explanation      blue bibcodes open ADS page with paths to full text
Author name code: matsumoto
ADS astronomy entries on 2022-09-14
=author:"Matsumoto, Takuma" 

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Title: Physical properties of the inner solar corona derived from
    radio scintillation observations with the Akatsuki spacecraft
Authors: Chiba, Shota; Yamazaki, Atsushi; Murata, Yasuhiro; Murakami,
   Go; Asmar, Sami; Paetzold, Martin; Miyoshi, Yoshizumi; Iwai, Kazumasa;
   Ando, Hiroki; Häusler, Bernd; Tokumaru, Munetoshi; Imamura, Takeshi;
   Matsumoto, Takuma; Takeuchi, Hiroshi
2022cosp...44.1345C    Altcode:
  The acceleration of the solar wind mainly occurs in the outer corona
  at heliocentric distances of about 5-20 $R_{S}$ (= solar radii),
  where the coronal heating by magnetohydrodynamic waves and the
  wave-induced magnetic pressure are thought to play major roles in
  the acceleration. The mechanisms have not been fully confirmed by
  observations because the acceleration region is too close to the Sun to
  be observed by in-situ probes. Recently, however, the inner heliosphere
  observation network is getting ready, such as NASA's Parker Solar Probe
  and ESA's Solar orbiter. The radio occultation observation covers the
  acceleration region fully and can obtain the large-scale process of the
  plasma complementary to in-situ observation. The JAXA's Venus orbiter
  Akatsuki conducted the radio occultation observations on either side of
  the superior conjunction. The observations covered various solar cycle
  periods from solar maximum to solar minimum. Key physical processes in
  the acceleration region can be observed with radio occultation. Coronal
  plasma traversing the ray path disturbs radio wave's amplitudes and
  frequency, from which we can derive physical parameters such as the
  flow speed and wave's amplitudes. In this research, we analyze data
  taken by radio occultation observations carried out using Akatsuki's
  signals during the superior conjunction periods in 2011, 2016, 2018,
  and 2021. The radial velocity and the turbulence characteristics
  (power-law exponent, axial ratio and inner scale) were retrieved
  from the intensity scintillation time series taken in 2016 by fitting
  a theoretical spectrum to the observed power spectra. In the radial
  distribution of the derived solar wind velocity, fast winds originating
  from regions near a coronal hole and slow winds from other regions
  were identified. We also found that the inner scale increases with the
  heliocentric distance and that the fast solar wind has larger inner
  scales than the slow solar wind. We also applied wavelet analysis
  to the frequency time series taken in 2011 to detect quasi-periodic
  fluctuations (QPC), that are thought to represent acoustic waves,
  and quantify the amplitude, the period, and the coherence time of
  each wave event. The density amplitude and the wave energy flux were
  estimated following the method of Miyamoto et al. (2014). We confirmed
  that the fractional density amplitude increases with distance up to
  $\sim$6 $R_{S}$. The amplitude reaches tens of percent, suggesting a
  possibility of wave breaking. The energy fluxes increase with distance
  up to $\sim$6 $R_{S}$, suggesting local generation of waves. It is
  probable that these radial distributions indicate that the Alfvén waves
  propagating from the photosphere generate acoustic waves in the outer
  corona, and the generated acoustic waves dissipate to heat the corona,
  as suggested by numerical models. The wave energy fluxes in the fast
  solar wind were larger than those in the slow wind. The results suggest
  that the fast solar wind originating from the coronal hole is powered
  by a larger injection of wave energy than the slow wind originating
  from other regions. In this presentation, we will also report results
  from the data taken by Akatsuki.

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Title: Observation of the Solar Corona Using Radio Scintillation
with the Akatsuki Spacecraft: Difference Between Fast and Slow Wind
Authors: Chiba, Shota; Imamura, Takeshi; Tokumaru, Munetoshi; Shiota,
   Daikou; Matsumoto, Takuma; Ando, Hiroki; Takeuchi, Hiroshi; Murata,
   Yasuhiro; Yamazaki, Atsushi; Häusler, Bernd; Pätzold, Martin
2022SoPh..297...34C    Altcode:
  The properties of the coronal plasma at heliocentric distances of 1.5 -
  8.9 R<SUB>⊙</SUB> (solar radii) were studied with radio-occultation
  observations using JAXA's Akatsuki spacecraft in 2016. Physical
  parameters that characterize the solar wind were retrieved from the
  intensity-scintillation time series by fitting a theoretical spectrum
  to the observed power spectra. The derived solar-wind velocity
  clearly shows a difference between the fast wind and the slow wind,
  which was identified based on IPS observations. The inner scale, at
  which fluid motions dissipate and kinetic energy is converted to heat,
  increases with the heliocentric distance, and the fast wind has larger
  inner scales than the slow wind. By applying wavelet analysis to the
  frequency time series, we detected quasi-periodic fluctuations in
  the electron density. The density oscillations are considered to be
  manifestations of acoustic waves, which were generated from Alfvén
  waves originating from the photosphere, and the energy fluxes of those
  acoustic waves were estimated. The relative density-amplitude peaks
  around 4 - 6 R<SUB>⊙</SUB> and the wave-energy flux decreases beyond
  ≈ 6 R<SUB>⊙</SUB>, implying that the acoustic waves dissipate to
  heat the corona. The phase-scintillation spectrum that we obtained
  cannot be expressed by a single power law. A break is seen around
  the frequency of 0.5 - 2 Hz beyond ≈ 6 R<SUB>⊙</SUB>, suggesting
  an excess power other than turbulence at lower frequencies. The
  enhancement of the relative density amplitude around 6 R<SUB>⊙</SUB>
  found by the wavelet analysis might explain this excess power. The
  acoustic wave-energy flux in the fast solar wind tends to exceed that
  in the slow wind, suggesting that the fast wind is powered by a larger
  injection of Alfvén-wave energy than the slow wind.

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Title: Probing the Physics of the Solar Atmosphere with the Multi-slit
    Solar Explorer (MUSE). I. Coronal Heating
Authors: De Pontieu, Bart; Testa, Paola; Martínez-Sykora, Juan;
   Antolin, Patrick; Karampelas, Konstantinos; Hansteen, Viggo; Rempel,
   Matthias; Cheung, Mark C. M.; Reale, Fabio; Danilovic, Sanja; Pagano,
   Paolo; Polito, Vanessa; De Moortel, Ineke; Nóbrega-Siverio, Daniel;
   Van Doorsselaere, Tom; Petralia, Antonino; Asgari-Targhi, Mahboubeh;
   Boerner, Paul; Carlsson, Mats; Chintzoglou, Georgios; Daw, Adrian;
   DeLuca, Edward; Golub, Leon; Matsumoto, Takuma; Ugarte-Urra, Ignacio;
   McIntosh, Scott W.; the MUSE Team
2022ApJ...926...52D    Altcode: 2021arXiv210615584D
  The Multi-slit Solar Explorer (MUSE) is a proposed mission composed of
  a multislit extreme ultraviolet (EUV) spectrograph (in three spectral
  bands around 171 Å, 284 Å, and 108 Å) and an EUV context imager (in
  two passbands around 195 Å and 304 Å). MUSE will provide unprecedented
  spectral and imaging diagnostics of the solar corona at high spatial
  (≤0.″5) and temporal resolution (down to ~0.5 s for sit-and-stare
  observations), thanks to its innovative multislit design. By obtaining
  spectra in four bright EUV lines (Fe IX 171 Å, Fe XV 284 Å, Fe XIX-Fe
  XXI 108 Å) covering a wide range of transition regions and coronal
  temperatures along 37 slits simultaneously, MUSE will, for the first
  time, "freeze" (at a cadence as short as 10 s) with a spectroscopic
  raster the evolution of the dynamic coronal plasma over a wide range of
  scales: from the spatial scales on which energy is released (≤0.″5)
  to the large-scale (~170″ × 170″) atmospheric response. We use
  numerical modeling to showcase how MUSE will constrain the properties of
  the solar atmosphere on spatiotemporal scales (≤0.″5, ≤20 s) and
  the large field of view on which state-of-the-art models of the physical
  processes that drive coronal heating, flares, and coronal mass ejections
  (CMEs) make distinguishing and testable predictions. We describe the
  synergy between MUSE, the single-slit, high-resolution Solar-C EUVST
  spectrograph, and ground-based observatories (DKIST and others), and
  the critical role MUSE plays because of the multiscale nature of the
  physical processes involved. In this first paper, we focus on coronal
  heating mechanisms. An accompanying paper focuses on flares and CMEs.

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Title: Physical properties of the solar corona studied by spacecraft
    radio scintillation and the difference between fast and slow winds
Authors: Chiba, Shota; Imamura, Takeshi; Tokumaru, Munetoshi; Shiota,
   Daikou; Ando, Hiroki; Matsumoto, Takuma; Takeuchi, Hiroshi; Murata,
   Yasuhiro; Yamazaki, Atsushi
2021AGUFMSH32B..06C    Altcode:
  The solar wind is a supersonic plasma flow streamed from the solar
  corona. The solar wind is classified into the fast wind (typically ~750
  km/s) and the slow wind (~300 km/s). The acceleration of the solar wind
  mainly occurs in the outer corona at heliocentric distances of &lt;10
  RS (= solar radii), where the coronal heating by magnetohydrodynamic
  waves and the wave-induced magnetic pressure are thought to play major
  roles in the acceleration. The mechanisms have not been fully confirmed
  by observations because the acceleration region is too close to the
  Sun to be observed by in-situ probes. Key physical processes in the
  acceleration region can be observed with radio occultation. Coronal
  plasma traversing the ray path disturbs radio waves amplitudes and
  frequency, from which we can derive physical parameters such as the
  flow speed and waves amplitudes. In this research, we analyze data
  taken by radio occultation observations carried out using JAXAs Venus
  orbiter Akatsuki's during the superior conjunction periods from May
  30 to June 15, 2016. Solar offset distances of about 1.49.0 RS were
  probed intermittently by 11 observations. Physical parameters were
  retrieved from the intensity scintillation time series by fitting a
  theoretical spectrum to the observed power spectra. The derived solar
  wind velocity clearly shows a difference between the fast wind and the
  slow wind, which were identified based on IPS observations. The inner
  scale, at which kinetic energy is converted to heat, increases with
  the heliocentric distance, and the fast wind has larger inner scales
  than the slow wind. By applying wavelet analysis to the frequency
  time series, we detected quasi-periodic fluctuations in the electron
  density. The density oscillations are considered as manifestations of
  acoustic waves, which were generated from Alfven waves originating
  from the photosphere, and the energy fluxes of those acoustic waves
  were estimated. The fractional density amplitude peaks around 46 RS
  and the wave energy flux decreases beyond ~6 RS , implying that the
  acoustic waves dissipate to heat the corona. The acoustic wave energy
  fluxes in the fast solar wind tend to exceed those in the slow wind,
  suggesting that the fast wind is powered by a larger injection of
  Alfven wave energy than the slow wind.

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Title: Three-body description of <SUP>9</SUP>C: Role of low-lying
    resonances in breakup reactions
Authors: Singh, Jagjit; Matsumoto, Takuma; Fukui, Tokuro; Ogata,
   Kazuyuki
2021PhRvC.104c4612S    Altcode: 2021arXiv210309511S
  Background: The <SUP>9</SUP>C nucleus and related capture reaction,
  <SUP>8</SUP>B (p ,γ ) <SUP>9</SUP>C , have been intensively studied
  with an astrophysical interest. Due to the weakly bound nature of
  <SUP>9</SUP>C, its structure is likely to be described as the three-body
  (<SUP>7</SUP>Be +p +p ). Its continuum structure is also important to
  describe reaction processes of <SUP>9</SUP>C, with which the reaction
  rate of the <SUP>8</SUP>B (p ,γ ) <SUP>9</SUP>C process have been
  extracted indirectly. <P />Purpose: We preform three-body calculations
  on <SUP>9</SUP>C and discuss properties of its ground and low-lying
  states via breakup reactions. <P />Methods: We employ the three-body
  model of <SUP>9</SUP>C using the Gaussian-expansion method combined with
  the complex-scaling method. This model is implemented in the four-body
  version of the continuum-discretized coupled-channels method, by which
  breakup reactions of <SUP>9</SUP>C are studied. The intrinsic spin of
  <SUP>7</SUP>Be is disregarded. <P />Results: By tuning a three-body
  interaction in the Hamiltonian of <SUP>9</SUP>C, we obtain the low-lying
  2<SUP>+</SUP> state with the resonant energy 0.781 MeV and the decay
  width 0.137 MeV, which is consistent with the available experimental
  information and a relatively high-lying second 2<SUP>+</SUP> wider
  resonant state. Our calculation predicts also sole 0<SUP>+</SUP> and
  three 1<SUP>−</SUP> resonant states. We discuss the role of these
  resonances in the elastic breakup cross section of <SUP>9</SUP>C
  on <SUP>208</SUP>Pb at 65 and 160 MeV/nucleon. <P />Conclusions:
  The low-lying 2<SUP>+</SUP> state is probed as a sharp peak of the
  breakup cross section, while the 1<SUP>−</SUP> states enhance the
  cross section around 3 MeV. Our calculations will further support the
  future and ongoing experimental campaigns for extracting astrophysical
  information and evaluating the two-proton removal cross sections.

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Title: Full compressible 3D MHD simulation of solar wind
Authors: Matsumoto, Takuma
2021MNRAS.500.4779M    Altcode: 2020arXiv200903770M; 2020MNRAS.tmp.3336M
  Identifying the heating mechanisms of the solar corona and the driving
  mechanisms of solar wind are key challenges in understanding solar
  physics. A full three-dimensional compressible magnetohydrodynamic (MHD)
  simulation was conducted to distinguish between the heating mechanisms
  in the fast solar wind above the open field region. Our simulation
  describes the evolution of the Alfvénic waves, which includes the
  compressible effects from the photosphere to the heliospheric distance s
  of 27 solar radii (R<SUB>⊙</SUB>). The hot corona and fast solar wind
  were reproduced simultaneously due to the dissipation of the Alfvén
  waves. The inclusion of the transition region and lower atmosphere
  enabled us to derive the solar mass-loss rate for the first time by
  performing a full three-dimensional compressible MHD simulation. The
  Alfvén turbulence was determined to be the dominant heating mechanism
  in the solar wind acceleration region (s &gt; 1.3 R<SUB>⊙</SUB>), as
  suggested by previous solar wind models. In addition, shock formation
  and phase mixing are important below the lower transition region
  (s &lt; 1.03 R<SUB>⊙</SUB>) as well.

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Title: Thermal responses in a coronal loop maintained by wave
    heating mechanisms
Authors: Matsumoto, Takuma
2018MNRAS.476.3328M    Altcode: 2018MNRAS.tmp..477M; 2017arXiv171207377M
  A full 3-dimensional compressible magnetohydrodynamic (MHD) simulation
  is conducted to investigate the thermal responses of a coronal loop to
  the dynamic dissipation processes of MHD waves. When the foot points
  of the loop are randomly and continuously forced, the MHD waves
  become excited and propagate upward. Then, 1-MK temperature corona
  is produced naturally as the wave energy dissipates. The excited
  wave packets become non-linear just above the magnetic canopy,
  and the wave energy cascades into smaller spatial scales. Moreover,
  collisions between counter-propagating Alfvén wave packets increase
  the heating rate, resulting in impulsive temperature increases. Our
  model demonstrates that the heating events in the wave-heated loops
  can be nanoflare-like in the sense that they are spatially localized
  and temporally intermittent.

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Title: Importance of MHD Waves Observed with Hinode
Authors: Matsumoto, Takuma
2018ASSL..449...79M    Altcode:
  No abstract at ADS

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Title: Competition between shock and turbulent heating in coronal
    loop system
Authors: Matsumoto, Takuma
2016MNRAS.463..502M    Altcode: 2016MNRAS.tmp.1154M; 2016arXiv160606019M
  2.5-dimensional magnetohydrodynamic (MHD) simulations are performed
  with high spatial resolution in order to distinguish between competing
  models of the coronal heating problem. A single coronal loop powered
  by Alfvén waves excited in the photosphere is the target of this
  study. The coronal structure is reproduced in our simulations as a
  natural consequence of the transportation and dissipation of Alfvén
  waves. Further, the coronal structure is maintained as the spatial
  resolution is changed from 25 to 3 km, although the temperature at the
  loop top increases with the spatial resolution. The heating mechanisms
  change gradually across the magnetic canopy at a height of 4 Mm. Below
  the magnetic canopy, both the shock and the MHD turbulence are dominant
  heating processes. Above the magnetic canopy, the shock heating rate
  reduces to less than 10 per cent of the total heating rate while the MHD
  turbulence provides significant energy to balance the radiative cooling
  and thermal conduction loss or gain. The importance of compressibility
  shown in this study would significantly impact on the prospects of
  successful MHD turbulence theory in the solar chromosphere.

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Title: Magnetohydrodynamic Shocks in and above Post-flare Loops:
    Two-dimensional Simulation and a Simplified Model
Authors: Takasao, Shinsuke; Matsumoto, Takuma; Nakamura, Naoki;
   Shibata, Kazunari
2015ApJ...805..135T    Altcode: 2015arXiv150405700T
  Solar flares are an explosive phenomenon where super-sonic flows and
  shocks are expected in and above the post-flare loops. To understand
  the dynamics of post-flare loops, a two-dimensional magnetohydrodynamic
  (2D MHD) simulation of a solar flare has been carried out. We found
  new shock structures in and above the post-flare loops, which were not
  resolved in the previous work by Yokoyama &amp; Shibata. To study the
  dynamics of flows along the reconnected magnetic field, the kinematics
  and energetics of the plasma are investigated along selected field
  lines. It is found that shocks are crucial to determine the thermal
  and flow structures in the post-flare loops. On the basis of the 2D MHD
  simulation, we developed a new post-flare loop model, which we defined
  as the pseudo-2D MHD model. The model is based on the one-dimensional
  (1D) MHD equations, where all variables depend on one space dimension,
  and all the three components of the magnetic and velocity fields
  are considered. Our pseudo-2D model includes many features of the
  multi-dimensional MHD processes related to magnetic reconnection
  (particularly MHD shocks), which the previous 1D hydrodynamic models are
  not able to include. We compared the shock formation and energetics of
  a specific field line in the 2D calculation with those in our pseudo-2D
  MHD model, and found that they give similar results. This model will
  allow us to study the evolution of the post-flare loops in a wide
  parameter space without expensive computational cost or neglecting
  important physics associated with magnetic reconnection.

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Title: Saturation of Stellar Winds from Young Suns
Authors: Suzuki, Takeru K.; Imada, Shinsuke; Kataoka, Ryuho; Kato,
   Yoshiaki; Matsumoto, Takuma; Miyahara, Hiroko; Tsuneta, Saku
2013PASJ...65...98S    Altcode: 2012arXiv1212.6713S
  We investigated mass losses via stellar winds from Sun-like
  main-sequence stars with a wide range of activity levels. We performed
  forward-type magnetohydrodynamical numerical experiments for Alfvén
  wave-driven stellar winds with a wide range of input Poynting flux
  from the photosphere. Increasing the magnetic field strength and
  the turbulent velocity at the stellar photosphere from the current
  solar level, the mass-loss rate rapidly at first increases, owing
  to suppression of the reflection of the Alfvén waves. The surface
  materials are lifted up by the magnetic pressure associated with
  the Alfvén waves, and the cool dense chromosphere is intermittently
  extended to 10%#8211;20% of the stellar radius. The dense atmospheres
  enhance the radiative losses, and eventually most of the input Poynting
  energy from the stellar surface escapes by radiation. As a result, there
  is no more sufficient energy remaining for the kinetic energy of the
  wind; the stellar wind saturates in very active stars, as observed in
  Wood et al. (2002, ApJ, 574, 412; 2005, ApJ, 628, L143). The saturation
  level is positively correlated with B<SUB>r,</SUB><SUB>0</SUB>
  f<SUB>0</SUB>, where B<SUB>r,</SUB><SUB>0</SUB> and f<SUB>0</SUB>
  are the magnetic field strength and the filling factor of open flux
  tubes at the photosphere. If B<SUB>r,</SUB><SUB>0</SUB> f<SUB>0</SUB>
  is relatively large gtrsim 5 G, the mass-loss rate could be as high as
  1000 times. If such a strong mass loss lasts for ∼ 1 billion years,
  the stellar mass itself would be affected, which could be a solution to
  the faint young Sun paradox. We derived a Reimers-type scaling relation
  that estimates the mass-loss rate from an energetics consideration of
  our simulations. Finally, we derived the evolution of the mass-loss
  rates, dot;{M} ∝ t<SUP>-1.23</SUP>, of our simulations, combining
  with an observed time evolution of X-ray flux from Sun-like stars,
  which are shallower than dot;{M} ∝ t<SUP>-2.33±0.55</SUP> in Wood
  et al. (2005).

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Title: Connecting the photosphere and the solar wind
Authors: Matsumoto, Takuma; Suzuki, Takeru Ken
2013AIPC.1539...38M    Altcode:
  We have performed 2.5 dimensional magnetohydrodynamic simulations for
  Alfvén wave propagation in the solar atmosphere. The coronal heating
  and the solar wind acceleration problems are our main target. Our
  simulation is self-consistent one in terms of the fact that we do not
  assume any background atmospheric structures. The hot corona and the
  high speed solar wind appeared in our numerical simulation as a natural
  consequence of Alfvén wave injection from the photosphere. Significant
  amount of the Alfvén wave energy is converted into the longitudinal
  wave around the chromosphere. The longitudinal wave damped rapidly
  as they propagated upward to the corona, which suggests that the
  shock heating is efficient in the low corona. Although the turbulent
  cascade was efficient dissipation mechanism in our simulation, we will
  concentrate on the shock heating mechanisms in this paper.

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Title: Connecting the Sun and the Solar Wind: The First
    2.5-dimensional Self-consistent MHD Simulation under the Alfvén
    Wave Scenario
Authors: Matsumoto, Takuma; Suzuki, Takeru Ken
2012ApJ...749....8M    Altcode: 2011arXiv1109.6707M
  The solar wind emanates from the hot and tenuous solar corona. Earlier
  studies using 1.5-dimensional simulations show that Alfvén waves
  generated in the photosphere play an important role in coronal heating
  through the process of nonlinear mode conversion. In order to understand
  the physics of coronal heating and solar wind acceleration together, it
  is important to consider the regions from photosphere to interplanetary
  space as a single system. We performed 2.5-dimensional, self-consistent
  magnetohydrodynamic simulations, covering from the photosphere to the
  interplanetary space for the first time. We carefully set up the grid
  points with spherical coordinates to treat the Alfvén waves in the
  atmosphere with huge density contrast and successfully simulate the
  solar wind streaming out from the hot solar corona as a result of the
  surface convective motion. The footpoint motion excites Alfvén waves
  along an open magnetic flux tube, and these waves traveling upward
  in the non-uniform medium undergo wave reflection, nonlinear mode
  conversion from Alfvén mode to slow mode, and turbulent cascade. These
  processes lead to the dissipation of Alfvén waves and acceleration of
  the solar wind. It is found that the shock heating by the dissipation
  of the slow-mode wave plays a fundamental role in the coronal heating
  process, whereas the turbulent cascade and shock heating drive the
  solar wind.

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Title: Propagation of Moreton Waves
Authors: Zhang, Yuzong; Kitai, Reizaburo; Narukage, Noriyuki;
   Matsumoto, Takuma; Ueno, Satoru; Shibata, Kazunari; Wang, Jingxiu
2011PASJ...63..685Z    Altcode:
  With the Flare-Monitoring Telescope (FMT) and Solar Magnetic Activity
  Research Telescope (SMART) at Hida observatory of Kyoto University,
  13 events of Moreton waves were captured at Hα center, Hα ±0.5 Å,
  and Hα ±0.8 Å wavebands since 1997. With such samples, we have
  studied the statistical properties of the propagation of Moreton
  waves. Moreton waves were all restricted in sectorial zones with a
  mean value of 92°. However, their accompanying EIT waves, observed
  simultaneously with SOHO/EIT at extreme-ultraviolet wavelength, were
  very isotropic with a quite extended scope of 193°. The average
  propagation speeds of the Moreton waves and the corresponding
  EIT waves were 664 km s<SUP>-1</SUP> and 205 km s<SUP>-1</SUP>,
  respectively. Moreton waves propagated either under large-scale
  close magnetic flux loops, or firstly in the sectorial region where
  two sets of magnetic loops separated from each other and diverged,
  and then stopped before the open magnetic flux region. The location
  swept by Moreton waves had a relatively weak magnetic field as compared
  to the magnetic fields at their sidewalls. The ratio of the magnetic
  flux density between the sidewall and the path falls in the range of
  1.4 to 3.7 at a height of 0.01 solar radii. Additionally, we roughly
  estimated the distribution of the fast magnetosonic speed between the
  propagating path and sidewalls in an event on 1997 November 3, and
  found a relatively low-fast magnetosonic speed in the path. We also
  found that the propagating direction of Moreton waves coincided with
  the direction of filament eruption in a few well-observed events. This
  favors an interpretation of the “Piston” model, although further
  studies are necessary for any definitive conclusion.

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Title: Internal Fine Structure of Ellerman Bombs
Authors: Hashimoto, Yuki; Kitai, Reizaburo; Ichimoto, Kiyoshi; Ueno,
   Satoru; Nagata, Shin'ichi; Ishii, Takako T.; Hagino, Masaoki; Komori,
   Hiroyuki; Nishida, Keisuke; Matsumoto, Takuma; Otsuji, Kenichi;
   Nakamura, Tahei; Kawate, Tomoko; Watanabe, Hiroko; Shibata, Kazunari
2010PASJ...62..879H    Altcode:
  We conducted coordinated observations of Ellerman bombs (EBs) between
  Hinode Satellite and Hida Observatory (HOP12). CaII H broad-band
  filter images of NOAA 10966 on 2007 August 9 and 10 were obtained
  with the Solar Optical Telescope (SOT) aboard the Hinode Satellite,
  and many bright points were observed. We identified a total of 4
  bright points as EBs, and studied the temporal variation of their
  morphological fine structures and spectroscopic characteristics. With
  high-resolution CaII H images of SOT, we found that the EBs, thus far
  thought of as single bright features, are composed of a few of fine
  subcomponents. Also, by using Stokes I/V filtergrams with Hinode/SOT,
  and CaII H spectroheliograms with Hida/Domeless Solar Telescope (DST),
  our observation showed: (1) The mean duration, the mean width, the
  mean length, and the mean aspect ratio of the subcomponents were
  390 s, 170 km, 450 km, and 2.7, respectively. (2) Subcomponents
  started to appear on the magnetic neutral lines, and extended their
  lengths from the original locations. (3) When the CaII H line of EBs
  showed the characteristic blue asymmetry, they are associated with the
  appearance or re-brightening of subcomponents. Summarizing our results,
  we obtained an observational view that elementary magnetic reconnections
  take place one by one successively and intermittently in EBs, and that
  their manifestation is the fine subcomponents of the EB phenomena.

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Title: Spicule Dynamics over a Plage Region
Authors: Anan, Tetsu; Kitai, Reizaburo; Kawate, Tomoko; Matsumoto,
   Takuma; Ichimoto, Kiyoshi; Shibata, Kazunari; Hillier, Andrew; Otsuji,
   Kenichi; Watanabe, Hiroko; Ueno, Satoru; Nagata, Shin'ichi; Ishii,
   Takako T.; Komori, Hiroyuki; Nishida, Keisuke; Nakamura, Tahei; Isobe,
   Hiroaki; Hagino, Masaoki
2010PASJ...62..871A    Altcode: 2010arXiv1002.2288A
  We studied spicular jets over a plage area and derived their
  dynamic characteristics using Hinode Solar Optical Telescope (SOT)
  high-resolution images. A target plage region was near to the west limb
  of the solar disk. This location permitted us to study the dynamics
  of spicular jets without any overlapping effect of spicular structures
  along the line of sight. In this work, to increase the ease with which
  we could identify spicules on the disk, we applied the image processing
  method `MadMax' developed by Koutchmy et al. (1989). It enhances fine,
  slender structures (like jets), over a diffuse background. We identified
  169 spicules over the target plage. This sample permited us to derive
  statistically reliable results regarding spicular dynamics. The
  properties of plage spicules can be summarized as follows: (1) In a
  plage area, we clearly identified spicular jet features. (2) They were
  shorter in length than the quiet region limb spicules, and followed a
  ballistic motion under constant deceleration. (3) The majority (80%)
  of the plage spicules showed a cycle of rise and retreat, while 10% of
  them faded out without a complete retreat phase. (4) The deceleration
  of the spicule was proportional to the velocity of ejection (i.e.,
  the initial velocity).

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Title: CaII K Spectral Study of an Emerging Flux Region using the
    Domeless Solar Telescope in Hida Observatory
Authors: Otsuji, Kenichi; Kitai, Reizaburo; Matsumoto, Takuma;
   Ichimoto, Kiyoshi; Ueno, Satoru; Nagata, Shin'ichi; Isobe, Hiroaki;
   Shibata, Kazunari
2010PASJ...62..893O    Altcode: 2010arXiv1005.2025O
  A cooperative observation with Hida Observatory and the Hinode
  satellite was performed on an emerging flux region. Successive CaII
  K spectro-heliograms of the emerging flux region were taken by the
  Domeless Solar Telescope of Hida Observatory. Hinode observed the
  emerging flux region with CaII H and FeI Stokes IQUV filtergrams. In
  this study, detailed dynamics and the temporal evolution of the
  magnetic flux emergence was studied observationally. The event was first
  detected in the photospheric magnetic field signals; 3 minutes later,
  a horizontal expansion of the dark area was detected. Then, 7 minutes
  later than the horizontal expansion, the emerging loops were detected
  with a maximal rise speed of 2.1 km s<SUP>-1</SUP> at chromospheric
  heights. The observed dynamics of the emerging magnetic flux from the
  photosphere to the upper chromosphere was very consistent with the
  results of previous simulation studies. A gradual rising phase of flux
  tubes with a weak magnetic strength was confirmed by our observation.

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Title: Temporal Power Spectra of the Horizontal Velocity of the
    Solar Photosphere
Authors: Matsumoto, Takuma; Kitai, Reizaburo
2010ApJ...716L..19M    Altcode: 2010arXiv1004.5173M
  We have derived the temporal power spectra of the horizontal velocity
  of the solar photosphere. The data sets for 14 quiet regions observed
  with the G-band filter of Hinode/SOT are analyzed to measure
  the temporal fluctuation of the horizontal velocity by using the
  local correlation tracking (LCT) method. Among the high resolution
  (~0farcs2) and seeing-free data sets of Hinode/SOT, we selected the
  observations whose duration is longer than 70 minutes and cadence is
  about 30 s. The so-called k-ω diagrams of the photospheric horizontal
  velocity are derived for the first time to investigate the temporal
  evolution of convection. The power spectra derived from k-ω diagrams
  typically have a double power-law shape bent over at a frequency of
  4.7 mHz. The power-law index in the high frequency range is -2.4, while
  the power-law index in the low frequency range is -0.6. The root mean
  square of the horizontal speed is about 1.1 km s<SUP>-1</SUP> when
  we use a tracer size of 0farcs4 in the LCT method. Autocorrelation
  functions of intensity fluctuation, horizontal velocity, and its
  spatial derivatives are also derived in order to measure the correlation
  time of the stochastic photospheric motion. Since one of the possible
  energy sources of the coronal heating is the photospheric convection,
  the power spectra derived in the present study will be of high value
  to quantitatively justify various coronal heating models.

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Title: Nonlinear Propagation of Alfvén Waves Driven by Observed
Photospheric Motions: Application to the Coronal Heating and Spicule
    Formation
Authors: Matsumoto, Takuma; Shibata, Kazunari
2010ApJ...710.1857M    Altcode: 2010arXiv1001.4307M
  We have performed MHD simulations of Alfvén wave propagation along
  an open flux tube in the solar atmosphere. In our numerical model,
  Alfvén waves are generated by the photospheric granular motion. As the
  wave generator, we used a derived temporal spectrum of the photospheric
  granular motion from G-band movies of Hinode/Solar Optical Telescope. It
  is shown that the total energy flux at the corona becomes larger and
  the transition region's height becomes higher in the case when we use
  the observed spectrum rather than the white/pink noise spectrum as
  the wave generator. This difference can be explained by the Alfvén
  wave resonance between the photosphere and the transition region. After
  performing Fourier analysis on our numerical results, we have found that
  the region between the photosphere and the transition region becomes
  an Alfvén wave resonant cavity. We have confirmed that there are at
  least three resonant frequencies, 1, 3, and 5 mHz, in our numerical
  model. Alfvén wave resonance is one of the most effective mechanisms
  to explain the dynamics of the spicules and the sufficient energy flux
  to heat the corona.

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Title: Nonlinear Propagation of Alfven Waves Driven by Observed
Photospheric Motions: Application to the Coronal Heating and Spicule
    Formation
Authors: Matsumoto, Takuma; Shibata, Kazunari
2010cosp...38.2919M    Altcode: 2010cosp.meet.2919M
  We have performed MHD simulations of Alfven wave propagation along an
  open ux tube in the solar atmosphere. In our numerical model, Alfven
  waves are generated by the photospheric granular motion. As the wave
  generator, we used a derived temporal spectrum of the photo-spheric
  granular motion from G-band movies of Hinode/SOT. It is shown that the
  total energy ux at the corona becomes larger and the transition region
  height becomes higher in the case when we use the observed spectrum
  rather than white/pink noise spectrum as the wave gener-ator. This
  difference can be explained by the Alfven wave resonance between
  the photosphere and the transition region. After performing Fourier
  analysis on our numerical results, we have found that the region
  between the photosphere and the transition region becomes an Alfven
  wave resonant cavity. We have conrmed that there are at least three
  resonant frequencies, 1, 3 and 5 mHz, in our numerical model. Alfven
  wave resonance is one of the most effective mechanisms to explain
  the dynamics of the spicules and the sufficient energy ux to heat
  the corona.

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Title: Cooperative Observation of Ellerman Bombs between the Solar
    Optical Telescope aboard Hinode and Hida/Domeless Solar Telescope
Authors: Matsumoto, Takuma; Kitai, Reizaburo; Shibata, Kazunari;
   Nagata, Shin'ichi; Otsuji, Kenichi; Nakamura, Tahei; Watanabe, Hiroko;
   Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu,
   Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.; Lites, Bruce W.;
   Shine, Richard A.; Title, Alan M.
2008PASJ...60..577M    Altcode:
  High-resolution CaIIH broad-band filter images of NOAA10933 on 2007
  January 5 were obtained by the Solar Optical Telescope aboard the Hinode
  satellite. Many small-scale (∼1") bright points were observed outside
  the sunspot and inside the emerging flux region. We identified some of
  these bright points with Ellerman bombs (EBs) by using Hα images taken
  by the Domeless Solar Telescope at Hida observatory. The sub-arcsec
  structures of two EBs seen in CaIIH were studied in detail. Our
  observation showed the following two aspects: (1) The CaIIH bright
  points identified with EBs were associated with the bipolar magnetic
  field structures, as reported by previous studies. (2)The structure
  of the CaIIH bright points turned out to consist of the following two
  parts: a central elongated bright core (0.7" × 0.5") located along
  the magnetic neutral line and a diffuse halo (1.2"×1.8").

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Title: Height Dependence of Gas Flows in an Ellerman Bomb
Authors: Matsumoto, Takuma; Kitai, Reizaburo; Shibata, Kazunari;
   Otsuji, Kenichi; Naruse, Takuya; Shiota, Daikou; Takasaki, Hiroyuki
2008PASJ...60...95M    Altcode:
  We performed spectroscopic observations of Ellerman bombs (EBs) in
  an active region of NOAA 10705 at Hida Observatory on 2004 November
  24. The photospheric velocity fields of EBs have for the first time
  been investigated spectroscopically. From the Doppler shifts of a
  TiII absorption line (6559.576Å) and a broad Hα emission line,
  we derived the photospheric velocity and the lower chromospheric
  velocity, respectively. The photospheric velocity of EBs was ∼
  0.2kms<SUP>-1</SUP>, indicating downward flow, on average. We found
  that the photospheric velocity variation of EBs has a good temporal
  correlation with the Hα wing emission variation. On the other hand, the
  chromospheric velocity showed an upward flow of ∼1-3kms<SUP>-1</SUP>
  on the average. From the characteristics of the flow field, we
  conclude that the observed EB occurred at the upper photospheric
  level. We suggest that it is important to know the motions of EBs in
  the photosphere because a plausible triggering mechanism of EBs is
  magnetic reconnection in the low-lying atmosphere.

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Title: Multi-scale Interlocked Simulation of Solar Eruption
Authors: Kusano, Kanya; Sugiyama, Tooru; Inoue, Satoshi; Shiota, Daiko;
   Asano, Eiji; Matsumoto, Takuma; Kataoka, Ryuho; Shibata, Kazunari
2008cosp...37.1659K    Altcode: 2008cosp.meet.1659K
  The onset process of solar eruption, which arises as solar flares and/or
  coronal mass ejections (CME), is one of the most important subject
  in space and astrophysical plasma physics, because it is the typical
  phenomena of the explosive energy liberation in plasma as well as the
  primary cause of space weather disturbances. However, not only the onset
  mechanism but even the physical condition to trigger it are not yet well
  clarified. In particular, the mutual relationship between large-scale
  magnetic configuration and small-scale reconnection dynamics in the
  CME initiation is hardly understood, although it is quite important
  from the view point both of the multi-scale plasma physics and the
  space weather forecast. The objective of this paper is to develop a
  new type of simulation framework to shed a light to this long-standing
  problem. Our simulation is performed by the incorporation of multiple
  models, each of which can calculate the different dynamics at different
  scales. They are constituted of the active region model, the global
  corona model, the interplanetary space model, and the fluid-particle
  interlocked model, which is able to handle the calculation of energetic
  particle acceleration in macro-scale magnetic environment. We have
  applied the new model to simulate the eruptive event caused by the
  X-class flare occurred on December 13, 2006, using vector magnetic
  field data observed by Hinode, Solar Optical Telescope. In this talk,
  after a brief review of the theories proposed so far for the flare
  and CME initiation, we show the basic algorithm of our model. Then,
  we present the result of the first-ever datadriven simulation of the
  solar eruption. The detail comparison between the simulation and the
  observation is also reported. Finally, we are discussing about the
  predictability of solar eruption, based on the numerical experiments
  with the multi-scale interlocked model.

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Title: Chromospheric Anemone Jets as Evidence of Ubiquitous
    Reconnection
Authors: Shibata, Kazunari; Nakamura, Tahei; Matsumoto, Takuma; Otsuji,
   Kenichi; Okamoto, Takenori J.; Nishizuka, Naoto; Kawate, Tomoko;
   Watanabe, Hiroko; Nagata, Shin'ichi; UeNo, Satoru; Kitai, Reizaburo;
   Nozawa, Satoshi; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi;
   Shimizu, Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.; Berger,
   Thomas E.; Lites, Bruce W.; Shine, Richard A.; Title, Alan M.
2007Sci...318.1591S    Altcode: 2008arXiv0810.3974S
  The heating of the solar chromosphere and corona is a long-standing
  puzzle in solar physics. Hinode observations show the ubiquitous
  presence of chromospheric anemone jets outside sunspots in active
  regions. They are typically 3 to 7 arc seconds = 2000 to 5000 kilometers
  long and 0.2 to 0.4 arc second = 150 to 300 kilometers wide, and their
  velocity is 10 to 20 kilometers per second. These small jets have an
  inverted Y-shape, similar to the shape of x-ray anemone jets in the
  corona. These features imply that magnetic reconnection similar to that
  in the corona is occurring at a much smaller spatial scale throughout
  the chromosphere and suggest that the heating of the solar chromosphere
  and corona may be related to small-scale ubiquitous reconnection.

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Title: Small-Scale Magnetic-Flux Emergence Observed with Hinode
    Solar Optical Telescope
Authors: Otsuji, Kenichi; Shibata, Kazunari; Kitai, Reizaburo; Ueno,
   Satoru; Nagata, Shin'ichi; Matsumoto, Takuma; Nakamura, Tahei;
   Watanabe, Hiroko; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto,
   Kiyoshi; Shimizu, Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.;
   Lites, Bruce; Shine, Richard A.; Title Alan M.
2007PASJ...59S.649O    Altcode: 2007arXiv0709.3207O
  We observed small-scale magnetic-flux emergence in a sunspot moat region
  by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We
  analyzed filtergram images observed at wavelengths of Fe 6302Å, G band,
  and CaII H. In Stokes I images of Fe 6302Å, emerging magnetic flux was
  recognized as dark lanes. In the G band, they showed to be their shapes
  almost the same as in Stokes I images. These magnetic fluxes appeared
  as dark filaments in CaII H images. Stokes V images of Fe 6302Å showed
  pairs of opposite polarities at footpoints of each filament. These
  magnetic concentrations were identified to correspond to bright points
  in G band/CaII H images. From an analysis of time-sliced diagrams, we
  derived the following properties of emerging flux, which are consistent
  with those of previous studies: (1) Two footpoints separate each other
  at a speed of 4.2kms<SUP>-1</SUP> during the initial phase of evolution,
  and decrease to about 1kms<SUP>-1</SUP> 10minutes later. (2) CaII H
  filaments appear almost simultaneously with the formation of dark lanes
  in Stokes I in an observational cadence of 2minutes. (3) The lifetime
  of the dark lanes in the Stokes I and G band is 8minutes, while that
  of Ca filament is 12minutes. An interesting phenomena was observed,
  that an emerging flux tube expanded laterally in the photosphere with a
  speed of 3.8kms<SUP>-1</SUP>. A discussion on the horizontal expansion
  of the flux tube is given with refernce to previous simulation studies.

---------------------------------------------------------
Title: Umbral Fine Structures in Sunspots Observed with Hinode Solar
    Optical Telescope
Authors: Kitai, Reizaburo; Watanabe, Hiroko; Nakamura, Tahei; Otsuji,
   Ken-ichi; Matsumoto, Takuma; UeNo, Satoru; Nagata, Shin'ichi; Shibata,
   Kazunari; Muller, Richard; Ichimoto, Kiyoshi; Tsuneta, Saku; Suematsu,
   Yoshinori; Katsukawa, Yukio; Shimizu, Toshifumi; Tarbell, Theodore D.;
   Shine, Richard A.; Title, Alan M.; Lites, Bruce
2007PASJ...59S.585K    Altcode: 2007arXiv0711.3266K
  A high resolution imaging observation of a sunspot umbra was made with
  the Hinode Solar Optical Telescope. Filtergrams at wavelengths of the
  blue and green continua were taken during three consecutive days. The
  umbra consisted of a dark core region, several diffuse components,
  and numerous umbral dots. We derived basic properties of umbral dots
  (UDs), especially their temperatures, lifetimes, proper motions,
  spatial distribution, and morphological evolution. The brightness
  of UDs is confirmed to depend on the brightness of their surrounding
  background. Several UDs show fission and fusion. Thanks to the stable
  condition of the space observation, we could for the first time follow
  the temporal behavior of these events. The derived properties of the
  internal structure of the umbra are discussed from the viewpoint of
  magnetoconvection in a strong magnetic field.