TitleThe evolution of inverted magnetic fields through the inner heliosphereABSTRACT
Publication TypeJournal Article
Year of Publication2020
AuthorsMacneil, AR, Owens, MJ, Wicks, RT, Lockwood, M, Bentley, SN, Lang, M
JournalMonthly Notices of the Royal Astronomical Society
Volume494
Pagination3642 - 3655
Date Published04-2020
ISSN0035-8711
KeywordsAstrophysics - Solar and Stellar Astrophysics; magnetic fields; parker solar probe; Physics - Space Physics; plasmas; Solar Probe Plus; Solar wind; Sun: heliosphere
Abstract

Local inversions are often observed in the heliospheric magnetic field (HMF), but their origins and evolution are not yet fully understood. Parker Solar Probe has recently observed rapid, Alfvénic, HMF inversions in the inner heliosphere, known as ’switchbacks’, which have been interpreted as the possible remnants of coronal jets. It has also been suggested that inverted HMF may be produced by near-Sun interchange reconnection; a key process in mechanisms proposed for slow solar wind release. These cases suggest that the source of inverted HMF is near the Sun, and it follows that these inversions would gradually decay and straighten as they propagate out through the heliosphere. Alternatively, HMF inversions could form during solar wind transit, through phenomena such velocity shears, draping over ejecta, or waves and turbulence. Such processes are expected to lead to a qualitatively radial evolution of inverted HMF structures. Using Helios measurements spanning 0.3-1 au, we examine the occurrence rate of inverted HMF, as well as other magnetic field morphologies, as a function of radial distance r, and find that it continually increases. This trend may be explained by inverted HMF observed between 0.3 and 1 au being primarily driven by one or more of the above in-transit processes, rather than created at the Sun. We make suggestions as to the relative importance of these different processes based on the evolution of the magnetic field properties associated with inverted HMF. We also explore alternative explanations outside of our suggested driving processes which may lead to the observed trend.

URLhttps://academic.oup.com/mnras/article/494/3/3642/5819029
DOI10.1093/mnras/staa951


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