In-situ Switchback Formation in the Expanding Solar Wind

Recent near-Sun solar-wind observations from Parker Solar Probe have found a highly dynamic magnetic environment, permeated by abrupt radial-field reversals, or "switchbacks." We show that many features of the observed turbulence are reproduced by a spectrum of Alfvénic fluctuations advect...

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Bibliographic Details
Published inAstrophysical journal. Letters Vol. 891; no. 1; p. L2
Main Authors Squire, J., Chandran, B. D. G., Meyrand, R.
Format Journal Article
LanguageEnglish
Published The American Astronomical Society 01.03.2020
Subjects
Alfven waves
Interplanetary turbulence
Solar magnetic fields
Solar wind
Space plasmas
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Summary:Recent near-Sun solar-wind observations from Parker Solar Probe have found a highly dynamic magnetic environment, permeated by abrupt radial-field reversals, or "switchbacks." We show that many features of the observed turbulence are reproduced by a spectrum of Alfvénic fluctuations advected by a radially expanding flow. Starting from simple superpositions of low-amplitude outward-propagating waves, our expanding-box compressible magnetohydrodynamic simulations naturally develop switchbacks because (i) the normalized amplitude of waves grows due to expansion and (ii) fluctuations evolve toward spherical polarization (i.e., nearly constant field strength). These results suggest that switchbacks form in situ in the expanding solar wind and are not indicative of impulsive processes in the chromosphere or corona.
Bibliography:AAS22532
ISSN:2041-8205
2041-8213
DOI:10.3847/2041-8213/ab74e1