Non-Maxwellian Analysis of the Transition-region Line Profiles Observed by the Interface Region Imaging Spectrograph

Kód výsledku v IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F17%3A00478682" target="_blank" >RIV/67985815:_____/17:00478682 - isvavai.cz</a>

Výsledek na webu

<a href="http://hdl.handle.net/11104/0274742" target="_blank" >http://hdl.handle.net/11104/0274742</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/aa71a8" target="_blank" >10.3847/1538-4357/aa71a8</a>

Jazyk výsledku

angličtina

Název v původním jazyce

Non-Maxwellian Analysis of the Transition-region Line Profiles Observed by the Interface Region Imaging Spectrograph

Popis výsledku v původním jazyce

We investigate the nature of the spectral line profiles for transition-region (TR) ions observed with the Interface Region Imaging Spectrograph (IRIS). In this context, we analyzed an active-region observation performed by IRIS in its 1400 Angstrom spectral window. The TR lines are found to exhibit significant wings in their spectral profiles, which can be well fitted with a non-Maxwellian kappa-distribution. The fit with a kappa-distribution can perform better than a double-Gaussian fit, especially for the strongest line, Si IV 1402.8 angstrom. Typical values of kappa found are about 2, occurring in a majority of spatial pixels where the TR lines are symmetric, i.e., the fit can be performed. Furthermore, all five spectral lines studied (from Si IV, O IV, and S IV) appear to have the same full-width at half-maximum irrespective of whether the line is an allowed or an intercombination transition. A similar value of kappa is obtained for the electron distribution by the fitting of the line intensities relative to Si IV 1402.8 angstrom, if photospheric abundances are assumed. These distributions, however, do not remove the presence of non-thermal broadening. Instead, they actually increase the non-thermal width. This is because, for kappa-distributions, TR ions are formed at lower temperatures. The large observed non-thermal width lowers the opacity of the Si IV line sufficiently enough for this line to become optically thin.

Název v anglickém jazyce

Non-Maxwellian Analysis of the Transition-region Line Profiles Observed by the Interface Region Imaging Spectrograph

Popis výsledku anglicky

We investigate the nature of the spectral line profiles for transition-region (TR) ions observed with the Interface Region Imaging Spectrograph (IRIS). In this context, we analyzed an active-region observation performed by IRIS in its 1400 Angstrom spectral window. The TR lines are found to exhibit significant wings in their spectral profiles, which can be well fitted with a non-Maxwellian kappa-distribution. The fit with a kappa-distribution can perform better than a double-Gaussian fit, especially for the strongest line, Si IV 1402.8 angstrom. Typical values of kappa found are about 2, occurring in a majority of spatial pixels where the TR lines are symmetric, i.e., the fit can be performed. Furthermore, all five spectral lines studied (from Si IV, O IV, and S IV) appear to have the same full-width at half-maximum irrespective of whether the line is an allowed or an intercombination transition. A similar value of kappa is obtained for the electron distribution by the fitting of the line intensities relative to Si IV 1402.8 angstrom, if photospheric abundances are assumed. These distributions, however, do not remove the presence of non-thermal broadening. Instead, they actually increase the non-thermal width. This is because, for kappa-distributions, TR ions are formed at lower temperatures. The large observed non-thermal width lowers the opacity of the Si IV line sufficiently enough for this line to become optically thin.

Druh

J_imp - Článek v periodiku v databázi Web of Science

CEP obor

—

OECD FORD obor

10308 - Astronomy (including astrophysics,space science)

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

2017

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

842

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

18

Strana od-do

"1/1"-"1/18"

Kód UT WoS článku

000403205400004

EID výsledku v databázi Scopus

2-s2.0-85021088241