Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with the First Parker Solar Probe Observations - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue The Astrophysical Journal Supplement Année : 2020

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

Jia Huang
J. Kasper
D. Vech
K. Klein
M. Stevens
B. Alterman
Tereza Ďurovcová
  • Fonction : Auteur
Kristoff Paulson
  • Fonction : Auteur
Bennett Maruca
  • Fonction : Auteur
Ramiz Qudsi
  • Fonction : Auteur
A. Case
K. Korreck
Lan Jian
  • Fonction : Auteur
Marco Velli
A. Hegedus
  • Fonction : Auteur
C. Bert
  • Fonction : Auteur
J. Holmes
  • Fonction : Auteur
Stuart Bale
Davin Larson
Roberto Livi
P. Whittlesey
Marc Pulupa
Robert Macdowall
David Malaspina
John Bonnell
Peter Harvey
Keith Goetz

Résumé

We present a technique for deriving the temperature anisotropy of solar wind protons observed by the Parker Solar Probe (PSP) mission in the near-Sun solar wind. The radial proton temperature measured by the Solar Wind Electrons, Alphas, and Protons (SWEAP) Solar Probe Cup is compared with the orientation of local magnetic field measured by the FIELDS fluxgate magnetometer, and the proton temperatures parallel and perpendicular to the magnetic field are extracted. This procedure is applied to different data products, and the results are compared and optimum timescales for data selection and trends in the uncertainty in the method are identified. We find that the moment-based proton temperature anisotropy is more physically consistent with the expected limits of the mirror and firehose instabilities, possibly because the nonlinear fits do not capture a significant non-Maxwellian shape to the proton velocity distribution function near the Sun. The proton beam has a small effect on total proton temperature anisotropy owing to its much smaller density relative to the core compared to what was seen by previous spacecraft farther from the Sun. Several radial trends in the temperature components and the variation of the anisotropy with parallel plasma beta are presented. Our results suggest that we may see stronger anisotropic heating as PSP moves closer to the Sun, and that a careful treatment of the shape of the proton distribution may be needed to correctly describe the temperature.

Dates et versions

hal-03259393 , version 1 (14-06-2021)

Identifiants

Citer

Jia Huang, J. Kasper, D. Vech, K. Klein, M. Stevens, et al.. Proton Temperature Anisotropy Variations in Inner Heliosphere Estimated with the First Parker Solar Probe Observations. The Astrophysical Journal Supplement, 2020, 246 (2), pp.70. ⟨10.3847/1538-4365/ab74e0⟩. ⟨hal-03259393⟩
23 Consultations
0 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More