Solar Seminar (Zasshikai) Home Page (FY2023)

Solar Seminar (13:30-15:00 Monday, Room 504 5th floor building NO.4) Access

Next presenters

Date Time Section Speaker File
6/12 13:30-15:00
Otsu upload or download

Please upload your presentation file!!

Date Section Speaker File
Asai upload or download
Ueno upload or download
Nagata upload or download
Natsume&Yoshihisa upload or download
Shirato upload or download

For Speakers
Presentation time for speaker is
60 minutes as a guide, and 30 minuites discussion.
(A speaker can use the full time of one seminar.)
Contents of talk are
:about your study
:review of recent interesting paper and share information of recent study of the Sun.
Language of slide and talks
Master cource students : Language of slide and talk could be Japanese
Doctor cource students and over : Slide must be English, and talking language could be Japanese
(If those who could not understand Japanese attend the seminar, it is preferable that you talk in English)
Title and Abstract
Please send the title and abstract of your presentation by the day before.
Presentation files
Please upload your presentation files by the start of the seminar.
If the presentation file has very large volume, please zip the file before uploading.
If you do not want to make public your unpublished results, please delete the relevant part before submission.
For Audiences
Honoring speakers
Plase clap your hands as a closure of a presentation to express your respection to a speaker.
For everyone
Publication sharing
Please send a copy of the submitted version of any paper on which they are working to the zasshikai mailing list just after submission
  • Useful webpage list for solar observers.
  • See also Ishii-san's Webpage and Webpage of Astronomical Observatory.

  • Speakers
    Asai, Ueno, Nagata, Ishii, Kou,
    Mishra, Shirato, Otsu, Shimada,
    Kida, Natsume, Yoshihisa, and Suzuki

    Presentations in 2023-1st semester (13:30-15:00)

    Date Name Title Abstract File
    Asai (title) (abstract)

    Ueno Consideration of the importance of measuring 3D velocity field of erupting filaments for the space weather prediction Until now, our observatory has focused on the measurement of three- dimensional velocity field of erupting filaments from the viewpoint of space weather research by using SMART/T1, CHAIN-project. On the other hand, recently, especially arrival time of the CME to the geo-magnetosphere has been able to be predicted in higher accuracy than before by computer simulations without information of filament's 3D velocity field. I would like to consider and discuss the present importance of measuring 3D velocity field of erupting filaments for the space weather prediction with everyone. Moreover, I will introduce the result of improvement of the spectroheliograph at Ica University, Peru that we did in last March in order to raise the capture rate of filament eruptions.

    Nagata (title) (abstract)

    Ishii Event Report of SMART (Solar Magnetic Activity Research Telescope) / SDDI (Solar Dynamics Doppler Imager) from 2022 to 2023 Today, I would like to talk about 'Event Report of SMART (Solar Magnetic Activity Research Telescope) / SDDI (Solar Dynamics Doppler Imager) from 2022 to 2023'.

    14.7 MB
    Kou ASO-S Data is partially opened On Monday I would like to give a talk on the status of ASO-S after launch how the released data looks like as a continuation of the introduction to the instrument of ASO-S I presented on 2022/10/31. Most of the information comes from the "ASO-S Data Analysis Guidance" held on 2023/04/11.

    2.2 MB
    Mishra Instabilities in Different Magnetized Structures of the Solar Atmosphere In this talk I will briefly review some observational results of Rayleigh-Taylor instability, Kelvin-Helmholtz instability, and hybrid KH-RT instability in the solar atmosphere. After that, I will discuss my some new results regarding the evolution and impact of these instability in the solar atmosphere. I will also discuss the limitations of my results and future perspectives that could be explored to enhance our understanding about the evolution, growth, and impact of these instabilities in different magnetized structures.

    31.8 MB
    (No seminar because of JpGU)

    5/29 Practice for M2 interm report
    Natsume 太陽フレアに伴う諸現象の、 4つの彩層ラインでのSun-as-a-star解析 太陽フレアも恒星フレアも、表面での突発的な増光現象であるが、太陽フレアでは これを空間分解して観測することが可能である一方、恒星フレアでは空間積分したものに 相当するスペクトルや光度が観測でき、空間情報は失われてしまう。そこで、恒星の現象を 太陽物理学の知見で理解するために、Sun-as-a-star解析と呼ばれる、太陽のデータを 空間積分し恒星の観測データを模したデータを得る解析が近年行われている。 Namekata et al 2022aはその解析の活用例であり、太陽型星スーパーフレア (最大級太陽フレアの 10 倍以上の規模のフレア)に伴う Hα 線の吸収成分と、 フレアに伴う太陽プラズマ 噴出現象の Sun-as-a-star 解析の比較から、 このスーパーフレアもプ ラズマ噴出を伴っていたことを明らかにした。 Namekataらは Hα 線のみを用いたが、他の彩層ラインも含む同時観測により、 各ラインの形成高度や温度、密度等への感度の違いから、より多くの物理情報を得られる可能性がある。 複数の彩層ラインの太陽撮像分光データを用いたSun-as-a-star解析を行い、 どのような相違点があるのかを調べることを目的として、 京都大学飛騨天文台DSTで観測した太陽フレアに伴う吸収と増光について、 Hα 線とCa II K線、Ca II 8542Å、He I 10830Åの4つの彩層ラインのスペクトルの Sun-as-a-star解析を行った。解析を行った現象は、、2022年8月19日活動領域NOAA 13078の (1)04:30-05:30(UT)のツーリボンフレア、(2)05:15-60:00のフレアの増光とフィラメントの ドップラーシフト、(3)08:00-09:00のフレアの増光とフィラメントのドップラーシフトの3つである。 今回の発表では、(2)を発表する。 解析の結果、フィラメントのドップラーシフトについては、 HeとHαのwingでのプロファイルが似ており、フィラメントに関しては似た吸収感度を持つこと、 Hα中心の増光の部分でも、He中心付近では吸収が見えている場合があることが分かった。 フレアの増光はCa II KにHαに比べて吸収成分の影響が小さく、増光のスペクトルを検出しやすいことが分かった。

    Practice for M2 interm report
    Yoshihisa 衝撃波と乱流的効果によるコロナ加熱を考慮したプロミネンス形成についての1.5次元MHDシミュレーション プロミネンスに代表される太陽プラズマの凝縮現象は、長年にわたって観測されているが、 その形成メカニズムや物理的性質は十分に解明されていない。 最も有力なメカニズムの一つである「彩層蒸発-凝縮モデル」では、プロミネンスは熱非平衡と 暴走的な冷却によって形成されると考えられている。プロミネンス形成の熱的進化を理解するためには、 冷却と加熱の両方の物理変数や時間に対する依存性を考慮する必要がある。しかし、多くの先行研究では、 加熱項は簡略化のためにad hocな形でのみ考慮されている。 また、実際の太陽大気が凝結現象に与える影響を考えるには、コロナだけでなく、光球の対流運動や、 温度や密度構造が大きく変化する彩層の影響も考慮する必要がある。 そこで、本研究では、光球からコロナに至る領域でのAlfven波加熱を考慮した1.5次元MHDシミュレーションにより、 形成過程を検討することにした。プロミネンスを再現するために、窪んだ磁力線と足元に集中した局所加熱項を導入した。 その結果、(1)境界摂動に由来する衝撃波の通過と衝突が凝縮を誘発すること、(2)プロミネンスが足元に近づいた際に、 コロナでの加熱が上昇するため圧力が上昇してプロミネンスを押し返していることを確認した。 前者の結果は、表面での対流運動が凝縮を誘発していることを示し、プロミネンスの普遍性を裏付けている。

    Shirato Observational study of the relationship between wave propagation and magnetic fields in the lower solar atmosphere over the entire solar surface using SMART/SDDI One of the most promising mechanisms in the chromospheric and coronal heating problem is the wave heating theory. Among acoustic waves excited by the turbulence motion at the photosphere, those with a frequency lower than ‘cutoff frequency’ cannot propagate into the upper layers. However, in regions where the magnetic field lines are inclined, it is thought that the cutoff frequency becomes lower than surrounding regions. To verify this observationally, it is important to focus on the relationship between the wave propagation and the magnetic field distribution at lower chromosphere. However, there are a number of studies working on this topic, but the best of my knowledge, all of them analyzed the relationship in a localized region, espicially disc center. In order to fill the blank, this study conducted spectroscopic imaging observations of the entire solar surface for more than 12 hours on May 4, 2022, using the SMART/SDDI at the Hida Observatory of Kyoto University. We extracted parameters such as intensity and velocity using Hα lines, calculated power spectra and phase differences, and investigated the relationship between the magnetic field structure and wave propagation not only in the quiet region but also in the plage region, active region, and enhanced network at various scales. As a result, it was found that there are characteristic distributions of oscillation power, especially in the 3-minute and 5-minute periods, in the propagation of waves in the quiet region network, active region, enhanced network, and dark filament. In addition, many observational studies have shown that the power of the 5-minute Doppler velocity of absorption lines in the chromosphere is stronger in the network region where the magnetic field lines are inclined. In this talk, I will present some of the results obtained and discuss their physical interpretations.

    Otsu (title) (abstract)

    Shimada (title) (abstract)

    Kida (title) (abstract)

    Natsume (title) (abstract)

    Yoshihisa (title) (abstract)

    (No Seminar because of National Holiday)

    (title) (abstract)

    (title) (abstract)


    Presentations in 2023-2nd semester (13:30-15:00)

    Date Name Title Abstract File
    TBD (title) (abstract)


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