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

Result code in 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>

Result on the web

<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>

Result language

angličtina

Original language name

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

Original language description

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.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

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OECD FORD branch

10308 - Astronomy (including astrophysics,space science)

Project

Result was created during the realization of more than one project. More information in the Projects tab.

Continuities

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

Publication year

2017

Confidentiality

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

Name of the periodical

Astrophysical Journal

ISSN

0004-637X

e-ISSN

—

Volume of the periodical

842

Issue of the periodical within the volume

1

Country of publishing house

US - UNITED STATES

Number of pages

18

Pages from-to

"1/1"-"1/18"

UT code for WoS article

000403205400004

EID of the result in the Scopus database

2-s2.0-85021088241