IRIS Mg ii Observations and Non-LTE Modeling of Off-limb Spicules in a Solar Polar Coronal Hole

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F20%3A00534671" target="_blank" >RIV/67985815:_____/20:00534671 - isvavai.cz</a>

Result on the web

<a href="https://doi.org/10.3847/1538-4357/ab5db1" target="_blank" >https://doi.org/10.3847/1538-4357/ab5db1</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.3847/1538-4357/ab5db1" target="_blank" >10.3847/1538-4357/ab5db1</a>

Result language

angličtina

Original language name

IRIS Mg ii Observations and Non-LTE Modeling of Off-limb Spicules in a Solar Polar Coronal Hole

Original language description

We investigated the off-limb spicules observed in the Mg ii h and k lines by IRIS in a solar polar coronal hole. We analyzed the large data set of obtained spectra to extract quantitative information about the line intensities, shifts, and widths. The observed Mg ii line profiles are broad and double peaked at lower altitudes, broad but flat topped at middle altitudes, and narrow and single peaked with the largest Doppler shifts at higher altitudes. We use one-dimensional non-LTE vertical slab models (i.e., models that consider departures from local thermodynamic equilibrium) in single-slab and multi-slab configurations to interpret the observations and to investigate how a superposition of spicules along the line of sight (LOS) affects the synthetic Mg ii line profiles. The used multi-slab models either are static, i.e., without any LOS velocities, or assume randomly assigned LOS velocities of individual slabs, representing the spicule dynamics. We conducted such single-slab and multi-slab modeling for a broad set of model input parameters and showed the dependence of the Mg ii line profiles on these parameters. We demonstrated that the observed line widths of the h and k line profiles are strongly affected by the presence of multiple spicules along the LOS. We later showed that the profiles obtained at higher altitudes can be reproduced by single-slab models representing individual spicules. We found that the multi-slab model with a random distribution of the LOS velocities ranging from -25 to 25 km s(-1) can well reproduce the width and the shape of Mg ii profiles observed at middle altitudes.

Czech name

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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

—

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

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2020

Confidentiality

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

Name of the periodical

Astrophysical Journal

ISSN

1538-4357

e-ISSN

—

Volume of the periodical

888

Issue of the periodical within the volume

1

Country of publishing house

US - UNITED STATES

Number of pages

17

Pages from-to

42

UT code for WoS article

000507612800001

EID of the result in the Scopus database

2-s2.0-85080953903