On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F17%3A00482570" target="_blank" >RIV/67985815:_____/17:00482570 - isvavai.cz</a>
Result on the web
<a href="http://dx.doi.org/10.3847/1538-4357/aa86ef" target="_blank" >http://dx.doi.org/10.3847/1538-4357/aa86ef</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.3847/1538-4357/aa86ef" target="_blank" >10.3847/1538-4357/aa86ef</a>
Alternative languages
Result language
angličtina
Original language name
On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI
Original language description
In this paper we aim to determine which radiation mechanism is responsible for such enhancement being seen above the limb, at chromospheric heights around or below 1000 km. Using a simple analytical approach, we compare two candidate mechanisms, the hydrogen recombination continuum (Paschen) and the Thomson continuum due to scattering of disk radiation on flare electrons. Both mechanisms depend on the electron density, which is typically enhanced during the impulsive phase of a flare as the result of collisional ionization (both thermal and also non-thermal due to electron beams). We conclude that for electron densities higher than 10(12) cm(-3), the Paschen recombination continuum significantly dominates the Thomson scattering continuum and there is some contribution from the hydrogen free-free emission. This is further supported by detailed radiation-hydrodynamical (RHD) simulations of the flare chromosphere heated by the electron beams. We use the RHD code FLARIX to compute the temporal evolution of the flareheating in a semi-circular loop. The synthesized continuum structure above the limb resembles the off-limb flare structures detected by HMI, namely their height above the limb, as well as the radiation intensity. These results are consistent with recent findings related to hydrogen Balmer continuum enhancements, which were clearly detected in disk flares by the IRIS near-ultraviolet spectrometer.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - 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)
Result continuities
Project
<a href="/en/project/GA16-18495S" target="_blank" >GA16-18495S: Advanced solar science with IRIS</a><br>
Continuities
P - Projekt vyzkumu a vyvoje financovany z verejnych zdroju (s odkazem do CEP)
Others
Publication year
2017
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Astrophysical Journal
ISSN
0004-637X
e-ISSN
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Volume of the periodical
847
Issue of the periodical within the volume
1
Country of publishing house
US - UNITED STATES
Number of pages
6
Pages from-to
"48/1"-"48/6"
UT code for WoS article
000411341100024
EID of the result in the Scopus database
2-s2.0-85030175047