Parker Solar Probe analysis across the Alfvénic transition: velocity shear, magnetic deflection, and switchback formation
Issued Date
2026-04-01
Resource Type
ISSN
00358711
eISSN
13652966
Scopus ID
2-s2.0-105033002996
Journal Title
Monthly Notices of the Royal Astronomical Society
Volume
547
Issue
2
Rights Holder(s)
SCOPUS
Bibliographic Citation
Monthly Notices of the Royal Astronomical Society Vol.547 No.2 (2026)
Suggested Citation
Goodwill J., Adhikari S., Payne D., Bandyopadhyay R., Badman S., Pecora F., Pongkitiwanichakul P., Pradata R., Romeo O., Roy S., Ruffolo D., Stevens M., Thepthong P., Usmanov A., Wang J., Goldstein M.L., Chhiber R., Matthaeus W.H. Parker Solar Probe analysis across the Alfvénic transition: velocity shear, magnetic deflection, and switchback formation. Monthly Notices of the Royal Astronomical Society Vol.547 No.2 (2026). doi:10.1093/mnras/stag242 Retrieved from: https://repository.li.mahidol.ac.th/handle/123456789/115845
Title
Parker Solar Probe analysis across the Alfvénic transition: velocity shear, magnetic deflection, and switchback formation
Author's Affiliation
Corresponding Author(s)
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Abstract
Close to the Sun, Parker Solar Probe (PSP) traverses the sub-Alfvénic solar wind, a magnetically controlled plasma environment. Farther from the Sun, the magnetic field amplitude and plasma density weaken enough to establish a super-Alfvénic environment where kinetic energy and turbulence become more prominent. Switchbacks (i.e. large directional deviations from the mean field) are shown to occur almost exclusively in the super-Alfvénic regime. In this study, we analyse magnetic fluctuations from PSP encounters 8 through 19 to study their relationship to Alfvén Mach number (M<inf>A</inf>) and switchback parameter (Z). We find that the fluctuation of the magnetic field magnitude normalized to the mean magnetic field and of the radial velocity normalized to local Alfvén speed increase with both Alfvén Mach number and switchback parameter. However, there is distinct saturation in the increments of the normalized radial velocity fluctuations in the Alfvén Mach number range of ~4–6. Results are interpreted in terms of the Chandrasekhar criterion for Kelvin–Helmholtz activity. Overall, these findings are in agreement with earlier studies suggesting switchback generation through non-linear shear flow dynamics.