Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with First Parker Solar Probe Observations
Abstract
We report proton temperature anisotropy variations in the inner heliosphere with Parker Solar Probe (PSP) observations. Using a linear fitting method, we derive proton temperature anisotropy with temperatures measured by the Solar Probe Cup (SPC) from the SWEAP instrument suite and magnetic field observations from the FIELDS instrument suite. The observed radial dependence of temperature variations in the fast solar wind implies stronger perpendicular heating and parallel cooling than previous results from Helios measurements made at larger radial distances. The anti-correlation between proton temperature anisotropy and parallel plasma beta is retained in fast solar wind. However, the temperature anisotropies of the slow solar wind seem to be well constrained by the mirror and parallel firehose instabilities. The perpendicular heating of the slow solar wind inside 0.24 AU may contribute to its same trend up against mirror instability thresholds as fast solar wind. These results suggest that we may see stronger anisotropy heating than expected in inner heliosphere.
Keywords
Cite
@article{arxiv.1912.03871,
title = {Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with First Parker Solar Probe Observations},
author = {Jia Huang and Justin C. Kasper and Daniel Vech and Kristopher G. Klein and Michael L. Stevens and Mihailo Martinovic and Benjamin L. Alterman and Tereza Ďurovcová and Kristoff Paulson and Bennett A. Maruca and Ramiz A. Qudsi and Anthony W. Case and Kelly Korreck and Lan K. Jian and Marco Velli and Benoit Lavraud and Alexander M. Hegedus and C. M. Bert and J. Holmes and Stuart D. Bale and Davin E. Larson and Roberto Livi and Phyllis Whittlesey and Marc Pulupa and Robert J. MacDowall and David M. Malaspina and John W. Bonnell and Peter R. Harvey and Keith goetz and Thierry Dudok de Wit},
journal= {arXiv preprint arXiv:1912.03871},
year = {2020}
}
Comments
Submit to ApJ special issue for Parker Solar Probe first results