| Date |
|
Name |
Title |
Abstract |
File |
| 4/11 |
long |
Ichimoto |
Solar Projects in 2022 |
(abstract) |
pdf
10.1 MB |
| 4/18 |
main |
Yokoyama |
(title) |
(abstract) |
(extension)
MB |
|
short |
(absent) |
|
|
(extension)
MB |
| 4/25 |
main |
Asai |
(title) |
(abstract) |
(extension)
MB |
|
short |
Kihara |
CMEs and SEPs During November–December 2020: A Challenge for Real-Time Space Weather Forecasting |
I will introduce following paper;
CMEs and SEPs During November–December 2020: A Challenge for Real-Time Space Weather Forecasting
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2021SW002993
| pdf
3.6MB |
| 5/2 |
special |
Ishii |
【構成員向け】計算機ガイダンス |
計算機ガイダンス、日本語で実施します。
質問があれば、事前にメールで送ってもらると助かります。質問というほどでもない、ぼんやりした？不安？みたいなものとか気になってるけど、誰に聞けばよいのかわからない疑問とかでも
構いません。あ、あと、回答者というか、ガイダンス側は、西田さん、永田さん、石井、で担当します。 |
pptx
1.8MB |
| 5/9 |
main |
Ueno |
History and future plan of the CHAIN-project's instruments, researches and capacity building |
Our observatory has promoted the CHAIN (Continuous H-Alpha Imaging Network) project since around 2006 as one of Japanese activities under the International Heliophysical Year (IHY) 2007 program and International Space Weather Initiative (ISWI) program. Main purposes of this project are reinforcement of multi-wavelength H-alpha observations of the full-disk Sun by formation of an
international network of ground-based solar stations, and to research solar eruptive phenomena and shock waves on the solar surface. However, I think that young students and new staffs of our observatory don't know this project well. Therefore, I will introduce the history and future plan of the CHAIN project in this seminar.
|
pdf
8.7MB |
|
short |
Kotani |
Chromospheric emission from nanoflare heating in RADYN simulations |
I'll introduce the following paper in tomorrow's short talk.
title: Chromospheric emission from nanoflare heating in RADYN simulations
authors: H. Bakke, M. Carlsson, L. Rouppe van der Voort, B. V. Gudiksen, V. Polito, P. Testa, and B. De Pontieu (Astronomy & Astrophysics, 2022)
https://ui.adsabs.harvard.edu/abs/2022A%26A...659A.186B/abstract'
|
pptx
4.2MB |
| 5/16 |
main |
Nagata |
(title) |
(abstract) |
(extension)
MB |
|
short |
Shimada |
Grand Minima in a spherical non-kinematic α^2Ω mean-field dynamo model |
I will introduce the following paper;
Grand Minima in a spherical non-kinematic α^2Ω mean-field dynamo model
https://www.swsc-journal.org/articles/swsc/full_html/2020/01/swsc190074/swsc190074.html
|
pdf
109.3MB |
| 5/23 |
|
|
(No Seminar because of JpGU Space Weather session) |
|
|
| 5/30 |
Guest Talk |
Vladimir Airapetian (NASA/GSFC) |
Solar Physics Living With the Current and Young Sun |
Discovery of over 5000 exoplanets in our Galaxy suggests that close-in rocky exoplanets in the habitable zones around magnetically active G, K and M dwarfs should be exposed to high stellar coronal X-ray and Extreme UV (EUV) and wind mass fluxes. Kepler and TESS missions have revealed frequent superflares on cool G, K and M planet hosting dwarf stars, providing a mechanism by which host stars may have profound effects on the physical and chemical evolution of exoplanetary atmospheres. Solar observations indicate that energetic flares are usually accompanied by ejection of coronal magnetized plasma referred to as coronal mass ejections or CMEs. As CMEs propagate out from the solar corona into interplanetary space, they drive shocks. Shocks are the sites of efficient acceleration of solar energetic particles (SEPs) to GeV energies. SEPs can penetrate (exo)planetary atmospheres and cause significant changes in atmospheric chemistry. While stellar superflares can be directly observed and characterized in X-ray, FUV/UV, optical and radio bands, the signatures of their CME and SEP counterparts remain elusive and need detail theoretical modeling. The major questions this leads to are: Can we extend solar models to simulate energetic environments of young solar type stars? Can we relate and scale the properties of solar/stellar superflares associated CMEs with the fluence and particle energy spectra from active K and M dwarfs? Here, I will review the recent Sun-as-a Star observations of sunspots and associated active regions in optical, FUV, EUV and X-ray bands and their implications for stellar active regions from active stars. I will describe our recent multi-observatory international project “Magnetic Lives of Young Suns” that coordinates HST- XMM-Newton, TESS, NICER and ground-based observations taken with CFHT observations of young (0.1-0.6 Gyr) solar-like (G and K type) dwarfs. These data provide critical inputs to the data-constrained three-dimensional (3D) fully thermodynamic magnetohydrodynamic (MHD) models of coronae, and winds from young solar-like stars. I will then present recent results of data-constrained 3D MHD models of superlares and CMEs from young solar-like stars coupled to the kinetic models of SEP events, the crucial factor for understanding of the rise of the feedstock molecules of life on early Venus, Earth Mars and young rocky exoplanets.
|
(extension)
MB |
| 6/6 |
Guest Talk |
Prof.Kariyappa Rangaiah (Former Professor of Indian Institute of Astrophysics, India) |
Solar Spectral Irradiance (SSI) Variability |
It is of great interest and importance to study the variabilities of solar spectral irradiance (SSI) in heliophysics, in Earth’s climate, and space weather applications. In this talk, the important results of the solar variability observed in EUV, UV & X-ray using the spatially resolved and segmented full-disk images of the Sun in relation to the underlying photospheric magnetic field are discussed. |
(extension)
MB |
| 6/13 |
main |
Nishida |
What factors determine durations of solar flares? |
In today's solar seminar, I will talk about my research on 2D MHD simulation of solar flares.
"What factors determine durations of solar flares?"
K. Nishida, N. Nishizuka, K. Shibata
|
(extension)
MB |
|
short |
Yamasaki |
Determining the dynamics and magnetic fields in He I 10830 Å during a solar filament eruption |
In today’s short talk, I will introduce the following paper:
Determining the dynamics and magnetic fields in He I 10830 Å during a solar filament eruption
https://ui.adsabs.harvard.edu/abs/2020A%26A...640A..71K/abstract
|
(extension)
3.2MB |
| 6/20 |
main |
Ishii |
'Demonstration of Solar Spectral Observation at Taiyoh-kan, Kwasan Observatory in open days' and 'Comparisone with flare/prominence spectrum constructed by SMART/SDDI (e.g. flares on 2022-Apr-30, flare on 2022-Mar-15)' |
Today I would like to introduce 'Demonstration of Solar Spectral Observation at Taiyoh-kan, Kwasan Observatory in open days' and 'Comparisone with flare/prominence spectrum constructed by SMART/SDDI (e.g. flares on 2022-Apr-30, flare on 2022-Mar-15)'.
|
(extension)
11.6MB |
|
short |
Shirato |
Role of Longitudinal Waves in Alfvén-wave-driven Solar Wind |
In tomorrow’s short talk, I’d like to introduce the following paper.
Title: Role of Longitudinal Waves in Alfvén-wave-driven Solar Wind
Authors: Shimizu, Kimihiko ; Shoda, Munehito ; Suzuki, Takeru K.
Abstract:https://ui.adsabs.harvard.edu/abs/2022ApJ...931...37S/abstract
|
pptx
2.2MB |
| 6/27 |
main |
Kawamura |
Kawamura+(2022 to-be-resubmitted):
CME association over the domain of flare magnitudes & sunspot areas |
I have worked on statistical study of CME association for flares. At the last my talk at Zasshikai last year, CME association rate was introduced as an empirical function of flare energy and sunspot area. We have updated by introducing energy fraction, which is a kind of a normalized representative of a flare. Additionally, I will show integration of our study of CME association of solar flare with superflare observations.
|
(extension)
MB |
|
short |
Otsu |
Sun-as-a-star Spectroscopic Observations of the Line-of-sight Velocity of a Solar Eruption on 2021 October 28
|
In today's short talk, I will introduce the following paper:
https://ui.adsabs.harvard.edu/abs/2022ApJ...931...76X/abstract
|
pptx
2.2 MB |
| 7/4 |
main |
Denis |
A fast-filament eruption observed in the H-alpha Line, imaging spectroscopy diagnostics and numerical modeling |
In my talk, I will be introducing some results of my work about the filament eruption observed by SMART/SDDI. In particular, I will discuss the acceleration process of the eruption by combining observation and numerical modeling.
|
(extension)
MB |
|
short |
Kida (canceled) |
(title) |
(abstract) |
(extension)
MB |
| 7/11 |
|
|
(No Seminar because of the lecture by Bamba-san (Associate Professor of University of Tokyo)) |
|
|
| 7/18 |
|
|
(No Seminar because of National Holiday) |
|
|
| Date |
|
Name |
Title |
Abstract |
File |
| 10/3 |
main |
Yamasaki |
Investigation of the magnetic field structure of dark filaments by using a spectro-polarimetric observation with He I 1083 nm |
(abstract) |
pdf
6.5 MB |
|
short |
Kida |
|
canceled |
|
| 10/10 |
|
|
(No Seminar because of National Holiday) |
|
|
| 10/17 |
main |
Kotani |
Statistical Study of Solar Small Flares in the Quiet Region Using SMART/SDDI and SDO/AIA |
In the quiet region of the Sun, small-scale brightening events have been observed. These brightenings are mainly observed in EUV corresponding to transition regions and coronal temperatures. However, how they are observed in the spectral lines corresponding to the chromosphere, represented by the H-alpha lines, is not thoroughly studied. The contribution of small flares (=EUV brightening) in the quiet region to coronal heating has attracted much attention, and understanding their physical mechanisms is a fundamental issue in solar physics. In this study, we aimed to reveal the spectral behavior of the H-alpha line of small flares in the quiet region by conducting imaging spectroscopic observations of the Ha line using SMART/SDDI and imaging observations using SDO/AIA in many events. We also attempted to understand their physical mechanisms by comparing them with the scaling laws investigated in large-scale flares. Our main results are as follows. (1) Roughly only half of the events showed the H-alpha line center brightening and redshift. (2) Brightening in the H-alpha line center is weak. (typically 4-8 %, maximum: 20 %) (3) The H-alpha light curve peak tend to precede the peak at coronal wavelengths. (4) The spectra could be explained by the weak heated chromospheric condensation, but the redshift velocities were less than three times the values expected from the Fisher (1989) equation. (5) Our results were consistent with the Shibata & Yokoyama scaling law by considering the magnetic field strength difference with the active region.
In this main talk, I will introduce these results and discuss the physical mechanism of small flares in the quiet region inferred from them as much as possible.
|
pdf
9.2 MB |
|
short |
Hashimoto |
Alfvén wave heating in partially ionized thin threads of solar prominences |
https://ui.adsabs.harvard.edu/abs/2021A%26A...650A..45M/abstract
|
pdf
0.7 MB |
| 10/24 |
main |
Kihara |
The Observational Study of Solar Energetic Particle Events Focusing on Timescale |
Solar Energetic Particles (SEPs) are high-energy particles that originate from solar activity. SEPs cause radiation hazards for astronauts and airline passengers or damage satellites, which results in serious social impacts. Although past studies show some relations between coronal mass ejections (CMEs) and SEP events, they have considerable scatters and suggest some unknown factors between them. In order to advance our understanding of how the properties of CMEs affect those of SEPs, and especially to clarify what causes the variation in the timescales of SEPs, we have conducted a statistical study (Kihara et al., 2020). It revealed that the onset time (TO) becomes shorter when the CME erupts near the foot point of Parker spiral connected to the observer and has a negative correlation with CME speed. However, even if the source and speed of CMEs are similar, the distribution of TO is slightly dispersed. We further investigated two events with different TOs and found that the associated flares and radio bursts differed. In addition, we examined the timing of the proton release and found that the CMEs were accelerated around the release time of the proton in the event with longer TO. In this talk, I will present our results and discuss the cause of the delayed release of the proton.
|
pdf
4.8 MB |
|
short |
Matsuda |
(title) |
(abstract) |
(extension)
MB |
| 10/31 |
main |
Shirato |
A full disc analysis of the correlation of magnetic structures and propagation of waves by SMART/SDDI |
(abstract) |
pdf
4.3 MB |
|
short |
Huang |
Advanced Space-based Solar Observatory (ASOS): an overview
Design of the Full-disk MagnetoGraph (FMG) onboard the ASO-S
|
In today's short talk, I'd like to share with you the Chinese solar observation satellite called ASO-S, which was launched in Oct, 9th this year.
https://iopscience.iop.org/article/10.1088/1674-4527/19/11/156/pdf
https://iopscience.iop.org/article/10.1088/1674-4527/19/11/157/pdf
|
pptx
6.3 MB |
| 11/7 |
|
|
(No Seminar because 10th Solar Polarization Workshop will be held in this week.) |
|
|
| 11/14 |
main |
Shimada |
Suppression of dynamo mechanism in global solar dynamo simulation at high Reynolds number |
Solar magnetic activities show 11 yr regular cycle (solar cycle). In order to maintain the regular cycle by the global dynamo works in the solar convection zone, the dynamo mechanisms (alpha-effect, Omega-effect) need to be suppressed when the global magnetic field significantly enhanced. In this context, previous works (Racine et al. 2011, Augustson et al. 2015, Strugarek et al. 2018) analyze the dynamo mechanism works in global MHD simulation and conclude that Omega-effect is significantly suppressed via Lorentz force feedback from the global magnetic field, and it saturates global dynamo. However, the contribution from the global magnetic field is overestimated because of low magnetic Reynolds number (Rm~100) in their simulations, and whether this saturation mechanism works at solar convection zone (Rm~10^10) is still questionable. From these backgrounds, our study aims to understand the saturation mechanism works at further high magnetic Reynolds number. We analyze both alpha-effect and Omega-effect work in global MHD simulation at high magnetic Reynolds number (Rm500). We found that alpha-effect is suppressed when global magnetic field strength reaches equipartition value with small-scale turbulence. This tendency is consistent with the analytic model derived by Gruzinov & Diamond (1994). Suppression of Omega-effect is driven by the variation of the small-scale magnetic field which is completely different mechanism from the mechanism proposed previously. Our future work is to investigate how the suppression of each effect saturates global dynamo.
|
(extension)
MB |
|
short |
Asai |
“Twin Extreme Ultraviolet Waves in the Solar Corona”, “Genesis and Coronal-jet-generating Eruption of a Solar Minifilament Captured by IRIS Slit-raster Spectra” |
I will introduce the following two papers:
“Twin Extreme Ultraviolet Waves in the Solar Corona”, Zheng, R. et al., 2022, ApJL, 929, id.L4
https://doi.org/10.3847/2041-8213/ac61e3
“Genesis and Coronal-jet-generating Eruption of a Solar Minifilament Captured by IRIS Slit-raster Spectra”, Panesar, et al., 2022, ApJ, 939, id.25
https://doi.org/10.3847/1538-4357/ac8d65
|
pdf
51.3 MB |
| 11/21 |
main |
Otsu |
Title 1 : Sun-as-a-star Analyses of Various Solar Active Events Using Hα Spectral Images Taken by SMART/SDDI (Otsu+ 2022)
Title 2 : Multiwavelength Sun-as-a-star Analysis of M8.7 Flare on 2022 Oct. 2
|
Abstract 1 : Sun-as-a-star analyses in which observational data is spatially integrated are useful for interpreting stellar data. For future applications to stellar observations, we performed Sun-as-a-star analyses of Hα spectra for various active events on the Sun, not only for flares and filament eruptions/surges on the solar disk, but also for eruptions of off limb prominences using Hα spectral images taken by the Solar Magnetic Activity Research Telescope/Solar Dynamics Doppler Imager at Hida Observatory, Kyoto University. All the analyzed events show emission relative to the pre-event state and the changes in their Hα equivalent widths are all on the orders of 10−4 Å. Sun-as-a-star Hα spectra exhibit different features depending on the causes of the emission: (i) flares show emission at the Hα line center, together with red asymmetry and line broadening, as reported in a previous study, (ii) filament eruptions with and without flares show emission near the Hα line center, accompanied by blueshifted/redshifted absorption; notably, the disappearance of dark filaments leads to the apparent enhancement of the Hα line center emission, and (iii) eruptions of off-limb prominences show blueshifted/redshifted emission. These spectral features enable us to identify the active phenomena on Sun-like stars. We have also found that even the filament eruptions showing redshifted absorptions in Sun-as-a-star Hα spectra lead to coronal mass ejections (CMEs). This result suggests that even if the falling components of stellar filament eruptions are detected as redshifted absorptions in Hα spectra, such stellar filament eruptions may also develop into CMEs.
Abstract 2: In order to make clear that stellar CMEs occurred or not, it would be best way to observe signatures of stellar CME candidate simultaneously. To prepare for such analysis, it's important to establish a picture of how solar CMEs (or pre-/post- CME event) are observed in multiple signatures from Sun-as-a-star perspective. To this end, we are analyzing an M8.7 flare on 2022 Oct. 2 which are the first M-class flare with simultaneous observation of SDO/EVE and SMART/SDDI. Today, I would like to show prelimenary results about this event from Sun-as-a-star perspective.
|
pdf
3.4 MB |
|
short |
Ueno |
Specifications of the Chinese H-alpha Solar Explorer (CHASE) |
For many years in the past, full-disk solar H-alpha telescopes were not mounted on any artificial satellite. One main reason is that it has been thought that the necessity to mount it on satellites with spending huge expenses is low, because H-alpha solar observations can be realized relatively easily from the ground. However, in October 2021, the group led by Nanjing University of China realized the launching of the CHASE satellite that has the full-disk H-alpha spectroheliograph at last. Our observatory has especially promoted full-disk solar H-alpha observations through the SMART/SDDI and CHAIN project. Therefore, it is necessary for us to grasp instrumental and observational specifications and the operational plan of the CHASE satellite well in order to consider our future plan. In August 2022, five papers about the CHASE satellite were published in the journal "Science China – Physics, Mechanics and Astronomy". I would like to introduce this satellite by extracting some essential points from these papers in this short-talk.
|
pptx
31.9 MB |
| 11/28 |
main |
Kida |
(title) |
(abstract) |
(extension)
MB |
|
short |
Nagata |
(title) |
(abstract) |
(extension)
MB |
| 12/5 |
main |
Hashimoto |
Part I : Plasma diagnostics and Alfven wave heating of solar prominences by multiwavelength observations with DST, Part II : Spectropolarimetry of solar prominences in He I 10830 Å with DST
|
【PartI】The heating mechanism of solar prominences is less understood, and heating by Alfven wave is a good candidate. To research on Alfven wave heating of prominences, we derived radiative loss and Alfven wave flux by conducting multi-wavelength observation with DST and performing plasma diagnostics. As a result, Alfven wave flux is larger than radiative loss in the central part of prominences. This result suggests that the Alfven wave is a possible source of prominence heating.
【PartII】The magnetic field is an important quantity for understanding the properties of solar prominences (or filaments); their structures are determined by magnetic fields, and thermal conduction and Alfven waves in prominences are controlled by magnetic fields. Polarimetry allows us to measure magnetic fields directly. We observed several prominences in He I 10830 Å with the spectropolarimeter on DST. We performed Stokes inversions by using the inversion code HAZEL and constructed 2D maps of magnetic field vectors. As a result, the field strength of quiescent prominences are less than 40 G, which is consistent with previous studies. On the contrary, the field strength of AR prominences are less than 100 G, which is weaker than previous results of filament observations. This inconsistency may be because strong magnetic fields of previous studies come from AR on the chromosphere, not from the filaments.
|
pdf
2.3 MB |
|
short |
Ishii |
Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude |
Today, I would like to introduce : McIntosh et al. Solar Phys (2020) 295:163（https://ui.adsabs.harvard.edu/abs/2020SoPh..295..163M/abstract） for short talk.
|
pptx
4.5 MB |
| 12/12 |
main |
Matsuda |
(title) |
光球よりも上層の彩層・コロナは光球よりも温度が高く、上層に向かって何らかのメカニズムによってエネルギーを伝播させる必要がある。本研究では、エネルギーを運ぶメカニズムの一つである振動に注目した。太陽光球は5 分振動など、様々な周波数の変動が重なって振動している。太陽の振動は速度場で最も顕著だが、強度や吸収線の幅など他の観測量も振動を示し、太陽大気の温度や密度の変化によって引き起こされる。振動の時系列に対してフーリエ変換を行うことで、周波数ごとの振幅や各振動間の位相差を導くことができる。そこで得られた速度変動と温度変動の位相差から各周波数の振動がエネルギーをどのように運ぶのかが分かる。本研究では形成高度の違う複数の吸収線を用いることで高度によってエネルギー輸送に違いが出てくるのかを調べた。観測は京都大学飛騨天文台ドームレス太陽望遠鏡の水平分光器を用いて、光球内の様々な高度で形成された吸収線が存在する波長領域(6495 ± 10 Å)、彩層で形成される吸収線であるHα(6563 Å)、Ca II(8542 Å)、He I(10830 Å) を含む波長領域で同時に分光スキャンを行った。ディスクセンター付近の黒点を視野に入れ、AO を用いて黒点を追尾することでシーイングによる像の揺れを抑え、より高周波まで解析が可能となった。吸収線の中心波長と強度の時間変化から、その吸収線の形成高度での速度と温度の時間変化を求め、その変動の位相差の解析を行った。その結果、光球の静穏領域では周期5分付近の振動によるエネルギー輸送が下向きであることが分かった。して、周波数が大きくなるほど速度と温度の位相差が大きくなっており、周期3分よりも高周波では光球下部でエネルギー輸送が上向きになっていることが分かった。今回の発表では、複数の吸収線から得られた結果を詳しく紹介する。
|
(extension)
MB |
|
short |
Nishida |
A fundamental mechanism of solar eruption |
Today, I will introduce the following paper: Jiang et al. Nature Astronomy volume 5, pages 1126–1138 (2021)（https://www.nature.com/articles/s41550-021-01414-z） |
pdf
16.7 MB |
| 12/19 |
Guest Talk |
Kawate (核融合科学研究所) |
A tabletop device for investigating spectropolarimetric responses to anisotropic/magnetized plasmas |
Spectropolarimetry is a popular tool for investigating the dynamics of magnetized plasmas. On the other hand, relating polarization signals to the anisotropic fields is not so simple in astrophysical plasmas where non-equilibrium plasmas in three dimensions dynamically create non-uniform anisotropic field structures. Experimental validation is needed in a simpler system by controlling atomic interaction with external fields and particles. We set up an inductively-coupled plasma (ICP) device designed especially for spectropolarimetric measurements of plasmas interacting with external radiations, particle beams, and magnetic fields. The device consists of a quartz pipe coupling an antenna and of a vacuum chamber made of stainless steel. A radio-frequency (RF) power supply of 13.56 MHz with a forward RF power of 5 kW at maximum is used for plasma production. Density of neutral particles is controlled by vacuum pumps and a mass-flow controller, whereas it is monitored by pressure gauges. The typical electron temperature and density of the plasma are Te ~ 1-10 eV and Ne ~ 1e17-18 m-3, respectively, and these are comparable values to those of solar prominence. We performed experiments by setting the device in front of the focal plane of the Horizontal Spectrograph of the Domeless Solar Telescope at Hida Observatory of Kyoto University. By using the system for spectropolarimetric measurements, we directly compared helium spectra emitted from solar prominences and the laboratory plasmas. In the presentation, I introduce the background of atomic polarization, our apparatus, and obtained spectra by the experiments.
|
pdf
5.6 MB |
| 12/26 |
main |
Natsume |
4つの彩層ラインでの太陽フレアに伴う現象の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、太陽のデータを敢えて空間積分し恒星の観測データと比較可能にす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。複数彩層ラインの解析を通して、彩層ダイナミクスについて単一のラインの場合より多くのSun-as-a-starの情報を得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NOAA13078の (1)13:30-14:30のツーリボンフレア、(2)14:15-15:00のフレアの増光とフィラメントのドップラーシフト、(3)17:00-18:00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。これらの現象の解析の結果、フレアの増光について、He以外の３つの彩層ラインでred-asymmetryを持つ増光があること、Ca II KがHαと比べて増光が大きく長く続く場合があることがわかった。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。今回の発表では、この結果の詳細について解説する。
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7.0 MB |
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short |
Denis |
Imaging spectroscopy diagnostics of the flare-loops associated with the X8.2 flare on 2017 Sep 10 |
Basically, I will be presenting preliminary results of my analysis using H-alpha and Soft X-ray observations. |
(extension)
MB |
| 1/9 |
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(No Seminar because of National Holiday) |
(title) |
(abstract) |
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| 1/16 |
main |
Yoshihisa |
The Relation Between Prominence formation and Heating Mechanism -Initial Condensation and Subsequent Dynamics- |
(abstract) |
pdf
2.3 MB |
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short |
Kawamura |
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(postponed to next week) |
(extension)
MB |
| 1/23 |
main |
Huang |
(title) |
(abstract) |
(extension)
MB |
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short |
Kawamura |
Krista&Reinard(2017) Statistical Study of Solar Dimmings Using CoDiT, ApJ |
(abstract) |
pdf
1.4 MB |
| 2/27 |
Guest Seminar |
Andy |
Coronal Plasma Composition Evolution and Solar Activity |
Composition of plasma in the solar corona is a tracer of the flow of plasma and energy from the solar interior. A complete understanding of coronal abundances not only provides us another perspective to look at complex processes such as wave propagation, wave absorption, convection, reconnection, and reconfiguration of magnetic fields and coronal heating, but it also has significant implications for solar-like stars. The method to parameterise and study coronal elemental abundances, is to use the first ionisation potential (FIP) bias, defined as taking the ratio of an element’s coronal to photospheric abundance with respect to H. In this seminar, we introduce FIP bias as a proxy to understand processes in different solar structures, ranging from small brightenings to active regions, using a wide range of techniques such as extreme-ultraviolet and radio imaging, and spectroscopy to study to the evolution of these solar structures, and interpret the physical processes underneath.
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46.2 MB |