Sharp Alfvenic impulses in the near-Sun solar wind
File(s)
Author(s)
Type
Journal Article
Abstract
Measurements of the near-Sun solar wind by Parker Solar Probe have revealed the presence of largenumbers of discrete Alfv ́enic impulses with an anti-Sunward sense of propagation. These are similarto those previously observed near 1 AU, in high speed streams over the Sun’s poles and at 60 solarradii. At 35 solar radii, however, they are typically shorter and sharper than seen elsewhere. Inaddition, these spikes occur in “patches” and there are also clear periods within the same stream whenthey do not occur; the timescale of these patches might be related to the rate at which the spacecraftmagnetic footpoint tracks across the coronal hole from which the plasma originated. While the velocityfluctuations associated with these spikes are typically under 100 km/s, due to the rather low Alfv ́enspeeds in the streams observed by the spacecraft to date, these are still associated with large angulardeflections of the magnetic field - and these deflections are not isotropic. These deflections do notappear to be related to the recently reported large scale, pro-rotation solar wind flow. Estimates ofthe size and shape of the spikes reveal high aspect ratio flow-aligned structures with a transverse scaleof≈104km. These events might be signatures of near-Sun impulsive reconnection events.
Date Issued
2020-02-03
Date Acceptance
2019-11-21
Citation
The Astrophysical Journal: an international review of astronomy and astronomical physics, 2020, 246 (2), pp.1-8
ISSN
0004-637X
Publisher
American Astronomical Society
Start Page
1
End Page
8
Journal / Book Title
The Astrophysical Journal: an international review of astronomy and astronomical physics
Volume
246
Issue
2
Copyright Statement
© 2020. The American Astronomical Society. All rights reserved. This is an author-created, un-copyedited version of an article accepted for publication in The Astrophysical Journal: an international review of astronomy and astronomical physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at https://doi.org/10.3847/1538-4365/ab5b15
Sponsor
Science and Technology Facilities Council (STFC)
Identifier
https://iopscience.iop.org/article/10.3847/1538-4365/ab5b15
Grant Number
ST/S000364/1
Subjects
Science & Technology
Physical Sciences
Astronomy & Astrophysics
SPEED
JETS
WAVES
Science & Technology
Physical Sciences
Astronomy & Astrophysics
Solar wind
Solar corona
Space plasmas
SPEED
JETS
WAVES
0201 Astronomical and Space Sciences
0202 Atomic, Molecular, Nuclear, Particle and Plasma Physics
0306 Physical Chemistry (incl. Structural)
Astronomy & Astrophysics
Publication Status
Published
Article Number
ARTN 45