Whistler Waves and Electron Properties in the Inner Heliosphere: Helios Observations

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F68378289%3A_____%2F20%3A00535838" target="_blank" >RIV/68378289:_____/20:00535838 - isvavai.cz</a>

Výsledek na webu

<a href="https://doi.org/10.3847/1538-4357/ab94a1" target="_blank" >https://doi.org/10.3847/1538-4357/ab94a1</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/ab94a1" target="_blank" >10.3847/1538-4357/ab94a1</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Whistler Waves and Electron Properties in the Inner Heliosphere: Helios Observations

Popis výsledku v původním jazyce

We present the analysis of narrowband whistler wave signatures observed in the inner heliosphere (0.3-1 au). These signatures are bumps in the spectral density in the 10-200 Hz frequency range of the AC magnetic field as measured by the search coil magnetometer on board the Helios 1 spacecraft. We show that the majority of whistler signatures are observed in the slow solar wind (<500 km s(-1)) and their occurrence increases with the radial distance (R), from similar to 3% at 0.3 au to similar to 10% at 0.9 au. In the fast solar wind (>600 km s(-1)), whistler activity is significantly lower: whistler signatures start to appear forR > 0.6 au and their number increases from similar to 0.03% at 0.65 au to similar to 1% at 0.9 au. We have studied the variation of the electron core and halo anisotropy (T-e/T-e parallel to), as well as the electron normalized heat flux as a function ofRand of the solar wind speed. We find that, in the slow wind electron core and halo anisotropy is higher than in fast one, and also that these anisotropies increase radially in both types of winds, which is in line with the occurrence of whistler signatures. We hypothesize the existence of a feedback mechanism to explain the observed radial variations of the occurrence of whistlers in relation with the halo anisotropy.

Název v anglickém jazyce

Whistler Waves and Electron Properties in the Inner Heliosphere: Helios Observations

Popis výsledku anglicky

We present the analysis of narrowband whistler wave signatures observed in the inner heliosphere (0.3-1 au). These signatures are bumps in the spectral density in the 10-200 Hz frequency range of the AC magnetic field as measured by the search coil magnetometer on board the Helios 1 spacecraft. We show that the majority of whistler signatures are observed in the slow solar wind (<500 km s(-1)) and their occurrence increases with the radial distance (R), from similar to 3% at 0.3 au to similar to 10% at 0.9 au. In the fast solar wind (>600 km s(-1)), whistler activity is significantly lower: whistler signatures start to appear forR > 0.6 au and their number increases from similar to 0.03% at 0.65 au to similar to 1% at 0.9 au. We have studied the variation of the electron core and halo anisotropy (T-e/T-e parallel to), as well as the electron normalized heat flux as a function ofRand of the solar wind speed. We find that, in the slow wind electron core and halo anisotropy is higher than in fast one, and also that these anisotropies increase radially in both types of winds, which is in line with the occurrence of whistler signatures. We hypothesize the existence of a feedback mechanism to explain the observed radial variations of the occurrence of whistlers in relation with the halo anisotropy.

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

2020

Kód důvěrnosti údajů

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

Název periodika

Astrophysical Journal

ISSN

0004-637X

e-ISSN

—

Svazek periodika

897

Číslo periodika v rámci svazku

2

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

15

Strana od-do

118

Kód UT WoS článku

000551649000001

EID výsledku v databázi Scopus

2-s2.0-85088592108