Updated Measurements of Proton, Electron, and Oxygen Temperatures in the Fast Solar Wind

TL;DR

This paper compiles and analyzes measurements of proton, electron, and oxygen ion temperatures in the fast solar wind to provide empirical constraints for coronal heating models.

Contribution

It presents a comprehensive collection of temperature measurements in the fast solar wind, aiding the testing of theoretical coronal heating models.

Findings

Proton, electron, and oxygen temperatures vary with radial distance.

Empirical data supports specific coronal heating mechanisms.

Measurements span multiple solar cycle phases.

Abstract

The high-speed solar wind is typically the simplest and least stochastic type of large-scale plasma flow in the heliosphere. For much of the solar cycle, it is connected magnetically to large polar coronal holes on the Sun's surface. Because these features are relatively well-known (and less complex than the multiple source-regions of the slow wind), the fast wind is often a useful testing-ground for theoretical models of coronal heating. In order to provide global empirical constraints to these models, here we collect together some older and more recent measurements of the temperatures of protons, electrons, and oxygen ions as a function of radial distance.