Woodham, LD;
Wicks, RT;
Verscharen, D;
Owen, CJ;
Maruca, BA;
Alterman, BL;
(2019)
Parallel-propagating Fluctuations at Proton-kinetic Scales in the Solar Wind Are Dominated By Kinetic Instabilities.
The Astrophysical Journal Letters
, 884
(2)
, Article L53. 10.3847/2041-8213/ab4adc.
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Abstract
We use magnetic helicity to characterize solar wind fluctuations at proton-kinetic scales from Wind observations. For the first time, we separate the contributions to helicity from fluctuations propagating at angles quasi-parallel and oblique to the local mean magnetic field, B0. We find that the helicity of quasi-parallel fluctuations is consistent with Alfvén-ion cyclotron and fast magnetosonic-whistler modes driven by proton temperature anisotropy instabilities and the presence of a relative drift between α-particles and protons. We also find that the helicity of oblique fluctuations has little dependence on proton temperature anisotropy and is consistent with fluctuations from the anisotropic turbulent cascade. Our results show that parallel-propagating fluctuations at proton-kinetic scales in the solar wind are dominated by proton temperature anisotropy instabilities and not the turbulent cascade. We also provide evidence that the behavior of fluctuations at these scales is independent of the origin and macroscopic properties of the solar wind.
| Type: | Article |
|---|---|
| Title: | Parallel-propagating Fluctuations at Proton-kinetic Scales in the Solar Wind Are Dominated By Kinetic Instabilities |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.3847/2041-8213/ab4adc |
| Publisher version: | https://doi.org/10.3847/2041-8213/ab4adc |
| Language: | English |
| Additional information: | This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Space plasmas; Plasma astrophysics; Plasma physics; Solar wind; Heliosphere; Interplanetary turbulence; Alfven waves; Slow solar wind; Fast solar wind |
| 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 UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Space and Climate Physics > Advanced Instrumentation Systems |
| URI: | https://discovery-pp.ucl.ac.uk/id/eprint/10083737 |
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