Solar Chromospheric Network as a Source for Solar Wind Switchbacks

TL;DR

This study investigates the connection between solar chromospheric network features and solar wind switchbacks, suggesting that the medium scale of switchbacks may originate from the spatial distribution of chromospheric spicules and flux tubes.

Contribution

It provides high-resolution observational evidence linking chromospheric network structures to the scale of solar wind switchbacks, proposing a physical mechanism for their origin.

Findings

Inter-spicule distances are 0.4-1.5 Mm, smaller than SB medium scale.

Flux tube inter-distances peak at around 0.7 Mm, matching SB scales.

Flux tube aspect ratios are similar to SB aspect ratios.

Abstract

Recent studies suggest that the magnetic switchbacks (SBs) detected by the Parker Solar Probe (PSP) carry information on the scales of solar supergranulation (large scale) and granulation (medium scale). We test this claim using high-resolution H-alpha images obtained with the visible spectro-polarimeters (VIS) of the Goode Solar Telescope (GST) in Big Bear Solar Observatory (BBSO). As possible solar sources, we count all the spicule-like features standing along the chromospheric networks near the coronal hole boundary visible in the H-alpha blue-wing but absent in the red-wing images and measure the geometric parameters of dense sections of individual flux tubes. Intervals between adjacent spicules located along the chromospheric networks are found in the range of 0.4-1.5 Mm (0.03 deg - 0.12 deg) tending to be smaller than the medium scale of SBs. Inter-distances between all pairs of the flux tubes are also counted and they appear in a single peak distribution around 0.7 Mm (0.06 deg) unlike the waiting time distribution of SBs in a scale-free single power-law form. Length-to-diameter ratio of the dense section of flux tubes is as high as 6-40, similar to the aspect ratio of SBs. Number of spicules along a network can be as high as 40-100, consistent with numerous SBs within a patch. With these numbers, it is agued that the medium scale of SBs can be understood as an equilibrium distance resulting from random walk within each diverging magnetic field funnels connected to the chromospheric networks.