Evolution of Relative Drifts in the Expanding Solar Wind: Helios Observations

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F19%3A10395973" target="_blank" >RIV/00216208:11320/19:10395973 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=uItHiXFiV" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=uItHiXFiV</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1007/s11207-019-1490-y" target="_blank" >10.1007/s11207-019-1490-y</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Evolution of Relative Drifts in the Expanding Solar Wind: Helios Observations

Popis výsledku v původním jazyce

Ion velocity distribution functions (VDFs) measured in-situ in the solar wind show often large deviations from asimple Maxwellian distribution. Even amain part of the proton VDF (proton core) situated around the global maximum maintains abi-Maxwellian character. Moreover, skewness, related to a non-thermal tail or proton beam, is often observed. In addition to these two proton populations, various heavy ion species are present and their VDFs also exhibit the mentioned non-thermal features. In the proton core frame, minor components including ion beams drift along the interplanetary magnetic field and their average differential velocities decrease with an increasing distance from the Sun. We present reprocessing of the VDFs measured by the Helios spacecraft with a motivation to discuss evolutions of relative drifts between three dominant components - the proton core, proton beam, and alpha-particle core at different distances from the Sun. Our processing is based on assumptions that partial VDFs of all these components can be approximated by abi-Maxwellian distribution. We compare results of this novel procedure with those from previous computation results and introduce basic characteristics of the VDF components in both slow and fast solar wind streams. Finally, we investigate the correlated variations of the velocity ratios on the ion components and magnetic field orientations occurring independently on the radial distance from the Sun.

Název v anglickém jazyce

Evolution of Relative Drifts in the Expanding Solar Wind: Helios Observations

Popis výsledku anglicky

Ion velocity distribution functions (VDFs) measured in-situ in the solar wind show often large deviations from asimple Maxwellian distribution. Even amain part of the proton VDF (proton core) situated around the global maximum maintains abi-Maxwellian character. Moreover, skewness, related to a non-thermal tail or proton beam, is often observed. In addition to these two proton populations, various heavy ion species are present and their VDFs also exhibit the mentioned non-thermal features. In the proton core frame, minor components including ion beams drift along the interplanetary magnetic field and their average differential velocities decrease with an increasing distance from the Sun. We present reprocessing of the VDFs measured by the Helios spacecraft with a motivation to discuss evolutions of relative drifts between three dominant components - the proton core, proton beam, and alpha-particle core at different distances from the Sun. Our processing is based on assumptions that partial VDFs of all these components can be approximated by abi-Maxwellian distribution. We compare results of this novel procedure with those from previous computation results and introduce basic characteristics of the VDF components in both slow and fast solar wind streams. Finally, we investigate the correlated variations of the velocity ratios on the ion components and magnetic field orientations occurring independently on the radial distance from the Sun.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10305 - Fluids and plasma physics (including surface physics)

Projekt

Výsledek vznikl pri realizaci vícero projektů. Více informací v záložce Projekty.

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)

Rok uplatnění

2019

Kód důvěrnosti údajů

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

Název periodika

Solar Physics

ISSN

0038-0938

e-ISSN

—

Svazek periodika

294

Číslo periodika v rámci svazku

7

Stát vydavatele periodika

NL - Nizozemsko

Počet stran výsledku

15

Strana od-do

97

Kód UT WoS článku

000477049900002

EID výsledku v databázi Scopus

2-s2.0-85069439279