|2019/01/07||13:00-14:30||Y. Notsu||upload or download|
|2019/01/21||13:00-13:45||S. Okada||upload or download|
|13:45-14:30||S. Tokuda||upload or download|
|14:30-15:15||A. Machida||upload or download|
|04-09||K. Ichimoto||Solar Projects in 2018||I will talk about the Solar-C, progress at Hide in 2017 and future plan for discussion.|
|B. Kliem||Flux Rope Formation by a Confined Solar Flare Prior to a Coronal Mass Ejection||We present evidence that a magnetic flux rope, observed as an extreme-ultraviolet (EUV) hot channel, was formed before a coronal mass ejection (CME) and its associated long-duration flare during a preceding confined flare in a compound event in NOAA Active Region 12371. The confined flare spawns a vertical current sheet, where magnetic reconnection creates flare ribbons and loops, a nonthermal microwave source, and a hot channel. The hot channel is strongly sigmoidal and can only be interpreted as being part of a magnetic flux rope. The reconnection during the confined flare acts like ``tether-cutting reconnection'' which enhances the flux rope and leads the region to instability. The subsequent full eruption is seen as an accelerated rise of the hot channel, the formation of a fast halo CME, and the second, long-duration flare. Such rapid formation and destabilization of a flux rope is likely of general relevance and presents a difficulty for the forecast of CMEs.|
|04-16||K. Shibata||Solar Physics in Future 2018|
|04-23||K. Namekata||Time Resolved Spectroscopic Observation of an M-Dwarf Flare Star EV Lac during a Flare||
I'll introduce the following paper:
"Time Resolved Spectroscopic Observation of an M-Dwarf Flare Star EV Lac during a Flare"
Honda S., Notsu, Y., Namekata K., et al. accepted to PASJ.
|A. Asai||Moreton Wave Observed by Hida/SMART/SDDI||
I would like to talk about
"Moreton Wave Observed by Hida/SMART/SDDI"
at the today's Taiyo-Zasshikai as a main talk.
|05-07||D. Seki||RELATIONSHIP BETWEEN DISTRIBUTION OF MAGNETIC DECAY INDEX AND FILAMENT ERUPTIONS||
I will introduce the follow paper;
"RELATIONSHIP BETWEEN DISTRIBUTION OF MAGNETIC DECAY INDEX AND FILAMENT ERUPTIONS"
H. Li , Y. Liu , A. Elmhamdi , and A.-S. Kordi
The Astrophysical Journal, 830:132 (8pp), 2016 October 20
|S. Ueno||Investigation of long-term variations of solar activity and earth's upper atmosphere by using solar full-disk chromospheric images||
I would like to talk about
"Investigation of long-term variations of solar activity and earth's upper atmosphere by using solar full-disk chromospheric images".
For new members of our observatories, I will introduce old information
also, such as scientific purposes, database, old results of data analysis.
In today's short talk, I will mention disk counterparts
of solar spicules referring the following three papers:
1. "Search for high velocities in the disk counterpart of type II spicules"
O. Langangen, B. De Pontieu, M. Carlsson, V. H. Hansteen, G. Cauzzi, & K. Reardon
2008, ApJ, 679, L167
2. "On-disk counterparts of type II spicules in the Ca II 854.2nm and Hα lines"
L. Rouppe van der Voort, B. De Pontieu, T. M. D. Pereira, M. Carlsson, and V. Hansteen
2009, ApJ, 705, 272
3. "Heating signatures in the disk counterparts of solar spicules in Interface Region Imaging Spectrograph observations"
L. Rouppe van der Voort, B. De Pontieu, T. M. D. Pereira, M. Carlsson, and V. Hansteen
2015, ApJL, 799, 3
|05-21||T. Sakaue||The Threatening Magnetic and Plasma Environment of the TRAPPIST-1 Planets||
I will introduce the following paper in the short talk of tomorrow's seminar.
Title: The Threatening Magnetic and Plasma Environment of the TRAPPIST-1 Planets
Author: Garraffo, Cecilia; Drake, Jeremy J.; Cohen, Ofer; Alvarado-G将ﾑmez, Julian D.; Moschou, Sofia P.
I would like to talk about my recent collaborative research on Kunitomo's sunspot observation in Edo era.
Kunitomo Ikkannsai is the first Japanese man who made the Gregolian type reflective telescopes in Nagahama (Shiga pref.).
Using his own telescope, he observed the moon, planets and the sun and drawn them by a writing brush.
His drawings are kept by the descendants, and recently electrically scanned for scientific analysis.
This research is carried out by the interdisciplinary team, including Kyoto, Shiga and Ibaraki univ, NAOJ, National Institute of Japanese Literature and National Institute of Polar Research.
We performed the calibrations on the sunspot drawings of 1835-36 and reconstructed the butterfly diagram on the period, corresponding to just after the Dalton minimum (1790-1830) and the typical solar cycles restarted.
I will introduce Kunitomo's telescope and the result of the calibrations, and discuss about the accuracy of the sunspot drawings.
|05-28||C. Denis||High speed filament eruption on 2017 April 23 captured by the SMART/SDDI.||In this talk I am going to introduce the observational aspects of the event, as well as the kinematic properties of the filament eruption.|
|K. Nishida||Factors Determining Duration of Long-Duration Events and Impulsive Flares||We investigated the factors determining the durations of solar flares. By numerical simulation, we attempted to explain the durations of both long-duration events (LDEs) and impulsive flares using a unified model. By conducting 2.5-dimensional magnetohydrodynamic simulations of flares with a flux rope eruption, we investigated the dependence of the duration on the size of the inflow region for various magnetic configurations of quadrupolar loops under the flux rope as the initial conditions. The duration depended linearly on the size of the inflow region.|
|T.T. Ishii||H-alpha Surges at the Emerging Flux Region Observed before the Pore Formation (NOAA 12660)||
We observed point like jets and surges at the emerging flux region before/during pore formation (NOAA 12660) on 2017-May-22(JST) with SMART/SDDI at Hida Observatory, Kyoto University.
SMART/SDDI (Solar Dynamics DopplerImager) takes full-disk solar images with a field of view of 2520 arcsec^2 at multiple wavelengths around the H-alpha line (from 6561.9 A to 6563.7 A, with resolution of 0.25 A).
Comparing H-alpha surge activities and magnetic field evolution using SDO/HMI data, we found following results.
(1) At the beginning of observation (21:45UT), this region was covered by weak negative polarity.
(2) Point like jets(surges) occurred continuously from 22:00 UT to 01:00UT.
(3) Positive polarity flux appeared around 22:30UT.
(4) AFS (Arch filament system) in H-alpha was seen around 03:00 UT, and pore with negative polarity was formed.
(5) Around 05:00 UT, pore with positive polarity was formed.
(6a) After 01:00UT, long surges occurred.
(6b) After the formation of AFS, large surges occurred.
This result is the first observational result with magnetic field data confirmed Kurokawa (1988 Vistas in Astronomy), the first manifestation of the emerging flux region in the solar surface is a surge activity.
|06-11||Y.W. Huang||current status of DST Horizontal Spectro-polarimeter in Hida Observatory||I will talk about "current status of DST Horizontal Spectro-polarimeter in Hida Observatory", mainly the calibration accuracy and the problem we are facing with now.|
|06-20||S. Tokuda||狭帯域チューナブルフィルターの1/8 Å ブロックの開発と彩層微細構造の撮像観測|
|06-25||Y. Notsu||Recent observational attempts to measure stellar winds and stellar CMEs of active stars||
This talk is partly motivated by Sakaue-san's recent theoretical work on M-dwarf atmosphere.
I will briefly (quickly) mention the following papers.
Instead of explaining each paper in detail, I try to overview the recent attempts.
(If there are many Q&As and take long time, I will only focus on stellar winds.)
"Evidence for a Weak Wind from the Young Sun" (Wood et al. 2014 ApJL)
"New Mass-Loss Measurements from Astrospheric Lyα Absorption" (Wood et al. 2005 ApJL)
"Astrospheres and Solar-like Stellar Winds" (Wood 2004 Living Review)
"Radio emission and mass loss rate limits of four young solar-type stars" (Fichtinger et al. 2017)
"Constraining Stellar Coronal Mass Ejections through Multi-wavelength Analysis of the Active M Dwarf EQ Peg" (Crosley & Osten 2018 ApJ)
"Investigating magnetic activity in very stable stellar magnetic fields. Long-term photometric and spectroscopic study of the fully convective M4 dwarf V374 Pegasi" (Vida et al. 2016 A&A)
|H. Isobe||An Intense geomagnetic storm by spotless Sun during Maunder minimum.|
|07-02||K. Hirose||On Quasi-biennial Oscillations in Chromospheric Macrospicules and Their Potential Relation to the Global Solar Magnetic Field||
I will introduce the paper below,
"On Quasi-biennial Oscillations in Chromospheric Macrospicules and Their Potential Relation to the Global Solar Magnetic Field"
T. S. Kiss and R. Erdelyi
The Astrophysical Journal, Volume 857, Issue 2, article id. 113, 9 pp. (2018)
|K. Namekata||Emergence and Decay of Sunspots and Star spots||Recently, many superflares on solar-type stars were discovered by the Kepler Space Telescope (Maehara et al. 2012). Such active stars are thought to have large star spots (Notsu et al. 2013), and superflares are considered to occur through magnetic reconnection like solar flares (Namekata et al. 2017). The emergence and decay of such large star spots are important for the understanding of superflare events as well as underlying stellar dynamo. However, there are few study which reported the temporal evolution of star spots because of its difficulty in measurements. Here, we have developed a simple method to measure temporal evolutions of star spots area with Kepler data by tracing local minima of the light curves (cf, Maehara et al. 2017). We will report the statistical properties of lifetimes, emerging and decay rates of star spots on solar-type stars. We will compare them with those of sunspots and discuss how to understand them on the basis of sunspot physics.|
|07-09||S. Okada||A statistical study of transverse wave oscillations in a quiescent prominence||
I will introduce the following paper in the short talk of tomorrow's solar seminar.
"A statistical study of transverse wave oscillations in a quiescent prominence"
A. Hillier, R.J.Morton, and R.Erdelyi
The Astrophysical Jounal Letters, 779:L16(6pp), 2013 December 20
|D. Seki||statistical study of the precursors of filament eruptions||
Filaments, the dense cooler plasmas floating in the solar corona supported by the magnetic fields, often show some activations before the eruptions. In our previous study (Seki et al. 2017 ), we quantified the filament activation prior to the eruption on 2016 November 5 03:40 UT by the standard deviation of the line-of-sight (LOS) velocity map of the filament. The LOS velocities were calculated by applying the Beckers’ cloud model to 73 multi-wavelengths images around Hα taken by the SDDI. As a result, we found the increase of the standard deviation prior to eruption. However, we had analyzed only one event in that study, so that it had been unclear whether the increase can be generally seen in filament eruptions.
In this study, we surveyed 12 filaments including 2 quiescent filaments, 4 active region fila- ments, and 6 intermediate filaments in the same way as our previous work. We confirmed that in all the 12 filament disappearance events, the standard deviation increased before filaments disappeared. Moreover, we found that the time-scale of the increase is different in the types of filaments and some observational facts that possibly contribute to clarify the reason of the increase. We concluded that this quantity could probably be used as the precursor of the filament eruptions, combining it with the Hα center image and the LOS velocity map.
|10-01||S. Tokuda||Evolution of Complex 3D Motions in Spicules||
I will introduce the following paper as the short talk.
"Evolution of Complex 3D Motions in Spicules"
Rahul Sharma, Gary Verth, and Robertus Erdelyi
The Astrophysical Jounal, Volume 853, Issue 1, article id. 61, 9 pp.(2018)
|A.D. Kawamura||Parially Ionized Plasma Flow Around a Reconnection|
|10-09||P. Heinzel||White-light flares and stellar superflares||I will present an overview of observations and modeling of the so-called solar white-light flares (WLF), extending this also to UV continua detected from space. There is a continuing discussion about relevant physical mechanisms which are responsible for solar and stellar WLFs and the main problem is to distinguish between photospheric and chromospheric contributions to the spectral intensity. On the other hand, a purely chromospheric component can be well separated in limb flares where we detected the WLF emission just above the solar limb and this corresponds to the chromospheric heights - I will present also some recent results of numerical RHD simulations with the Flarix code. Finally, it appeared that also the whole flare loops, both cool (misleadingly called 'post' flare loops), as well hot ones, emit in the visible continuum and this was detected by SDO/HMI instrument at loop heights. This latter issue is directly related to a novel idea that also stellar superflares may be partially due to WL loop emission (Heinzel & Shibata 2018).|
|10-15||A. Machida||Temporal evolution of arch filaments as seen in He I 10830A||
"Temporal evolution of arch filaments as seen in He I 10830A"
S. J. Gonzalez Manrique et al. (2018)
|Y. Notsu||Superflares on solar-type stars observed with Kepler: An updated view with APO 3.5m telescope spectroscopic observations and Gaia-DR2 data|
|10-22||K. Nishida||MHD simulation of large amplitude oscillations in prominence|
|K. Hirose||a statistical study of high-speed and small-scale blue/red shifted events||I'll talk about my study, using SMART/SDDI data.|
|10-29||K. otsuji||Prediction of Solar Eruptions Using Filament Metadata||I will introduce the papers shown below: "Prediction of Solar Eruptions Using Filament Metadata" Aggarwal, Ashna; Schanche, Nicole; Reeves, Katharine K.; Kempton, Dustin; Angryk, Rafal The Astrophysical Journal Supplement Series, Volume 236, Issue 1, article id. 15, 13 pp. (2018) http://ads.nao.ac.jp/abs/2018ApJS..236...15A|
|K. Kihara||Solar flare prediction with image recognition model using deep learning||In my talk, I will briefly introduce "machine learning", "image recognition using deep learning", and some previous studies predicting solar flares with machine learning.|
|11-05||H. Isobe||A review of the 0.1 reconnection rate problem||In the short talk today I will introduce a review paper by Paul Cassak et al. "A review of the 0.1 reconnection rate problem" Cassak, P. A.; Liu, Y.-H.; Shay, M. A., Journal of Plasma Physics, Volume 83, id. 715830501 (2017) http://adsabs.harvard.edu/abs/2017JPlPh..83e7101C|
|Y. Kotani||simulation of anemone jets in photosphere||Anemone jets , which form inverse Y shape and have a bright footpoint , have been observed in solar atmosphere in various scales. Shibata et al.(2007) proposed these anemone jets can be explained by magnetic reconnection regardless its scale and spicules may be ~100 km size anemone jets. Motivated this paper , We try 3d MHD simulation of less than 100 km size jets including gravity and simple radiative cooling. In my talk, I will briefly introduce anemone jets and early result of our simulation.|
|11-12||T.T. Ishii||Dependence of Coronal Mass Ejection Properties on Their Solar Source Active Region Characteristics and Associated Flare Reconnection Flux||Today, I would like to introduce the following paper for short talk. Dependence of Coronal Mass Ejection Properties on Their Solar Source Active Region Characteristics and Associated Flare Reconnection Flux Pal, Sanchita; Nandy, Dibyendu; Srivastava, Nandita; Gopalswamy, Nat; Panda, Suman 2018, ApJ, 865, 4 http://adsabs.harvard.edu/abs/2018ApJ...865....4P|
|D. Yamasaki||SMART/T4 Stokes Vector Inversion Code||Solar Magnetic Activity Research Telescope (SMART)/T4 at Hida Observatory is a filter magnetograph, consists of a rotating wave plate, tandem Fabry-Perot Filters which scan the Fe I 6302.5A line with ~ 130mA bandwidth, a polarizing beam splitter, and two CCD cameras simultaneously taking orthogonally polarized light with frame rate of 30 frames per second. Stokes Vector data, which SMART/T4 takes, have a higher polarimetric sensitivity ~ 10^-4 and a higher time resolution ~ 60 sec comparing to other magnetographs. However, a Stoke Vector Inversion Code for SMART/T4 is still under development, so that we do not have any means to deduce vector magnetic fields right now. In this study, we introduced the Look Up Table (LUT) method for our SMART/T4 Inversion Code. We compared the SMART/T4 vector magnetic field data with Solar Dynamics Observatory (SDO)/Helioseismic and Magnetic Imager (HMI) data to assess our Inversion Code. As a result of this assessment, we found one possibility that Stokes Vector data which SMART/T4 takes might include some crosstalk from Stokes V to Stokes Q/U. In order to confirm this hypothesis, a polarimetric calibration experiment was held on 8th November. Now I am making a great effort on the data analysis of the experiment. I wish I could show you a part of results tomorrow(today).|
|S. Okada||Temperature analysis of solar prominences by multi-wavelength observations||I will talk about my study, "Temperature analysis of solar prominences by multi-wavelength observations".|
|11-19||S. Ueno||Formation of an Active Region Filament Driven By a Series of Jets||In August 2018, the result of Hida-FSO-HINODE-IRIS campaign observation (IHOP0322) was published on ApJ by J. Wang-san (Yunnan Observatories) et al.. Therefore, this time, I would like to introduce outline of this campaign observation in August 2016 at especially Hida Observatory and contents of this paper. Reference: "Formation of an Active Region Filament Driven By a Series of Jets" J. Wang, X. Yan, Z. Qu, S. UeNo, K. Ichimoto, L. Deng, W. Cao and Z. Liu 2018, ApJ 863, 180|
|S. Tokuda||Development of 1/8 Elements of the Universal Tunable Filter and Observation of Fine Scale Dynamics in the Solar Chromosphere||I will talk about my study, "Development of 1/8 Elements of the Universal Tunable Filter and Observation of Fine Scale Dynamics in the Solar Chromosphere".|
|12-03||A. Ayumi||Report on MUSER site visit and PSTEP-SEP-CDAW||As a short talk speaker, I will talk about the following two topics: 1. Report on MUSER site visit 2. PSTEP-SEP-CDAW.|
|A. Machida||Environmental effects on the evolution of the emerging flux region||From the inner sun, magnetic flux appears due to the magnetic instability. This area is called emerging flux region. In recent studies, it is expected that the magnetic structure (magnetic field line is open or closed, i.e. inside or outside the coronal hole) of the point where magnetic flux appears will affect the evolution of the emerging flux region. So the aim of this study is to find whether such an effect really exists or not. Especially, we now focus on the LOS velocity and magnetic flux. As a first step, we calculated the LOS velocity of one emerging flux region (which became NOAA12700) with very fine time resolution (15sec) for only one day data, using cloud model. From this work, we found that filaments in that region rise intermittently. Then, as a second step, we analyzed three emerging flux regions with rough time resolution (~1hour, now) but for three days. They emerged in different places from the view of the magnetic field; two is inside and one is outside the coronal hole. I will discuss the difference of the evolution of each emerging flux regions.|
|12-10||C. Denis||Observational Study on Energy Release Mechanisms of Explosive Events on the Sun I. Dynamics processes of the Moreton wave on 2014 March 29||Shock waves associated with explosive events are fundamental physical processes in solar and stellar plasmas, whose properties and effects have widely been discussed in the framework of magnetohydrodynamics (MHD) theory. In the Sun's chromosphere a large-scale wavelike propagating disturbance, known as Moreton wave, occasionally happens in association with strong flares and coronal mass ejections (CMEs). I will present a study of a Moreton wave that accompanied an X-class flare on 2014 March 29. This event was successfully detected in multiwavelength imaging in H alpha line by the Flare Monitoring Telescope (FMT) in operation at Ica National University, Peru. We made use of FMT wing (H alpha -/+0.8 A) observations to investigate the Doppler characteristics of the Moreton wave. The Doppler analysis reveals a downward motion of the chromospheric material with a velocity of about 6 km/s, at the front of the Moreton wave. On the other hand, the estimated surface velocity of the Moreton wave ranges between 640-859 km/s. We also performed the temperature-emission measure analysis of the associated coronal wave, based on extreme ultraviolet (EUV) data taken by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory. Considering these results and with the aid of the MHD linear theory, the characteristics of the shock front such as the compression ratio and the Alfven and the fast-mode Mach numbers are discussed. We also examine the interaction of the shock front with the chromospheric material.|
|12-17||T. Sakaue||Magnetized atmosphere and wind of cool stars||Cool stars offer the good opportunities to investigate what environments the Earth-like exoplanets are in, and how they are affected by the host star. In particular, the stellar wind and radiation from the stellar atmosphere have a great impact on the interplanetary space, but the observation of them is still challenging. We have, therefore, studied the stellar atmosphere and wind of the cool main-sequence star (M-type star) by performing the Magneto-Hydro-Dynamics (MHD) numerical simulation. Among several stellar wind theories, it is the plausible idea that the non-linear process of Alfven wave leads to the heating and driving the stellar wind. The propagation of Alfven wave in the inhomogeneous media is affected by the turbulent dissipation, in which the reflected Alfven wave interacts with the outward wave, or by the non-linear mode coupling, which leads to the formation of the shock wave and consequently contribute to heating the stellar wind. The latter non-linear process has been well investigated to account for the dynamics of the lower solar atmosphere (Kudoh & Shibata 1999) and driving the solar wind (Suzuki & Inutsuka 2005), but not discussed for the atmosphere and stellar wind of the cool main-sequence star. In this study, therefore, we focus on the non-linear propagation of the Alfven wave, and succeeded in numerical experiments of the self-consistent heating and driving the stellar atmosphere and wind. By investigating the reproduced stellar and solar wind structure, we find (1) the difference in the dynamics of stellar and solar chromosphere (spicules) and (2) the similar dependence of the stellar and solar wind parameters on their magnetic open flux tube geometry.|
|12-17||A. Tei||彩層スペクトル線観測と non-LTE 計算で探るスピキュール||太陽の低温な光球と高温なコロナの間にある彩層では、スピキュールというジェット現象が普遍的に見られるが、その物理機構はまだ明らかになっていない。また近年、スピキュールと高温な構造との繋がりが示唆されるようになり、スピキュールがコロナの加熱にどう寄与しているのかも注目されている。我々は、彩層温度で形成する Mg II k スペクトル線を用いて、極域コロナホールのスピキュールの物理量を統計的に理解することを試みた。リム外で観測される Mg II k 線プロファイルは、スピキュールの下部から先端にかけて、 その線輪郭がダブルピーク、フラット、シングルピークと変化し、線放射強度は減少、線幅は（一旦増加し ）減少する。この観測的特徴を理解するため、1次元 non-LTE 輻射輸送計算を用いたモデリングを行なった。その結果、線放射強度は圧力に大きく依存すること、圧力が同じ場合は温度が高いほど線幅が減少し、そのうちの高温領域では電離の効果によって線放射強度も減少することがわかった。高高度で観測されるプロファイルは、視線方向に重なりがない（少ない）と考えられ、0.1- 0.5 [erg/cm3] 程度の圧力であると推定された。特にスピキュールの先端では、Mg II の電離温度に達していることが示唆された。また、低高度で観測される広い線幅は、最大振幅 ±25km/s の視線速度をもつ複数のスピキュールが視線方向に重なっていることで説明でき、観測される線放射強度は、圧力 P ~ 0.1- 0.2 [erg/cm3] のモデルとよく合うことが分かった。|
|12-17||Y.W. Huang||Development of NLTE Radiative transfer code and its application to solar erupting plasma|
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