Coherent deflection pattern and associated temperature enhancements in the near-Sun solar wind

TL;DR

This study identifies a coherent pattern of magnetic and velocity deflections in the near-Sun solar wind, linked to interchange reconnection processes at the Sun, with associated temperature enhancements and scale consistent with coronal bright point activity.

Contribution

It provides in situ evidence connecting solar wind deflections and temperature increases to interchange reconnection at coronal bright points, supported by Parker Solar Probe data and simulations.

Findings

Deflections are Alfvénic, arc-polarised, with consistent orientation.

Temperature increases are aligned with magnetic field, especially during switchbacks.

Deflection scale is about 1 Mm, matching coronal jet activity.

Abstract

Measurements of transverse magnetic field and velocity components from Parker Solar Probe have revealed a coherent quasi-periodic pattern in the near-Sun solar wind. As well as being Alfv\'enic and arc-polarised, these deflections were characterised by a consistent orientation and an increased proton core temperature, which was greater parallel to the magnetic field. We show that switchbacks represent the largest deflections within this underlying structure, which is itself consistent with the expected outflow from interchange reconnection simulations. Additionally, the spatial scale of the deflections was estimated to be around $1$\,Mm on the Sun, comparable to the jetting activity observed at coronal bright points within the base of coronal plumes. Therefore, our results could represent the in situ signature of interchange reconnection from coronal bright points within plumes, complementing recent numerical and observational studies. We also found a consistent relationship between the proton core temperature and magnetic field angle across the Parker Solar Probe encounters and discussed how such a persistent signature could be more indicative of an in situ mechanism creating a local increase in temperature. In future, observations of minor ions, radio bursts and remote sensing images could help further establish the connection between reconnection events on the Sun and signatures in the solar wind.