|07-09||13:30-14:00||S. Okada||upload or download|
|14:00-15:00||D. Seki||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«Ρmez, 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||·Ρζ` [iutB^[Μ1/8 Å ubNΜJΖΚwχΧ\’ΜBΟͺ|
|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 LyΏ 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 Beckersf cloud model to 73 multi-wavelengths images around HΏ 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 HΏ center image and the LOS velocity map.
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