Magnetic cloud fit by uniform-twist toroidal flux ropes

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F17%3A00484734" target="_blank" >RIV/67985815:_____/17:00484734 - isvavai.cz</a>

Výsledek na webu

<a href="http://dx.doi.org/10.1051/0004-6361/201731412" target="_blank" >http://dx.doi.org/10.1051/0004-6361/201731412</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1051/0004-6361/201731412" target="_blank" >10.1051/0004-6361/201731412</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Magnetic cloud fit by uniform-twist toroidal flux ropes

Popis výsledku v původním jazyce

Magnetic clouds are bent, and for some observations, a toroidal rather than a cylindrical flux rope is needed for a local approximation of the cloud fields. We therefore try to derive an axially symmetric uniform-twist force-free field in a toroid, either exactly, or approximately, and to compare it with observations. Equations following from the conditions of solenoidality and force-freeness in toroidally curved cylindrical coordinates were solved analytically. The magnetic field and velocity observations of a magnetic cloud were compared with solutions obtained using a nonlinear least-squares method. Three solutions of (nearly) uniform-twist magnetic fields in a toroid were obtained. All are exactly solenoidal, and in the limit of high aspect ratios, they tend to the Gold-Hoyle field. The first solution has an exactly uniform twist, the other two solutions have a nearly uniform twist and approximate force-free fields. The analysis of a magnetic cloud observation showed that these fields may fit the observed field equally well as the already known approximately linear force-free (Miller-Turner) field, but it also revealed that the geometric parameters of the toroid might not be reliably determined from fits, when (nearly) uniform-twist model fields are used. Sets of parameters largely differing in the size of the toroid and its aspect ratio yield fits of a comparable quality.n

Název v anglickém jazyce

Magnetic cloud fit by uniform-twist toroidal flux ropes

Popis výsledku anglicky

Magnetic clouds are bent, and for some observations, a toroidal rather than a cylindrical flux rope is needed for a local approximation of the cloud fields. We therefore try to derive an axially symmetric uniform-twist force-free field in a toroid, either exactly, or approximately, and to compare it with observations. Equations following from the conditions of solenoidality and force-freeness in toroidally curved cylindrical coordinates were solved analytically. The magnetic field and velocity observations of a magnetic cloud were compared with solutions obtained using a nonlinear least-squares method. Three solutions of (nearly) uniform-twist magnetic fields in a toroid were obtained. All are exactly solenoidal, and in the limit of high aspect ratios, they tend to the Gold-Hoyle field. The first solution has an exactly uniform twist, the other two solutions have a nearly uniform twist and approximate force-free fields. The analysis of a magnetic cloud observation showed that these fields may fit the observed field equally well as the already known approximately linear force-free (Miller-Turner) field, but it also revealed that the geometric parameters of the toroid might not be reliably determined from fits, when (nearly) uniform-twist model fields are used. Sets of parameters largely differing in the size of the toroid and its aspect ratio yield fits of a comparable quality.n

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

Projekt

<a href="/cs/project/GA17-06065S" target="_blank" >GA17-06065S: Variace slunečního větru a jejich vazba na dynamiku magnetosféry Země</a><br>

Návaznosti

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

Rok uplatnění

2017

Kód důvěrnosti údajů

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

Název periodika

Astronomy & Astrophysics

ISSN

1432-0746

e-ISSN

—

Svazek periodika

608

Číslo periodika v rámci svazku

December

Stát vydavatele periodika

FR - Francouzská republika

Počet stran výsledku

12

Strana od-do

"A118/1"-"A118/12"

Kód UT WoS článku

000418458600012

EID výsledku v databázi Scopus

2-s2.0-85038411817