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"
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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 <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.
---------------------------------------------------------
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.
---------------------------------------------------------
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 > 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 < 1.03 R<SUB>⊙</SUB>) as well.
---------------------------------------------------------
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.
---------------------------------------------------------
Title: Importance of MHD Waves Observed with Hinode
Authors: Matsumoto, Takuma
2018ASSL..449...79M Altcode:
No abstract at ADS
---------------------------------------------------------
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.
---------------------------------------------------------
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 & 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.
---------------------------------------------------------
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).
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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).
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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").
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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.
---------------------------------------------------------
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.