English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Plus monthly

Global: Zendy Tools annual

Global: Zendy Tools monthly

Global: Zendy Free Plan

The higher charge states found in slow ($<$400km s$^{-1}$) solar wind streamscompared to fast streams have supported the hypothesis that the slow windoriginates in closed coronal loops, and released intermittently throughreconnection. Here we examine whether a highly ionized slow wind can also formalong steady and open magnetic field lines. We model the steady-state solaratmosphere using AWSoM, a global magnetohydrodynamic model driven by Alfv{\'e}nwaves, and apply an ionization code to calculate the charge state evolutionalong modeled open field lines. This constitutes the first charge statescalculation covering all latitudes in a realistic magnetic field. The ratios$O^{+7}/O^{+6}$ and $C^{+6}/C^{+5}$ are compared to in-situ Ulyssesobservations, and are found to be higher in the slow wind, as observed;however, they are under-predicted in both wind types. The modeled ion fractionsof S, Si, and Fe are used to calculate line-of-sight intensities, which arecompared to EIS observations above a coronal hole. The agreement is partial,and suggests that all ionization rates are under-predicted. Assuming thepresence of suprathermal electrons improved the agreement with both EIS andUlysses observations; importantly, the trend of higher ionization in the slowwind was maintained. The results suggest there can be a sub-class of slow windthat is steady and highly ionized. Further analysis shows it originates fromcoronal hole boundaries (CHB), where the modeled electron density andtemperature are higher than inside the hole, leading to faster ionization. Thisproperty of CHBs is global, and observationally supported by EUV tomography.

A Steady-State Picture of Solar Wind Acceleration and Charge State Composition Derived from a Global Wave-Driven MHD Model