Bruno, Roberto;
De Marco, Rossana;
D'Amicis, Raffaella;
Perrone, Denise;
Marcucci, Maria Federica;
Telloni, Daniele;
Marino, Raffaele;
... Livi, Stefano; + view all
(2024)
Comparative Study of the Kinetic Properties of Proton and Alpha Beams in the Alfvénic Wind Observed by SWA-PAS On Board Solar Orbiter.
The Astrophysical Journal
, 969
, Article 106. 10.3847/1538-4357/ad47b3.
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Abstract
The problems of heating and acceleration of solar wind particles are of significant and enduring interest in astrophysics. The interactions between waves and particles are crucial in determining the distributions of proton and alpha particles, resulting in non-Maxwellian characteristics, including temperature anisotropies and particle beams. These processes can be better understood as long as the beam can be separated from the core for the two major components of the solar wind. We utilized an alternative numerical approach that leverages the clustering technique employed in machine learning to differentiate the primary populations within the velocity distribution rather than employing the conventional bi-Maxwellian fitting method. Separation of the core and beam revealed new features for protons and alphas. We estimated that the total temperature of the two beams was slightly higher than that of their respective cores, and the temperature anisotropy for the cores and beams was larger than 1. We concluded that the temperature ratio between alphas and protons largely over 4 is due to the presence of a massive alpha beam, which is approximately 50% of the alpha core. We provided evidence that the alpha core and beam populations are sensitive to Alfvénic fluctuations and the surfing effect found in the literature can be recovered only when considering the core and beam as a single population. Several similarities between proton and alpha beams would suggest a common and local generation mechanism not shared with the alpha core, which may not have necessarily been accelerated and heated locally.
| Type: | Article |
|---|---|
| Title: | Comparative Study of the Kinetic Properties of Proton and Alpha Beams in the Alfvénic Wind Observed by SWA-PAS On Board Solar Orbiter |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/1538-4357/ad47b3 |
| Publisher version: | https://doi.org/10.3847/1538-4357/ad47b3 |
| Language: | English |
| Additional information: | © The Author(s), 2024. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licence (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. https://creativecommons.org/licenses/by/4.0/ |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10196974 |
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