TY - JOUR
T1 - Implications for Additional Plasma Heating Driving the Extreme-ultraviolet Late Phase of a Solar Flare with Microwave Imaging Spectroscopy
AU - Zhang, Jiale
AU - Chen, Bin
AU - Yu, Sijie
AU - Tian, Hui
AU - Wei, Yuqian
AU - Chen, Hechao
AU - Tan, Guangyu
AU - Luo, Yingjie
AU - Chen, Xingyao
N1 - Funding Information:
This work is supported by National Key R&D Program of China No. 2021YFA1600500 and NSFC grants 11825301 and 11790304. EOVSA operation is supported by NSF grant AST-1910354 and AGS-2130832 to NJIT. B.C. acknowledges support by NSF grant AGS-1654382 to NJIT. The SDO is a mission for NASA’s Living With a Star (LWS) Program. The GOES is a joint effort of NASA and the National Oceanic and Atmospheric Administration (NOAA).
Publisher Copyright:
© 2022. The Author(s).
PY - 2022/6/1
Y1 - 2022/6/1
N2 - Extreme-ultraviolet late phase (ELP) refers to the second extreme-ultraviolet (EUV) radiation enhancement observed in certain solar flares, which usually occurs tens of minutes to several hours after the peak of soft X-ray emission. The coronal loop system that hosts the ELP emission is often different from the main flaring arcade, and the enhanced EUV emission therein may imply an additional heating process. However, the origin of the ELP remains rather unclear. Here we present the analysis of a C1.4 flare that features such an ELP, which is also observed in microwave wavelengths by the Expanded Owens Valley Solar Array. Similar to the case of the ELP, we find a gradual microwave enhancement that occurs about 3 minutes after the main impulsive phase microwave peaks. Radio sources coincide with both foot points of the ELP loops and spectral fits on the time-varying microwave spectra demonstrate a clear deviation of the electron distribution from the Maxwellian case, which could result from injected nonthermal electrons or nonuniform heating to the footpoint plasma. We further point out that the delayed microwave enhancement suggests the presence of an additional heating process, which could be responsible for the evaporation of heated plasma that fills the ELP loops, producing the prolonged ELP emission.
AB - Extreme-ultraviolet late phase (ELP) refers to the second extreme-ultraviolet (EUV) radiation enhancement observed in certain solar flares, which usually occurs tens of minutes to several hours after the peak of soft X-ray emission. The coronal loop system that hosts the ELP emission is often different from the main flaring arcade, and the enhanced EUV emission therein may imply an additional heating process. However, the origin of the ELP remains rather unclear. Here we present the analysis of a C1.4 flare that features such an ELP, which is also observed in microwave wavelengths by the Expanded Owens Valley Solar Array. Similar to the case of the ELP, we find a gradual microwave enhancement that occurs about 3 minutes after the main impulsive phase microwave peaks. Radio sources coincide with both foot points of the ELP loops and spectral fits on the time-varying microwave spectra demonstrate a clear deviation of the electron distribution from the Maxwellian case, which could result from injected nonthermal electrons or nonuniform heating to the footpoint plasma. We further point out that the delayed microwave enhancement suggests the presence of an additional heating process, which could be responsible for the evaporation of heated plasma that fills the ELP loops, producing the prolonged ELP emission.
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U2 - 10.3847/1538-4357/ac6ce3
DO - 10.3847/1538-4357/ac6ce3
M3 - Article
AN - SCOPUS:85132996775
SN - 0004-637X
VL - 932
JO - Astrophysical Journal
JF - Astrophysical Journal
IS - 1
M1 - 53
ER -