On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI

Kód výsledku v 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>

Výsledek na webu

<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>

Jazyk výsledku

angličtina

Název v původním jazyce

On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI

Popis výsledku v původním jazyce

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.

Název v anglickém jazyce

On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI

Popis výsledku anglicky

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.

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/GA16-18495S" target="_blank" >GA16-18495S: Pokročilý výzkum Slunce se satelitem IRIS</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

Astrophysical Journal

ISSN

0004-637X

e-ISSN

—

Svazek periodika

847

Číslo periodika v rámci svazku

1

Stát vydavatele periodika

US - Spojené státy americké

Počet stran výsledku

6

Strana od-do

"48/1"-"48/6"

Kód UT WoS článku

000411341100024

EID výsledku v databázi Scopus

2-s2.0-85030175047