reconnection is thought to play an important role in determining the dynamics and material composition of the slow solar wind that originates from near coronal-hole boundaries. To explore the implications of this process we simulate the dynamic evolution of a solar wind stream along a newly-opened magnetic flux tube. The initial condition is composed of a piecewise continuous dynamic equilibrium in which the regions above and below the reconnection site are extracted from steady-state solutions along open and closed field lines. The initial discontinuity at the reconnection site is highly unstable and evolves as a Riemann problem, decomposing into an outward-propagating shock and inward-propagating rarefaction that eventually develop into a classic N-wave configuration. This configuration ultimately propagates into the heliosphere as a coherent structure and the entire system eventually settles to a quasi-steady wind solution. In addition to simulating the fluid evolution we also calculate the time-dependent non-equilibrium ionization of oxygen in real time in order to construct in situ diagnostics of the conditions near the reconnection site. This idealized description of the plasma dynamics along a newly-opened magnetic field line provides a baseline for predicting and interpreting the implications of interchange reconnection for the slow solar wind. Notably, the density and velocity within the expanding N-wave are generally enhanced over the ambient wind, as is the O7+/O6+ ionization ratio, which exhibits a discontinuity across the reconnection site that is transported by the flow and arrives later than the propagating N-wave.

Solar Spicules, Filigrees, and Solar Wind Switchbacks

“…inner reconnection (Moore et al 2015;Sterling & Moore 2016;). If the reconnection occurs higher to bring up materials from below via rarefaction waves (Scott et al 2022), then JBPs would hardly form underneath the cool ejecta. 2.…”

“…This hypothesis is supported by Owens et al's (2018) model in which a kinked structure resulting from interchange reconnection may be preserved into space if the reconnection occur in the sufficiently high corona. Other models in line with this hypothesis include formation of the kinked field lines by shear motion (Schwadron & McComas 2021) and the so-called N-wave mechanism that an outward-propagating shockrarefaction system overtakes the leading shock to form a shockrarefactionshock triplet to become a kinked structure in space (Scott et al 2022).…”

“…The different behaviors of spicules with those of EUV activity can be reconciled if they are like cool and hot jets in the BP models. Cool jets in the BP model (Scott et al 2022) are driven by the rarefaction waves in high beta plasma, in which case neither twisted field lines nor JBPs are necessary. They can just be ejected along the open fields rooted in filigree, which work as a conduit for chromospheric ejecta.…”

Understanding the Duration of Solar and Stellar Flares at Various Wavelengths

“…The code includes the physics relevant to coronal loops and flares, including radiative losses from the chromosphere through corona, thermal conduction with either the Spitzer-Härm approximation or turbulent suppression of conduction, and heating functions due to direct heating or from an electron beam (Bradshaw & Cargill 2013;. The loop geometry is very general, and can include open or closed loops (e.g., Scott et al 2022), with a uniform or expanding cross-sectional area of any specified form. In this paper, we examine closed loops both with and without area expansion.…”

Helium Abundance Periods Observed by the Solar Probe Cup on Parker Solar Probe: Encounters 1–14

“…The various heavy-ion features that remain imprinted in the plasma once it leaves the corona provide insight to processes active in the corona. Therefore, the ion and elemental composition measured throughout the heliosphere are important tracers of the eruption processes (Lynch et al 2011;Rakowski et al 2011;Laming et al 2023;Rivera et al 2023), solar-wind release and dynamic outflow (Landi et al 2012b;Scott et al 2022), and properties of the plasma's source region (Xu & Borovsky 2015;Zurbuchen et al 2016;Ervin et al 2023;Lynch et al 2023).…”