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Thermal instability in the impulsive phase of solar flares with sub-THz component

Published online by Cambridge University Press:  23 December 2024

V. V. Smirnova Open the ORCID record for V. V. Smirnova [Opens in a new window] ,
Yu. T. Tsap Open the ORCID record for Yu. T. Tsap [Opens in a new window] ,
G. G. Motorina Open the ORCID record for G. G. Motorina [Opens in a new window] ,
A. S. Morgachev  and
M. Bárta
V. V. Smirnova*
Affiliation:
Crimean Astrophysical Observatory of Russian Academy of Sciences, Nauchny, 298409, Russia
Yu. T. Tsap
Affiliation:
Crimean Astrophysical Observatory of Russian Academy of Sciences, Nauchny, 298409, Russia
G. G. Motorina
Affiliation:
Central Astronomical Observatory at Pulkovo of Russian Academy of Sciences, St. Petersburg, 196140, Russia Ioffe Institute, Polytekhnicheskaya, 26, St. Petersburg, 194021, Russia Astronomical Institute of the Czech Academy of Sciences, Ondřejov, 25165, Czech Republic
A. S. Morgachev
Affiliation:
Central Astronomical Observatory at Pulkovo of Russian Academy of Sciences, St. Petersburg, 196140, Russia
M. Bárta
Affiliation:
Astronomical Institute of the Czech Academy of Sciences, Ondřejov, 25165, Czech Republic
*
email: [email protected]
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Abstract

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Coronal rain is formed in the post-impulsive phase of solar flares due to the thermal instability of coronal plasma in EUV loops. As a result, the sub-terahertz (sub-THz) emission flux in the post-impulsive phase of solar flares can be increased due to the increasing of the optical thickness of the thermal source. This suggests that sub-THz observations can be used as a diagnostic tool for coronal rain.

This work is aimed to analyse the relationship between the sub-THz radiation and variations of the temperature and the emission measure of the EUV coronal plasma during the post-impulsive phase of the SOL2022-05-04T08:45 solar flare.

Based on the two-dimensional temperature and emission measure distributions obtained from the AIA/SDO EUV intensity data, it was found that the temperature decreases whereas the emission measure reaches the maximum near the sub-THz flare peak. This circumstance and peculiarities of the radiation time profiles in different wave ranges show evidence in favor of the significant contribution of the thermal coronal loop plasma to the flare sub-THz radiation at least for some flare events. The sub-THz emission may be associated with a coronal condensation, accompanied by the formation of coronal rain.

Keywords

Sunflaressub-therahertz radiation
Type
Poster Paper
Information
Proceedings of the International Astronomical Union , Volume 19 , Symposium S365: Dynamics of Solar and Stellar Convection Zones and Atmospheres , December 2023 , pp. 414 - 419
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Creative Commons
Creative Common License - CCCreative Common License - BY
This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
Copyright
© The Author(s), 2024. Published by Cambridge University Press on behalf of International Astronomical Union

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