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

Next presenters

Date	Time	Section	Speaker	File
6/2	13:30-15:00		Otsu	upload or download

Please upload your presentation file!!

Date	Section	Speaker	File
4/14		Asai	upload or download
4/21		Ueno	upload or download
4/28		Ishii	upload or download
5/12		Dai	upload or download
5/12		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If you do not want to make public your unpublished results, please delete the relevant part before submission.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.

Date

Name

Title

Abstract

File

4/14

Asai

4/21

Ueno

Multi-wavelength 2D Spectroscopy of the Solar Flare at δ-type Sunspot Region

At the ASJ Annual Meeting last month, I reported on results of the analysis of multi-wavelength spectroheliograph data (H-alpha, H-beta, H-gamma and CaII K) on the M-class flare that occurred on November 25, 2024 and a dark filament, plage around δ-type sunspot region (AR13906). However, since I couldn't make time for discussion at the ASJ meeting, I would like to introduce these analyses again in this Solar Seminar with adding some additional slides.

4/28

Ishii

Today, I would like to introduce following paper,
Identifying Coronal Mass Ejection Active Region Sources: An Automated Approach Julio Hernandez Camero(1), Lucie M. Green(1), and Alex Pinel Neparidze(2)
(1)Mullard Space Science Laboratory, University College London, UK
(2)University College London, UK
ApJ, 973, 63, 2025
https://ui.adsabs.harvard.edu/abs/2025ApJ...979...63H/abstract

5/12

Dai

End-view Observations of longitudinal oscillations of a quiescent prominence

Combining the Doppler velocities derived from the spectroscopic data provided by CHASE/HIS and SDO/AIA EUV data, we present the end-view Observations of longitudinal oscillations of a quiescent prominence, Based on the 3D velocity (values and directions) variations of the oscillation, we confirmed that the direction of the oscillations was longitudinal, and the geometry of the magnetic dip could be accurately described: the curvature radius of the magnetic dip was the smallest at its bottom and increased towards the sides, with a range of values of 87-258 Mm. Compared to the general pendulum model (Semicircular geometry), the calculations based on the variation of V3D are more realistic and accurate.

5/19

Shirato

Report on the re-analysis of full-disk oscillation data

In addressing the chromospheric and coronal heating problem, it is essential to clarify the relationship between wave propagation in the solar atmosphere and magnetic field structures in order to understand the mechanisms of energy transport to the upper layers from the perspective of wave dynamics. In particular, in quiet-Sun regions, a key focus is how low-frequency acoustic waves propagate into the upper atmosphere and dissipate their energy. It has been proposed that when relatively strong, inclined magnetic fields are present, the acoustic cutoff frequency is reduced, allowing low-frequency waves to leak into the chromosphere (De Pontieu et al. 2004). Indeed, observational studies have reported that magnetic elements and chromospheric mottles often exhibit oscillations with periods of 5–7 minutes, whereas 3-minute oscillations are more common within the internetwork regions (Jess et al. 2023). However, most of the observational studies conducted thus far have been limited to small areas near the disk center and short time spans of only 2–3 hours at most.
In this study, we analyzed over 12 hours of full-disk spectroscopic imaging data in the Hα line obtained on May 4, 2022, with the SMART/SDDI instrument at Hida Observatory, Kyoto University. We investigated the spatial distribution of oscillation power in Doppler velocity and intensity through time-series analysis. As a result, in addition to the commonly observed 3- and 5-minute chromospheric oscillations, we found the presence of oscillations with a 20-minute period across the entire solar disk. Notably, the 20-minute oscillation power showed a remarkable spatial correlation with inclined magnetic fields in quiet regions, as well as with strong magnetic field regions such as enhanced network, plage, and active regions. We also observed that the oscillation power tended to be stronger closer to the limb. Due to the short duration of past observations, there have been very few reports of such 20-minute oscillations, and their nature remains unclear. Furthermore, we focused on quiet-Sun regions to examine the center-to-limb variation of oscillation power and phase difference, and explored the relationship with network structures. In this presentation, we report these findings and discuss their implications.

6/2

Otsu

6/9

Guest Seminar

Yamasaki

6/16

Mishra

6/23

Shimada

6/30

Natsume

7/7

Yoshihisa

7/14

Ichihara

Date

Name

Title

Abstract

File

10/6

Nagata

10/20

10/27

11/10

11/17

12/1

12/8

12/15

12/22

1/5

1/19

1/26