arXiv subjects

Chloe P. Wilkins

Publications and source records attributed to Chloe P. Wilkins.

3 recordsLinked to original sources

arXiv2026

Calculation of Field Line Slippage Rates in Coronal Simulations

We present the Universal Slippage calculator (\texttt{USlip}), an extension of the Universal Fieldline Tracer (\texttt{UFiT}), that computes magnetic field line slippage rates from an input magnetic field defined on a structured grid. The slippage rate provides a local, physically grounded diagnostic of non-ideal evolution, directly quantifying departures from ideal frozen-in motion. We outline the theoretical formulation and describe an efficient numerical implementation. The method is validated against analytical solutions and applied to simulations using three coronal codes treating varying spatial scales, all of which are standard inputs for \texttt{USlip}. In all the examples considered, the slippage rate not only identifies where magnetic connectivity changes occur, but also accurately reproduces the observed direction of field-line slippage. The consistency of the results across analytical tests and multiple simulation platforms demonstrates that \texttt{USlip} is a robust and versatile tool for diagnosing three-dimensional reconnection in dynamically evolving systems.

astro-ph.SR↗

arXiv2026

Solar Wind Dependence on Source Distance from the Open-Closed Boundary

The origin and variability of the slow solar wind remains an open question in solar physics, but is thought to be closely linked to dynamics at the Sun's open-closed magnetic flux boundary (OCB). Interchange magnetic reconnection at the OCB has been proposed as a mechanism for releasing closed-field plasma into the heliosphere, but observational evidence linking solar wind composition to OCB topology remains limited. We relate in situ solar wind measurements by Ulysses over a 10-year period to the magnetic topology of their source regions using two coronal magnetic field models: a potential field source surface model and a magnetofrictional model. We find a strong dependence of solar wind composition on the distance of the source magnetic flux from the OCB. Enhanced ion charge-state ratios, elemental abundances, and compositional variability are found to be concentrated within a supergranular-scale region (around 25 Mm) surrounding the OCB, consistent with the spatial scales of interchange magnetic reconnection. This variability decreases systematically with increasing distance from the boundary, with coronal hole wind exhibiting more uniform fast-wind signatures. We also find that the composition of solar wind emerging from regions close to the OCB is influenced by the strength of neighbouring closed magnetic fields, with stronger fields preferentially associated with slow-wind properties. These results indicate that the composition of the slow wind is strongly governed by the magnetic topology of the OCB, providing compelling evidence that interchange reconnection plays a crucial role in slow solar wind release and structure.

astro-ph.SR↗

arXiv2025

The Sun's open-closed flux boundary and the origin of the slow solar wind

The Sun's open-closed flux boundary (OCB) separates closed and open magnetic field lines, and is the site for interchange magnetic reconnection processes thought to be linked to the origin of the slow solar wind (SSW). We analyze the global magnetic field structure and OCB from 2010 December to 2019 December using three coronal magnetic field models: a potential-field source-surface (PFSS) model, a static equilibrium magnetofrictional model, and a time-dependent magnetofrictional model. We analyze the model and cycle dependence of the OCB length on the photosphere, as well as the magnetic flux in the vicinity of the OCB. Near solar maximum, the coronal magnetic field for each model consists predominantly of long, narrow coronal holes, and nearly all the open flux lies within 1 supergranule diameter (25 Mm) of the OCB. By comparing to interplanetary scintillation measurements of SSW speeds, we argue that the fraction of open flux within this 25 Mm band is a good predictor of the amount of SSW in the heliosphere. Importantly, despite its simplicity, we show that the PFSS model estimates this fraction as well as the time-dependent model. We discuss the implications of our results for understanding SSW origins and interchange reconnection at the OCB.

astro-ph.SR↗