Electrons in the Young Solar Wind: First Results from the Parker Solar Probe

J. S Halekas; P Whittlesey; D. E Larson; D McGinnis; M Maksimovic; M Berthomier; J. C Kasper; A. W Case; K. E Korreck; M. L Stevens; K. G Klein; S. D Bale; R. J MacDowall; M. P Pulupa; D. M Malaspina; K Goetz; P. R Harvey

doi:10.3847/1538-4365/ab4cec

Back

Electrons in the Young Solar Wind: First Results from the Parker Solar Probe

Journal article

Open access

Peer reviewed

Electrons in the Young Solar Wind: First Results from the Parker Solar Probe

J. S Halekas, P Whittlesey, D. E Larson, D McGinnis, M Maksimovic, M Berthomier, J. C Kasper, A. W Case, K. E Korreck, M. L Stevens, …

The Astrophysical journal. Supplement series, Vol.246(2), p.22

02/01/2020

DOI: 10.3847/1538-4365/ab4cec

Files and links (1)

url

https://doi.org/10.3847/1538-4365/ab4cecView

Published (Version of record) Open Access

Abstract

The Solar Wind Electrons Alphas and Protons experiment on the Parker Solar Probe (PSP) mission measures the three-dimensional electron velocity distribution function. We derive the parameters of the core, halo, and strahl populations utilizing a combination of fitting to model distributions and numerical integration for ∼100,000 electron distributions measured near the Sun on the first two PSP orbits, which reached heliocentric distances as small as ∼0.17 au. As expected, the electron core density and temperature increase with decreasing heliocentric distance, while the ratio of electron thermal pressure to magnetic pressure (βe) decreases. These quantities have radial scaling consistent with previous observations farther from the Sun, with superposed variations associated with different solar wind streams. The density in the strahl also increases; however, the density of the halo plateaus and even decreases at perihelion, leading to a large strahl/halo ratio near the Sun. As at greater heliocentric distances, the core has a sunward drift relative to the proton frame, which balances the current carried by the strahl, satisfying the zero-current condition necessary to maintain quasi-neutrality. Many characteristics of the electron distributions near perihelion have trends with solar wind flow speed, βe, and/or collisional age. Near the Sun, some trends not clearly seen at 1 au become apparent, including anticorrelations between wind speed and both electron temperature and heat flux. These trends help us understand the mechanisms that shape the solar wind electron distributions at an early stage of their evolution.

Slow solar wind

Solar physics

Solar wind

Details

Title: Subtitle: Electrons in the Young Solar Wind: First Results from the Parker Solar Probe
Creators: J. S Halekas - University of Iowa
P Whittlesey - University of California, Berkeley
D. E Larson - University of California, Berkeley
D McGinnis - University of Iowa
M Maksimovic - Université Paris Cité
M Berthomier - Laboratoire de Physique des Plasmas
J. C Kasper - University of Michigan–Ann Arbor
A. W Case - Smithsonian Astrophysical Observatory
K. E Korreck - Smithsonian Astrophysical Observatory
M. L Stevens - Smithsonian Astrophysical Observatory
K. G Klein - University of Arizona
S. D Bale - University of California, Berkeley
R. J MacDowall - Goddard Space Flight Center
M. P Pulupa - University of California, Berkeley
D. M Malaspina - Laboratory for Atmospheric and Space Physics
K Goetz - University of Minnesota
P. R Harvey - University of California Space Sciences Laboratory, Berkeley, CA 94720, USA
Resource Type: Journal article
Publication Details: The Astrophysical journal. Supplement series, Vol.246(2), p.22
Publisher: The American Astronomical Society
DOI: 10.3847/1538-4365/ab4cec
ISSN: 0067-0049
eISSN: 1538-4365
Number of pages: 9
Grant note: NNN06AA01C / NASA
Alternative title: Electrons in the Young Solar Wind: First Results from the Parker Solar Probe
Language: English
Date published: 02/01/2020
Academic Unit: Physics and Astronomy
Record Identifier: 9984428677002771

Metrics

1 Record Views

100 Times Cited - Web of Science

See more details