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 Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

We report proton temperature anisotropy variations in the inner heliospherewith Parker Solar Probe (PSP) observations. Using a linear fitting method, wederive proton temperature anisotropy with temperatures measured by the SolarProbe Cup (SPC) from the SWEAP instrument suite and magnetic field observationsfrom the FIELDS instrument suite. The observed radial dependence of temperaturevariations in the fast solar wind implies stronger perpendicular heating andparallel cooling than previous results from Helios measurements made at largerradial distances. The anti-correlation between proton temperature anisotropyand parallel plasma beta is retained in fast solar wind. However, thetemperature anisotropies of the slow solar wind seem to be well constrained bythe mirror and parallel firehose instabilities. The perpendicular heating ofthe slow solar wind inside 0.24 AU may contribute to its same trend up againstmirror instability thresholds as fast solar wind. These results suggest that wemay see stronger anisotropy heating than expected in inner heliosphere.

Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with First Parker Solar Probe Observations