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Author name code: okamoto
ADS astronomy entries on 2022-09-14
author:"Okamoto, Takenori J."
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Title: Quiet Sun Center to Limb Variation of the Linear Polarization
Observed by CLASP2 Across the Mg II h and k Lines
Authors: Rachmeler, L. A.; Bueno, J. Trujillo; McKenzie, D. E.;
Ishikawa, R.; Auchère, F.; Kobayashi, K.; Kano, R.; Okamoto,
T. J.; Bethge, C. W.; Song, D.; Ballester, E. Alsina; Belluzzi,
L.; Pino Alemán, T. del; Ramos, A. Asensio; Yoshida, M.; Shimizu,
T.; Winebarger, A.; Kobelski, A. R.; Vigil, G. D.; Pontieu, B. De;
Narukage, N.; Kubo, M.; Sakao, T.; Hara, H.; Suematsu, Y.; Štěpán,
J.; Carlsson, M.; Leenaarts, J.
2022ApJ...936...67R Altcode: 2022arXiv220701788R
The CLASP2 (Chromospheric LAyer Spectro-Polarimeter 2) sounding rocket
mission was launched on 2019 April 11. CLASP2 measured the four Stokes
parameters of the Mg II h and k spectral region around 2800 Å along a
200″ slit at three locations on the solar disk, achieving the first
spatially and spectrally resolved observations of the solar polarization
in this near-ultraviolet region. The focus of the work presented here
is the center-to-limb variation of the linear polarization across these
resonance lines, which is produced by the scattering of anisotropic
radiation in the solar atmosphere. The linear polarization signals of
the Mg II h and k lines are sensitive to the magnetic field from the
low to the upper chromosphere through the Hanle and magneto-optical
effects. We compare the observations to theoretical predictions
from radiative transfer calculations in unmagnetized semiempirical
models, arguing that magnetic fields and horizontal inhomogeneities
are needed to explain the observed polarization signals and spatial
variations. This comparison is an important step in both validating and
refining our understanding of the physical origin of these polarization
signatures, and also in paving the way toward future space telescopes
for probing the magnetic fields of the solar upper atmosphere via
ultraviolet spectropolarimetry.
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Title: Shock Recovery of Granite with a Decaying Shock Wave: Feather
Features Formation in Quartz
Authors: Tada, T.; Kurosawa, K.; Ono, H.; Hamann, C.; Okamoto, T.;
Niihara, T.; Matsui, T.
2022LPICo2678.1733T Altcode:
We carried out shock recovery of granite with decaying compressive
pulses, focusing on Feather Features (FFs) formation in quartz. FFs
were formed at 8-18GPa.
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Title: 2021 Stellar Occultation Observation of Asteroid (3200)
PHAETHON for the DESTINY+ Flyby
Authors: Arai, T.; Yoshida, F.; Hayamizu, T.; Akitaya, H.; Okamoto,
T.; Noda, H.; Ishiguro, M.; Urakawa, S.; Horaguchi, T.; Yamamoto,
M. -Y.; Hashimoto, G.; Matsuura, S.; Marshall, S.; Destiny+ Occultation
Observation Team
2022LPICo2678.2916A Altcode:
Result of stellar occultation of Phaethon in 2021 in Japan is reported.
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Title: Shock Effects in Pre-Heated Basalt: Search for the Criteria
for Producing Mosaicism
Authors: Ono, H.; Kurosawa, K.; Niihara, T.; Mikouchi, T.; Tomioka,
N.; Okamoto, T.; Matsui, T.
2022LPICo2678.1566O Altcode:
We conducted a shock recovery experiment using basalt with a pre-heating
devise. The recovered sample was processed into a thin section and
investigated.
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Title: Shock Recovery of Granite with a Decaying Shock Wave:
Fragmentation, Formation of Stishovite, and Onset of Melting at Low
(<20 GPa) Shock Pressure
Authors: Hamann, C.; Kurosawa, K.; Kaufmann, F. E. D.; Ono, H.; Tada,
T.; Niihara, T.; Okamoto, T.; Matsui, T.
2022LPICo2678.2020H Altcode:
Fragmemtation, stishovite formation, and shear-induced melting in
granite at low (<20 GPa) shock pressure are investigated in novel
shock-recovery experiments.
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Title: Development Status of DESTINY+ Onboard Cameras for Flyby
Imaging of (3200) Phaethon
Authors: Ishibashi, K.; Hong, P.; Okamoto, T.; Yamada, M.; Okudaira,
O.; Suzaki, Y.; Ishimaru, T.; Ozaki, N.; Hosonuma, T.; Sato, S.;
Arai, T.; Yoshida, F.; Kagitani, M.; Kameda, S.; Miyabara, T.; Ohta,
M.; Takashima, T.
2022LPICo2678.1729I Altcode:
We present the development status of two cameras onboard DESTINY+
spacecraft for flyby imaging of the asteroid (3200) Phaethon.
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Title: Shock Recovery of Macro Blocks of Rocky Materials with Decaying
Shock Waves
Authors: Kurosawa, K.; Ono, H.; Niihara, T.; Mikouchi, T.; Sakaiya,
T.; Kondo, T.; Tomioka, N.; Genda, H.; Tada, T.; Tada, R.; Kayama,
M.; Koike, M.; Sano, Y.; Matsuzaki, T.; Murayama, M.; Satake, W.;
Okamoto, T.; Matsui, T.
2021LPICo2609.6163K Altcode:
We have developed an experimental technique for shock recovery with
decaying compressive pulses. The method allows as to collect a shocked
sample experienced a variety of peak pressure depending on the initial
location only at a single shot.
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Title: Mapping of Solar Magnetic Fields from the Photosphere to the
Top of the Chromosphere with CLASP2
Authors: McKenzie, D.; Ishikawa, R.; Trujillo Bueno, J.; Auchere, F.;
del Pino Aleman, T.; Okamoto, T.; Kano, R.; Song, D.; Yoshida, M.;
Rachmeler, L.; Kobayashi, K.; Narukage, N.; Kubo, M.; Ishikawa, S.;
Hara, H.; Suematsu, Y.; Sakao, T.; Bethge, C.; De Pontieu, B.; Vigil,
G.; Winebarger, A.; Alsina Ballester, E.; Belluzzi, L.; Stepan, J.;
Asensio Ramos, A.; Carlsson, M.; Leenaarts, J.
2021AAS...23810603M Altcode:
Coronal heating, chromospheric heating, and the heating &
acceleration of the solar wind, are well-known problems in solar
physics. Additionally, knowledge of the magnetic energy that
powers solar flares and coronal mass ejections, important drivers
of space weather, is handicapped by imperfect determination of the
magnetic field in the sun's atmosphere. Extrapolation of photospheric
magnetic measurements into the corona is fraught with difficulties and
uncertainties, partly due to the vastly different plasma beta between
the photosphere and the corona. Better results in understanding
the coronal magnetic field should be derived from measurements of
the magnetic field in the chromosphere. To that end, we are pursuing
quantitative determination of the magnetic field in the chromosphere,
where plasma beta transitions from greater than unity to less than
unity, via ultraviolet spectropolarimetry. The CLASP2 mission, flown
on a sounding rocket in April 2019, succeeded in measuring all four
Stokes polarization parameters in UV spectral lines formed by singly
ionized Magnesium and neutral Manganese. Because these ions produce
spectral lines under different conditions, CLASP2 thus was able to
quantify the magnetic field properties at multiple heights in the
chromosphere simultaneously, as shown in the recent paper by Ishikawa
et al. In this presentation we will report the findings of CLASP2,
demonstrating the variation of magnetic fields along a track on
the solar surface and as a function of height in the chromosphere;
and we will illustrate what is next for the CLASP missions and the
demonstration of UV spectropolarimetry in the solar chromosphere.
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Title: Development of Two Types of NIR Spectral Camera for Lunar
Missions SLIM and LUPEX
Authors: Saiki, K.; Ohtake, M.; Nakauchi, Y.; Shiraishi, H.; Ishihara,
Y.; Sato, H.; Honda, C.; Maeda, T.; Yamanaka, C.; Nagaoka, H.;
Sakai, S.; Sawai, S.; Fukuda, S.; Kushiki, K.; Ebizuka, N.; Sasaki,
M.; Okamoto, T.; Kayama, M.; Demura, H.; Kitazato, K.; Ogawa, Y.;
Mikouchi, T.; Hirano, T.
2021LPI....52.2303S Altcode:
The concept and development status of two spectroscopic cameras for
the lunar missions Smart Lander for Investigating Moon (SLIM) project
and Lunar Polar Exploration (LUPEX) project are introduced.
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Title: Current Status of DESTINY+ and Updated Understanding of Its
Target Asteroid (3200) Phaethon
Authors: Arai, T.; Yoshida, F.; Kobayashi, M.; Ishibashi, K.; Kimura,
H.; Hirai, T.; Hong, P.; Wada, K.; Senshu, H.; Yamada, M.; Srama,
R.; Krüger, H.; Ishiguro, M.; Yabuta, H.; Nakamura, T.; Kobayashi,
S.; Watanabe, J.; Ito, T.; Ootsubo, T.; Ohtsuka, K.; Tachibana, S.;
Mikouchi, T.; Morota, T.; Komatsu, M.; Nakamura-Messenger, K.; Sasaki,
S.; Hiroi, T.; Abe, S.; Urakawa, S.; Hirata, N.; Demura, H.; Komatsu,
G.; Noguchi, T.; Sekiguchi, T.; Kinoshita, D.; Kaneda, H.; Kameda,
S.; Matsuura, S.; Ito, M.; Yamaguchi, A.; Yanagisawa, T.; Kurosaki,
H.; Okamoto, T.; Nakato, A.; Yano, H.; Yoshikawa, M.; Dunham, D. W.;
Buie, M. W.; Taylor, P. A.; Marshall, S.; Ozaki, N.; Yamamoto, T.;
Imamura, H.; Toyota, H.; Nishiyama, K.; Takashima, T.
2021LPI....52.1896A Altcode:
We present the current status Of DESTINY+ mission, review the results
of extensive astronomical observation of the target asteroid (3200)
Phaethon.
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Title: Development of Cameras Onboard DESTINY+ Spacecraft for Flyby
Observation of (3200) Phaethon
Authors: Ishibashi, K.; Hong, P.; Okamoto, T.; Ishimaru, T.; Okazaki,
N.; Hosonuma, T.; Sato, S.; Arai, T.; Yoshida, F.; Okudaira, O.;
Kagitani, M.; Miyabara, T.; Ohta, M.; Takashima, T.
2021LPI....52.1405I Altcode:
We present the development status of two cameras onboard DESTINY+
spacecraft for observing the asteroid (3200) Phaethon and the
preparation for the flyby imaging with them.
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Title: A puzzling non-detection of [O III] and [C II] from a z ≈
7.7 galaxy observed with ALMA
Authors: Binggeli, C.; Inoue, A. K.; Hashimoto, T.; Toribio, M. C.;
Zackrisson, E.; Ramstedt, S.; Mawatari, K.; Harikane, Y.; Matsuo,
H.; Okamoto, T.; Ota, K.; Shimizu, I.; Tamura, Y.; Taniguchi, Y.;
Umehata, H.
2021A&A...646A..26B Altcode: 2020arXiv201113319B
Context. Characterizing the galaxy population in the early Universe
holds the key to understanding the evolution of these objects and
the role they played in cosmic reionization. However, there have been
very few observations at the very highest redshifts to date. <BR />
Aims: In order to shed light on the properties of galaxies in the
high-redshift Universe and their interstellar media, we observe the
Lyman-α emitting galaxy <ASTROBJ>z7_GSD_3811</ASTROBJ> at z = 7.664
with bands 6 and 8 at the Atacama Large Millimeter/submillimeter Array
(ALMA). <BR /> Methods: We target the far-infrared [O III] 88 μm and
[C II] 158 μm emission lines and dust continuum in the star-forming
galaxy z7_GSD_3811 with ALMA. We combine these measurements with
earlier observations in the rest-frame ultraviolet (UV) in order to
characterize the object and compare the results to those of earlier
studies that observed [O III] and [C II] emission in high-redshift
galaxies. <BR /> Results: The [O III] 88 μm and [C II] 158 μm
emission lines are undetected at the position of z7_GSD_3811, with
3σ upper limits of 1.6 × 10<SUP>8</SUP> L<SUB>⊙</SUB> and 4.0
× 10<SUP>7</SUP> L<SUB>⊙</SUB>, respectively. We do not detect
any dust continuum in band 6 nor band 8. The measured rms in the
band 8 and band 6 continua are 26 and 9.9 μJy beam<SUP>-1</SUP>,
respectively. Similar to several other high-redshift galaxies,
z7_GSD_3811 exhibits low [C II] emission for its star formation rate
compared to local galaxies. Furthermore, our upper limit on the [O
III] line luminosity is lower than the previously observed [O III]
lines in high-redshift galaxies with similar UV luminosities. Our
ALMA band 6 and 8 dust continuum observations imply that z7_GSD_3811
likely has a low dust content, and our non-detections of the [O III]
and [C II] lines could indicate that z7_GSD_3811 has a low metallicity
(Z ≲ 0.1 Z<SUB>⊙</SUB>).
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Title: Mapping solar magnetic fields from the photosphere to the
base of the corona
Authors: Ishikawa, Ryohko; Bueno, Javier Trujillo; del Pino Alemán,
Tanausú; Okamoto, Takenori J.; McKenzie, David E.; Auchère,
Frédéric; Kano, Ryouhei; Song, Donguk; Yoshida, Masaki; Rachmeler,
Laurel A.; Kobayashi, Ken; Hara, Hirohisa; Kubo, Masahito; Narukage,
Noriyuki; Sakao, Taro; Shimizu, Toshifumi; Suematsu, Yoshinori; Bethge,
Christian; De Pontieu, Bart; Dalda, Alberto Sainz; Vigil, Genevieve D.;
Winebarger, Amy; Ballester, Ernest Alsina; Belluzzi, Luca; Štěpán,
Jiří; Ramos, Andrés Asensio; Carlsson, Mats; Leenaarts, Jorrit
2021SciA....7.8406I Altcode: 2021arXiv210301583I
Routine ultraviolet imaging of the Sun's upper atmosphere shows the
spectacular manifestation of solar activity; yet we remain blind to
its main driver, the magnetic field. Here we report unprecedented
spectropolarimetric observations of an active region plage and
its surrounding enhanced network, showing circular polarization in
ultraviolet (Mg II $h$ & $k$ and Mn I) and visible (Fe I) lines. We
infer the longitudinal magnetic field from the photosphere to the
very upper chromosphere. At the top of the plage chromosphere the
field strengths reach more than 300 gauss, strongly correlated with
the Mg II $k$ line core intensity and the electron pressure. This
unique mapping shows how the magnetic field couples the different
atmospheric layers and reveals the magnetic origin of the heating in
the plage chromosphere.
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Title: Optical design of the Chromospheric LAyer Spectro-Polarimeter
(CLASP2)
Authors: Tsuzuki, Toshihiro; Ishikawa, Ryohko; Kano, Ryouhei; Narukage,
Noriyuki; Song, Donguk; Yoshida, Masaki; Uraguchi, Fumihiro; Okamoto,
Takenori J.; McKenzie, David; Kobayashi, Ken; Rachmeler, Laurel;
Auchere, Frederic; Trujillo Bueno, Javier
2020SPIE11444E..6WT Altcode:
Chromospheric LAyer Spectro-Polarimeter (CLASP2) was a sounding
rocket experiment, which is a follow-up mission to the Chromospheric
Lyman-Alpha Spectro-Polarimeter (CLASP1) in 2015. To measure the
magnetic fields in the upper solar atmosphere in a highly quantitative
manner, CLASP2 changes the target wavelengths from the hydrogen Ly-α
line (121.567 nm) to Mg II lines near 280 nm. We reused the main
structure and most of the optical components in the CLASP1 instrument,
which reduced the turnaround time and cost. We added a magnifying
optical system to maintain the wavelength resolution, even at the
longer wavelength of CLASP2. Here, we describe the optical design and
performance of the CLASP2 instrument.
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Title: IRIS Mg II Observations and Non-LTE Modeling of Off-limb
Spicules
Authors: Tei, A.; Gunár, S.; Heinzel, P.; Okamoto, T. J.; Štěpán,
J.; Jejčič, S.; Shibata, K.
2020AGUFMSH0010008T Altcode:
We investigated the off-limb spicules observed in the Mg II h and k
spectral lines by Interface Region Imaging Spectrograph (IRIS) in a
solar polar coronal hole. We analyzed the large data set of obtained
spectra to extract quantitative information about the line intensities,
line shifts, and line widths. The observed Mg II line profiles are
broad and double peaked at lower altitudes, broad but flat topped
at middle altitudes, and narrow and single peaked with the largest
Doppler shifts at higher altitudes. We used one-dimensional non-LTE
vertical slab models (i.e., models that consider departures from local
thermodynamic equilibrium) in single-slab and multi-slab configurations
to interpret the observations and to investigate how a superposition
of spicules along a line of sight (LOS) affects the synthetic Mg II
line profiles. The employed multi-slab models are either static,
i.e., without any LOS velocities, or assume randomly assigned LOS
velocities of individual slabs, representing the spicule dynamics. We
performed such single-slab and multi-slab modeling for a broad set of
model input parameters and examined the dependence of the Mg II line
profiles on these parameters. In this presentation, we demonstrate that
the observed line widths of the Mg h and k line profiles are strongly
affected by the presence of multiple spicules along the LOS. We also
show that the profiles obtained at higher altitudes can be reproduced
by single-slab models representing individual spicules. We found that
the multi-slab model with a random distribution of the LOS velocities
ranging from −25 to 25 km/s can well reproduce the width and the
shape of the Mg II profiles observed at middle altitudes.
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Title: Flyby Observation of Asteroid (3200) Phaethon to Be Conducted
by Cameras Onboard DESTINY+ Spacecraft
Authors: Ishibashi, K.; Hong, P.; Okamoto, T.; Ishimaru, T.; Sato,
S.; Yamada, M.; Okudaira, O.; Arai, T.; Yoshida, F.; Kameda, S.;
Kagitani, M.; Iwata, T.; Okada, T.; Takashima, T.
2020LPI....51.1698I Altcode:
We will report the progress of conceptual studies of the flyby
observation of the asteroid (3200) Phaethon by DESTINY+ spacecraft
with two onboard cameras.
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Title: Detections of far-infrared [O III] and dust emission in a
galaxy at z = 8.312: Early metal enrichment in the heart of the
reionization era
Authors: Tamura, Y.; Mawatari, K.; Hashimoto, T.; Inoue, A. K.;
Zackrissonm, E.; Christensen, L.; Binggeli, C.; Matsuda, Y.; Matsuo,
H.; Takeuchi, T. T.; Asano, R. S.; Sunaga, K.; Shimizu, I.; Okamoto,
T.; Yoshida, N.; Lee, M.; Shibuya, T.; Taniguchi, Y.; Umehata, H.;
Hatsukade, B.; Kohno, K.; Ota, K.
2020IAUS..341..211T Altcode:
We present ALMA detection of the [O III] 88 μm line and 850
μm dust continuum emission in a Y-dropout Lyman break galaxy,
MACS0416_Y1. The [O III] detection confirms the object with a
spectroscopic redshift to be z = 8.3118±0.0003. The 850 μm
continuum intensity (0.14 mJy) implies a large dust mass on the
order of 4×10<SUP>6</SUP>M<SUB>⊙</SUB>. The ultraviolet-to-far
infrared spectral energy distribution modeling, where the [O
III] emissivity model is incorporated, suggests the presence
of a young (τ<SUB>age</SUB> ≍ 4 Myr), star-forming (SFR ≍
60M<SUB>⊙</SUB>yr<SUP>-1</SUP>), and moderately metal-polluted
(Z ≍ 0.2Z<SUB>⊙</SUB>) stellar component with a stellar mass of
3 × 10<SUP>8</SUP>M<SUB>⊙</SUB>. An analytic dust mass evolution
model with a single episode of star formation does not reproduce
the metallicity and dust mass in ≍ 4 Myr, suggesting an underlying
evolved stellar component as the origin of the dust mass.
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Title: Estimating the Temperature and Density of a Spicule from 100
GHz Data Obtained with ALMA
Authors: Shimojo, Masumi; Kawate, Tomoko; Okamoto, Takenori J.;
Yokoyama, Takaaki; Narukage, Noriyuki; Sakao, Taro; Iwai, Kazumasa;
Fleishman, Gregory D.; Shibata, Kazunari
2020ApJ...888L..28S Altcode: 2019arXiv191205714S
We succeeded in observing two large spicules simultaneously with the
Atacama Large Millimeter/submillimeter Array (ALMA), the Interface
Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly
(AIA) on board the Solar Dynamics Observatory. One is a spicule seen
in the IRIS Mg II slit-jaw images and AIA 304 Å images (Mg II/304 Å
spicule). The other one is a spicule seen in the 100 GHz images obtained
with ALMA (100 GHz spicule). Although the 100 GHz spicule overlapped
with the Mg II/304 Å spicule in the early phase, it did not show any
corresponding structures in the IRIS Mg II and AIA 304 Å images after
the early phase. It suggests that the spicules are individual events and
do not have a physical relationship. To obtain the physical parameters
of the 100 GHz spicule, we estimate the optical depths as a function
of temperature and density using two different methods. One is using
the observed brightness temperature by assuming a filling factor,
and the other is using an emission model for the optical depth. As a
result of comparing them, the kinetic temperature of the plasma and
the number density of ionized hydrogen in the 100 GHz spicule are
∼6800 K and 2.2 × 10<SUP>10</SUP> cm<SUP>-3</SUP>. The estimated
values can explain the absorbing structure in the 193 Å image, which
appear as a counterpart of the 100 GHz spicule. These results suggest
that the 100 GHz spicule presented in this Letter is classified to a
macrospicule without a hot sheath in former terminology.
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Title: IRIS Mg II Observations and Non-LTE Modeling of Off-limb
Spicules in a Solar Polar Coronal Hole
Authors: Tei, Akiko; Gunár, Stanislav; Heinzel, Petr; Okamoto,
Takenori J.; Štěpán, Jiří; Jejčič, Sonja; Shibata, Kazunari
2020ApJ...888...42T Altcode: 2019arXiv191112243T
We investigated the off-limb spicules observed in the Mg II h and k
lines by IRIS in a solar polar coronal hole. We analyzed the large data
set of obtained spectra to extract quantitative information about the
line intensities, shifts, and widths. The observed Mg II line profiles
are broad and double peaked at lower altitudes, broad but flat topped
at middle altitudes, and narrow and single peaked with the largest
Doppler shifts at higher altitudes. We use one-dimensional non-LTE
vertical slab models (I.e., models that consider departures from local
thermodynamic equilibrium) in single-slab and multi-slab configurations
to interpret the observations and to investigate how a superposition
of spicules along the line of sight (LOS) affects the synthetic Mg
II line profiles. The used multi-slab models either are static, I.e.,
without any LOS velocities, or assume randomly assigned LOS velocities
of individual slabs, representing the spicule dynamics. We conducted
such single-slab and multi-slab modeling for a broad set of model
input parameters and showed the dependence of the Mg II line profiles
on these parameters. We demonstrated that the observed line widths
of the h and k line profiles are strongly affected by the presence
of multiple spicules along the LOS. We later showed that the profiles
obtained at higher altitudes can be reproduced by single-slab models
representing individual spicules. We found that the multi-slab model
with a random distribution of the LOS velocities ranging from -25 to
25 km s<SUP>-1</SUP> can well reproduce the width and the shape of Mg
II profiles observed at middle altitudes.
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Title: High-frequency Wave Propagation Along a Spicule Observed
by CLASP
Authors: Yoshida, Masaki; Suematsu, Yoshinori; Ishikawa, Ryohko;
Okamoto, Takenori J.; Kubo, Masahito; Kano, Ryouhei; Narukage,
Noriyuki; Bando, Takamasa; Winebarger, Amy R.; Kobayashi, Ken;
Trujillo Bueno, Javier; Auchère, Frédéric
2019ApJ...887....2Y Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) sounding
rocket experiment, launched in 2015 September, observed the hydrogen
Lyα line (121.6 nm) in an unprecedented high temporal cadence of
0.3 s. CLASP performed sit-and-stare observations of the quiet Sun
near the limb for 5 minutes with a slit perpendicular to the limb
and successfully captured an off-limb spicule evolving along the
slit. The Lyα line is well suited for investigating how spicules
affect the corona because it is sensitive to higher temperatures than
other chromospheric lines, owing to its large optical thickness. We
found high-frequency oscillations of the Doppler velocity with periods
of 20-50 s and low-frequency oscillation of periods of ∼240 s on
the spicule. From a wavelet analysis of the time sequence data of
the Doppler velocity, in the early phase of the spicule evolution,
we found that waves with a period of ∼30 s and a velocity amplitude
of 2-3 km s<SUP>-1</SUP> propagated upward along the spicule with a
phase velocity of ∼470 km s<SUP>-1</SUP>. In contrast, in the later
phase, possible downward and standing waves with smaller velocity
amplitudes were also observed. The high-frequency waves observed in
the early phase of the spicule evolution would be related with the
dynamics and the formation of the spicules. Our analysis enabled us to
identify the upward, downward, and standing waves along the spicule
and to obtain the velocity amplitude of each wave directly from the
Doppler velocity for the first time. We evaluated the energy flux
by the upward-propagating waves along the spicule, and discussed the
impact to the coronal heating.
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Title: Estimating the temperature and density of a spicule from 100
GHz data obtained with ALMA
Authors: Shimojo, M.; Kawate, T.; Okamoto, T. J.; Yokoyama, T.
2019AGUFMSH41F3336S Altcode:
We succeeded in observing two large spicules simultaneously with the
Atacama Large Millimeter/submillimeter Array (ALMA), the Interface
Region Imaging Spectrograph explorer (IRIS), and the Atmospheric
Imaging Assembly (AIA) onboard the Solar Dynamics Observatory. One is
a spicule seen in the IRIS Mg II slit-jaw images and AIA 304 Å images
(MgII/304Å spicule). The other one is a spicule seen in the 100 GHz
images obtained with ALMA (100 GHz spicule). Although the 100 GHz
spicule in the early phase overlapped with the MgII/304Å spicule,
we cannot find any remarkable enhancement temporally and spatially
caused by the 100 GHz spicule in the IRIS Mg II and AIA 304 Å
images. Moreover, there is no overlapped region between the 100 GHz
spicule and Mg II/304Å spicule in the late phase. It would suggest
that the spicules are individual events and do not have a physical
relationship. To obtain the physical parameters of the 100 GHz spicule
from the ALMA data, we estimated two optical depths of the 100 GHz
spicule from the observed brightness temperature and an emission model
with assumed temperature and density. As a result of comparing them,
the temperature and density of the 100 GHz spicule are 4000 - 7000 K
and 2.2×10<SUP>10</SUP> cm<SUP>-3</SUP>. The estimated values can
explain the absorbing structure that is the counterpart of the 100
GHz spicule in the 193Å image.
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Title: Explosive Crater Experiments of Porous Gypsum Targets
Authors: Nakamura, A. M.; Ogawa, K.; Murakami, Y.; Yamasaki, Y.;
Nagaashi, Y.; Nomura, K.; Kadono, T.; Suetsugu, R.; Kawai, N.; Tanaka,
S.; Okamoto, T.
2019LPICo2157.6349N Altcode:
Explosive crater experiments were conducted using porous gypsum targets
to investigate the similarity between the results of explosive and
impact events for porous targets.
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Title: Novel gratings for astronomical observations
Authors: Ebizuka, N.; Okamoto, T.; Takeda, M.; Hosobata, T.; Yamagata,
Y.; Sasaki, M.; Kamizuka, T.; Tanaka, I.; Hattori, T.; Ozaki, S.;
Aoki, W.
2019SPIE11180E..69E Altcode:
We introduce novel gratings for next generation instruments of the TMT
(Thirty Meter Telescope), the 8.2 m Subaru telescope, other ground-based
and space-borne telescopes. The reflector facet transmission (RFT)
grating which is a surface relief grating with sawtooth shaped grating
lattice of an acute vertex angle, is developed for the WFOS of the
TMT. The hybrid grism (direct vision grating) for the MOIRCSof the 8.2m
Subaru Telescope is developed as a prototype of the RFT grating. The
volume binary grating is developed for a high-dispersion echelle
grism of the nuMOIRCS as the first light instrument of the ULTIMATE
Subaru. We also developing a silicon grism for the MIMIZUKU of the 6.5m
telescope of the University of Tokyo Atacama Observatory in Chile and
a quasi-Bragg (QB) immersion grating.
---------------------------------------------------------
Title: The Chromospheric Layer Spectro-Polarimeter (CLASP2) Sounding
Rocket Mission: First Results
Authors: McKenzie, David Eugene; Ishikawa, Ryohko; Kano, Ryouhei;
Rachmeler, Laurel; Trujillo Bueno, Javier; Kobayashi, Ken; Song,
Donguk; Yoshida, Masaki; Auchere, Frederic; Okamoto, Takenori
2019AAS...23412601M Altcode:
A major challenge for heliophysics is to decipher the magnetic structure
of the chromosphere, because of its vital role in the transport of
energy into the corona and solar wind. Routine satellite measurements
of the chromospheric magnetic field will dramatically improve our
understanding of the chromosphere and its connection to the rest of
the solar atmosphere. Before such a satellite can be considered for
flight, we must refine the measurement techniques by exploring emission
lines with a range of magnetic sensitivities. In 2015, CLASP achieved
the first measurement of linear polarization produced by scattering
processes in a far UV resonance line (hydrogen Lyman-α), and the
first exploration of the magnetic field (via the Hanle effect) and
geometrical complexity in quiet regions of the chromosphere-corona
transition region. These measurements are a first step towards
routine quantitative characterization of the local thermal and magnetic
conditions in this key layer of the solar atmosphere. <P />Nonetheless,
Lyman-α is only one of the magnetically sensitive spectral lines in the
UV spectrum. CLASP2 extends the capability of UV spectropolarimetry by
acquiring ground-breaking measurements in the Mg II h and k spectral
lines near 280 nm, whose cores form about 100 km below the Lyman-α
core. These lines are sensitive to a larger range of field strengths
than Lyman-α, through both the Hanle and Zeeman effects. CLASP2 will
capture measurements of linear and circular polarization to enable the
first determination of all 4 Stokes parameters in chromospheric UV
radiation. Coupled with numerical modeling of the observed spectral
line polarization (anisotropic radiation pumping with Hanle, Zeeman
and magneto-optical effects), CLASP2 is a pathfinder for determination
of the magnetic field's strength and direction, as well as of the
geometry of the plasma in the upper solar chromosphere. <P />CLASP2
will launch from White Sands Missile Range in April 2019. In this
presentation, we will summarize the characteristics of the CLASP2
flight, the performance of the UV telescope and spectropolarimeter,
and our preliminary findings.
---------------------------------------------------------
Title: Multi-wavelength Multi-height Study of Super Strong Surface
and Coronal Magnetic Fields in Active Region 12673
Authors: Wang, Haimin; Chen, Bin; Jing, Ju; Yu, Sijie; Liu, Chang;
Yurchyshyn, Vasyl B.; Ahn, Kwangsu; Okamoto, Takenori; Toriumi, Shin;
Cao, Wenda; Gary, Dale E.
2019AAS...23440205W Altcode:
Using the joint observations of Goode Solar telescope (GST), Expanded
Owens Valley Solar Array (EOVSA), Solar Dynamics Observatory (SDO)
and Hinode, we study the Solar Active Region (AR) 12673 in September
2017, which is the most flare productive AR in the solar cycle 24. GST
observations show the strong photospheric magnetic fields (nearly
6000 G) in polarity inversion line (PIL) and apparent photospheric
twist. Consistent upward flows are also observed in Dopplergrams
of Hinode, HMI and GST at the center part of that section of PIL,
while the down flows are observed in two ends, indicating that the
structure was rising from subsurface. Combining Non-Linear Force Free
Extrapolation and EOVSA microwave imaging spectroscopy, we also look
into the coronal structure of magnetic fields in this unusual AR,
including the evolution before and after the X9.3 flare on September
6, 2017. Coronal fields between 1000 and 2000 gauss are found above
the flaring PIL at the height range between 8 and 4Mm, outlining the
structure of a fluxrope or sheared arcade.
---------------------------------------------------------
Title: Lyman-α imaging polarimetry with the CLASP2 sounding rocket
mission
Authors: Kano, Ryouhei; Ishikawa, Ryohko; McKenzie, David Eugene;
Trujillo Bueno, Javier; Song, Donguk; Yoshida, Masaki; Okamoto,
Takenori; Rachmeler, Laurel; Kobayashi, Ken; Auchere, Frederic
2019AAS...23430216K Altcode:
Ultraviolet polarimetry offers a unique opportunity to explore the upper
solar chromosphere and the transition region (TR) to the million-degree
corona. These outer atmospheric regions play a key role in the transfer
of mass and energy from the solar photosphere to the corona. With
a sounding rocket experiment called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP), in September 2015 we succeeded in obtaining
the first measurement of the linear polarization produced by scattering
processes in the hydrogen Lyman-α line of the solar disk radiation. The
analysis and interpretation of such spectro-polarimetric observation
allowed us to obtain information on the geometrical complexity of
the corrugated surface that delineates the TR, as well as on the
magnetic field strength via the Hanle effect. At the same time, the
CLASP slit-jaw (SJ) optics system, which is a Lyman-α filter imager
characterized by a FWHM= 7 nm, allowed us to obtain broad-band Stokes-I
and Q/I images over a large field of view. The obtained broad-band
Q/I images are dominated by the scattering polarization signals of the
Lyman-α wings, and not by the much weaker line-center signals where
the Hanle effect operates. Recently, Alsina Ballester et al. (2019,
ApJ, in press) showed that the scattering polarization signals of the
Lyman-α wings are sensitive to chromospheric magnetic fields via the
magneto-optical effects. Therefore, Lyman-α imaging polarimetry is of
scientific interest also for magnetic-field investigations. On April
11, 2019, we performed another sounding rocket experiment, called
the Chromospheric LAyer Spectro-Polarimeter (CLASP2). We used the
same instrument after significant modifications in order to obtain
spectro-polarimetric observations of a plage and a quiet region in
the ionized magnesium lines around 280 nm (i.e., the Mg II h &
k lines). At the same time, the CLASP2 SJ optics system allowed us to
obtain broad-band Q/I and U/I images at the Lyman-α wavelength, in
addition to the well-known SJ intensity images. In this presentation,
we provide a first overview of the CLASP2 SJ data.
---------------------------------------------------------
Title: Shock Devolatilization/Vaporization of Evaporites in an
Open System
Authors: Kurosawa, K.; Moriwaki, R.; Komatsu, G.; Okamoto, T.; Yabuta,
H.; Matsui, T.
2019LPI....50.2442K Altcode:
Shock vaporization/devolatilization from evaporitic minerals, halite
and gypsum, was investigated in an open system.
---------------------------------------------------------
Title: Cameras to Be Installed on the Destiny+ Spacecraft: Telescopic
Camera for Phaethon (TCAP) and Multiband Camera for Phaethon (MCAP)
Authors: Ishibashi, K.; Kameda, S.; Kagitani, M.; Hong, P.; Yamada,
M.; Okudaira, O.; Arai, T.; Yoshida, F.; Sato, S.; Ishimaru, T.;
Okamoto, T.; Iwata, T.; Okada, T.; Takashima, T.
2019LPI....50.1758I Altcode:
We will report the progress of conceptual studies of the telescopic
camera and the multiband camera for the asteroid 3200 Phaethon flyby
mission DESTINY+.
---------------------------------------------------------
Title: Blue-wing enhancement of the chromospheric Mg II h and k
lines in a solar flare
Authors: Tei, Akiko; Sakaue, Takahito; Okamoto, Takenori J.; Kawate,
Tomoko; Heinzel, Petr; UeNo, Satoru; Asai, Ayumi; Ichimoto, Kiyoshi;
Shibata, Kazunari
2018PASJ...70..100T Altcode: 2018PASJ..tmp...61T; 2018arXiv180305237T
We performed coordinated observations of AR 12205, which showed a
C-class flare on 2014 November 11, with the Interface Region Imaging
Spectrograph (IRIS) and the Domeless Solar Telescope (DST) at Hida
Observatory. Using spectral data in the Si IV 1403 Å, C II 1335 Å,
and Mg II h and k lines from IRIS and the Ca II K, Ca II 8542 Å, and
Hα lines from DST, we investigated a moving flare kernel during the
flare. In the Mg II h line, the leading edge of the flare kernel showed
an intensity enhancement in the blue wing and a smaller intensity of the
blue-side peak (h2v) than that of the red-side one (h2r). The blueshift
lasted for 9-48 s with a typical speed of 10.1 ± 2.6 km s<SUP>-1</SUP>,
which was followed by a high intensity and a large redshift with a speed
of up to 51 km s<SUP>-1</SUP> detected in the Mg II h line. The large
redshift was a common property for all six lines, but the blueshift
prior to it was found only in the Mg II lines. Cloud modeling of the
Mg II h line suggests that the blue-wing enhancement with such a peak
difference could have been caused by a chromospheric-temperature (cool)
upflow. We discuss a scenario in which an upflow of cool plasma is
lifted up by expanding hot plasma owing to the deep penetration of
non-thermal electrons into the chromosphere. Furthermore, we found
that the blueshift persisted without any subsequent redshift in the
leading edge of the flare kernel during its decaying phase. The cause
of such a long-lasting blueshift is also discussed.
---------------------------------------------------------
Title: ALMA Observations of the Solar Chromosphere on the Polar Limb
Authors: Yokoyama, Takaaki; Shimojo, Masumi; Okamoto, Takenori J.;
Iijima, Haruhisa
2018ApJ...863...96Y Altcode: 2018arXiv180701411Y
We report the results of the Atacama Large Millimeter/sub-millimeter
Array (ALMA) observations of the solar chromosphere on the southern
polar limb. Coordinated observations with the Interface Region Imaging
Spectrograph (IRIS) are also conducted. ALMA provided unprecedented
high spatial resolution in the millimeter band (≈2.″0) at 100
GHz frequency with a moderate cadence (20 s). The results are as
follows. (1) The ALMA 100 GHz images show saw-tooth patterns on the
limb, and a comparison with Solar Dynamics Observatory/Atmospheric
Imaging Assembly 171 Å images shows a good correspondence of the limbs
with each other. (2) The ALMA animation shows a dynamic thorn-like
structure elongating from the saw-tooth patterns on the limb, with
lengths reaching at least 8″, thus suggesting jet-like activity in
the ALMA microwave range. These ALMA jets are in good correspondence
with the IRIS jet clusters. (3) A blob-ejection event is observed. By
comparing with the IRIS Mg II slit-jaw images, the trajectory of the
blob is located along the spicular patterns.
---------------------------------------------------------
Title: Wavefront error measurements and alignment of CLASP2 telescope
with a dual-band pass cold mirror coated primary mirror
Authors: Yoshida, Masaki; Song, Donguk; Ishikawa, Ryoko; Kano, Ryouhei;
Katsukawa, Yukio; Suematsu, Yoshinori; Narukage, Noriyuki; Kubo,
Masahito; Shinoda, Kazuya; Okamoto, Takenori J.; McKenzie, David E.;
Rachmeler, Laurel A.; Auchère, Frédéric; Trujillo Bueno, Javier
2018SPIE10699E..30Y Altcode:
"Chromospheric LAyer Spectro-Polarimeter (CLASP2)" is the next sounding
rocket experiment of the "Chromospheric Lyman-Alpha Spectro-Polarimeter
(CLASP)" that succeeded in observing for the first time the linear
polarization spectra in the hydrogen Lyman-α line (121.6 nm) and is
scheduled to be launched in 2019. In CLASP2, we will carry out full
Stokes-vector spectropolarimetric observations in the Mg ii h and k
lines near 280 nm with the spectro-polarimeter (SP), while imaging
observations in the Lyman-α line will be conducted with the slitjaw
optics (SJ). For the wavelength selection of CLASP2, the primary
mirror of the telescope uses a new dual-band pass cold mirror coating
targeting both at 121.6 nm and 280 nm. Therefore, we have to perform
again the alignment of the telescope after the installation of the
recoated primary mirror. Before unmounting the primary mirror from
the telescope structure, we measured the wave-front error (WFE) of the
telescope. The measured WFE map was consistent with what we had before
the CLASP flight, clearly indicating that the telescope alignment has
been maintained even after the flight. After the re-coated primary
mirror was installed the WFE was measured, and coma aberration was
found to be larger. Finally, the secondary mirror shim adjustments
were carried out based on the WFE measurements. In CLASP2 telescope,
we improved a fitting method of WFE map (applying 8th terms circular
Zernike polynomial fitting instead of 37th terms circular Zernike
fitting) and the improved method enables to achieve better performance
than CLASP telescope. Indeed, WFE map obtained after the final shim
adjustment indicated that the required specification (< 5.5 μm
RMS spot radius) that is more stringent than CLASP telescope was met.
---------------------------------------------------------
Title: Optical alignment of the high-precision UV spectro-polarimeter
(CLASP2)
Authors: Song, Donguk; Ishikawa, Ryohko; Kano, Ryouhei; Yoshida,
Masaki; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Shinoda, Kazuya;
Hara, Hirohisa; Okamoto, Takenori J.; Auchère, Frédéric; McKenzie,
David E.; Rachmeler, Laurel A.; Trujillo Bueno, Javier
2018SPIE10699E..2WS Altcode:
Chromospheric LAyer Spectro-Polarimeter (CLASP2) is our next sounding
rocket experiment after the success of Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP1). CLASP2 is scheduled to launch in 2019,
and aims to achieve high precision measurements (< 0.1 %) of the
linear and circular polarizations in the Mg ii h and k lines near the
280 nm, whose line cores originate in the upper solar chromosphere. The
CLASP2 spectro-polarimeter follows very successful design concept of
the CLASP1 instrument with the minimal modification. A new grating was
fabricated with the same radius of curvature as the CLASP1 grating, but
with a different ruling density. This allows us to essentially reuse
the CLASP1 mechanical structures and layout of the optics. However,
because the observing wavelength of CLASP2 is twice longer than that
of CLASP1, a magnifier optical system was newly added in front of the
cameras to double the focal length of CLASP2 and to maintain the same
wavelength resolution as CLASP1 (0.01 nm). Meanwhile, a careful optical
alignment of the spectro-polarimeter is required to reach the 0.01 nm
wavelength resolution. Therefore, we established an efficient alignment
procedure for the CLASP2 spectro-polarimeter based on an experience
of CLASP1. Here, we explain in detail the methods for achieving the
optical alignment of the CLASP2 spectro-polarimeter and discuss our
results by comparing with the performance requirements.
---------------------------------------------------------
Title: DESTINY+ Mission: Flyby of Geminids Parent Asteroid (3200)
Phaethon and In-Situ Analyses of Dust Accreting on the Earth
Authors: Arai, T.; Kobayashi, M.; Ishibashi, K.; Yoshida, F.; Kimura,
H.; Wada, K.; Senshu, H.; Yamada, M.; Okudaira, O.; Okamoto, T.;
Kameda, S.; Srama, R.; Kruger, H.; Ishiguro, M.; Yabuta, H.; Nakamura,
T.; Watanabe, J.; Ito, T.; Ohtsuka, K.; Tachibana, S.; Mikouchi,
T.; Komatsu, M.; Nakamura-Messenger, K.; Sasaki, S.; Hiroi, T.; Abe,
S.; Urakawa, S.; Hirata, N.; Demura, H.; Komatsu, G.; Noguchi, T.;
Sekiguchi, T.; Inamori, T.; Yano, H.; Yoshikawa, M.; Ohtsubo, T.;
Okada, T.; Iwata, T.; Nishiyama, K.; Toyota, T.; Kawakatsu, Y.;
Takashima, T.
2018LPI....49.2570A Altcode:
DESTINY+ is a flyby mission of asteroid Phaethon proposed for JAXA/ISAS
Epsilon class small program with a launch target in 2022. Mission
overview is presented.
---------------------------------------------------------
Title: Shock Vaporization and Post-Impact Chemistry in an Open System
Without any Diaphragms
Authors: Kurosawa, K.; Okamoto, T.; Yabuta, H.; Komatsu, G.; Matsui, T.
2018LPI....49.1960K Altcode:
We developed a new experimental method for gas guns, which allows us to
investigate shock vaporization in an open system without contaminations
from the gun.
---------------------------------------------------------
Title: Telescopic CAmera for Phaethon (TCAP) and Multiband CAmera
for Phaethon (MCAP) to be Installed on the DESTINY+ Spacecraft
Authors: Ishibashi, K.; Kameda, S.; Kagitani, M.; Yamada, M.; Okudaira,
O.; Okamoto, T.; Arai, T.; Yoshida, F.; Ishimaru, T.; Sato, S.;
Takashima, T.; Iwata, T.; Okada, T.
2018LPI....49.2126I Altcode:
Conceptual studies of the two cameras, a telescopic camera and a
multiband camera, for the DESTINY+ mission, an asteroid flyby mission,
have been carried out.
---------------------------------------------------------
Title: Super-strong Magnetic Field in Sunspots
Authors: Okamoto, Takenori J.; Sakurai, Takashi
2018ApJ...852L..16O Altcode: 2017arXiv171208700O
Sunspots are the most notable structure on the solar surface with
strong magnetic fields. The field is generally strongest in a dark area
(umbra), but sometimes stronger fields are found in non-dark regions,
such as a penumbra and a light bridge. The formation mechanism of such
strong fields outside umbrae is still puzzling. Here we report clear
evidence of the magnetic field of 6250 G, which is the strongest field
among Stokes I profiles with clear Zeeman splitting ever observed on
the Sun. The field was almost parallel to the solar surface and located
in a bright region sandwiched by two opposite-polarity umbrae. Using
a time series of spectral data sets, we discuss the formation process
of the super-strong field and suggest that this strong field region
was generated as a result of compression of one umbra pushed by the
horizontal flow from the other umbra, such as the subduction of the
Earth’s crust in plate tectonics.
---------------------------------------------------------
Title: Scaling of Impact-Generated Cavity-Size for Highly Porous
Targets and Its Application to Cometary Surfaces
Authors: Okamoto, T.; Nakamura, A. M.
2017LPI....48.1817O Altcode:
New scaling relations for targets with porosities larger than 30% were
obtained and the results were applied for estimating crater dimensions
on a comet.
---------------------------------------------------------
Title: Generation of Reduced Carbon Compounds by "Low" Velocity
Impacts
Authors: Ishibashi, K.; Kurosawa, K.; Okamoto, T.; Matsui, T.
2017LPI....48.2141I Altcode:
Impact experiments with meteorite analogues at relatively low velocity
(i.e., 6.5 km/s) generated a large amount of reductive gases species
such as CH4.
---------------------------------------------------------
Title: Hydrocode Modeling of the Material Ejection by Spallation
Authors: Kurosawa, K.; Okamoto, T.; Genda, H.
2017LPI....48.1855K Altcode:
The launch of high-speed lightly-shocked ejecta was investigated. We
found that the ejection velocity can exceed the upper limit in the
shock physics.
---------------------------------------------------------
Title: Dust Sensor with a Large Detection Area Using Polyimide Film
for Martian Moons Exploration
Authors: Kobayashi, M.; Okudaira, O.; Kurosawa, K.; Okamoto, T.;
Senshu, H.; Wada, K.; Sasaki, S.; Kimura, H.; Nakamura, M.
2017LPI....48.2342K Altcode:
This is about a concept of a science instrument for discovery of
martian dust ring. The instrument is one of payloads of Martian Moons
Exploration by JAXA.
---------------------------------------------------------
Title: Helical Motions of Fine-structure Prominence Threads Observed
by Hinode and IRIS
Authors: Okamoto, Takenori J.; Liu, Wei; Tsuneta, Saku
2016ApJ...831..126O Altcode: 2016arXiv160800123O
Fine-structure dynamics in solar prominences holds critical clues
to understanding their physical nature of significant space-weather
implications. We report evidence of rotational motions of horizontal
helical threads in two active-region prominences observed by the
Hinode and/or Interface Region Imaging Spectrograph satellites at
high resolution. In the first event, we found transverse motions
of brightening threads at speeds up to 55 km s<SUP>-1</SUP> seen in
the plane of the sky. Such motions appeared as sinusoidal space-time
trajectories with a typical period of ∼390 s, which is consistent
with plane-of-sky projections of rotational motions. Phase delays at
different locations suggest the propagation of twists along the threads
at phase speeds of 90-270 km s<SUP>-1</SUP>. At least 15 episodes of
such motions occurred in two days, none associated with an eruption. For
these episodes, the plane-of-sky speed is linearly correlated with the
vertical travel distance, suggestive of a constant angular speed. In the
second event, we found Doppler velocities of 30-40 km s<SUP>-1</SUP> in
opposite directions in the top and bottom portions of the prominence,
comparable to the plane-of-sky speed. The moving threads have about
twice broader line widths than stationary threads. These observations,
when taken together, provide strong evidence for rotations of helical
prominence threads, which were likely driven by unwinding twists
triggered by magnetic reconnection between twisted prominence magnetic
fields and ambient coronal fields.
---------------------------------------------------------
Title: Dust Sensor with Large Detection Area Using Polyimide Film
and Piezoelectric Elements
Authors: Kobayashi, M.; Okudaira, O.; Kurosawa, K.; Okamoto, T.;
Matsui, T.
2016LPICo1980.4047K Altcode:
We describe the development of dust particles sensor in space with
large area (1m × 1m scale). The sensor has just a thin film of
polyimide attached with small tips of piezoelectric elements. We
performed experiments to characterize the sensor.
---------------------------------------------------------
Title: Joint SDO and IRIS Observations of a Novel, Hybrid
Prominence-Coronal Rain Complex
Authors: Liu, Wei; Antolin, Patrick; Sun, Xudong; Gao, Lijia; Vial,
Jean-Claude; Gibson, Sarah; Okamoto, Takenori; Berger, Thomas;
Uitenbroek, Han; De Pontieu, Bart
2016usc..confE..99L Altcode:
Solar prominences and coronal rain are intimately related phenomena,
both involving cool material at chromospheric temperatures within the
hot corona and both playing important roles as part of the return flow
of the chromosphere-corona mass cycle. At the same time, they exhibit
distinct morphologies and dynamics not yet well understood. Quiescent
prominences consist of numerous long-lasting, filamentary downflow
threads, while coronal rain is more transient and falls comparably
faster along well-defined curved paths. We report here a novel, hybrid
prominence-coronal rain complex in an arcade-fan geometry observed
by SDO/AIA and IRIS, which provides new insights to the underlying
physics of such contrasting behaviors. We found that the supra-arcade
fan region hosts a prominence sheet consisting of meandering threads
with broad line widths. As the prominence material descends to the
arcade, it turns into coronal rain sliding down coronal loops with
line widths 2-3 times narrower. This contrast suggests that distinct
local plasma and magnetic conditions determine the fate of the cool
material, a scenario supported by our magnetic field extrapolations
from SDO/HMI. Specifically, the supra-arcade fan (similar to those
in solar flares; e.g., McKenzie 2013) is likely situated in a current
sheet, where the magnetic field is weak and the plasma-beta could be
close to unity, thus favoring turbulent flows like those prominence
threads. In contrast, the underlying arcade has a stronger magnetic
field and most likely a low-beta environment, such that the material
is guided along magnetic field lines to appear as coronal rain. We
will discuss the physical implications of these observations beyond
prominence and coronal rain.
---------------------------------------------------------
Title: VizieR Online Data Catalog: New Numerical Galaxy Catalog
(nu<SUP>2</SUP>GC) (Makiya+,
Authors: Makiya, R.; Enoki, M.; Ishiyama, T.; Kobayashi, M. A. R.;
Nagashima, M.; Okamoto, T.; Okoshi, K.; Oogi, T.; Shirakata, H.
2016yCat.100680025M Altcode:
The mock galaxy catalog calculated by the nu<SUP>2</SUP>-GC model
descri the paper. <P />File light-cone_nu2gc-H2.dat contains the
galaxies having B-band apparent magnitude brighter than 28 [AB mag] and
located at the redshift range 0<z<20.0, with 1 deg<SUP>2</SUP>
aperture. <P />We also provide "box-type" mock galaxy catalogs,
catalog<SUB>nu2gc-L</SUB>z**.dat, that contain the simulated galaxies
in the 1.12<SUP>3</SUP> (Gpc/h)<SUP>3</SUP> size box at redshift
z = 0.0, 0.48, 1.01, 1.97, 2.95, 6.97. For each simulated galaxy,
redshift, comoving distance, stellar mass, gas mass, black hole mass,
star formation rate, metallicity, and magnitude in B-, V-, SDSS-rp
and 2MASS-Ks bands are given. <P />Terms of Use : When you write
papers using these catalogs, we would be very grateful if you could
refer the following two papers: Ishiyama et al., 2015PASJ...67...61I,
Makiya et al., 2016PASJ...68...25M. <P />(7 data files).
---------------------------------------------------------
Title: Novel diffraction gratings for next generation spectrographs
with high spectral dispersion
Authors: Ebizuka, N.; Okamoto, T.; Hosobata, T.; Yamagata, Y.; Sasaki,
M.; Uomoto, M.; Shimatsu, T.; Sato, S.; Hashimoto, N.; Tanaka, I.;
Hattori, T.; Ozaki, S.; Aoki, W.
2016SPIE.9912E..2ZE Altcode:
As a transmission grating, a surface-relief (SR) grating with sawtooth
shaped ridges and volume phase holographic (VPH) grating are widely
used for instruments of astronomical observations. However the SR
grating is difficult to achieve high diffraction efficiency at high
angular dispersion, and the VPH grating has low diffraction efficiency
in high diffraction orders. We propose novel gratings that solve these
problems. We introduce the hybrid grism which combines a high refractive
index prism with a replicated transmission grating, which has sawtooth
shaped ridges of an acute apex angle. The birefringence VPH (B-VPH)
grating which contains an anisotropic medium, such as a liquid crystal,
achieves diffraction efficiency up to 100% at the first diffraction
order for natural polarization and for circular polarization. The
quasi-Bragg (QB) grating which consists of long rectangular mirrors
aligned in parallel precisely, like a window blind, achieves diffraction
efficiency of 60% or more in higher than the 4th diffraction order. The
volume binary (VB) grating with narrow grooves also achieves diffraction
efficiency of 60% or more in higher than the 6th diffraction order. The
reflector facet transmission (RFT) grating which is a SR grating with
sawtooth shaped ridges of an acute apex angle achieves diffraction
efficiency up to 80% in higher than the 4th diffraction order.
---------------------------------------------------------
Title: Ultra-High-Speed Imaging of the Impact Ejecta: Comparison
with a SPH Simulation
Authors: Okamoto, T.; Kurosawa, K.; Genda, H.; Matsui, T.
2016LPI....47.2515O Altcode:
We conducted impact experiments to investigate the high-speed ejecta
from near the impact point, comparing the results with those of SPH
simulations.
---------------------------------------------------------
Title: Shock Vaporization of Water Ice in an Open System Investigated
Using a Two-Stage Light Gas Gun
Authors: Kurosawa, K.; Okamoto, T.; Yabuta, H.; Komatsu, G.; Matsui, T.
2016LPI....47.1838K Altcode:
We constructed a new experimental system to investigate shock
vaporization and post-impact chemistry of icy materials.
---------------------------------------------------------
Title: Laboratory Simulation of Shooting Star by Using a Two-Stage
Light Gas Gun
Authors: Senshu, H.; Kurosawa, K.; Okamoto, T.; Matsui, T.
2016LPI....47.2142S Altcode:
We conducted a experimental study to simulate shooting stars in the
laboratory. We successfully obtained spectroscopic data of the simulated
shooting stars.
---------------------------------------------------------
Title: Resonant Absorption of Transverse Oscillations and Associated
Heating in a Solar Prominence. II. Numerical Aspects
Authors: Antolin, P.; Okamoto, T. J.; De Pontieu, B.; Uitenbroek,
H.; Van Doorsselaere, T.; Yokoyama, T.
2015ApJ...809...72A Altcode: 2015arXiv150609108A
Transverse magnetohydrodynamic (MHD) waves are ubiquitous in
the solar atmosphere and may be responsible for generating the
Sun’s million-degree outer atmosphere. However, direct evidence
of the dissipation process and heating from these waves remains
elusive. Through advanced numerical simulations combined with
appropriate forward modeling of a prominence flux tube, we provide
the observational signatures of transverse MHD waves in prominence
plasmas. We show that these signatures are characterized by a
thread-like substructure, strong transverse dynamical coherence,
an out-of-phase difference between plane-of-the-sky motions and
line-of-sight velocities, and enhanced line broadening and heating
around most of the flux tube. A complex combination between resonant
absorption and Kelvin-Helmholtz instabilities (KHIs) takes place
in which the KHI extracts the energy from the resonant layer and
dissipates it through vortices and current sheets, which rapidly
degenerate into turbulence. An inward enlargement of the boundary
is produced in which the turbulent flows conserve the characteristic
dynamics from the resonance, therefore guaranteeing detectability of
the resonance imprints. We show that the features described in the
accompanying paper through coordinated Hinode and Interface Region
Imaging Spectrograph observations match the numerical results well.
---------------------------------------------------------
Title: Resonant Absorption of Transverse Oscillations and Associated
Heating in a Solar Prominence. I. Observational Aspects
Authors: Okamoto, Takenori J.; Antolin, Patrick; De Pontieu, Bart;
Uitenbroek, Han; Van Doorsselaere, Tom; Yokoyama, Takaaki
2015ApJ...809...71O Altcode: 2015arXiv150608965O
Transverse magnetohydrodynamic waves have been shown to be ubiquitous
in the solar atmosphere and can, in principle, carry sufficient energy
to generate and maintain the Sun’s million-degree outer atmosphere
or corona. However, direct evidence of the dissipation process of these
waves and subsequent heating has not yet been directly observed. Here we
report on high spatial, temporal, and spectral resolution observations
of a solar prominence that show a compelling signature of so-called
resonant absorption, a long hypothesized mechanism to efficiently
convert and dissipate transverse wave energy into heat. Aside
from coherence in the transverse direction, our observations show
telltale phase differences around 180° between transverse motions
in the plane-of-sky and line-of-sight velocities of the oscillating
fine structures or threads, and also suggest significant heating from
chromospheric to higher temperatures. Comparison with advanced numerical
simulations support a scenario in which transverse oscillations trigger
a Kelvin-Helmholtz instability (KHI) at the boundaries of oscillating
threads via resonant absorption. This instability leads to numerous
thin current sheets in which wave energy is dissipated and plasma is
heated. Our results provide direct evidence for wave-related heating
in action, one of the candidate coronal heating mechanisms.
---------------------------------------------------------
Title: The impact of dust in host galaxies on quasar luminosity
functions.
Authors: Shirakata, H.; Okamoto, T.; Enoki, M.; Nagashima, M.;
Kobayashi, M. A. R.; Ishiyama, T.; Makiya, R.
2015MNRAS.450L...6S Altcode: 2014arXiv1412.1478S
We have investigated effects of dust attenuation on quasar luminosity
functions at z ∼ 2 using a semi-analytic galaxy formation model
combined with a large cosmological N-body simulation. We estimate the
dust attenuation of quasars self-consistently with that of galaxies by
considering the dust in their host bulges. We find that the luminosity
of the bright quasars is strongly dimmed by the dust attenuation,
∼2 mag in the B-band. Assuming the empirical bolometric corrections
for active galactic nuclei (AGNs) by Marconi et al., we find that
this dust attenuation is too strong to explain the B-band and X-ray
quasar luminosity functions simultaneously. We consider two possible
mechanisms that weaken the dust attenuation. As such a mechanism, we
introduce a time delay for AGN activity, that is, gas fuelling to a
central black hole starts sometime after the beginning of the starburst
induced by a major merger. The other is the anisotropy in the dust
distribution. We find that in order to make the dust attenuation of
the quasars negligible, either the gas accretion into the black holes
has to be delayed at least three times the dynamical time-scale of
their host bulges or the dust covering factor is as small as ∼0.1.
---------------------------------------------------------
Title: First High-resolution Spectroscopic Observations of an Erupting
Prominence Within a Coronal Mass Ejection by the Interface Region
Imaging Spectrograph (IRIS)
Authors: Liu, Wei; De Pontieu, Bart; Vial, Jean-Claude; Title, Alan
M.; Carlsson, Mats; Uitenbroek, Han; Okamoto, Takenori J.; Berger,
Thomas E.; Antolin, Patrick
2015ApJ...803...85L Altcode: 2015arXiv150204738L
Spectroscopic observations of prominence eruptions associated with
coronal mass ejections (CMEs), although relatively rare, can provide
valuable plasma and three-dimensional geometry diagnostics. We report
the first observations by the Interface Region Imaging Spectrograph
mission of a spectacular fast CME/prominence eruption associated with
an equivalent X1.6 flare on 2014 May 9. The maximum plane-of-sky and
Doppler velocities of the eruption are 1200 and 460 km s<SUP>-1</SUP>,
respectively. There are two eruption components separated by ∼200
km s<SUP>-1</SUP> in Doppler velocity: a primary, bright component
and a secondary, faint component, suggesting a hollow, rather than
solid, cone-shaped distribution of material. The eruption involves
a left-handed helical structure undergoing counterclockwise (viewed
top-down) unwinding motion. There is a temporal evolution from upward
eruption to downward fallback with less-than-free-fall speeds and
decreasing nonthermal line widths. We find a wide range of Mg ii k/h
line intensity ratios (less than ∼2 expected for optically-thin
thermal emission): the lowest ever reported median value of 1.17
found in the fallback material, a comparably high value of 1.63 in
nearby coronal rain, and intermediate values of 1.53 and 1.41 in
the two eruption components. The fallback material exhibits a strong
(\gt 5σ ) linear correlation between the k/h ratio and the Doppler
velocity as well as the line intensity. We demonstrate that Doppler
dimming of scattered chromospheric emission by the erupted material
can potentially explain such characteristics.
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Title: First High-resolution Spectroscopic Observations by IRIS
of a Fast, Helical Prominence Eruption Associated with a Coronal
Mass Ejection
Authors: Liu, W.; De Pontieu, B.; Okamoto, T. J.; Vial, J. C.; Title,
A. M.; Antolin, P.; Berger, T. E.; Uitenbroek, H.
2014AGUFMSH11D..04L Altcode:
High-resolution spectroscopic observations of prominence eruptions and
associated coronal mass ejections (CMEs) are rare but can provide
valuable plasma and energy diagnostics. New opportunities have
recently become available with the advent of the Interface Region
Imaging Spectrograph (IRIS) mission equipped with high resolution of
0.33-0.4 arcsec in space and 1 km/s in velocity, together with the
Hinode Solar Optical Telescope of 0.2 arcsec spatial resolution. We
report the first result of joint IRIS-Hinode observations of a
spectacular prominence eruption occurring on 2014-May-09. IRIS
detected a maximum redshift of 450 km/s, which, combined with the
plane-of-sky speed of 800 km/s, gives a large velocity vector of 920
km/s at 30 degrees from the sky plane. This direction agrees with the
source location at 30 degrees behind the limb observed by STEREO-A
and indicates a nearly vertical ejection. We found two branches of
redshifts separated by 200 km/s appearing in all strong lines at
chromospheric to transition-region temperatures, including Mg II k/h,
C II, and Si IV, suggesting a hollow, rather than solid, cone in the
velocity space of the ejected material. Opposite blue- and redshifts
on the two sides of the prominence exhibit corkscrew variations both
in space and time, suggestive of unwinding rotations of a left-handed
helical flux rope. Some erupted material returns as nearly streamline
flows, exhibiting distinctly narrow line widths (~10 km/s), about
50% of those of the nearby coronal rain at the apexes of coronal
loops, where the rain material is initially formed out of cooling
condensation. We estimate the mass and kinetic energy of the ejected
and returning material and compare them with those of the associated
CME. We will discuss the implications of these observations for CME
initiation mechanisms.
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Title: Experimental investigation for cavity dimensions of highly
porous small bodies
Authors: Okamoto, T.; Nakamura, A.; Hasegawa, S.
2014acm..conf..393O Altcode:
Small bodies were probably very porous during the formation of the solar
system. In order to understand the surface evolution of highly porous
bodies, it is necessary to investigate the impact process for targets
with such high porosity. In this study, impact experiments with sintered
glass-bead targets of 87 and 94 % porosities were conducted. Growth
of cavities with time and the final cavity dimensions were analyzed
and compared with previous studies of porous targets. <P />Impact
experiments were conducted using a two-stage light-gas gun at ISAS,
Japan. The projectiles of a few millimeters were composed of titanium,
aluminum, nylon, and basalt. The impact velocities ranged from 1.8
to 7.2 km s^{-1}. In order to observe the inside of the targets, we
used a flash X-ray system and a micro-X-ray tomography instrument. <P
/>The track shape was found to be divided into two types, elongated
'carrot' shape and short 'bulb' shape [1]. The figures on the left
and right present a transmission image of the bulb shape track and a
sketch of a cross section of the cavity, respectively. The results
of the final maximum diameter, D_max and the final entrance-hole
diameter, D_ent show that both dimensions tend to increase with impact
velocity and decrease with target porosity. We adopted the scaling
law of crater diameter [2] for our analysis of D_max and D_ent. The
following empirical relations are obtained for targets with porosity
≥ 87 %: <P />{D_max}/{d_p}(ρ_t/ρ_p)^{0.4} =10^{-1.52±0.27}
({Y}/ρ_t{v_0^2})^{-0.49 ± 0.07}, <P />{D_ent}/{d_p}(ρ_t/ρ_p)^{0.4}
=10^{-2.12±0.39} ({Y}/ρ_t{v_0^2})^{-0.53 ± 0.11}, <P />where d_p,
ρ_t, ρ_p, Y, and v_0 are the projectile diameter, target density,
projectile density, target compressive strength, and the impact
velocity, respectively. The results of the depth from the entrance hole
to the maximum diameter of the cavity, L_max, shows that L_max decreases
with impact velocity and increases with target porosity. If we assume
that a projectile decelerates by inertial drag [1], the characteristic
length L_0, which is the depth from the surface where the kinetic energy
of the projectile becomes 1/e of the initial energy, is described as
follows: <P />L_0={2ρ_p}/{3C_dρ_t}d_p, <P />where C_d is the drag
coefficient that increases with dynamic pressure normalized by tensile
strength of the projectile [1]. We found that L_max/d_p increases with
L_0/d_p. It indicates that L_max depends on the degree of projectile
deformation or disruption through the drag coefficient and also depends
on the projectile-target density ratio. We will also discuss the growth
of the cavity volume, maximum diameter, and depth of the cavity with
time using dimensionless parameters of crater scaling [3].
---------------------------------------------------------
Title: The Interface Region Imaging Spectrograph (IRIS)
Authors: De Pontieu, B.; Title, A. M.; Lemen, J. R.; Kushner, G. D.;
Akin, D. J.; Allard, B.; Berger, T.; Boerner, P.; Cheung, M.; Chou,
C.; Drake, J. F.; Duncan, D. W.; Freeland, S.; Heyman, G. F.; Hoffman,
C.; Hurlburt, N. E.; Lindgren, R. W.; Mathur, D.; Rehse, R.; Sabolish,
D.; Seguin, R.; Schrijver, C. J.; Tarbell, T. D.; Wülser, J. -P.;
Wolfson, C. J.; Yanari, C.; Mudge, J.; Nguyen-Phuc, N.; Timmons,
R.; van Bezooijen, R.; Weingrod, I.; Brookner, R.; Butcher, G.;
Dougherty, B.; Eder, J.; Knagenhjelm, V.; Larsen, S.; Mansir, D.;
Phan, L.; Boyle, P.; Cheimets, P. N.; DeLuca, E. E.; Golub, L.;
Gates, R.; Hertz, E.; McKillop, S.; Park, S.; Perry, T.; Podgorski,
W. A.; Reeves, K.; Saar, S.; Testa, P.; Tian, H.; Weber, M.; Dunn, C.;
Eccles, S.; Jaeggli, S. A.; Kankelborg, C. C.; Mashburn, K.; Pust, N.;
Springer, L.; Carvalho, R.; Kleint, L.; Marmie, J.; Mazmanian, E.;
Pereira, T. M. D.; Sawyer, S.; Strong, J.; Worden, S. P.; Carlsson,
M.; Hansteen, V. H.; Leenaarts, J.; Wiesmann, M.; Aloise, J.; Chu,
K. -C.; Bush, R. I.; Scherrer, P. H.; Brekke, P.; Martinez-Sykora,
J.; Lites, B. W.; McIntosh, S. W.; Uitenbroek, H.; Okamoto, T. J.;
Gummin, M. A.; Auker, G.; Jerram, P.; Pool, P.; Waltham, N.
2014SoPh..289.2733D Altcode: 2014arXiv1401.2491D; 2014SoPh..tmp...25D
The Interface Region Imaging Spectrograph (IRIS) small explorer
spacecraft provides simultaneous spectra and images of the photosphere,
chromosphere, transition region, and corona with 0.33 - 0.4 arcsec
spatial resolution, two-second temporal resolution, and 1 km
s<SUP>−1</SUP> velocity resolution over a field-of-view of up to
175 arcsec × 175 arcsec. IRIS was launched into a Sun-synchronous
orbit on 27 June 2013 using a Pegasus-XL rocket and consists of a
19-cm UV telescope that feeds a slit-based dual-bandpass imaging
spectrograph. IRIS obtains spectra in passbands from 1332 - 1358 Å,
1389 - 1407 Å, and 2783 - 2834 Å, including bright spectral lines
formed in the chromosphere (Mg II h 2803 Å and Mg II k 2796 Å) and
transition region (C II 1334/1335 Å and Si IV 1394/1403 Å). Slit-jaw
images in four different passbands (C II 1330, Si IV 1400, Mg II k
2796, and Mg II wing 2830 Å) can be taken simultaneously with spectral
rasters that sample regions up to 130 arcsec × 175 arcsec at a variety
of spatial samplings (from 0.33 arcsec and up). IRIS is sensitive to
emission from plasma at temperatures between 5000 K and 10 MK and will
advance our understanding of the flow of mass and energy through an
interface region, formed by the chromosphere and transition region,
between the photosphere and corona. This highly structured and dynamic
region not only acts as the conduit of all mass and energy feeding
into the corona and solar wind, it also requires an order of magnitude
more energy to heat than the corona and solar wind combined. The
IRIS investigation includes a strong numerical modeling component
based on advanced radiative-MHD codes to facilitate interpretation of
observations of this complex region. Approximately eight Gbytes of data
(after compression) are acquired by IRIS each day and made available
for unrestricted use within a few days of the observation.
---------------------------------------------------------
Title: Outcome of impact disruption of iron meteorites at room
temperature
Authors: Katsura, T.; Nakamura, A.; Takabe, A.; Okamoto, T.; Sangen,
K.; Hasegawa, S.; Liu, X.; Mashimo, T.
2014acm..conf..255K Altcode:
The iron meteorites and some M-class asteroids are generally understood
to originate in the cores of differentiated planetesimals or in the
local melt pools of primitive bodies. On these primitive bodies and
planetesimals, a wide range of collisional events at different mass
scales, temperatures, and impact velocities would have occurred. Iron
materials have a brittle-ductile transition at a certain temperature,
which depends on metallurgical factors such as grain size and purity,
and on conditions such as strain-rate and confining pressure [1]. An
evolutional scenario of iron meteorite parent bodies was proposed in
which they formed in the terrestrial planet region, after which they
were scattered into the main belt by collisions, Yarkovsky thermal
forces, and resonances [2]. In this case, they may have experienced
collisional evolution in the vicinity of the Earth before they were
scattered into the main belt. The size distribution of iron bodies in
the main belt may therefore have depended on the disruption threshold
of iron bodies at temperature above the brittle-ductile transition. <P
/>This paper presents the results of impact-disruption experiments
of iron meteorite and steel specimens mm-cm in size as projectiles
or targets conducted at room temperature using three light-gas guns
and one powder gun. Our iron specimens were almost all smaller in size
than their counterparts (as targets or projectiles, respectively). The
fragment size distribution of iron material was different from that
of rocks. In iron fragmentation, a higher percentage of the mass
is concentrated in larger fragments, i.e., the mass fraction of
fine fragments is much less than that of rocks shown in the Figure
(left). This is probably due to the ductile nature of the iron materials
at room temperature. Furthermore, the Figure (right) shows that the
largest fragment mass fraction f is dependent not only on the energy
density but also on the size of the specimens. In order to obtain
a generalized empirical relationship for f, we assumed a power-law
dependence of f on initial peak pressure P_0 normalized by a dynamic
strength, Y, which was defined to be dependent on the size of the iron
material. A least-squares fit to the data of iron meteorite specimens
resulted in the following relationship: f∝ ({P_0}/{Y})^{-2.1}. The
deformation of the iron materials was found to be most significant
when the initial pressure greatly exceeded the dynamic strength of
the material.
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Title: ALMA Will Determine the Spectroscopic Redshift z > 8 with
FIR [O III] Emission Lines
Authors: Inoue, A. K.; Shimizu, I.; Tamura, Y.; Matsuo, H.; Okamoto,
T.; Yoshida, N.
2014ApJ...780L..18I Altcode: 2013arXiv1312.0684I
We investigate the potential use of nebular emission lines in the
rest-frame far-infrared (FIR) for determining spectroscopic redshift
of z > 8 galaxies with the Atacama Large Millimeter/submillimeter
Array (ALMA). After making a line emissivity model as a function of
metallicity, especially for the [O III] 88 μm line which is likely to
be the strongest FIR line from H II regions, we predict the line fluxes
from high-z galaxies based on a cosmological hydrodynamics simulation
of galaxy formation. Since the metallicity of galaxies reaches at ~0.2
Z <SUB>⊙</SUB> even at z > 8 in our simulation, we expect the
[O III] 88 μm line as strong as 1.3 mJy for 27 AB objects, which
is detectable at a high significance by <1 hr integration with
ALMA. Therefore, the [O III] 88 μm line would be the best tool to
confirm the spectroscopic redshifts beyond z = 8.
---------------------------------------------------------
Title: Study on the Triggering Process of Solar Flares Based on
Hinode/SOT Observations
Authors: Bamba, Y.; Kusano, K.; Yamamoto, T. T.; Okamoto, T. J.
2013ApJ...778...48B Altcode: 2013arXiv1309.5465B
We investigated four major solar flare events that occurred in
active regions NOAA 10930 (2006 December 13 and 14) and NOAA 11158
(2011 February 13 and 15) by using data observed by the Solar Optical
Telescope on board the Hinode satellite. To reveal the trigger mechanism
of solar flares, we analyzed the spatio-temporal correlation between the
detailed magnetic field structure and the emission image of the Ca II
H line at the central part of flaring regions for several hours prior
to the onset of the flares. In all the flare events, we observed that
the magnetic shear angle in the flaring regions exceeded 70°, as well
as that characteristic magnetic disturbances developed at the centers
of flaring regions in the pre-flare phase. These magnetic disturbances
can be classified into two groups depending on the structure of their
magnetic polarity inversion lines; the so-called opposite-polarity
and reversed-shear magnetic field recently proposed by our group,
although the magnetic disturbance in one event of the four samples is
too subtle to clearly recognize the detailed structure. The result
suggests that some major solar flares are triggered by rather small
magnetic disturbances. We also show that the critical size of the
flare-trigger field varies among flare events and briefly discuss how
the flare-trigger process depends on the evolution of active regions.
---------------------------------------------------------
Title: Penetration Depth of Dust Grains into Highly Porous Primitive
Bodies
Authors: Okamoto, T.; Nakamura, A. M.; Hasegawa, S.; Kurosawa, K.;
Ikezaki, K.; Tsuchiyama, A.
2013LPI....44.1824O Altcode: 2013LPICo1719.1824O
To investigate the penetration depth of dust into small primitive
bodies, we conducted impact experiments and obtained a deceleration
model of dust penetration.
---------------------------------------------------------
Title: Calibrating an updated smoothed particle hydrodynamics scheme
within gcd+
Authors: Kawata, D.; Okamoto, T.; Gibson, B. K.; Barnes, D. J.; Cen, R.
2013MNRAS.428.1968K Altcode: 2012MNRAS.tmp..115K; 2009arXiv0902.4002K
We adapt a modern scheme of smoothed particle hydrodynamics
(SPH) to our tree N-body/SPH galactic chemodynamics code gcd+. The
applied scheme includes implementations of the artificial viscosity
switch and artificial thermal conductivity proposed by Morris &
Monaghan, Rosswog & Price and Price to model discontinuities and
Kelvin-Helmholtz instabilities more accurately. We first present
hydrodynamics test simulations and contrast the results to runs
undertaken without artificial viscosity switch or thermal conduction. In
addition, we also explore the different levels of smoothing by adopting
larger or smaller smoothing lengths, i.e. a larger or smaller number
of neighbour particles, N<SUB>nb</SUB>. We demonstrate that the new
version of gcd+ is capable of modelling Kelvin-Helmholtz instabilities
to a similar level as the mesh code, athena. From the Gresho vortex,
point-like explosion and self-similar collapse tests, we conclude that
setting the smoothing length to keep N<SUB>nb</SUB> as high as ∼58
is preferable to adopting smaller smoothing lengths. We present our
optimized parameter sets from the hydrodynamics tests.
---------------------------------------------------------
Title: Laboratory experiments on crater scaling-law for sedimentary
rocks in the strength regime
Authors: Suzuki, A.; Hakura, S.; Hamura, T.; Hattori, M.; Hayama, R.;
Ikeda, T.; Kusuno, H.; Kuwahara, H.; Muto, Y.; Nagaki, K.; Niimi,
R.; Ogata, Y.; Okamoto, T.; Sasamori, T.; Sekigawa, C.; Yoshihara,
T.; Hasegawa, S.; Kurosawa, K.; Kadono, T.; Nakamura, A. M.; Sugita,
S.; Arakawa, M.
2012JGRE..117.8012S Altcode: 2012JGRE..11708012S
We systematically conducted impact cratering experiments with
sedimentary rocks at 0.8-7.1 km/s using various projectiles
with 1.1-15 g/cm<SUP>3</SUP> in density. The crater diameter,
depth, and volume are investigated and compared with the results
for igneous rocks. Then, using the non-dimensional parameters,
the normalized crater diameter π<SUB>D</SUB>, the normalized
depth π<SUB>d</SUB>, the normalized volume π<SUB>V</SUB>, the
target strength per specific energy π<SUB>3</SUB>, and the target
and projectile density ratio π<SUB>4</SUB>, the scaling laws,
π<SUB>D</SUB> = (1.43 ± 0.25)π<SUB>3</SUB><SUP>-0.22±0.02</SUP>
π<SUB>4</SUB><SUP>0.11±0.07</SUP>, π<SUB>d</SUB>
= (0.22 ± 0.04)π<SUB>3</SUB><SUP>-0.25±0.02</SUP>
π<SUB>4</SUB><SUP>0.01±0.05</SUP>, and π<SUB>V</SUB>
= (0.11 ± 0.04) π<SUB>3</SUB><SUP>-0.71±0.05</SUP>
π<SUB>4</SUB><SUP>0.23±0.17</SUP>, are obtained. The comparison
with the results of igneous rocks suggests that the characteristic
properties of sedimentary rocks such as the lower strength and the
strong shock wave attenuation rate are actually effective for the
cratering of sedimentary rocks.
---------------------------------------------------------
Title: The Aquila comparison project: the effects of feedback and
numerical methods on simulations of galaxy formation
Authors: Scannapieco, C.; Wadepuhl, M.; Parry, O. H.; Navarro, J. F.;
Jenkins, A.; Springel, V.; Teyssier, R.; Carlson, E.; Couchman,
H. M. P.; Crain, R. A.; Dalla Vecchia, C.; Frenk, C. S.; Kobayashi,
C.; Monaco, P.; Murante, G.; Okamoto, T.; Quinn, T.; Schaye, J.;
Stinson, G. S.; Theuns, T.; Wadsley, J.; White, S. D. M.; Woods, R.
2012MNRAS.423.1726S Altcode: 2011arXiv1112.0315S; 2012MNRAS.tmp.2970S
We compare the results of various cosmological gas-dynamical codes
used to simulate the formation of a galaxy in the Λ cold dark
matter structure formation paradigm. The various runs (13 in total)
differ in their numerical hydrodynamical treatment [smoothed particle
hydrodynamics (SPH), moving mesh and adaptive mesh refinement] but
share the same initial conditions and adopt in each case their latest
published model of gas cooling, star formation and feedback. Despite the
common halo assembly history, we find large code-to-code variations in
the stellar mass, size, morphology and gas content of the galaxy at z=
0, due mainly to the different implementations of star formation and
feedback. Compared with observation, most codes tend to produce an
overly massive galaxy, smaller and less gas rich than typical spirals,
with a massive bulge and a declining rotation curve. A stellar disc
is discernible in most simulations, although its prominence varies
widely from code to code. There is a well-defined trend between the
effects of feedback and the severity of the disagreement with observed
spirals. In general, models that are more effective at limiting the
baryonic mass of the galaxy come closer to matching observed galaxy
scaling laws, but often to the detriment of the disc component. Although
numerical convergence is not particularly good for any of the codes,
our conclusions hold at two different numerical resolutions. Some
differences can also be traced to the different numerical techniques;
for example, more gas seems able to cool and become available for
star formation in grid-based codes than in SPH. However, this effect
is small compared to the variations induced by different feedback
prescriptions. We conclude that state-of-the-art simulations cannot
yet uniquely predict the properties of the baryonic component of
a galaxy, even when the assembly history of its host halo is fully
specified. Developing feedback algorithms that can effectively regulate
the mass of a galaxy without hindering the formation of high angular
momentum stellar discs remains a challenge.
---------------------------------------------------------
Title: Flows and dynamics in prominences and cavities
Authors: Okamoto, Takenori Joten
2012shin.confE.212O Altcode:
In this talk, we will introduce a peculiar phenomenon, a
slowly-rising column of cool material from the lower atmosphere in
quiescent prominence observations by the Solar Optical Telescope
aboard Hinode. The apparent ascent speed of the column is 2 km/s,
while the fine structures of the column exhibit much faster motion
of up to 20 km/s. The column eventually becomes a faint low-lying
prominence. Interestingly, an overlying coronal cavity associated with
the appearance of the column seen in the X-ray and EUV moves upward
at 5 km/s. We investigated the relationship between these episodes and
suggest that they are due to the emergence of a helical flux rope that
undergoes reconnection with lower coronal fields, possibly carrying
material into the coronal cavity. Under the assumption of the emerging
flux scenario, the lower velocity of 2 km/s and the higher one of 20
km/s in the column are attributed to the rising motion of the emerging
flux and to the outflow driven by magnetic reconnection between the
emerging flux and the pre-existing coronal field, respectively. Our
presentation gives a coherent explanation of the enigmatic phenomenon
of the rising column with the emergence of the helical rope and its
effect on the corona. Here we would like to discuss our suggestion
and another possibility to explain this phenomenon, and consider how
to perform good observations to connect activities in small and large
scales in the future.
---------------------------------------------------------
Title: Experimental Study of Momentum Transfer Efficiency for High
Porosity Targets
Authors: Aoki, T.; Nakamura, A. M.; Okamoto, T.; Hasegawa, S.
2012LPICo1667.6207A Altcode:
We performed impact experiments of high porosity targets in order to
study momentum transfer efficiency. It was found from analysis of
high-speed camera images that the ejecta carry a few tens % of the
projectile momentum.
---------------------------------------------------------
Title: Laboratory Penetration Experiments of High Velocity Projectiles
into Very Porous Targets on Exotic Origin of Dusts in Primitive Bodies
Authors: Okamoto, T.; Nakamura, A. M.; Hasegawa, S.; Kurosawa, K.;
Ikezaki, K.; Tsuchiyama, A.
2012LPICo1667.6065O Altcode:
To understand dusts penetration into high porous bodies, we conducted
impact experiments at velocities of 2-7 km/s into high-porosity targets
of 80-90% porosity.Our results indicate that dusts can only be captured
at the surface of small bodies.
---------------------------------------------------------
Title: Emergence of Twisted Flux in Prominence Observations
Authors: Okamoto, T. J.; Tsuneta, S.; Berger, T. E.; Lites, B. W.
2012ASPC..455..123O Altcode:
The emergence of twisted flux is a key process for supply of magnetic
flux into the corona as well as solar dynamic activities such as sunspot
formation and trigger of coronal mass ejections. In particular, there
are numerous discussions about the role and necessity of twisted flux
emergence for origin of prominences. However, the difficulty to measure
vector magnetic fields has not allowed us to investigate the detailed
relationship between emerging twisted flux and prominence. Hinode has
changed the situation. The Spectro-Polarimeter aboard Hinode has high
sensitivity to weaker magnetic fields of fine structures, and provides
opportunities to detect weak horizontal magnetic fields. As a result,
we have obtained signatures of twisted flux emergence associated with
prominences: The observational features are "broadening and narrowing
of a region dominated by horizontal magnetic field" and "rotating
direction of horizontal field" on the photosphere. Moreover, the data
show the interaction between the emerging twisted flux and granules,
and that the flux rope has high intrinsic strength 650 G, while the
flux density is as low as 100 G. Theoretical research with numerical
simulation on the basis of these results is active. In addition, we
investigate activities of a coronal cavity overlying a prominence on
the limb, and suggest the existence of twisted flux rope to explain the
activities of prominence and the coronal cavity comprehensively. Here
we introduce both these observational and theoretical results, and
discuss the details about emerging twisted flux.
---------------------------------------------------------
Title: Laboratory Impact Study on Velocity of the Fastest Ejecta
from Porous Small Bodies
Authors: Nakamura, A. M.; Okamoto, T.; Kiyomizu, K.; Aoki, T.; Nagaoka,
H.; Hasegawa, S.
2012LPICo1667.6337N Altcode:
We conducted laboratory impact experiments in order to study velocity
filed of ejecta from porous targets with porosity of 40-94 %. We showed
the fastest ejecta velocity depends on porosity and impact velocity
and much lower than those of rocks.
---------------------------------------------------------
Title: Capture of Hypervelocity Dusts by Highly Porous Small Bodies
Authors: Okamoto, T.; Nakamura, A. M.; Hasegawa, S.; Kurosawa, K.;
Ikezaki, K.; Tsuchiyama, A.
2012LPI....43.1782O Altcode:
We conducted dust impact experiments into highly porous brittle targets
using a flash X-ray system and showed that the deceleration process
of projectiles and the cavity morphology is similar to those reported
for aerogel targets.
---------------------------------------------------------
Title: The baryons in the Milky Way satellites
Authors: Parry, O. H.; Eke, V. R.; Frenk, C. S.; Okamoto, T.
2012MNRAS.419.3304P Altcode: 2011MNRAS.tmp.1998P; 2011arXiv1105.3474P
We investigate the formation and evolution of satellite galaxies using
smoothed particle hydrodynamics (SPH) simulations of a Milky Way (MW)
like system, focusing on the best resolved examples, analogous to the
classical MW satellites. Comparing with a pure dark matter simulation,
we find that the condensation of baryons has had a relatively minor
effect on the structure of the satellites' dark matter haloes. The
stellar mass that forms in each satellite agrees relatively well
over three levels of resolution (a factor of ∼64 in particle mass)
and scales with (sub)halo mass in a similar way in an independent
semi-analytical model. Our model provides a relatively good match to
the average luminosity function of the MW and M31. To establish whether
the potential wells of our satellites are realistic, we measure their
masses within observationally determined half-light radii, finding that
they have somewhat higher mass-to-light ratios than those derived for
the MW dSphs from stellar kinematic data; the most massive examples are
most discrepant. A statistical test yields an ∼6 per cent probability
that the simulated and observationally derived distributions of masses
are consistent. If the satellite population of the MW is typical,
our results could imply that feedback processes not properly captured
by our simulations have reduced the central densities of subhaloes,
or that they initially formed with lower concentrations, as would be
the case, for example, if the dark matter were made of warm, rather
than cold particles.
---------------------------------------------------------
Title: You Cannot Press Out the Black Hole
Authors: Ida, D.; Okamoto, T.
2012PThPh.127..163I Altcode: 2011arXiv1105.6173I
It is shown that a ball-shaped black hole region homeomorphic with D^n
cannot be pressed out, along whichever axis penetrating the black hole
region, into a black ring with a doughnut-shaped black hole region
homeomorphic with S^1 × D^{n-1}. A more general prohibition law for
the change of the topology of black holes, including a version of
no-bifurcation theorems for black holes, is given.
---------------------------------------------------------
Title: Generation and propagation of Alfvenic waves in spicules
Authors: De Pontieu, B.; Okamoto, T. J.; Rouppe van der Voort, L.;
Hansteen, V. H.; Carlsson, M.
2011AGUFMSH13B1956D Altcode:
Both spicules and Alfven waves have recently been implicated in
playing a role in the heating of the outer atmosphere. Yet we do
not know how spicules or Alfven waves are generated. Here we focus
on the properties of Alfvenic waves in spicules and their role in
forming spicules. We use high-resolution observations taken with the
Solar Optical Telescope onboard Hinode, and with the CRISP Fabry-Perot
Interferometer at the Swedish Solar Telescope (SST) in La Palma to study
the generation and propagation of Alfvenic waves in spicules and their
disk counterparts. Using automated detection algorithms to identify
propagating waves in limb spicules, we find evidence for both up-
and downward propagating as well as standing waves. Our data suggests
significant reflection of waves in and around spicules and provides
constraints for theoretical models of spicules and wave propagation
through the chromosphere. We also show observational evidence (using
SST data) of the generation of Alfven waves and the role they play in
forming spicules.
---------------------------------------------------------
Title: Temporary capture of asteroids by Jupiter/Saturn
Authors: Higuchi, A.; Okamoto, T.; Ida, S.
2011epsc.conf.1832H Altcode: 2011DPS....43.1832H
Irregular satellites observed around giant planets are thought to be
object that were initially in the heliocentric orbits and later been
captured into their current orbits around their host planets. To clarify
the possibility of their origin in the asteroid belt, we calculated
the orbit of mass-less particles initially distributed around the outer
asteroid belt under the perturbations by Jupiter and Saturn. We found
that the asteroids can be the candidates for the irregular satellites,
not only of Jupiter but also of Saturn.
---------------------------------------------------------
Title: Propagating Waves Along Spicules
Authors: Okamoto, Takenori J.; De Pontieu, Bart
2011ApJ...736L..24O Altcode: 2011arXiv1106.4270O
Alfvénic waves are thought to play an important role in coronal heating
and acceleration of solar wind. Here we investigate the statistical
properties of Alfvénic waves along spicules (jets that protrude into
the corona) in a polar coronal hole using high-cadence observations of
the Solar Optical Telescope on board Hinode. We developed a technique
for the automated detection of spicules and high-frequency waves. We
detected 89 spicules and found (1) a mix of upward propagating, downward
propagating, as well as standing waves (occurrence rates of 59%, 21%,
and 20%, respectively); (2) the phase speed gradually increases with
height; (3) upward waves dominant at lower altitudes, standing waves
at higher altitudes; (4) standing waves dominant in the early and late
phases of each spicule, while upward waves were dominant in the middle
phase; (5) in some spicules, we find waves propagating upward (from
the bottom) and downward (from the top) to form a standing wave in the
middle of the spicule; and (6) the medians of the amplitude, period,
and velocity amplitude were 55 km, 45 s, and 7.4 km s<SUP>-1</SUP>,
respectively. We speculate that upward propagating waves are produced
near the solar surface (below the spicule) and downward propagating
waves are caused by reflection of (initially) upward propagating
waves off the transition region at the spicule top. The mix of upward
and downward propagating waves implies that exploiting these waves
to perform seismology of the spicular environment requires careful
analysis and may be problematic.
---------------------------------------------------------
Title: Lunar BroadBand Seismometer System in the Japanese lunar
landing mission SELENE-2: its science goals and instrument details
Authors: Shiraishi, H.; Kobayashi, N.; Takeuchi, N.; Murakami, H.;
Lognonne, P.; Giardini, D.; Christensen, U. R.; Okamoto, T.; Kuge,
K.; Zhao, D.; Mocquet, A.; Mimoun, D.; de Raucourt, S.; Nebut, T.;
Tillier, S.; Kawamura, T.; Mance, D.; Zweifel, P.; Bierwirth, M.;
Roll, R.; Ishihara, Y.; Araki, E.; Ogawa, K.; Yamada, R.; Shirai,
K.; Iijima, Y.; Hayakawa, M.; Tanaka, S.; Kakuma, H.; Yamada, I.
2010AGUFM.U51B0039S Altcode:
SELENE-2 is the first lunar landing mission of Japan. We are developing
a broadband seismometer system as a powerful candidate for a payload
instrument. In this paper, we demonstrate the necessity of broadband
seismometer observation and its scientific targets. The Apollo projects
in 1970's installed an equilateral triangle seismograph network
at apexes where Apollo 12,14,15 and 16 landed. The passive seismic
observation had lasted for over 7 years and it provided us with the
first information on the lunar seismicity and the lunar structure down
to a depth of 1,000km. It, however, had two drawbacks: (1) the size of
the network is limited within 1,000km, and (2) the sensitivity of the
seismometers with a limited narrow band of 0.17Hz is marginal to detect
the small deep moonquakes which occurred frequently. In addition, due
to the strong scattering of seismic waves, P and S wave arrivals could
not be picked up accurately, and the typical picking error is up to
10sec. Because of these problems, the lunar velocity models obtained so
far are less certain, in particular, at depths greater than 200km. In
the SELENE-2 project we plan to have only one landing site and so we
cannot run a seismic network observation by the project alone. Thus, we
need to obtain more information from the feeble seismic waveforms using
a broadband (0.02-50Hz) seismometer having 10 times higher sensitivity
than that of the Apollo seismometers to overcome the drawback (2) as
mentioned above. The characteristic frequency of the shallow layer is
about 0.12Hz for the seismic velocity model of Nakamura(1981). Below
that frequency, we expect clear detection of seismic phases reflected
and converted at an internal discontinuity such as the core-mantle
boundary. The long-period seismic waveforms may provide us not only
information on the depth of an internal discontinuity but also seismic
velocity contrast at the boundary. Another scientific target is to
determine the corner frequency of deep moonquakes which can provide
us information on the physical state in the source region. Although
it was suggested that the corner frequency of deep moonquakes is much
smaller than that of earthquakes, the result is not conclusive because
of the narrow band of the Apollo seismometers. To realize the highly
sensitive broadband seismic observation in a timely manner, we make
use of the heritage of a short-period seismometer(SP) developed in the
past Lunar-A project and a long-period broadband seismometer VBB(LP)
developed in the ExoMars project. We customize these seismic sensors
to work properly under the severe conditions at the lunar surface. The
thermal shield module is the key technology to realize high performance
in the seismic observation on the moon.
---------------------------------------------------------
Title: A rising cool column associated with formation of prominence
and coronal cavity
Authors: Okamoto, T. J.; Tsuneta, S.; Berger, T. E.
2010AGUFMSH51A1665O Altcode:
A prominence consists of relatively cool chromospheric plasma found
above the solar limb at coronal heights where the temperature and
density are typically two order of magnitude higher and lower,
respectively. Prominences are frequently associated with larger
coronal structures known as coronal cavities. There are numerous
observational studies on prominences with multi-wavelength and
with high-spatial resolution and also on the relationship between
cavities and coronal mass ejections, while less analyses on activities
inside coronal cavities. Continuous observations were performed of a
quiescent prominence with the Hinode satellite on 2006 December 23
and 24. In the Ca II H-line channel of the Solar Optical Telescope
we observed a peculiar slowly-rising column of cool material from the
lower atmosphere. The apparent ascent speed of the column is 2 km/s,
while the fine structures of the column exhibit much faster motion
of up to 20 km/s. The column eventually becomes a faint low-lying
prominence. An overlying coronal cavity associated with the appearance
of the column seen in the X-ray and EUV moves upward at 5 km/s. We
discuss the relationship between these episodes and suggest that
they are due to the emergence of a helical flux rope that undergoes
reconnection with lower coronal fields, possibly carrying material into
the coronal cavity. Under the assumption of the emerging flux scenario,
the lower velocity of 2 km/s and the higher one of 20 km/s in the column
are attributed to the rising motion of the emerging flux and to the
outflow driven by magnetic reconnection between the emerging flux and
the pre-existing coronal field, respectively. Our presentation gives a
coherent explanation of the enigmatic phenomenon of the rising column
with the emergence of the helical rope and its effect on the corona.
---------------------------------------------------------
Title: A Rising Cool Column as a Signature of Helical Flux Emergence
and Formation of Prominence and Coronal Cavity
Authors: Okamoto, Takenori J.; Tsuneta, Saku; Berger, Thomas E.
2010ApJ...719..583O Altcode: 2010arXiv1006.4633O
Continuous observations were performed of a quiescent prominence
with the Solar Optical Telescope on board the Hinode satellite
on 2006 December 23 and 24. A peculiar slowly rising column of
~10<SUP>4</SUP> K plasma develops from the lower atmosphere during
the observations. The apparent ascent speed of the column is 2 km
s<SUP>-1</SUP>, while the fine structures of the column exhibit much
faster motion of up to 20 km s<SUP>-1</SUP>. The column eventually
becomes a faint low-lying prominence. An overlying coronal cavity
associated with the appearance of the column seen in the X-ray and
EUV moves upward at ~5 km s<SUP>-1</SUP>. We discuss the relationship
between these episodes and suggest that they are due to the emergence
of a helical flux rope that undergoes reconnection with lower coronal
fields, possibly carrying material into the coronal cavity. Under
the assumption of the emerging flux scenario, the lower velocity of 2
km s<SUP>-1</SUP> and the higher one of 20 km s<SUP>-1</SUP> in the
column are attributed to the rising motion of the emerging flux and
to the outflow driven by magnetic reconnection between the emerging
flux and the pre-existing coronal field, respectively. The present
paper gives a coherent explanation of the enigmatic phenomenon of the
rising column with the emergence of the helical rope and its effect
on the corona. We discuss the implications that the emergence of such
a helical rope has on the dynamo process in the convection zone.
---------------------------------------------------------
Title: Emergence of Helical Flux and the Formation of an Active
Region Filament Channel
Authors: Lites, B. W.; Kubo, M.; Berger, T.; Frank, Z.; Shine, R.;
Tarbell, T.; Title, A.; Okamoto, T. J.; Otsuji, K.
2010ApJ...718..474L Altcode:
We present comprehensive observations of the formation and evolution
of a filament channel within NOAA Active Region (AR) 10978 from
Hinode/Solar Optical Telescope and TRACE. We employ sequences
of Hinode spectro-polarimeter maps of the AR, accompanying Hinode
Narrowband Filter Instrument magnetograms in the Na I D1 line, Hinode
Broadband Filter Instrument filtergrams in the Ca II H line and G-band,
Hinode X-ray telescope X-ray images, and TRACE Fe IX 171 Å image
sequences. The development of the channel resembles qualitatively
that presented by Okamoto et al. in that many indicators point to
the emergence of a pre-existing sub-surface magnetic flux rope. The
consolidation of the filament channel into a coherent structure takes
place rapidly during the course of a few hours, and the filament form
then gradually shrinks in width over the following two days. Particular
to this filament channel is the observation of a segment along its
length of horizontal, weak (500 G) flux that, unlike the rest of the
filament channel, is not immediately flanked by strong vertical plage
fields of opposite polarity on each side of the filament. Because this
isolated horizontal field is observed in photospheric lines, we infer
that it is unlikely that the channel formed as a result of reconnection
in the corona, but the low values of inferred magnetic fill fraction
along the entire length of the filament channel suggest that the bulk
of the field resides somewhat above the low photosphere. Correlation
tracking of granulation in the G band presents no evidence for either
systematic flows toward the channel or systematic shear flows along
it. The absence of these flows, along with other indications of these
data from multiple sources, reinforces (but does not conclusively
demonstrate) the picture of an emerging flux rope as the origin of
this AR filament channel.
---------------------------------------------------------
Title: Quiescent Prominence Dynamics Observed with the Hinode Solar
Optical Telescope. I. Turbulent Upflow Plumes
Authors: Berger, Thomas E.; Slater, Gregory; Hurlburt, Neal; Shine,
Richard; Tarbell, Theodore; Title, Alan; Lites, Bruce W.; Okamoto,
Takenori J.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Magara, Tetsuya;
Suematsu, Yoshinori; Shimizu, Toshifumi
2010ApJ...716.1288B Altcode:
Hinode/Solar Optical Telescope (SOT) observations reveal two new
dynamic modes in quiescent solar prominences: large-scale (20-50 Mm)
"arches" or "bubbles" that "inflate" from below into prominences, and
smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are
related in that they are always dark in visible-light spectral bands,
they rise through the bright prominence emission with approximately
constant speeds, and the small-scale upflows are sometimes observed to
emanate from the top of the larger bubbles. Here we present detailed
kinematic measurements of the small-scale turbulent upflows seen in
several prominences in the SOT database. The dark upflows typically
initiate vertically from 5 to 10 Mm wide dark cavities between the
bottom of the prominence and the top of the chromospheric spicule
layer. Small perturbations on the order of 1 Mm or less in size
grow on the upper boundaries of cavities to generate plumes up to
4-6 Mm across at their largest widths. All plumes develop highly
turbulent profiles, including occasional Kelvin-Helmholtz vortex
"roll-up" of the leading edge. The flows typically rise 10-15 Mm before
decelerating to equilibrium. We measure the flowfield characteristics
with a manual tracing method and with the Nonlinear Affine Velocity
Estimator (NAVE) "optical flow" code to derive velocity, acceleration,
lifetime, and height data for several representative plumes. Maximum
initial speeds are in the range of 20-30 km s<SUP>-1</SUP>, which
is supersonic for a ~10,000 K plasma. The plumes decelerate in the
final few Mm of their trajectories resulting in mean ascent speeds
of 13-17 km s<SUP>-1</SUP>. Typical lifetimes range from 300 to 1000
s (~5-15 minutes). The area growth rate of the plumes (observed as
two-dimensional objects in the plane of the sky) is initially linear
and ranges from 20,000 to 30,000 km<SUP>2</SUP> s<SUP>-1</SUP> reaching
maximum projected areas from 2 to 15 Mm<SUP>2</SUP>. Maximum contrast of
the dark flows relative to the bright prominence plasma in SOT images
is negative and ranges from -10% for smaller flows to -50% for larger
flows. Passive scalar "cork movies" derived from NAVE measurements show
that prominence plasma is entrained by the upflows, helping to counter
the ubiquitous downflow streams in the prominence. Plume formation
shows no clear temporal periodicity. However, it is common to find
"active cavities" beneath prominences that can spawn many upflows in
succession before going dormant. The mean flow recurrence time in these
active locations is roughly 300-500 s (5-8 minutes). Locations remain
active on timescales of tens of minutes up to several hours. Using a
column density ratio measurement and reasonable assumptions on plume
and prominence geometries, we estimate that the mass density in the
dark cavities is at most 20% of the visible prominence density, implying
that a single large plume could supply up to 1% of the mass of a typical
quiescent prominence. We hypothesize that the plumes are generated from
a Rayleigh-Taylor instability taking place on the boundary between
the buoyant cavities and the overlying prominence. Characteristics,
such as plume size and frequency, may be modulated by the strength
and direction of the cavity magnetic field relative to the prominence
magnetic field. We conclude that buoyant plumes are a source of
quiescent prominence mass as well as a mechanism by which prominence
plasma is advected upward, countering constant gravitational drainage.
---------------------------------------------------------
Title: Response of the Solar Atmosphere to the Emergence of
`Serpentine' Magnetic Field
Authors: Harra, L. K.; Magara, T.; Hara, H.; Tsuneta, S.; Okamoto,
T. J.; Wallace, A. J.
2010SoPh..263..105H Altcode:
Active region magnetic flux that emerges to the photosphere from
below will show complexity in the structure, with many small-scale
fragmented features appearing in between the main bipole and then
disappearing. Some fragments seen will be absorbed into the main
polarities and others seem to cancel with opposite magnetic field. In
this paper we investigate the response of the corona to the behaviour
of these small fragments and whether energy through reconnection
will be transported into the corona. In order to investigate this we
analyse data from the Hinode space mission during flux emergence on
1 - 2 December 2006. At the initial stages of flux emergence several
small-scale enhancements (of only a few pixels size) are seen in the
coronal line widths and diffuse coronal emission exists. The magnetic
flux emerges as a fragmented structure, and coronal loops appear
above these structures or close to them. These loops are large-scale
structures - most small-scale features predominantly stay within the
chromosphere or at the edges of the flux emergence. The most distinctive
feature in the Doppler velocity is a strong ring of coronal outflows
around the edge of the emerging flux region on the eastern side which
is either due to reconnection or compression of the structure. This
feature lasts for many hours and is seen in many wavelengths. We
discuss the implications of this feature in terms of the onset of
persistent outflows from an active region that could contribute to
the slow solar wind.
---------------------------------------------------------
Title: Scattering Polarization in the Fe I 630 nm Emission Lines at
the Extreme Limb of the Sun
Authors: Lites, B. W.; Casini, R.; Manso Sainz, R.; Jurčák, J.;
Ichimoto, K.; Ishikawa, R.; Okamoto, T. J.; Tsuneta, S.; Bellot
Rubio, L.
2010ApJ...713..450L Altcode:
Spectro-polarimetric observations with the Solar Optical Telescope
onboard Hinode reveal the emission spectrum of the Fe I 630 nm lines
at the solar limb. The emission shell extends for less than 1” thereby
making it extremely difficult to detect from ground-based observatories
viewing the limb through the Earth's atmosphere. The linear polarization
signal is clearly due to scattering and it is predominantly oriented
in the radial direction. Using a comprehensive atomic model of
iron, we are able to interpret qualitatively the observed signals,
including the radial orientation of the linear polarization. The Hanle
effect causes the linear polarization of the Fe I 630 nm lines to be
sensitive to magnetic fields between ~0.1 G and ~40 G, and also to
be sensitive to the field's topology for stronger fields. The overall
degree of observed polarization can be reproduced by randomly oriented
horizontal magnetic fields of strength ≈2 G. The discovery of their
scattering polarization signals thus opens a new diagnostic opportunity
for these lines.
---------------------------------------------------------
Title: Hinode/SOT Measurements of Flows and Waves in Solar Prominences
Authors: Berger, Thomas; Okamoto, Takenori; Schmieder, Brigitte
2010cosp...38.2913B Altcode: 2010cosp.meet.2913B
We review Hinode Solar Optical Telescope (SOT) measurements of flows
and waves in quies-cent and active solar prominences. In quiescent
prominences, Hinode/SOT observations have revealed a new mode of
buoyant transport in the form of dark upflows that originate at
the chromospheric base of the prominence. The upflows can take the
form of large-scale (10 Mm) "bubbles" that rise through the entire
prominence into the overlying coronal cavity, or they can take the form
of numerous small-scale (1 Mm) plumes that generate from an apparent
Rayleigh-Taylor instability on the boundary between the prominence and
the impinging buoy-ant flow system. The episodic flows directly inject
mass, magnetic flux, and helicity into the overlying coronal cavity,
moving the system towards destabilization and eruption in the form of
CMEs. Hinode/SOT quiescent prominence observations have also verified
the existence of ubiquitous downflow streams and vortex flows confirming
that prominences are far from magne-tostatic conditions. Tracking and
doppler measurements of prominence downflows find speeds of 5-15 km s-1
and imply that the trajectories are not strictly vertical. Active region
promi-nence studies find counter-streaming flows along horizontal
magnetic field lines with velocities of 20-30 km s-1 ; upflows,
downflow streams, and rotational flows have not been observed in
these systems. Active Region prominence field lines exhibit transverse
oscillations indicative of Alfv`n waves with periods of several minutes,
amplitudes of 1 Mm, and wavelengths of 250 Mm or more. These properties
are consistent with magnetic field strengths of 50 gauss or more at
typical prominence density conditions and carry enough energy to heat
the surrounding prominence/corona transition region (PCTR).
---------------------------------------------------------
Title: Small-scale oscillations in a quiescent prominence observed
by HINODE/SOT. Prominence oscillations
Authors: Ning, Z.; Cao, W.; Okamoto, T. J.; Ichimoto, K.; Qu, Z. Q.
2009A&A...499..595N Altcode:
Context: Investigations of the behavior of small-scale threads can
provide an alternative approach to studying prominence dynamics and
understanding its origin and nature. <BR />Aims: The behavior of
threads are analyzed in a quiescent prominence, including drifting
and both the horizontally and vertically oscillating motions. These
indicate waves in the solar prominence. <BR />Methods: We used the Hα
images at a setting wavelength of +0.076 Å. A quiescent prominence
was observed by HINODE/SOT on 2008 January 15 for about 3 h in
total. <BR />Results: Consistent with previous findings, prominences
show numerous thread-like structures. Some threads clearly exhibit both
vertically and horizontally oscillatory motions, while others are only
drifting. Complicated cases show both drifting and oscillatory motions
simultaneously. In the upper part of the prominence, the threads are
oscillating independently of each other. We find that three threads
oscillate with the same phase for at least two periods. The oscillations
seem to be strongly damped since they disappear after a few periods. The
maximum number of observed periods is 8 in our observations. In the
lower part of the prominence, however, the different threads have a
mixed character with the individual oscillatory motions unstable for
one entire period. Most oscillatory motions will disappear after a half
period or less, while the new oscillatory motions are excited nearby. A
5-min period is predominant, and the oscillating amplitudes show an
average value of ±3.5 km s<SUP>-1</SUP>. We find some upflows in the
spicule layer, and they appear to transport the mass from photosphere
(or spicules themselves) to the prominence. These upflows have an
average velocity amplitude of 0.8 km s<SUP>-1</SUP>. <BR />Conclusions:
The threads exhibit three distinct behaviors. The first is only
drifting, the second is typically oscillating, and the third shows
both characteristics. There are no substantial differences between
the periods of horizontally and vertically oscillating threads in
this prominence.
---------------------------------------------------------
Title: Waveform inversion for slip distribution of the 2006 Java
tsunami earthquake by using 2.5D finite-difference Green's function
Authors: Okamoto, T.; Takenaka, H.
2009EP&S...61E..17O Altcode:
We first incorporate the large effect of near-source heterogeneity on
teleseismic body waveforms in the inversion of the slip distribution
of the 2006 Java tsunami earthquake. We incorporate the effect by
computing the response of an assumed "2.5D" model structure of the
Java trench by a 2.5D finite-difference method. Based on a simulation
of inversion, we suggest that intense smearing is possible when we
apply 1D Green's functions in the analysis, and that it may obscure
the slip pattern. In the inversion of real data, we confirm macroscopic
features, such as a long duration (∼165 s) and a slow rupture velocity
(∼1.25 km/s). The region of the initial rupture is found to be
isolated from the eastern broad region in which we further identify
a heterogeneous slip distribution. Most of these regions are likely
to be at the sedimentary plate interface where the accreted sediment
and the subducting plate are in contact. In particular, the nearly
“isolated” feature of a shallow slip region suggests a possible
faulting in the shallowest part of the sedimentary plate interface
without being strongly enforced by the rupture propagated from the
deeper part of the fault. Such heterogeneity suggests a highly variable
frictional behavior at the sedimentary plate interface.
---------------------------------------------------------
Title: Prominence Formation Associated with an Emerging Helical
Flux Rope
Authors: Okamoto, Takenori J.; Tsuneta, Saku; Lites, Bruce W.; Kubo,
Masahito; Yokoyama, Takaaki; Berger, Thomas E.; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shibata, Kazunari; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
2009ApJ...697..913O Altcode: 2009arXiv0904.0007O
The formation and evolution process and magnetic configuration of
solar prominences remain unclear. In order to study the formation
process of prominences, we examine continuous observations of a
prominence in NOAA AR 10953 with the Solar Optical Telescope on
the Hinode satellite. As reported in our previous Letter, we find
a signature suggesting that a helical flux rope emerges from below
the photosphere under a pre-existing prominence. Here we investigate
more detailed properties and photospheric indications of the emerging
helical flux rope, and discuss their relationship to the formation of
the prominence. Our main conclusions are: (1) a dark region with absence
of strong vertical magnetic fields broadens and then narrows in Ca II
H-line filtergrams. This phenomenon is consistent with the emergence
of the helical flux rope as photospheric counterparts. The size of the
flux rope is roughly 30,000 km long and 10,000 km wide. The width is
larger than that of the prominence. (2) No shear motion or converging
flows are detected, but we find diverging flows such as mesogranules
along the polarity inversion line. The presence of mesogranules may
be related to the emergence of the helical flux rope. (3) The emerging
helical flux rope reconnects with magnetic fields of the pre-existing
prominence to stabilize the prominence for the next several days. We
thus conjecture that prominence coronal magnetic fields emerge in
the form of helical flux ropes that contribute to the formation and
maintenance of the prominence.
---------------------------------------------------------
Title: Effect of Near-Source Trench Structure on Teleseismic Body
Waveforms: AN Application of a 2.5D Fdm to the Java Trench
Authors: Okamoto, T.; Takenaka, H.
2009aogs...13..215O Altcode:
We study strong effect of near-source structure on teleseismic body
waveforms from two well-recorded aftershocks of the 2006 Java tsunami
earthquake. We assume a two-dimensional, heterogeneous model of the
Java trench structure on the basis of recent seismic surveys. We
compute synthetic waveforms by an efficient "2.5-dimensional" (2.5D)
finite-difference method. A "waveform relocation technique" which
combines a non-linear inversion of source parameters with a grid
search procedure is applied in order to correct possible systematic
bias in hypocentral parameters. Simulation of inversion shows that
the resolution of the source position obtained by using 2.5D Green's
functions is better than that for 1D Green's functions. The synthetic
waveforms obtained by the inversion of true data with 2.5D Green's
functions reproduce well the observed large later phases, and retrieved
moment tensors are similar to those of Global CMT. Thus, the effect of
the near-source structure can be reproduced by 2.5D model, and with
the 2.5D synthetics we can obtain improved source parameters at the
trench regions where only teleseismic data are available.
---------------------------------------------------------
Title: Chemical Abundance Patterns in the Local Dwarf Galaxies in
the CDM Universe
Authors: Nagashima, M.; Okamoto, T.
2008ASPC..399..475N Altcode:
We present chemical properties of dwarf galaxies in a semi-analytic
galaxy formation model. We find a good match with observations
of the Local dwarf spheroidals. The supernova feedback is a key to
understanding the different metal abundances of the Local Group dwarf
spheroidals from those associated with the Milky Way.
---------------------------------------------------------
Title: High Resolution Observations of Spicules with Hinode/SOT
Authors: Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Shimizu, T.;
Okamoto, T.; Tsuneta, S.; Tarbell, T.; Shine, R. A.
2008ASPC..397...27S Altcode:
High time cadence unprecedented images at the limb with Ca II H line
filtergraph from the Solar Optical Telescope (SOT) aboard Hinode
have revealed that a spicule consists of highly dynamic multi-threads
(typically twin) as thin as a few tenths of an arcsecond, and shows
prominent lateral movement or oscillation with rotation on its axis
during its life. This multi-thread structure and lateral motion indicate
that the spicules can be driven by magnetic reconnection at unresolved
spatial scales at their footpoints.
---------------------------------------------------------
Title: Galaxy Formation
Authors: Okamoto, T.
2008ASPC..393..111O Altcode: 2007arXiv0712.0086O
I review the current status of theoretical studies of galaxy
formation. I outline the importance of the physics of baryonic component
in galaxy formation by showing results obtained by using two major
tools, semi-analytical approaches and cosmological simulations. In
particular, I emphasize the role of feedback in galaxy formation and
discuss whether apparent conflicts between the standard theory of
structure formation, the cold dark matter model, and observations can
be solved by the feedback. I also discuss future prospects in numerical
simulations of galaxy formation.
---------------------------------------------------------
Title: Giant Chromospheric Anemone Jet Observed with Hinode and
Comparison with Magnetohydrodynamic Simulations: Evidence of
Propagating Alfvén Waves and Magnetic Reconnection
Authors: Nishizuka, N.; Shimizu, M.; Nakamura, T.; Otsuji, K.; Okamoto,
T. J.; Katsukawa, Y.; Shibata, K.
2008ApJ...683L..83N Altcode: 2008arXiv0810.3384N
Hinode discovered a beautiful giant jet with both cool and hot
components at the solar limb on 2007 February 9. Simultaneous
observations by the Hinode SOT, XRT, and TRACE 195 Å satellites
revealed that hot (~5 × 10<SUP>6</SUP> K) and cool (~10<SUP>4</SUP>
K) jets were located side by side and that the hot jet preceded the
associated cool jet (~1-2 minutes). A current-sheet-like structure
was seen in optical (Ca II H), EUV (195 Å), and soft X-ray emissions,
suggesting that magnetic reconnection is occurring in the transition
region or upper chromosphere. Alfvén waves were also observed with
Hinode SOT. These propagated along the jet at velocities of ~200
km s<SUP>-1</SUP> with amplitudes (transverse velocity) of ~5-15 km
s<SUP>-1</SUP> and a period of ~200 s. We performed two-dimensional MHD
simulation of the jets on the basis of the emerging flux-reconnection
model, by extending Yokoyama and Shibata's model. We extended the model
with a more realistic initial condition (~10<SUP>6</SUP> K corona) and
compared our model with multiwavelength observations. The improvement
of the coronal temperature and density in the simulation model allowed
for the first time the reproduction of the structure and evolution of
both the cool and hot jets quantitatively, supporting the magnetic
reconnection model. The generation and the propagation of Alfvén
waves are also reproduced self-consistently in the simulation model.
---------------------------------------------------------
Title: Emerging Helical Flux Rope Associated with Prominence Formation
Observed by Hinode
Authors: Okamoto, Takenori
2008AstHe.101..385O Altcode:
The new Japan/US/UK solar physics satellite Hinode enables the highest
resolution imaging of prominences as yet seen with a temporal uniformity
that allows long-hours of diffraction-limited movies and a capability of
photospheric vector magnetic field measurements. The author investigates
formation and evolution processes of active-region prominences with the
Solar Optical Telescope observations. Here a discovery about emergence
of a helical flux rope associated with prominence formation is reported
and the property of the helical flux rope is discussed.
---------------------------------------------------------
Title: Emergence of a helical flux rope and prominence formation
Authors: Okamoto, T. J.; Tsuneta, S.; Lites, B. W.; Kubo, M.; Yokoyama,
T.; Berger, T. E.; Ichimoto, K.; Katsukawa, Y.; Nagata, S.; Shibata,
K.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title,
A. M.
2008AGUSMSP43B..06O Altcode:
We report a discovery about emergence of a helical flux rope. The
episode may be related to the formation and evolution of an active
region prominence. Statistical studies by previous authors indicate that
numerous prominences have the inverse-polarity configuration suggesting
the helical magnetic configurations. There are two theoretical
models about formation of such a coronal helical magnetic field in
association with prominences: flux rope model and sheared-arcade
model. We have so far no clear observational evidence to support
either model. In order to find a clue about the formation of the
prominence, we had continuous observations of NOAA AR 10953 with the
SOT during 2007 April 28 to May 9. A prominence was located over the
polarity inversion line in the south-east of the main sunspot. These
observations provided us with a time series of vector magnetic fields
on the photosphere under the prominence. We found four new features:
(1) The abutting opposite-polarity regions on the two sides along
the polarity inversion line first grew laterally in size and then
narrowed. (2) These abutting regions contained vertically-weak,
but horizontally-strong magnetic fields. (3) The orientations of
the horizontal magnetic fields along the polarity inversion line on
the photosphere gradually changed with time from a normal- polarity
configuration to an inverse-polarity one. (4) The horizontal-magnetic
field region was blueshifted. These indicate that helical flux rope
emerges from below the photosphere into the corona along the polarity
inversion line under the prominence. We suggest that this supply of a
helical magnetic flux possibly into the corona is related to formation
and maintenance of active-region prominences.
---------------------------------------------------------
Title: Hinode SOT Observations of Solar Quiescent Prominence Dynamics
Authors: Berger, Thomas E.; Shine, Richard A.; Slater, Gregory L.;
Tarbell, Theodore D.; Title, Alan M.; Okamoto, Takenori J.; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Suematsu, Yoshinori; Tsuneta, Saku; Lites,
Bruce W.; Shimizu, Toshifumi
2008ApJ...676L..89B Altcode:
We report findings from multihour 0.2” resolution movies of
solar quiescent prominences (QPs) observed with the Solar Optical
Telescope (SOT) on the Hinode satellite. The observations verify
previous findings of filamentary downflows and vortices in QPs. SOT
observations also verify large-scale transverse oscillations in QPs,
with periods of 20-40 minutes and amplitudes of 2-5 Mm. The upward
propagation speed of several waves is found to be ~10 km s<SUP>-1</SUP>,
comparable to the sound speed of a 10,000 K plasma, implying that
the waves are magnetoacoustic in origin. Most significantly, Hinode
SOT observations reveal that dark, episodic upflows are common in
QPs. The upflows are 170-700 km in width, exhibit turbulent flow,
and rise with approximately constant speeds of ~20 km s<SUP>-1</SUP>
from the base of the prominence to heights of ~10-20 Mm. The upflows
are visible in both the Ca II H-line and Hα bandpasses of SOT. The new
flows are seen in about half of the QPs observed by SOT to date. The
dark upflows resemble buoyant starting plumes in both their velocity
profile and flow structure. We discuss thermal and magnetic mechanisms
as possible causes of the plumes.
---------------------------------------------------------
Title: Emergence of a Helical Flux Rope under an Active Region
Prominence
Authors: Okamoto, Takenori J.; Tsuneta, Saku; Lites, Bruce W.; Kubo,
Masahito; Yokoyama, Takaaki; Berger, Thomas E.; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shibata, Kazunari; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
2008ApJ...673L.215O Altcode: 2008arXiv0801.1956O
Continuous observations were obtained of NOAA AR 10953 with the Solar
Optical Telescope (SOT) on board the Hinode satellite from 2007 April
28 to May 9. A prominence was located over the polarity inversion
line (PIL) to the southeast of the main sunspot. These observations
provided us with a time series of vector magnetic fields on the
photosphere under the prominence. We found four features: (1) The
abutting opposite-polarity regions on the two sides along the PIL first
grew laterally in size and then narrowed. (2) These abutting regions
contained vertically weak but horizontally strong magnetic fields. (3)
The orientations of the horizontal magnetic fields along the PIL on
the photosphere gradually changed with time from a normal-polarity
configuration to an inverse-polarity one. (4) The horizontal magnetic
field region was blueshifted. These indicate that helical flux rope
was emerging from below the photosphere into the corona along the PIL
under the preexisting prominence. We suggest that this supply of a
helical magnetic flux to the corona is associated with evolution and
maintenance of active region prominences.
---------------------------------------------------------
Title: Giant chromospheric jet observed with Hinode and magnetic
reconnection model
Authors: Nishizuka, Naoto; Shimizu, Masaki; Nakamura, Tahei; Otsuji,
Kenichi; Okamoto, Takenori; Shibata, Kazunari; Katsukawa, Yukio
2008cosp...37.2239N Altcode: 2008cosp.meet.2239N
Heating of the solar chromosphere and corona is one of the long-standing
puzzles in astronomy and also a key to understand the Sun-Earth
connection through solar wind and EUV/X-ray radiation. A solar space
telescope mission Hinode revealed that solar chromosphere is much more
dynamic than had been thought and is full of tiny jets, which may be
a key to resolve the puzzle of chromospheric and coronalheating. It
has long been observed that H-alpha jets called surges often occur in
the chromosphere. They have been believed to be produced by magnetic
reconnection, which is an energy conversion mechanism from magnetic
energy into thermal and kinetic energies of plasma when anti-parallel
magnetic fields encounter and reconnect with each other. Hinode's
new chromospheric observations (with Calcium II H broad band filter)
revealed that jets are ubiquitous in the chromosphere and some of the
jets show evidence of magnetic reconnection. However, there have not
been simultaneous observations of the chromospheric jets at X-ray,
EUV, and Optical (at Calcium II H line) wavelengths until now. Here
we report first multi-wavelength observations of a chromospheric
jet with Solar Optical Telescope (SOT) and X-Ray Telescope (XRT)
on board Hinode and TRACE 195A filter. With its unprecedented high
quality instruments at both optical and X-rays, Hinode discovered a
beautiful, giant jet with both cool (104 K) and hot (5x106 K) components
at the solar limb. TRACE satellite also observed the same jet with
EUV telescope and revealed the existence of both hot (106 K) and cool
(unknown temperature) components. These data set are probably the best
multi-wavelength observations of solar jets until now. We also performed
magnetohydrodynamic simulation of the jet based on the reconnection
model and found that it can explain various observational facts very
well. It has often been argued that some of solar jets are produced by
magnetic reconnection, but previous observations had a limitation on
spatial and temporal resolutions and temperature coverage. Using these
new data and twodimensional magnetohydrodynamic simulations of the jet,
we showed, for the first time, how hot and cool jets are heated and
accelerated during the reconnection, including associated generation of
Alfvén waves. This jet formation dynamics would show a proto-tyep of
reconnection e model of solar jets and can be applied for other small
jets discovered by Hinode, which might heat the chromosphere and corona.
---------------------------------------------------------
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: Hinode SOT observations of plume upflows and cascading
downflows in quiescent solar prominences
Authors: Berger, T.; Shine, R.; Slater, G.; Tarbell, T.; Title, A.;
Lites, B.; Tsuneta, S.; Okamoto, T. J.; Ichimoto, K.; Katsukawa, Y.;
Sekii, T.; Suematsu, Y.; Shimizu, T.
2007AGUFMSH53A1065B Altcode:
We present several Hinode SOT filtergram movies of quiescent solar
prominences that show newly discovered "plume-like" upflows and
cascading "waterfall-like" downflows that persist for the entire
multi-hour duration of the observations. The flow speeds are on the
order of 10 km/sec with typical widths of 400-700 km. Preliminary
calculations show that if the upflows are buoyancy driven, the
associated thermal perturbation is on the order of 10,000 K, sufficient
to explain the dark appearance of the upflows in the interference
filter passbands. In addition we observe rotational vortices and
body oscillations within the prominences. These new observations
challenge current magnetostatic models of solar prominences by showing
that prominence plasmas are in constant motion, often in directions
perpendicular to the magnetic field lines proposed by the models. TRACE,
Hinode/EIS, and Hinode/XRT observations are used to investigate the
differential topology of the flows across temperature regimes.
---------------------------------------------------------
Title: Coronal Transverse Magnetohydrodynamic Waves in a Solar
Prominence
Authors: Okamoto, T. J.; Tsuneta, S.; Berger, T. E.; Ichimoto, K.;
Katsukawa, Y.; Lites, B. W.; Nagata, S.; Shibata, K.; Shimizu, T.;
Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title, A. M.
2007Sci...318.1577O Altcode: 2008arXiv0801.1958O
Solar prominences are cool 10<SUP>4</SUP> kelvin plasma clouds
supported in the surrounding 10<SUP>6</SUP> kelvin coronal plasma by
as-yet-undetermined mechanisms. Observations from Hinode show fine-scale
threadlike structures oscillating in the plane of the sky with periods
of several minutes. We suggest that these represent Alfvén waves
propagating on coronal magnetic field lines and that these may play
a role in heating the corona.
---------------------------------------------------------
Title: Triggering Mechanism for the Filament Eruption on 2005
September 13 in NOAA Active Region 10808
Authors: Nagashima, Kaori; Isobe, Hiroaki; Yokoyama, Takaaki; Ishii,
Takako T.; Okamoto, Takenori J.; Shibata, Kazunari
2007ApJ...668..533N Altcode: 2007arXiv0706.3519N
On 2005 September 13 a filament eruption accompanied by a halo coronal
mass ejection (CME) occurred in the most flare-productive active region,
NOAA 10808, in solar cycle 23. Using multiwavelength observations
before the filament eruption on September 13, we investigate the
processes leading to the catastrophic eruption. We find that the
filament slowly ascended at a speed of 0.1 km s<SUP>-1</SUP> over 2
days before the eruption. During slow ascension, many small flares were
observed close to the footpoints of the filament, where new magnetic
elements were emerging. On the basis of the observational facts, we
discuss the triggering mechanism leading to the filament eruption. We
suggest that the process toward the eruption is as follows. First,
a series of small flares played a role in changing the topology of
the loops overlying the filament. Second, the small flares gradually
changed the equilibrium state of the filament and caused the filament
to ascend slowly over 2 days. Finally, a C2.9 flare that occurred when
the filament was close to the critical point for loss of equilibrium
directly led to the catastrophic filament eruption right after it.
---------------------------------------------------------
Title: Examinations of the Relative Alignment of the Instruments
on SOT
Authors: Okamoto, T. J.; Katsukawa, Y.; Shimizu, T.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Tarbell, T. D.
2007ASPC..369...47O Altcode:
We report the results of the examination about the relative alignment
among the instruments on SOT. We employ a test data set obtained in the
natural sun-light test in May 2005, which has had a grid pattern over
the entire FOV. SOT has the filtergraph (FG) and the spectro-polarimeter
(SP). The FG consists of six broadband filter imagers (BFI) and six
narrowband filter imagers (NFI). We examined the displacements among
the images taken with different filters to an accuracy of better than
0.1 pixel corresponding to 0.02”. It is important to know relative
displacements and plate scales of these instruments for accurate
alignment of observational data. We note that the values measured in
our work are relative and it is needed to decide the absolute values
with another way.
---------------------------------------------------------
Title: High Resolution Observation of Spicules in Ca II H with
Hinode/SOT
Authors: Suematsu, Yoshinori; Katsukawa, Y.; Ichimoto, K.; Tsuneta, S.;
Okamoto, T.; Nagata, S.; Shimizu, T.; Tarbell, T.; Shine, R.; Title, A.
2007AAS...210.9411S Altcode: 2007BAAS...39..219S
High cadence observation with a Ca II H broadband filtergraph
(passband of 0.25 nm) of the Solar Optical Telescope (SOT) aboard
HINODE has revealed dynamical nature of solar limb spicules. Thanks to a
diffraction-limited and low-scattered light property of the instrument,
we can track the detailed evolution of individual spicules for the first
time with a spatial resolution of 0.2 arcsec. The spicules in Ca II
H are typically several arcsec tall and have multi-thread structure;
each threads are a few tenth of arcsec wide. It should be stressed
that most spicules do not show a simple up-and-down motion along a
rigid path line. They start with bright structure emanating from Ca II
H bright region, get widen and diffused with time and ascent, showing
expansion with lateral or even helical motion in tall events. Small and
short lived spicules tend to fade out after ascent. We will present
new findings of spicule dynamics in different magnetic environments
and discuss about long standing controversy of its motion and evolution.
---------------------------------------------------------
Title: Discovery Of Cool Cloud-like Structures In The Corona With
Hinode Solar Optical Telescope
Authors: Okamoto, Takenori; Tsuneta, S.; Katsukawa, Y.; Ichimoto,
K.; Suematsu, Y.; Shimizu, T.; Nagata, S.; Shibata, K.; Tarbell, T.;
Shine, R.; Berger, T.; Lites, B.; Myers, D.
2007AAS...210.9426O Altcode: 2007BAAS...39..221O
A solar observation satellite Hinode (Japanese for sun rise) was
launched in September 2006.Hinode carried 3 advanced solar telescopes,
visible light telescope, EUV imaging spectrometer, and X-ray telescope
to simultaneously observe the photosphere, chromosphere, transition
region, and corona. In the performance verification phase of the Hinode
spacecraft with its telescopes, we observed an active region AR10921
near the west limb of the solar disk on November 9 2006. At this point,
we planned to observe spicules on the limb with a broadband filter
dedicated to Ca II H line (3968A). Ca II-H emission line (3968A) comes
from plasma with temperature of approx. 10(4) K, which is much lower
than the coronal temperature of 10(6-7) K. In addition to spectacular
spicules, we find a large cloud-like structure located 10,000-20,000
km above the limb. The cloud has a very complex fine structure with
dominant horizontal thread-like structure. Some features are moving
horizontally and also have clear vertical oscillatory motions. The
periods and amplitudes of these oscillations are 130-250 seconds and
200-850 km, respectively. The vertical oscillatory motion sometimes
has a coherence length as long as 16,000 km. We conclude that from
various observational features this vertical oscillation is a signature
of Alfven waves propagating along the horizontal magnetic fields. We
will discuss their origin and implications.
---------------------------------------------------------
Title: e-SpaceCam : Development of a Remote Cooperative Observation
System for Telescopes with P2P(Peer-to-Peer) Agent Network Using
Location Information
Authors: Okamoto, T.; Kato, S.
2006IAUSS...2E.100O Altcode:
Introduction. It is very important for astronomical study and
observation to operate a telescope by oneself. However, there are
various problems such as the cost and location to use the telescope. The
most promising technology that solves those problems is a remote
telescope system. However, an old and usual remote telescope system
was Server & Client type system. Therefore, the remote telescope
owners and the remote telescope users have to manage their telescope by
themselves. Especially, enough knowledge of the network, the time and
cost to control the telescopes are necessary for the remote telescope
owners. So it is difficult for general telescope owners to offer their
telescopes as remote telescopes. We are developing a new environment
that manages the remote telescopes. The environment connects users
who want to use telescopes with the telescopes connected with PC
(RS232c, USB, etc) all over the world. Our goal is to develop an
environment by which users are able to cooperate and to share a lot
of telescopes and the observational data for the education and the
observation. Methods. Our remote telescope system is established on
the P2P agent network. Various agents execute tasks allocated instead
of users. (to retrieve, to connect, to control, etc) So users needn't
do irksome tasks. Our system mounts LL-Net (Location-based Logical
Network). LL-Net can manage user nodes on the P2P network by a key
made based on location information. Our system key is allocated by the
longitude and latitude. Results and Discussion. Users can retrieve
remote telescopes that suit them and connect with them. Telescope
owners can make their telescopes remote telescopes without troublesome
jobs. Logical network constructed with LL-Net enables telescopes which
the user hoped to be retrieved efficiently. We investigate more suitable
use of LL-Net for a remote telescope. We plan to realize to share the
observational data and to make remote telescopes cooperate.
---------------------------------------------------------
Title: The metal enrichment of galaxies and galaxy clusters in the
cold dark matter universe
Authors: Nagashima, M.; Lacey, C. G.; Okamoto, T.; Baugh, C. M.;
Frenk, C. S.; Cole, S.
2006AIPC..847..442N Altcode:
We investigate the metal enrichment due to type II and Ia supernovae
using semi-analytic models of galaxy formation based on the cold dark
matter model of the Universe.
---------------------------------------------------------
Title: Simulations of SH wave scattering due to cracks by the 2-D
finite difference method
Authors: Suzuki, Y.; Kawahara, J.; Okamoto, T.; Miyashita, K.
2006EP&S...58..555S Altcode:
We simulate SH wave scattering by 2-D parallel cracks using the finite
difference method (FDM), instead of the popularly used boundary integral
equation method (BIEM). Here special emphasis is put on simplicity;
we apply a standard FDM (fourth-order velocity-stress scheme with a
staggered grid) to media in cluding traction-freecracks, which are
expressed by arrays of grid points with zero traction. Two types of
accuracy tests based oncomparison with a reliable BIEM, suggest that
the present method gives practically sufficient accuracy, except for
the wavefields in the vicinity of cracks, which can be well handled
if the second-order FDM is used instead. As an application of this
method, we also simulate wave propagation in media with randomly
distributed cracks of the same length. We experimentally determine
the attenuation and velocity dispersion induced by scattering from
the synthetic seismograms, using a waveform averaging technique. It is
shown that the results are well explained by a theory based on the Foldy
approximation for crack densities of up to about 01. The presence of a
free surface does not affect the validity of the theory. A preliminary
experiment also suggests that the validity will not change even for
multi-scale cracks.
---------------------------------------------------------
Title: Filament Oscillations and Moreton Waves Associated with
EIT Waves
Authors: Okamoto, Takenori J.; Nakai, Hidekazu; Keiyama, Atsushi;
Narukage, Noriyuki; UeNo, Satoru; Kitai, Reizaburo; Kurokawa, Hiroki;
Shibata, Kazunari
2004ApJ...608.1124O Altcode:
In this paper we compare EUV Imaging Telescope (EIT) waves with
simultaneous phenomena seen in Hα in order to address the question
of what an EIT wave is. We surveyed the events associated with solar
flares larger than GOES M-class in 1999-2002. The Hα data are taken
with the Flare-monitoring Telescope (FMT) at the Hida Observatory
of Kyoto University. Among 14 simultaneous observations of EIT
waves and Hα, 11 were found to have filament eruptions, three were
associated with Moreton waves, and one was found to have only filament
oscillations. This shows that we cannot see clear wave fronts in
Hα even if EIT waves exist, but that it is possible to recognize
invisible waves by means of filament oscillations. The nature of
filament oscillations and Moreton waves associated with EIT waves is
examined in detail, and it is found that the filament oscillations
were caused by EIT waves.
---------------------------------------------------------
Title: Morphological Evolution of Cluster Galaxies
Authors: Okamoto, T.; Nagashima, M.
2003RMxAC..17...98O Altcode:
We investigate environmental effects on morphology evolution of bright
cluster galaxies (L > L[*]) in a Lambda -dominated cold dark matter
universe using a combination of N-body simulations and semi-analytic
(SA) model. We normalize our model parameters to reproduce the
properties of local galaxies, and then we study how ram pressure
stripping (RPS) and small starburst triggered by a minor merger (minor
burst) affect the morphologies of cluster galaxies. We find that the
morphological fraction of galaxies with intermediate bulge-to-total
luminosity ratios (B/Ts) cannot be reproduced and the effect of the
RPS is negligible unless we consider the minor burst.
---------------------------------------------------------
Title: Cloud mass function in a gas rich dwarf galaxy
Authors: Saitou, T.; Habe, A.; Okamoto, T.
2003IAUS..208..441S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Substructure of Galaxy Clusters and Cosmological Constant
Authors: Suwa, T.; Habe, A.; Yoshikawa, K.; Okamoto, T.
2003IAUS..208..447S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Environmental Effects on Evolution of Cluster Galaxies
Authors: Okamoto, T.; Nagashima, M.
2003IAUS..208..435O Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Full waveform moment tensor inversion by reciprocal finite
difference Green's function
Authors: Okamoto, T.
2002EP&S...54..715O Altcode:
We study two important aspects of the waveform moment tensor inversion
for the shallow earthquakes in the subduction region: the effect of
the intense lateral inhomogeneity in the structure, and the strategy
to invert the waveform data for the focal mechanisms. For the first
aspect, using a forward finite difference modeling, we demonstrate
that the effect of the inhomogeneity is quite large on the surface
waves with a period of about 20s, and the current knowledge on the
subduction region structure is practically effective in reproducing
the characteristics in the observed waveforms. For the second aspect,
we develop a reciprocal moment tensor inversion method that can generate
the Green's functions for a large quantity of source locations (19,200
in this study) in a realistic inhomogeneous structure by only three
finite difference calculations per a single station. The inversion with
a grid search scheme result in a reasonable source location, moment
tensor and fit of the waveforms using data from only two stations. The
constraint on the epicenter in the "transverse" direction is found
to be somewhat weak in the case of single-station inversions, but the
two-station inversion improves the constraint.
---------------------------------------------------------
Title: Study of Multiphase Interstellar Matter in a Gas Rich Dwarf
Galaxy
Authors: Saitou, T.; Okamoto, T.; Habe, A.
2002aprm.conf..289S Altcode:
Because of limitations in numerical resolution of cosmological
galaxy formation simulations, previous studies can not consider
multiphase structures of the ISM which should strongly affect galaxy
properties. For instance, the size of disk galaxies formed in numerical
simulations is smaller than that of observed galaxies. <P />In this
study, by increasing the numerical resolution, we take into account the
multiphase structure of ISM produced by radiative cooling, UV heating
and supernova feedback. We simulate evolutions of multiphase ISM in
a gas-rich dwarf galaxy, and obtain various aspects corresponding to
gas-rich dwarf galaxies, especially, giant molecular cloud associations
and superbubbles produced by subsequent supernovae. <P />The cloud
mass function in our models has a power law form with index α ∼-1.7
which agrees well with the observed values α ∼ -1.5 to -2.0. The
bubble size approximately corresponds to the scale height of a warm
(10<SUP>3</SUP> K< T<10<SUP>4</SUP> K) disk. <P />Our numerical
results show that feedback by SNe plays a very important role in
regulation of ISM evolution in a gas-rich dwarf galaxy.
---------------------------------------------------------
Title: Properties of Galaxies in Rich Clusters
Authors: Okamoto, T.; Nagashima, Masahiro
2001ASPC..222..149O Altcode: 2001pgf..conf..149O
No abstract at ADS
---------------------------------------------------------
Title: Formation and evolution of galactic halos in a cluster
of galaxies
Authors: Habe, A.; Okamoto, T.
2000NuPhS..80C0907H Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Galaxy Distribution in Clusters of Galaxies
Authors: Okamoto, T.; Yachi, S.; Habe, A.
1999IAUS..183..262O Altcode:
beta-discrepancy have been pointed out from comparison of optical
and X-ray observations of clusters of galaxies. To examine physical
reason of beta-discrepancy, we use N-body simulation which contains
two components, dark particles and galaxies which are identified
by using adaptive-linking friend of friend technique at a certain
red-shift. The gas component is not included here, since the gas
distribution follows the dark matter distribution in dark halos (Jubio
F. Navarro, Carlos S. Frenk and Simon D. M. White 1995). We find that
the galaxy distribution follows the dark matter distribution, therefore
beta-discrepancy does not exist, and this result is consistent with
the interpretation of the beta-discrepancy by Bahcall and Lubin (1994),
which was based on recent observation.
---------------------------------------------------------
Title: Formation and Evolution of Galactic Halos in Clusters of
Galaxies
Authors: Okamoto, T.; Habe, A.
1999ASSL..240...57O Altcode: 1999numa.conf...57O
No abstract at ADS
---------------------------------------------------------
Title: Formation and evoluton of galactic halos in a cluster of
galaxies
Authors: Habe, A.; Okamoto, T.
1998tx19.confE.516H Altcode:
We investigate time evolution both of a rich cluster of galaxies and its
member galactic halos in the standard cold dark matter (SCDM) universe,
using high resolution N-body simulations. In our numerical results,
we find out several hundreds of galactic halos inside of the cluster's
virial radius by using the adaptive friends-of-friends algorithm. A
number of halos formed at higher redshift have been tidally disrupted
till z = 0 in the cluster. Therefore we improve a method of deriving
merging history trees of galaxies by taking account of tidally stripped
galaxies. We find that at high redshift (z > 3), the fraction of
merging galaxies in the cluster formation region is higher than that of
the field. After z ~3, however, it rapidly decreases. The fraction of
the strongly stripped galaxies in the cluster increases with time from
z ~= 0.5. At z = 0 a clear correlation appears between the fraction
and the distance from the center of the cluster.
---------------------------------------------------------
Title: Optical Spectra and Semi-Empirical Model of a White-Light Flare
Authors: Ding, M. D.; Fang, C.; Gan, W. Q.; Okamoto, T.
1994ApJ...429..890D Altcode:
We derive a semi-empirical atmospheric model for the 1979 September 19
white-light flare (WLF), based on the observed continuum at 3590 to
3990 A and the Ca II K line profile. The model has a strongly heated
photosphere, but has a chromospheric structure within the range of
ordinary flare models. According to this model, the white-light
continuum is mainly produced by the H<SUP>-</SUP> emission in
the photosphere. A negative Balmer jump appears in the continuum
spectrum (without considering the line blanketing effect), due to the
Balmer continuum absorption in the chromosphere. From the spectral
features and model results, the traditional heating mechanisms that
are proposed to transport the energy from the corona down to deep
layers seem insufficient to fully explain the photospheric heating
for this WLF. The heating energy may originate within the photosphere
itself. The possible energy release processes are also discussed,
but a satisfactory explanation needs further quantitative studies.
---------------------------------------------------------
Title: Doppler Shifts of Metallic Lines for a White-Light Flare
Authors: Ding, M. D.; Fang, C.; Okamoto, T.
1994SoPh..149..143D Altcode:
In this paper we investigate the Doppler shifts of the metallic lines
for a 3B white-light flare on September 19, 1979. The results show
that there is no systematic shift at the line center, while there may
appear some asymmetry at the line wing. A possible heating process of
this flare is proposed to interpret the observed spectral features.
---------------------------------------------------------
Title: Construction of magneto-otical filters and their application
to solar observations.
Authors: Miyazaki, H.; Sakurai, T.; Okamoto, T.; Ichimoto, K.;
Miyashita, M.; Koyama, K.; Sakata, A.; Wada, S.
1993RNAOJ...2..417M Altcode: 1993RNOAJ...2..417M
The magneto-optical filter (MOF) is made of a transparent cell placed in
a strong magnetic field. The cell contains the vapor of material like
sodium. By utilizing the magneto-optical effect near the wavelength
of a spectral line, MOF provides a very narrow and stable passband,
which is particularly suitable for helioseimological observations. The
cell becomes less transparent as it ages, and can only be used in
observations for several months. The authors' aim was to construct a
filter that can be continuously used for several years without losing
the sodium vapor at the cell wall. This was achieved by heating the
whole cell to about 200°C.
---------------------------------------------------------
Title: Spectral analysis of the 3B flare on September 19, 1979:
asymmetries and shifts of metallic lines
Authors: Ding, Ming-de; Fang, Cheng; Okamoto, T.
1993ChA&A..17..413D Altcode:
The asymmetries and Doppler shifts of metallic lines of the 3B flare
on September 19, 1979 are investigated in this paper. The results
show that: (1) red asymmetries dominate in strong metallic lines,
but blue asymmetries also exist in some weak lines; (2) the maximum of
the line asymmetry always precedes the maximum of the line intensity;
(3) the blue asymmetry occurs generally in the early phase, and can
occasionally turn to a red one in the later phase; and (4) the line
center has no obvious shift, regardless of the line asymmetry. It is
proposed that, the mass motions around the temperature minimum region
caused by the impulsive heating or the propagation of the chromospheric
condensation can explain these observational results. The study on
metallic lines has an auxiliary help for understanding the dynamic
process in the lower atmosphere of solar flares.
---------------------------------------------------------
Title: Spectral analysis of the 3B flare on September 19, 1979:
asymmetry and Doppler shift of the metal lines.
Authors: Ding, Mingde; Fang, Cheng; Okamoto, T.
1993AcApS..13..245D Altcode:
The asymmetry and Doppler shift of metal lines of the 3B flare on
September 19, 1979 are investigated. The results show that: (1) red
asymmetries dominate in strong metal lines, but blue asymmetries also
exist in some weak lines; (2) the maximum of the line asymmetry always
precedes the maximum of the line intensity; (3) the blue asymmetry
occurs generally in the early phase and can turn to a red one in the
later phase; and (4) the line center has no obvious shift, regardless
of the line asymmetry. It is proposed that the mass motions around
the temperature minimum region caused by the impulsive heating or
the propagation of the chromospheric condensation can explain these
observational results. The study on metal lines can help understanding
the dynamic process in the lower atmosphere of solar flares.
---------------------------------------------------------
Title: Solar Flare Telescope project.
Authors: Ichimoto, K.; Sakurai, T.; Hiei, E.; Nishino, Y.; Shinoda, K.;
Noguchi, M.; Imai, H.; Irie, M.; Miyashita, M.; Tanaka, N.; Kumagai,
K.; Sano, I.; Suematsu, Y.; Okamoto, T.; Miyazaki, H.; Fukushima,
H.; Yose, Y.; Zhao, Z. W.
1993RNAOJ...1..375I Altcode: 1993RNOAJ...1..375I
The Solar Flare Telescope was built at Mitaka in 1989. This instrument
comprises four telescopes which observe (1) Hα images, (2) continuum
images, (3) vector magnetic fields, and (4) Doppler velocities,
respectively. The instrument aims at the study of energy build-up
and energy release in solar flares, in cooperation with the Solar-A
satellite (Yohkoh). The Solar Flare Telescope has been in operation
since 1990 December.
---------------------------------------------------------
Title: Semi-empirical model of the white light flare on September
19, 1979.
Authors: Fang, Cheng; Ding, Mingde; Okamoto, T.; Gan, Weiqun
1993ScChA..36..217F Altcode:
The intensities of the continuum emission and the Ca II Ka line of the
white light flare on Sep 19, 1979 are measured and analyzed. Their
variations with time are given. It is indicated that the continuum
emission of this flare appeared in the early impulsive phase and
lasted for about 5 - 6 min, with the time of maximum intensity 2 -
3 min earlier than that for the microwave radio burst. Based on the
non-LTE theory, a semi-empirical model at a time with the continuum
emission being relatively intensive is presented. The results show that
the temperature in the flare photosphere is increased by 150 - 250K,
and that the continuum emission is produced mainly by the negative
hydrogen ion.
---------------------------------------------------------
Title: Ca ii K line asymmetries in two well-observed solar flares
of October 18, 1990
Authors: Fang, C.; Hiei, E.; Okamoto, T.
1991SoPh..135...89F Altcode:
Two-dimensional evolutions of two flares of October 18, 1990 have been
well observed in the CaII K line with a CCD camera at Norikura station
of National Astronomical Observatory in Japan. There are two common
characteristics for the flares: 3 ∼- 5 min before the impulsive phase,
the heating already begins at the footpoints of the flares, but no
asymmetry in line emission has been detected. After the onset of the
impulsive phase, CaII K line emission at the footpoints shows strong
red asymmetry, with the maximum asymmetry occurring at the same time as
the peak of the radio bursts. The maximum downward velocity is about
30 ∼ 50 km s<SUP>−1</SUP>. For flare 1, blue and red asymmetries
were observed in two sides of the footpoint area. They developed and
attained a maximum nearly at the same time and the inferred Doppler
velocities are comparable (30 ∼ 40 km s<SUP>−1</SUP>). This implies
that two mass jets started from a small region and ejected along a
loop but in opposite directions with roughly equivalent momentum. A
possible mechanism has been discussed.
---------------------------------------------------------
Title: Thermal design of a superfluid helium dewar for infrared
telescope on-board space flyer unit
Authors: Fujii, G.; Hasui, T.; Hama, K.; Okamoto, T.; Machida, T.;
Murakami, M.; Matsumoto, T.; Okuda, H.; Kyoya, M.
1988tcls.rept..407F Altcode:
The Infrared Telescope in Space (IRTS) onboard Space Flyer Unit is
cooled down to 1.8 K by stored superfluid helium, allowing spectroscopic
observation even in far infrared regions. The cooled mission life time
is longer than several weeks. Minimization of heat leak to the lowest
temperature level is one of the primary design goals for the maximum
life time. The superfluid helium management at the launching site and
also in the zero-g situation should also be well planned.
---------------------------------------------------------
Title: Latitude distribution of the green corona for the period 1951
- 1985.
Authors: Okamoto, T.
1986TokRe..20..547O Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Facular limb-darkening functions for irradiance modeling.
Authors: Hirayama, T.; Okamoto, T.; Hudson, H. S.
1984NASCP2310...59H Altcode: 1984siva.work...59H
The limb-darkening function of faculae is an important factor in
estimating facular contributions to solar irradiance variations. The
authors review the existing photometric data and generate a synthetic
limb-darkening function for faculae, which is then compared with the
limb-darkening functions currently in use for irradiance modeling. It is
found that the excess facular flux ranges from 0.017 to 0.0349 of the
solar photospheric flux for the various representations. The present
limitation appears to be the lack of comprehensive photometric data.
---------------------------------------------------------
Title: Polarimetry with the coronograph of the Norikura
Observatory. II.
Authors: Shimizu, I.; Okamoto, T.
1984TokRe..20..240S Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Observation of the flare of 12 June 1982 by Norikura
coronagraph and Hinotori
Authors: Hiei, E.; Okamoto, T.; Tanaka, K.
1983SoPh...86..185H Altcode:
Flare activity was observed near the limb with two coronagraphs at the
Norikura Solar Observatory and the Soft X-ray Crystal Spectrometer
(SOX) aboard HINOTORI. A prominence activation occurred and then
Hα brightenings were seen on the disk near the prominence. The
prominence became very bright and its electron density increased to
10<SUP>12.8</SUP> cm<SUP>−3</SUP> in 1/2 hour. Loop prominence systems
appeared above the Hα brightenings about half an hour after the onset
of the flare, and were observed in the coronal lines CaXV 5694Å,
FeXIV 5303Å, and FeX 6374Å. Shifted and asymmetric profiles of the
emission line of 5303Å were sometimes observed, and turbulent phenomena
occurred even in the thermal phase. The energy release site of the
flare at the onset would be lower than 20 000 km above the solar limb.
---------------------------------------------------------
Title: Preliminary Observation of Missing Energy Flux of Sunspot
Authors: Hirayama, T.; Okamoto, T.
1981SoPh...73...37H Altcode:
We have searched for the missing energy flux of the sunspot by measuring
white-light photographs over the region around the sunspots exceeding
ten times of the diameter of spots. It was found that the excess
brightness amounts to 0.3-0.8% of the local continuum intensity
immediately beyond the penumbra and smoothly decrease to zero at
the edge of our inspected radii of 130 000-160000km. This result
suggests that the flux deficit in sunspots of the order of 30% over
the umbra-penumbra is roughly the same as the excess flux found in
the very large surrounding region which includes photospheric facular
contributions. Among nineteen spots fourteen showed this extended bright
ring. Narrow band photoelectric scans revealed that the excess radiation
originates in the continuum, not from weakened absorption lines.
---------------------------------------------------------
Title: Improvement of a visual photometer for measuring coronal
line intensities.
Authors: Miyazaki, H.; Okamoto, T.; Fukushima, H.
1981TokRe..19..532M Altcode:
No abstract at ADS
---------------------------------------------------------
Title: Helium Abundance from Optical Spectra of Quiescent Prominences.
Authors: Hirayama, T.; Nakagomi, Y.; Okamoto, T.
1979phsp.coll...48H Altcode: 1979phsp.conf...48H; 1979IAUCo..44...48H
The solar helium abundance is determined from observations of 11
quiescent prominences with a 25-cm coronagraph. The He/H abundance
ratio is found to be 16% + or - 4%. This corresponds to a value of
11.2 + or - 0.1 on the logarithmic scale where the hydrogen abundance
is set equal to 12.
---------------------------------------------------------
Title: Energy Flows of Extensive Air Showers near Sea Level (Abstract)
Authors: Jogo, N.; Kameda, T.; Maeda, T.; Mizushima, K.; Okamoto, T.
1977ICRC....8...24J Altcode: 1977ICRC...15h..24J
No abstract at ADS
---------------------------------------------------------
Title: Measurement of photographic density of neutral filters.
Authors: Okamoto, T.
1974TokRe..17...40O Altcode:
No abstract at ADS
---------------------------------------------------------
Title: A photographic measurement of filter with a densitometer.
Authors: Okamoto, T.
1970TokRe..15..188O Altcode:
No abstract at ADS
