Density Fluctuations Associated with Turbulence and Waves: First Observations by Solar Orbiter

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F21%3A00541525" target="_blank" >RIV/67985815:_____/21:00541525 - isvavai.cz</a>

Nalezeny alternativní kódy

RIV/68378289:_____/21:00541525

Výsledek na webu

<a href="https://www.aanda.org/articles/aa/full_html/2021/12/aa40936-21/aa40936-21.html" target="_blank" >https://www.aanda.org/articles/aa/full_html/2021/12/aa40936-21/aa40936-21.html</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/202140936" target="_blank" >10.1051/0004-6361/202140936</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Density Fluctuations Associated with Turbulence and Waves: First Observations by Solar Orbiter

Popis výsledku v původním jazyce

Aims. The aim of this work is to demonstrate that the probe-to-spacecraft potential measured by RPW on Solar Orbiter can be used to derive the plasma (electron) density measurement, which exhibits both a high temporal resolution and a high level of accuracy. To investigate the physical nature of the solar wind turbulence and waves, we analyze the density and magnetic field fluctuations around the proton cyclotron frequency observed by Solar Orbiter during the first perihelion encounter (∼0.5 AU away from the Sun).nMethods. We used the plasma density based on measurements of the probe-to-spacecraft potential in combination with magnetic field measurements by MAG to study the fields and density fluctuations in the solar wind. In particular, we used the polarization of the wave magnetic field, the phase between the compressible magnetic field and density fluctuations, and the compressibility ratio (the ratio of the normalized density fluctuations to the normalized compressible fluctuations of B) to characterize the observed waves and turbulence.nResults. We find that the density fluctuations are 180° out of phase (anticorrelated) with the compressible component of magnetic fluctuations for intervals of turbulence, whereas they are in phase for the circular-polarized waves. We analyze, in detail, two specific events with a simultaneous presence of left- and right-handed waves at different frequencies. We compare the observed wave properties to a prediction of the three-fluid (electrons, protons, and alphas) model. We find a limit on the observed wavenumbers, 10−6 < k < 7 × 10−6 m−1, which corresponds to a wavelength of 7 × 106 > λ > 106 m. We conclude that it is most likely that both the left- and right-handed waves correspond to the low-wavenumber part (close to the cut-off at ΩcHe + +) of the proton-band electromagnetic ion cyclotron (left-handed wave in the plasma frame confined to the frequency range ΩcHe + + < ω < Ωcp) waves propagating in the outwards and inwards directions, respectively. The fact that both wave polarizations are observed at the same time and the identified wave mode has a low group velocity suggests that the double-banded events occur in the source regions of the waves.

Název v anglickém jazyce

Density Fluctuations Associated with Turbulence and Waves: First Observations by Solar Orbiter

Popis výsledku anglicky

Aims. The aim of this work is to demonstrate that the probe-to-spacecraft potential measured by RPW on Solar Orbiter can be used to derive the plasma (electron) density measurement, which exhibits both a high temporal resolution and a high level of accuracy. To investigate the physical nature of the solar wind turbulence and waves, we analyze the density and magnetic field fluctuations around the proton cyclotron frequency observed by Solar Orbiter during the first perihelion encounter (∼0.5 AU away from the Sun).nMethods. We used the plasma density based on measurements of the probe-to-spacecraft potential in combination with magnetic field measurements by MAG to study the fields and density fluctuations in the solar wind. In particular, we used the polarization of the wave magnetic field, the phase between the compressible magnetic field and density fluctuations, and the compressibility ratio (the ratio of the normalized density fluctuations to the normalized compressible fluctuations of B) to characterize the observed waves and turbulence.nResults. We find that the density fluctuations are 180° out of phase (anticorrelated) with the compressible component of magnetic fluctuations for intervals of turbulence, whereas they are in phase for the circular-polarized waves. We analyze, in detail, two specific events with a simultaneous presence of left- and right-handed waves at different frequencies. We compare the observed wave properties to a prediction of the three-fluid (electrons, protons, and alphas) model. We find a limit on the observed wavenumbers, 10−6 < k < 7 × 10−6 m−1, which corresponds to a wavelength of 7 × 106 > λ > 106 m. We conclude that it is most likely that both the left- and right-handed waves correspond to the low-wavenumber part (close to the cut-off at ΩcHe + +) of the proton-band electromagnetic ion cyclotron (left-handed wave in the plasma frame confined to the frequency range ΩcHe + + < ω < Ωcp) waves propagating in the outwards and inwards directions, respectively. The fact that both wave polarizations are observed at the same time and the identified wave mode has a low group velocity suggests that the double-banded events occur in the source regions of the waves.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

—

Návaznosti

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2021

Kód důvěrnosti údajů

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Název periodika

Astronomy & Astrophysics

ISSN

0004-6361

e-ISSN

1432-0746

Svazek periodika

656

Číslo periodika v rámci svazku

Dec 14

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

13

Strana od-do

A19

Kód UT WoS článku

000730246400023

EID výsledku v databázi Scopus

2-s2.0-85121625755