|3/6||K.Namekata||upload or download|
|3/6||T.Anan||upload or download|
|3/6||K.Hirose||upload or download|
|4/11||K.Hirose||Introduction of Solar Seminar||pptx|
|4/11||K.Shibata||Solar Physics in Near Future||pptx|
|4/18||K.Ichimoto||Solar-C and Hida in 2016||pptx|
|5/2||A.D.Kawamura||Review on the White House's Action Plan for Space Weather||I will briefly review the action plan of White House of the United States, published Oct. 2015.
|5/2||S.Ueno||On 2015-04-27, I introduced several scientific themes of Hida/DST spectroheliograph
as a main-talk of the Solar Seminar.
But, I think I could not have enough time to introduce themes of CHAIN-project and
solar synoptic observation database at that time.
So, tomorrow, I would like to talk about
"Scientific Themes of CHAIN project and KYOTO Solar Synoptic Observation Image Database".
|5/9||S.Takashige|| I will review about the paper,
"Plasma compression in magnetic reconnection regions in the solar corona, E.Provornikova+, 2016".
|5/9||A.Asai||Quasi-Periodic Pulsations (QPPs) of H-alpha and white light emission associated with the 2013-May-14 Flare||pptx|
I will introduce a paper, "magnetic reconnection between a solar filament and nearby coronal loops" as a short talk in the seminar today.
The first author is Leping, Li and the paper was published from Naturephysics last week.
|5/2||K.Nishida||MHD simulation of large amplitude oscillations in prominence||pptx|
|5/30||T.Sakaue and A.Tei|
|6/6||K.Hirose||I will introduce the paper below at tomorrow's Solar Seminar.
'The initial trajectories of eruptive solar prominences' (B.P.Filippov, 2016)
|6/6||H.Isobe||Probing unresolved physics in reconnection region||pptx|
|6/13||Denis P. Cabezas||I will introduce the paper entitled:
"Chromospheric evaporation flows and density changes deduced from Hinode/EIS during an M1.6 flare" by Gomory et al.
|6/13||K.Otsuji||Current Helicity and Twist of Solar Magnetic Fields from Hinode/SOT SP||Current helicity and twist of solar magnetic fields are important in characterizing the dynamo mechanism working in the convection zone of the Sun. We have carried out a statistical study on the current helicity of solar active regions observed with the spectropolarimeter (SP) of the Hinode Solar Optical Telescope (SOT). We used SOT-SP data of 558 vector magnetograms of a total of 80 active regions obtained during the period from 2006 to 2012. we found a tendency that weak and inclined fields conform to the hemispheric sign rule and strong and vertical fields violate it. These different properties of helicity through the strong and weak magnetic field components give important clues in understanding the solar dynamo as well as the mechanism of formation and evolution of solar active regions.||pptx|
I will introduce the following paper:
"Wave Heating and Range of Stellar Activity in Late-Type Dwarfs"
Ulmschneider, P.; Fawzy, D.; Musielak, Z. E.; Stepien, K.
This paper is the Letter paper whose full papers are the following:
"Acoustic and magnetic wave heating in stars . I. Theoretical chromospheric models and emerging radiative fluxes"
"Acoustic and magnetic wave heating in stars . II. On the range of chromospheric activity"
"Acoustic and magnetic wave heating in stars . III. The chromospheric emission-magnetic filling factor relation"
|6/20||T.Anan||Chromospheric heating and spicule on the network boundaries in the quiet sun||
First, I briefly reviewed chromospheric heating studies.
Then I present our analysis of IRIS spectra.
If I have a time, I will introduce our developing new spectropolarimeter motivated by the chromospheric heating and spicule studies.
Observations with Solar Magnetic Activity Research Telescope (SMART) /
Solar Dynamics Doppler Imager (SDDI) at Hida Obs., Kyoto-U.
|I will introduce observations with SMART/SDDI.||pptx|
|7/11||U.Kou||Today in the short talk I will introduce the following paper
Title: Dynamic Hydrogen Ionization
Authors: Carlsson, Mats; Stein, R. F.
|7/11||A.D.Kawamura||Why NOAA 12192 did not cause CME? - III|
|10/17||D.Seki||I will talk about the paper, "Prominence and Filament Eruptions Observed by the Solar Dynamics Observatory: Statistical Properties, Kinematics, and Online Catalog", McCauley et al., 2015/5/26 for todayfs Solar Seminar as a short speaker.||pptx|
|10/17||T.Takahashi||Dynamical phenomena associated with coronal shock waves||I will talk about two topics in the seminar. The first topic will be about the interaction between solar prominences and flare associated coronal shock waves. The solar flare is an impulsive release of magnetic field energy stored in the corona. A part of the energy released during flares propagate in the form of MHD fast mode shocks in the corona. The flare associated shock waves sometimes interact with solar prominences, which is the only example of cosmological shock-cloud interaction of human timescale. I will talk about 3D MHD simulation of shock-prominence interaction, and discuss a phenomenological model of prominence acceleration and its applicability to coronal shock/prominence diagnostics. Then, I will talk about emission measure (EM) analysis of coronal shock waves with SDO/AIA data. EM analysis is found to be quite helpful in understanding quantitatively the physical nature of the shock, when applied to coronal shocks observed at the solar limb.|
|10/24||T.Anan||I would like to introduce a high spatial Ha movie of a flare taken by 1.6 m New Solar Telescope at Big Bear Solar Observatory.
The movie is the supplementary movie of Jing et al. 2016, Nature Scientific Reports.
Please download it from the bellow link, and discuss what can we study by using high resolution data.
|10/24||T.Nakamura||In today's seminar I will introduce a paper, Kennedy+15.
It researches chromospheric heating by non-thermal electron beam after flare occurred in terms of both numerical calculation and observation.
URL of Kennedy+15 : http://ads.nao.ac.jp/abs/2015A%26A...578A..72K
|10/24||H.Tamazawa||In today's seminar, I will introduce our recent study of Carrington storm
with historical document and relation between aurora size and Dst.
Because of preliminary study and the matter of license, I do not upload the presentation file in advance.
|10/31||K.Namekata||Validation of a Scaling Law for the Coronal Magnetic Field Strengths and Loop Lengths of Solar and Stellar Flares|
|10/31||K.Hirose||I am going to talk about my study about filament disappearance and small point-like plasma activation||pptx|
|11/7||Y.Notsu||Spectroscopic observations of active solar-analog stars having high X-ray luminosity, as a proxy of superflare stars||Recent studies of solar-type superflare stars have suggested that even old slowly-rotating stars similar to the Sun can have large starspots and superflares. We conducted high dispersion spectroscopy of 49 nearby solar-analog stars (G-type main sequence stars with Teff = 5,600-6,000 K) identified as ROSAT soft X-ray sources, which are not binary stars on the basis of the previous studies. We expected that these stars can be used as a proxy of bright solar-analog superflare stars, since superflare stars are expected to show strong X-ray luminosity. More than half (37) of the 49 target stars show no evidence of binarity, and atmospheric parameters (temperature, surface gravity, and metallicity) of them are within the range of ordinary solaranalog stars. We measured the intensity of Ca II 8542 and H lines, which are good indicators of the stellar chromospheric activity. The intensity of these lines indicates that all the target stars have large starspots. We also measured v sin i (projected rotational velocity) and Lithium abundance for the target stars. Li abundance is a key to understand the evolution of the stellar convection zone, which reflects the stellar age, mass and the rotational history. We confirmed that many of the target stars rapidly rotate and have high Li abundance, compared with the Sun, as suggested by many previous studies. There are, however, also some target stars that rotate slowly (v sin i = 2-3 km s-1) and have low Li abundance like the Sun. These results support that old and slowly-rotating stars similar to the Sun could have high activity level and large starspots. This is consistent with the results of our previous studies of solar-type superflare stars. In the future, it is important to conduct long-term monitoring observations of these active solar-analog stars in order to investigate the detailed properties of large starspots from the viewpoint of stellar dynamo theory.|
|11/14||guest talk||Dr. Jeongwoo Lee||Study of solar flares inside a large magnetic fan structure with NoRH observations||Understanding how solar eruption proceeds is an important step toward the ultimate goal of solar physics and space weather forecast. Although the exact mechanisms for solar eruptions are still under debate, it is generally believed that the key information lies in the characteristic magnetic configuration of source active regions. In this talk I will present an on-going study of two successive solar flares from NOAA AR 12371 that occurred on 2015 June 21. The photospheric magnetograms and coronal EUV images from the Solar Dynamic Observatory (SDO) imply that the active region consists of two sunspots embedded within a strikingly large magnetic fan structure. It is therefore of new interest how the compact sunspot fields were interacting with the extended overlying magnetic structure to produce the such successive flares, one associated with a sigmoid structure and the other, with a halo CME. We analyze the unique dataset from the Nobeyama Radioheliograph (NoRH) operated by Nagoya University to derive information on the primary energy release and high energy particles accelerated during the two flares. While the solar EUV images show a continuous change of the coronal features, the NoRH detected two well separated (>25 min) radio bursts with distinct properties of both spectral and spatial morphologies. We relate the former radio bursts to an impulsive energy release within a confined magnetic structure and the latter to the aftermath of the CME. Our ultimate goal is to figure out the magnetic connectivity change that is responsible for the transition from the confined flare to the eruptive flare within 40 min time interval|
|1/31||A.Tei, U.Kou and T.Sakaue|
|2/27||D.Seki||3 characteristic features of line-of-sight velocity of a filament as the precursor of filament eruptions||Filaments, the dense cooler plasmas in the solar corona, often become unstable and erupt into the interplanetary space as coronal mass ejections (CMEs). The CMEs may cause geomagnetic storms that result in various societal and economical impacts such as blackouts and satellite anomalies, so that it is important to predict when filament eruptions will occur. The aim of this study is to investigate the characteristics of eruptive filaments that can be used as the precursor of eruptions. For this purpose, we analyzed the solar full disk images captured by Solar Dynamics Doppler Imager(SDDI) installed on Solar Magnetic Activity Research Telescope(SMART) at Hida Obser- vatory, Kyoto University. SDDI can obtain solar full disk images in 73 wavelengths between Ha center-9A and Ha center+9A per 0.25A with the time resolution of about 15 seconds. Therefore this instrument can observe unprecedented detailed line-of-sight velocities of filaments. Focusing on this feature, the filamentfs line-of sight velocities for each pixel of the images by utilizing Beckersf cloud model was calculated and 3 features were found : 1. Increase in the amplitude of line-of-sight velocity of the filament's small scale motion 2. Increase in the oscillation amplitude of the global filamentfs motion 3. a mysterious downward motion and trigger for a filament eruption In this talk, I will introduce these 3 features and discuss the possibility for the prediction of filament eruptions.|
|2/27||K.Nishida||UNIFIED MODEL OF DURATIONS 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 carrying out 2.5D magnetohydrodynamic (MHD) simulations of flares with a flux rope eruption, we investigated the dependence of the duration on the size of the inflow region, while changing the magnetic configurations of quadrupolar loops under the flux rope in the initial conditions. The duration changed with the size of the inflow region, and we found a linear correlation between them.|
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