Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare
We present observations and analysis of an X1.8 noneruptive solar flare on 2012 October 23, which is characterized by an extremely large late-phase peak seen in the warm coronal extreme-ultraviolet (EUV) emissions (∼3 MK), with the peak intensity over 1.4 times that of the main flare peak. The flare...
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IOP Publishing
2024-01-01
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| Series: | The Astrophysical Journal |
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| Online Access: | https://doi.org/10.3847/1538-4357/ad8ba3 |
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| author | Shihan Li Yu Dai Mingde Ding Zhen Li Jinhan Guo Hao Wu |
| author_facet | Shihan Li Yu Dai Mingde Ding Zhen Li Jinhan Guo Hao Wu |
| author_sort | Shihan Li |
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| description | We present observations and analysis of an X1.8 noneruptive solar flare on 2012 October 23, which is characterized by an extremely large late-phase peak seen in the warm coronal extreme-ultraviolet (EUV) emissions (∼3 MK), with the peak intensity over 1.4 times that of the main flare peak. The flare is driven by a failed eruption of a magnetic flux rope, whose strong squeeze force acting on the overlying magnetic structures gives rise to an intense early heating of the late-phase loops. Based on differential emission measure analysis, it is found that the late-phase loops experience a “longer-than-expected” cooling, without the presence of any obvious additional heating, while their volume emission measure maintains a plateau for a long time before turning into an evident decay. Without the need for an additional heating, we propose that the special thermodynamic evolution of the late-phase loops revealed in this flare might arise from loop cross-sectional expansions with height, which are evidenced by both direct measurements from EUV images and by magnetic field extrapolation. By blocking the losses of both heat flux and mass from the corona, such an upward cross-sectional expansion not only elongates the loop-cooling time, but also more effectively sustains the loop density, therefore leading to a later-than-expected occurrence of the warm coronal late phase in combination with a sufficiently high late-phase peak. We further verify such a scenario by analytically solving the cooling process of a late-phase loop characterized by a variable cross section. |
| format | Article |
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| institution | Kabale University |
| issn | 1538-4357 |
| language | English |
| publishDate | 2024-01-01 |
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| series | The Astrophysical Journal |
| spelling | doaj-art-2cdbf3c4a7ec4accb62d68f32edfe5002024-12-18T09:53:00ZengIOP PublishingThe Astrophysical Journal1538-43572024-01-01977225710.3847/1538-4357/ad8ba3Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar FlareShihan Li0https://orcid.org/0009-0004-4898-638XYu Dai1https://orcid.org/0000-0001-9856-2770Mingde Ding2https://orcid.org/0000-0002-4978-4972Zhen Li3Jinhan Guo4https://orcid.org/0000-0002-4205-5566Hao Wu5School of Astronomy and Space Science, Nanjing University , Nanjing 210023, People's Republic of China ; ydai@nju.edu.cnSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People's Republic of China ; ydai@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210023, People's Republic of ChinaSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People's Republic of China ; ydai@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210023, People's Republic of ChinaSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People's Republic of China ; ydai@nju.edu.cn; Key Laboratory of Modern Astronomy and Astrophysics (Nanjing University) , Ministry of Education, Nanjing 210023, People's Republic of ChinaSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People's Republic of China ; ydai@nju.edu.cn; Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven , Celestijnenlaan 200B, B-3001 Leuven, BelgiumSchool of Astronomy and Space Science, Nanjing University , Nanjing 210023, People's Republic of China ; ydai@nju.edu.cnWe present observations and analysis of an X1.8 noneruptive solar flare on 2012 October 23, which is characterized by an extremely large late-phase peak seen in the warm coronal extreme-ultraviolet (EUV) emissions (∼3 MK), with the peak intensity over 1.4 times that of the main flare peak. The flare is driven by a failed eruption of a magnetic flux rope, whose strong squeeze force acting on the overlying magnetic structures gives rise to an intense early heating of the late-phase loops. Based on differential emission measure analysis, it is found that the late-phase loops experience a “longer-than-expected” cooling, without the presence of any obvious additional heating, while their volume emission measure maintains a plateau for a long time before turning into an evident decay. Without the need for an additional heating, we propose that the special thermodynamic evolution of the late-phase loops revealed in this flare might arise from loop cross-sectional expansions with height, which are evidenced by both direct measurements from EUV images and by magnetic field extrapolation. By blocking the losses of both heat flux and mass from the corona, such an upward cross-sectional expansion not only elongates the loop-cooling time, but also more effectively sustains the loop density, therefore leading to a later-than-expected occurrence of the warm coronal late phase in combination with a sufficiently high late-phase peak. We further verify such a scenario by analytically solving the cooling process of a late-phase loop characterized by a variable cross section.https://doi.org/10.3847/1538-4357/ad8ba3Solar flaresSolar coronaSolar extreme ultraviolet emissionHydrodynamics |
| spellingShingle | Shihan Li Yu Dai Mingde Ding Zhen Li Jinhan Guo Hao Wu Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare The Astrophysical Journal Solar flares Solar corona Solar extreme ultraviolet emission Hydrodynamics |
| title | Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare |
| title_full | Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare |
| title_fullStr | Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare |
| title_full_unstemmed | Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare |
| title_short | Enhanced Peak and Extended Cooling of the Extreme-ultraviolet Late Phase in a Confined Solar Flare |
| title_sort | enhanced peak and extended cooling of the extreme ultraviolet late phase in a confined solar flare |
| topic | Solar flares Solar corona Solar extreme ultraviolet emission Hydrodynamics |
| url | https://doi.org/10.3847/1538-4357/ad8ba3 |
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