On the Generation Mechanism of Electromagnetic Cyclotron Waves in the Solar Wind: Statistical Results from Wind Observations
Identifikátory výsledku
Kód výsledku v IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F19%3A10405502" target="_blank" >RIV/00216208:11320/19:10405502 - isvavai.cz</a>
Výsledek na webu
<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=7tMQ2IREH5" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=7tMQ2IREH5</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.3847/1538-4357/aaf8b8" target="_blank" >10.3847/1538-4357/aaf8b8</a>
Alternativní jazyky
Jazyk výsledku
angličtina
Název v původním jazyce
On the Generation Mechanism of Electromagnetic Cyclotron Waves in the Solar Wind: Statistical Results from Wind Observations
Popis výsledku v původním jazyce
Electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency are frequently observed in the solar wind, yet their generation mechanism is still an open question. Based on the Wind data from 2005-2015, this paper carries out a statistical study on the plasma characteristics associated with the occurrence of ECWs. The probability density distributions (PDDs) of proton temperature anisotropy (T-perpendicular to/T-parallel to) and proton parallel beta (beta(parallel to)) are investigated, where perpendicular to and parallel to refer to perpendicular and parallel to the background magnetic field, respectively. The PDDs depend on solar wind types as well as wave polarizations, and those for ECWs with left-handed (LH) polarization exhibit considerable differences from the PDDs for ambient solar winds. The distributions of occurrence rates of LH ECWs in (beta(parallel to), T-perpendicular to/T-parallel to) space show a tendency that the occurrence rates increase with proton temperature anisotropies. The beta(parallel to) with the maximum of occurrence rates is near 0.1 when T-perpendicular to/T-parallel to > 1, while it is around 1 when T-perpendicular to/T-parallel to < 1. The presence of alpha-proton differential flow with large kinetic energy corresponds to a much higher occurrence rate as well as the domination of LH polarization of ECWs. Based on these observations and existing theories, we propose that the proton cyclotron and parallel firehose instabilities with effects of alpha-proton differential flow are likely responsible for the local generation of LH ECWs in the solar wind. The generation mechanism of right-handed (RH) ECWs seems to be complicated and more discussions are needed in future research.
Název v anglickém jazyce
On the Generation Mechanism of Electromagnetic Cyclotron Waves in the Solar Wind: Statistical Results from Wind Observations
Popis výsledku anglicky
Electromagnetic cyclotron waves (ECWs) near the proton cyclotron frequency are frequently observed in the solar wind, yet their generation mechanism is still an open question. Based on the Wind data from 2005-2015, this paper carries out a statistical study on the plasma characteristics associated with the occurrence of ECWs. The probability density distributions (PDDs) of proton temperature anisotropy (T-perpendicular to/T-parallel to) and proton parallel beta (beta(parallel to)) are investigated, where perpendicular to and parallel to refer to perpendicular and parallel to the background magnetic field, respectively. The PDDs depend on solar wind types as well as wave polarizations, and those for ECWs with left-handed (LH) polarization exhibit considerable differences from the PDDs for ambient solar winds. The distributions of occurrence rates of LH ECWs in (beta(parallel to), T-perpendicular to/T-parallel to) space show a tendency that the occurrence rates increase with proton temperature anisotropies. The beta(parallel to) with the maximum of occurrence rates is near 0.1 when T-perpendicular to/T-parallel to > 1, while it is around 1 when T-perpendicular to/T-parallel to < 1. The presence of alpha-proton differential flow with large kinetic energy corresponds to a much higher occurrence rate as well as the domination of LH polarization of ECWs. Based on these observations and existing theories, we propose that the proton cyclotron and parallel firehose instabilities with effects of alpha-proton differential flow are likely responsible for the local generation of LH ECWs in the solar wind. The generation mechanism of right-handed (RH) ECWs seems to be complicated and more discussions are needed in future research.
Klasifikace
Druh
J<sub>imp</sub> - Článek v periodiku v databázi Web of Science
CEP obor
—
OECD FORD obor
10305 - Fluids and plasma physics (including surface physics)
Návaznosti výsledku
Projekt
—
Návaznosti
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Ostatní
Rok uplatnění
2019
Kód důvěrnosti údajů
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Údaje specifické pro druh výsledku
Název periodika
Astrophysical Journal
ISSN
0004-637X
e-ISSN
—
Svazek periodika
871
Číslo periodika v rámci svazku
2
Stát vydavatele periodika
US - Spojené státy americké
Počet stran výsledku
10
Strana od-do
175
Kód UT WoS článku
000457281200008
EID výsledku v databázi Scopus
2-s2.0-85061998960