Evolving solar wind flow properties of magnetic inversions observed by Helios. Macneil, A. R., Owens, M. J., Wicks, R. T., & Lockwood, M. Monthly Notices Of The Royal Astronomical Society, 501(4):5379–5392, 2021. Publisher: Oxford Univ Press Type: Article tex.date-modified: 2022-04-12 11:34:55 +0100![Evolving solar wind flow properties of magnetic inversions observed by Helios [link]](https://bibbase.org/img/filetypes/link.svg "link")
Paper doi abstract bibtex In its first encounter at solar distances as close as r = 0.16au, Parker Solar Probe observed numerous local reversals, or inversions, in the heliospheric magnetic field (HMF), which were accompanied by large spikes in solar wind speed. Both solar and in situ mechanisms have been suggested to explain the existence of HMF inversions in general. Previous work using Helios 1, covering 0.3-1au, observed inverted HMF to become more common with increasing r, suggesting that some heliospheric driving process creates or amplifies inversions. This study expands upon these findings, by analysing inversion-associated changes in plasma properties for the same large data set, facilitated by observations of 'strahl' electrons to identify the unperturbed magnetic polarity. We find that many inversions exhibit anticorrelated field and velocity perturbations, and are thus characteristically Alfvenic, but many also depart strongly from this relationship over an apparent continuum of properties. Inversions depart further from the 'ideal' Alfvenic case with increasing r, as more energy is partitioned in the field, rather than the plasma, component of the perturbation. This departure is greatest for inversions with larger density and magnetic field strength changes, and characteristic slow solar wind properties. We find no evidence that inversions that stray further from 'ideal' Alfvenicity have different generation processes from those which are more Alfvenic. Instead, different inversion properties could be imprinted based on transport or formation within different solar wind streams.
@article{Macneil2021,
title = {Evolving solar wind flow properties of magnetic inversions observed by {Helios}},
volume = {501},
issn = {0035-8711},
url = {https://doi.org/10.1093/mnras/staa3983},
doi = {10.1093/mnras/staa3983},
abstract = {In its first encounter at solar distances as close as r = 0.16au, Parker Solar Probe observed numerous local reversals, or inversions, in the heliospheric magnetic field (HMF), which were accompanied by large spikes in solar wind speed. Both solar and in situ mechanisms have been suggested to explain the existence of HMF inversions in general. Previous work using Helios 1, covering 0.3-1au, observed inverted HMF to become more common with increasing r, suggesting that some heliospheric driving process creates or amplifies inversions. This study expands upon these findings, by analysing inversion-associated changes in plasma properties for the same large data set, facilitated by observations of 'strahl' electrons to identify the unperturbed magnetic polarity. We find that many inversions exhibit anticorrelated field and velocity perturbations, and are thus characteristically Alfvenic, but many also depart strongly from this relationship over an apparent continuum of properties. Inversions depart further from the 'ideal' Alfvenic case with increasing r, as more energy is partitioned in the field, rather than the plasma, component of the perturbation. This departure is greatest for inversions with larger density and magnetic field strength changes, and characteristic slow solar wind properties. We find no evidence that inversions that stray further from 'ideal' Alfvenicity have different generation processes from those which are more Alfvenic. Instead, different inversion properties could be imprinted based on transport or formation within different solar wind streams.},
number = {4},
journal = {Monthly Notices Of The Royal Astronomical Society},
author = {Macneil, Allan R. and Owens, Mathew J. and Wicks, Robert T. and Lockwood, Mike},
year = {2021},
note = {Publisher: Oxford Univ Press
Type: Article
tex.date-modified: 2022-04-12 11:34:55 +0100},
pages = {5379--5392},
}
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Previous work using Helios 1, covering 0.3-1au, observed inverted HMF to become more common with increasing r, suggesting that some heliospheric driving process creates or amplifies inversions. This study expands upon these findings, by analysing inversion-associated changes in plasma properties for the same large data set, facilitated by observations of 'strahl' electrons to identify the unperturbed magnetic polarity. We find that many inversions exhibit anticorrelated field and velocity perturbations, and are thus characteristically Alfvenic, but many also depart strongly from this relationship over an apparent continuum of properties. Inversions depart further from the 'ideal' Alfvenic case with increasing r, as more energy is partitioned in the field, rather than the plasma, component of the perturbation. This departure is greatest for inversions with larger density and magnetic field strength changes, and characteristic slow solar wind properties. 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