Probing the Evolution of Solar Wind Temperature Anisotropies in the Inner Heliosphere

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F00216208%3A11320%2F25%3A10510636" target="_blank" >RIV/00216208:11320/25:10510636 - isvavai.cz</a>

Výsledek na webu

<a href="https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=xHcz4AGnOj" target="_blank" >https://verso.is.cuni.cz/pub/verso.fpl?fname=obd_publikace_handle&handle=xHcz4AGnOj</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/2041-8213/ae2792" target="_blank" >10.3847/2041-8213/ae2792</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Probing the Evolution of Solar Wind Temperature Anisotropies in the Inner Heliosphere

Popis výsledku v původním jazyce

Using solar wind measurements from Solar Orbiter, we investigated the distribution and evolution of the temperature anisotropy of alpha-particles (the ratio of perpendicular to parallel temperatures) in the inner heliosphere, between 0.29 and approximately 1 au. We also compared these observations with the corresponding proton temperature anisotropy to better understand the evolution of ion thermal properties in the expanding solar wind. We found that the slow wind (&lt;= 400 km s-1) exhibits higher alpha-particle anisotropy compared to the fast wind (&gt;= 600 km s-1), where the anisotropy values are mostly below one. The alpha-particle anisotropy increases as solar wind speed decreases, in contrast to protons, where anisotropy increases with solar wind speed. Additionally, we find that, regardless of the distance from the Sun, alpha-particle anisotropy is greater than proton anisotropy when the normalized differential speed between alpha-particles and protons (Delta V/VA) is less than 0.3. However, when Delta V/VA exceeds 0.4, the trend reverses, and proton anisotropy becomes larger. The radial evolution also shows distinct differences between fast and slow wind. In the fast wind, proton anisotropy decreases with distance from 0.29 to 1 au, while alpha-particle anisotropy shows no clear radial trend and remains nearly constant. In the slow wind, both proton and alpha anisotropies decrease with distance from the Sun. These results reveal distinct behaviors of alpha-particles and protons in the expanding solar wind, highlighting the dependence of ion heating on solar wind speed and differential flow.

Název v anglickém jazyce

Probing the Evolution of Solar Wind Temperature Anisotropies in the Inner Heliosphere

Popis výsledku anglicky

Using solar wind measurements from Solar Orbiter, we investigated the distribution and evolution of the temperature anisotropy of alpha-particles (the ratio of perpendicular to parallel temperatures) in the inner heliosphere, between 0.29 and approximately 1 au. We also compared these observations with the corresponding proton temperature anisotropy to better understand the evolution of ion thermal properties in the expanding solar wind. We found that the slow wind (&lt;= 400 km s-1) exhibits higher alpha-particle anisotropy compared to the fast wind (&gt;= 600 km s-1), where the anisotropy values are mostly below one. The alpha-particle anisotropy increases as solar wind speed decreases, in contrast to protons, where anisotropy increases with solar wind speed. Additionally, we find that, regardless of the distance from the Sun, alpha-particle anisotropy is greater than proton anisotropy when the normalized differential speed between alpha-particles and protons (Delta V/VA) is less than 0.3. However, when Delta V/VA exceeds 0.4, the trend reverses, and proton anisotropy becomes larger. The radial evolution also shows distinct differences between fast and slow wind. In the fast wind, proton anisotropy decreases with distance from 0.29 to 1 au, while alpha-particle anisotropy shows no clear radial trend and remains nearly constant. In the slow wind, both proton and alpha anisotropies decrease with distance from the Sun. These results reveal distinct behaviors of alpha-particles and protons in the expanding solar wind, highlighting the dependence of ion heating on solar wind speed and differential flow.

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

<a href="/cs/project/LUAUS25060" target="_blank" >LUAUS25060: Jak a kde je sluneční vítr urychlován a zahříván a jak tyto procesy ovlivňují jeho šíření heliosférou?</a><br>

Návaznosti

P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)<br>I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Rok uplatnění

2025

Kód důvěrnosti údajů

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

Název periodika

Astrophysical Journal Letters

ISSN

2041-8205

e-ISSN

2041-8213

Svazek periodika

995

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

7

Strana od-do

L68

Kód UT WoS článku

001641266300001

EID výsledku v databázi Scopus

—