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国立天文台　セミナー情報　/　Seminar Information

2021.10.18-2021.10.24

Oct 19 Tue　10:00～11:30　 太陽系小天体セミナー / Solar System Minor Body Seminar　zoom

Oct 20 Wed 15:30～17:00　 NAOJ Science Colloquium 　　　　　zoom

Oct 22 Thu 13:00～14:30 　 Solar and Space Plasma Seminar 　　 zoom

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2021.10.11-2021.10.17

Oct 12 Tue　10:00～11:30　 太陽系小天体セミナー / Solar System Minor Body Seminar　zoom

Oct 13 Wed 15:30～17:00　 NAOJ Science Colloquium 　　　　　zoom

Oct 14 Thu 9:00～11:00 　Final Defense for the doctoral thesis of the Department of Astronomical Science, SOKENDAI　　　 zoom

Oct 15 Fri 16:00～17:00 　 談話会 / NAOJSeminar　　　　 　 zoom　　　　　　　

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2021.10.4-2021.10.10

Oct 5 Tue　10:00～11:30　 太陽系小天体セミナー / Solar System Minor Body Seminar　zoom

Oct 6 Wed 15:30～17:00　 NAOJ Science Colloquium 　　　　　zoom

Oct 8 Fri 13:30～15:00 　Solar and Space Plasma Seminar　　　 zoom

Oct 8 Fri 16:00～17:00 　 談話会 / NAOJSeminar　　　　 　 zoom　　　　　　　

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2021.9.27-2021.10.3

Sep 28 Tue 10:00～11:30　Solar System Minor Body Seminar zoom 　

Sep 29 Wed 15:00～16:00 ALMA-J seminar 　　　 　 zoom　

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2021.9.20-2021.9.26

Sep 21 Tue 10:00～11:30　 太陽系小天体セミナー　　　　　　　 zoom

Sep 24 Fri 13:30～15:00 　Solar and Space Plasma Seminar 　　 zoom　

詳細は以下をご覧下さい

9月21日（火）

キャンパス：三鷹
セミナー名：太陽系小天体セミナー
定例・臨時の別：定例
日時：9月21日（火曜日）10時00分～11時30分
場所：zoom

世話人の連絡先
　名前：渡部潤一
備考：テレビ会議またはスカイプによる参加も可

9月24日（金）

Campus： Mitaka
Seminar： Solar and Space Plasma Seminar
Regularly Scheduled/Sporadic： Scheduled
Date and time：24 September (Fri), 13:30-15:00
Place： zoom
Speaker：Daiki Yamasaki
Affiliation： Kyoto University
Title：Numerical modeling of three-dimensional coronal magnetic field in the flare-productive solar active region NOAA 12673

Abstract：
Solar flares are the rapid energy release in the solar outer atmosphere, solar corona. The energy source of the solar flares is widely considered as the magnetic energy accumulated in solar active regions (ARs). Due to the observational limitation, however, it is hard to obtain the coronal vector magnetic field, and thus, we cannot directly detect the formation process of the magnetic flux ropes (MFRs). Hence, it is helpful to understand the formation and the evolution of the flare-productive ARs that the numerical modeling of the three-dimensional coronal magnetic field using an observable photospheric vector magnetic field. In our study, we focus on the AR 12673, which has produced many M-class and several X-class flares, one of which being an X9.3 flare, which is recorded as the largest solar flare in solar cycle 24. We studied the evolution of the three-dimensional flare-productive magnetic field within AR 12673, using a time series of nonlinear force-free field extrapolations of every 12 hr from 2017 September 4 00:00 UT to 6 00:00 UT. Our analysis found that three MFRs formed by September 4, one of which produced the X9.3 flare on September 6. One MFR has positive magnetic twist, which is a different sign from the other two MFRs. Since the temporal evolution of the magnetic flux of the MFR accumulating the positive twist is consistent with the profile of the GOES X-ray flux well observed from September 4 to 6, we suggest that the formation of the MFR having the positive twist is closely related to the occurrence of the M-class flares, including an M5.5 flare. We further found a magnetic null in the magnetic field surrounding the MFRs, in particular above the MFR having positive twist before the M5.5 flare, which is the largest M-flare observed during this period. By comparing with Atmospheric Imaging Assembly 1600 Å images, we found that the footpoints of the overlying field lines are anchored to the area where the brightening was initially observed. Therefore, we suggest that reconnection induced by the torus instability of the positively twisted MFR at the null possibly drove the M5.5 flare. In my presentation, I would also like to discuss the difference of the CME association between two homologous M-class flares observed in the AR 12673.

Facilitator
-Name：Munehito Shoda
Comment：in English,

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