Počet záznamů: 1
On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI
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SYSNO ASEP 0482570 Druh ASEP J - Článek v odborném periodiku Zařazení RIV J - Článek v odborném periodiku Poddruh J Článek ve WOS Název On the Nature of Off-limb Flare Continuum Sources Detected by SDO/HMI Tvůrce(i) Heinzel, Petr (ASU-R) RID, ORCID
Kleint, L. (CH)
Kašparová, Jana (ASU-R) RID, ORCID
Krucker, S. (CH)Zdroj.dok. Astrophysical Journal - ISSN 0004-637X
Roč. 847, č. 1 (2017), 48/1-48/6Poč.str. 6 s. Forma vydání Tištěná - P Jazyk dok. eng - angličtina Země vyd. US - Spojené státy americké Klíč. slova Sun ; chromosphere ; radiation mechanisms Vědní obor RIV BN - Astronomie a nebeská mechanika, astrofyzika Obor OECD Astronomy (including astrophysics,space science) CEP GA16-18495S GA ČR - Grantová agentura ČR Institucionální podpora ASU-R - RVO:67985815 UT WOS 000411341100024 EID SCOPUS 85030175047 DOI 10.3847/1538-4357/aa86ef Anotace 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. Pracoviště Astronomický ústav Kontakt Radka Svašková, bibl@asu.cas.cz, Tel.: 323 620 326 Rok sběru 2018
Počet záznamů: 1