Author name code: tsuneta
ADS astronomy entries on 2022-09-14
author:"Tsuneta, Saku"
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Title: Comparison of Scattering Polarization Signals Observed by
CLASP: Possible Indication of the Hanle Effect
Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.;
Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa,
Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.;
Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.;
Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso
Sainz, R.; De Pomtieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.
Bibcode: 2019ASPC..526..305I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP; Kano et
al. 2012; Kobayashi et al. 2012; Kubo et al. 2014) observed, for the
first time, the linear polarization produced by scattering processes
in the hydrogen Lyman-α (121.57 nm) and Si III (120.56 nm) lines of
the solar disk radiation. The complexity of the observed scattering
polarization (i.e., conspicuous spatial variations in Q/I and U/I
at spatial scales of 10″-20″ and the absence of center-to- limb
variation at the Lyman-α center; see Kano et al. 2017) motivated us
to search for possible hints of the operation of the Hanle effect by
comparing: (a) the Lyman-α line center signal, for which the critical
field strength (BH) for the onset of the Hanle effect is
53 G, (b) the Lyman-α wing, which is insensitive to the Hanle effect,
and (c) the Si III line, whose BH = 290 G. We focus on four
regions with different total unsigned photospheric magnetic fluxes
(estimated from SDO/HMI observations), and compare the corresponding
U/I spatial variations in the Lyman-α wing, Lyman-α center, and Si III
line. The U/I signal in the Lyman-α wing shows an antisymmetric spatial
distribution, which is caused by the presence of a bright structure in
all the selected regions, regardless of the total unsigned photospheric
magnetic flux. In an internetwork region, the Lyman-α center shows an
antisymmetric spatial variation across the selected bright structure,
but it does not show it in other more magnetized regions. In the Si III
line, the spatial variation of U/I deviates from the above-mentioned
antisymmetric shape as the total unsigned photospheric magnetic flux
increases. We argue that a plausible explanation of this differential
behavior is the operation of the Hanle effect. This work, presented
in an oral contribution at this Workshop, has been published on The
Astrophysical Journal (Ishikawa et al. 2017).
Title: CLASP Constraints on the Magnetization and Geometrical
Complexity of the Chromosphere-Corona Transition Region
Authors: Trujillo Bueno, J.; Štěpán, J.; Belluzzi, L.; Asensio
Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Ishikawa,
R.; Kano, R.; Winebarger, A.; Auchère, F.; Narukage, N.; Kobayashi,
K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...866L..15T
Altcode: 2018arXiv180908865T
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
suborbital rocket experiment that on 2015 September 3 measured
the linear polarization produced by scattering processes in the
hydrogen Lyα line of the solar disk radiation. The line-center
photons of this spectral line radiation mostly stem from the
chromosphere-corona transition region (TR). These unprecedented
spectropolarimetric observations revealed an interesting surprise,
namely that there is practically no center-to-limb variation (CLV) in
the Q/I line-center signals. Using an analytical model, we first show
that the geometric complexity of the corrugated surface that delineates
the TR has a crucial impact on the CLV of the Q/I and U/I line-center
signals. Second, we introduce a statistical description of the solar
atmosphere based on a 3D model derived from a state-of-the-art radiation
magnetohydrodynamic simulation. Each realization of the statistical
ensemble is a 3D model characterized by a given degree of magnetization
and corrugation of the TR, and for each such realization we solve the
full 3D radiative transfer problem taking into account the impact
of the CLASP instrument degradation on the calculated polarization
signals. Finally, we apply the statistical inference method presented
in a previous paper to show that the TR of the 3D model that produces
the best agreement with the CLASP observations has a relatively weak
magnetic field and a relatively high degree of corrugation. We emphasize
that a suitable way to validate or refute numerical models of the upper
solar chromosphere is by confronting calculations and observations
of the scattering polarization in ultraviolet lines sensitive to the
Hanle effect.
Title: A Statistical Inference Method for Interpreting the CLASP
Observations
Authors: Štěpán, J.; Trujillo Bueno, J.; Belluzzi, L.; Asensio
Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Kano, R.;
Winebarger, A.; Auchère, F.; Ishikawa, R.; Narukage, N.; Kobayashi,
K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...865...48S
Altcode: 2018arXiv180802725S
On 2015 September 3, the Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) successfully measured the linear polarization produced by
scattering processes in the hydrogen Lyα line of the solar disk
radiation, revealing conspicuous spatial variations in the Q/I and U/I
signals. Via the Hanle effect, the line-center Q/I and U/I amplitudes
encode information on the magnetic field of the chromosphere-corona
transition region, but they are also sensitive to the three-dimensional
structure of this corrugated interface region. With the help of a simple
line-formation model, here we propose a statistical inference method
for interpreting the Lyα line-center polarization observed by CLASP.
Title: Current State of UV Spectro-Polarimetry and its Future
Direction
Authors: Ishikawa, Ryohko; Sakao, Taro; Katsukawa, Yukio; Hara,
Hirohisa; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito;
Auchere, Frederic; De Pontieu, Bart; Winebarger, Amy; Kobayashi,
. Ken; Kano, Ryouhei; Narukage, Noriyuki; Trujillo Bueno, Javier;
Song, Dong-uk; Manso Sainz, Rafael; Asensio Ramos, Andres; Leenaarts,
Jorritt; Carlsson, Mats; Bando, Takamasa; Ishikawa, Shin-nosuke;
Tsuneta, Saku; Belluzzi, Luca; Suematsu, Yoshinori; Giono, Gabriel;
Yoshida, Masaki; Goto, Motoshi; Del Pino Aleman, Tanausu; Stepan,
Jiri; Okamoto, Joten; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Champey,
Patrick; Alsina Ballester, Ernest; Casini, Roberto; McKenzie, David;
Rachmeler, Laurel; Bethge, Christian
Bibcode: 2018cosp...42E1564I
Altcode:
To obtain quantitative information on the magnetic field in low beta
regions (i.e., upper chromosphere and above) has been increasingly
important to understand the energetic phenomena of the outer
solar atmosphere such as flare, coronal heating, and the solar wind
acceleration. In the UV range, there are abundant spectral lines that
originate in the upper chromosphere and transition region. However,
the Zeeman effect in these spectral lines does not give rise to easily
measurable polarization signals because of the weak magnetic field
strength and the larger Doppler broadening compared with the Zeeman
effect. Instead, the Hanle effect in UV lines is expected to be a
suitable diagnostic tool of the magnetic field in the upper atmospheric
layers. To investigate the validity of UV spectro-polarimetry and
the Hanle effect, the Chromospheric Lyman-Alpha Spectro-Polarimeter
(CLASP), which is a NASA sounding- rocket experiment, was launched at
White Sands in US on September 3, 2015. During its 5 minutes ballistic
flight, it successfully performed spectro-polarimetric observations
of the hydrogen Lyman-alpha line (121.57 nm) with an unprecedentedly
high polarization sensitivity of 0.1% in this wavelength range. CLASP
observed the linear polarization produced by scattering process in VUV
lines for the first time and detected the polarization signals which
indicate the operation of the Hanle effect. Following the success
of CLASP, we are confident that UV spectro-polarimetry is the way
to proceed, and we are planning the second flight of CLASP (CLASP2:
Chromospheric LAyer SpectroPolarimeter 2). For this second flight we
will carry out spectro-polarimetry in the Mg II h and k lines around
280 nm, with minimum modifications of the CLASP1 instrument. The linear
polarization in the Mg II k line is induced by scattering processes and
the Hanle effect, being sensitive to magnetic field strengths of 5 to 50
G. In addition, the circular polarizations in the Mg II h and k lines
induced by the Zeeman effect can be measurable in at least plage and
active regions. The combination of the Hanle and Zeeman effects could
help us to more reliably infer the magnetic fields of the upper solar
chromosphere. CLASP2 was selected for flight and is being developed for
launch in the spring of 2019.Based on these sounding rocket experiments
(CLASP1 and 2), we aim at establishing the strategy and refining the
instrument concept for future space missions to explore the enigmatic
atmospheric layers via UV spectro-polarimetry.
Title: Influence of the Atmospheric Model on Hanle Diagnostics
Authors: Ishikawa, Ryohko; Uitenbroek, Han; Goto, Motoshi; Iida,
Yusuke; Tsuneta, Saku
Bibcode: 2018SoPh..293...74I
Altcode:
We clarify the uncertainty in the inferred magnetic field vector via the
Hanle diagnostics of the hydrogen Lyman-α line when the stratification
of the underlying atmosphere is unknown. We calculate the anisotropy of
the radiation field with plane-parallel semi-empirical models under the
nonlocal thermal equilibrium condition and derive linear polarization
signals for all possible parameters of magnetic field vectors based on
an analytical solution of the atomic polarization and Hanle effect. We
find that the semi-empirical models of the inter-network region
(FAL-A) and network region (FAL-F) show similar degrees of anisotropy
in the radiation field, and this similarity results in an acceptable
inversion error (e.g., ∼40 G instead of 50 G in field strength and
∼100∘ instead of 90∘ in inclination) when
FAL-A and FAL-F are swapped. However, the semi-empirical models of FAL-C
(averaged quiet-Sun model including both inter-network and network
regions) and FAL-P (plage regions) yield an atomic polarization that
deviates from all other models, which makes it difficult to precisely
determine the magnetic field vector if the correct atmospheric model
is not known (e.g., the inversion error is much larger than 40% of
the field strength; >70 G instead of 50 G). These results clearly
demonstrate that the choice of model atmosphere is important for
Hanle diagnostics. As is well known, one way to constrain the average
atmospheric stratification is to measure the center-to-limb variation
of the linear polarization signals. The dependence of the center-to-limb
variations on the atmospheric model is also presented in this paper.
Title: Development of compact integral field unit for spaceborne
solar spectro-polarimeter
Authors: Suematsu, Y.; Koyama, M.; Sukegawa, T.; Enokida, Y.; Saito,
K.; Okura, Y.; Nakayasu, T.; Ozaki, S.; Tsuneta, S.
Bibcode: 2017SPIE10563E..4MS
Altcode:
A 1.5-m class aperture Solar Ultra-violet Visible and IR telescope
(SUVIT) and its instruments for the Japanese next space solar mission
SOLAR-C [1] are under study to obtain critical physical parameters in
the lower solar atmosphere. For the precise magnetic field measurements
covering field-of-view of 3 arcmin x3 acmin, a full stokes polarimetry
at three magnetic sensitive lines in wavelength range of 525 nm
to 1083 nm with a four-slit spectrograph of two dinesional image
scanning mechanism is proposed: one is a true slit and the other
three are pseudo-slits from integral field unit (IFU). To suit this
configuration, besides a fiber bundle IFU, a compact mirror slicer IFU
is designed and being developed. Integral field spectroscopy (IFS),
which is realized with IFU, is a two dimensional spectroscopy, providing
spectra simultaneously for each spatial direction of an extended
two-dimensional field. The scientific advantages of the IFS for studies
of localized and transient solar surface phenomena are obvious. There
are in general three methods [2][3] to realize the IFS depending on
image slicing devices such as a micro-lenslet array, an optical fiber
bundle and a narrow rectangular image slicer array. So far, there exist
many applications of the IFS for ground-based astronomical observations
[4]. Regarding solar instrumentations, the IFS of micro-lenslet array
was done by Suematsu et al. [5], the IFS of densely packed rectangular
fiber bundle with thin clads was realized [6] and being developed for
4-m aperture solar telescope DKIST by Lin [7] and being considered for
space solar telescope SOLAR-C by Katsukawa et al. [8], and the IFS with
mirror slicer array was presented by Ren et al. [9] and under study
for up-coming large-aperture solar telescope in Europe by Calcines
et al. [10] From the view point of a high efficiency spectroscopy,
a wide wavelength coverage, a precision spectropolarimetry and space
application, the image slicer consisting of all reflective optics is the
best option among the three. However, the image slicers are presently
limited either by their risk in the case of classical glass polishing
techniques (see Vivès et al. [11] for recent development) or by their
optical performances when constituted by metallic mirrors. For space
instruments, small sized units are much advantageous and demands that
width of each slicer mirror is as narrow as an optimal slit width (<
100 micron) of spectrograph which is usually hard to manufacture with
glass polishing techniques. On the other hand, Canon is developing
a novel technique for such as high performance gratings which can be
applicable for manufacturing high optical performance metallic mirrors
of small dimensions. For the space-borne spectrograph of SUVIT to be
aboard SOLAR-C, we designed the IFS made of a micro image slicer of 45
arrayed 30-micron-thick metal mirrors and a pseudo-pupil metal mirror
array re-formatting three pseudo-slits; the design is feasible for
optical configuration sharing a spectrograph with a conventional real
slit. According to the optical deign, Canon manufactured a prototype
IFU for evaluation, demonstrating high performances of micro image
slicer and pupil mirrors; enough small micro roughness for visible light
spectrographs, sharp edges for efficient image slices, surface figure
for high image quality, etc. In the following, we describe the optical
design of IFU feasible for space-borne spectrograph, manufacturing
method to attain high optical performance of metal mirrors developed
by Canon, and resulted performance of prototype IFU in detail.
Title: Instrument design and on-orbit performance of the solar
optical telescope aboard hinode (Solar-B)
Authors: Suematsu, Yoshinori; Ichimoto, Kiyoshi; Katsukawa, Yukio;
Tsuneta, Saku; Shimizu, Toshifumi
Bibcode: 2017SPIE10566E..2ZS
Altcode:
The Solar Optical Telescope (SOT) aboard Solar-B satellite (Hinode)
is designed to perform high-precision photometric and polarimetric
observations of the solar lower atmosphere in visible light spectra
(388-668 nm) with a spatial resolution of 0.2 to 0.3 arcsec. The
SOT consists of two components; the optical telescope assembly (OTA)
consisting of a 50-cm aperture Gregorian telescope with a collimating
lens unit and an active tip-tilt mirror for an image-stabilization and
an accompanying focal plane package (FPP) housing two filtergraphs and a
spectro-polarimeter. Since its first-light observation on 25 Oct. 2006,
the image-stabilization system has been working with performance
better than 0.01 arcsec rms and the SOT has been continuously
providing unprecedented solar data of high spatial resolution. Since
the opto-mechanical and -thermal performance of the OTA is crucial
to attain unprecedented high-quality solar observations, we here
describe in detail the instrument design and on-orbit diffraction-limit
performance of the OTA, the largest state-of-the-art solar telescope
yet flown in space.
Title: Indication of the Hanle Effect by Comparing the Scattering
Polarization Observed by CLASP in the Lyα and Si III 120.65 nm Lines
Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.;
Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa,
Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.;
Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.;
Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso
Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.
Bibcode: 2017ApJ...841...31I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding
rocket experiment that has provided the first successful measurement
of the linear polarization produced by scattering processes in
the hydrogen Lyα line (121.57 nm) radiation of the solar disk. In
this paper, we report that the Si III line at 120.65 nm also shows
scattering polarization and we compare the scattering polarization
signals observed in the Lyα and Si III lines in order to search for
observational signatures of the Hanle effect. We focus on four selected
bright structures and investigate how the U/I spatial variations vary
between the Lyα wing, the Lyα core, and the Si III line as a function
of the total unsigned photospheric magnetic flux estimated from Solar
Dynamics Observatory/Helioseismic and Magnetic Imager observations. In
an internetwork region, the Lyα core shows an antisymmetric spatial
variation across the selected bright structure, but it does not show
it in other more magnetized regions. In the Si III line, the spatial
variation of U/I deviates from the above-mentioned antisymmetric
shape as the total unsigned photospheric magnetic flux increases. A
plausible explanation of this difference is the operation of the Hanle
effect. We argue that diagnostic techniques based on the scattering
polarization observed simultaneously in two spectral lines with very
different sensitivities to the Hanle effect, like Lyα and Si III,
are of great potential interest for exploring the magnetism of the
upper solar chromosphere and transition region.
Title: Polarization Calibration of the Chromospheric Lyman-Alpha
SpectroPolarimeter for a 0.1% Polarization Sensitivity in the VUV
Range. Part II: In-Flight Calibration
Authors: Giono, G.; Ishikawa, R.; Narukage, N.; Kano, R.; Katsukawa,
Y.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.;
Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.;
Tsuneta, S.; Shimizu, T.; Sakao, T.; Cirtain, J.; Champey, P.; Asensio
Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu,
B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.
Bibcode: 2017SoPh..292...57G
Altcode:
The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding
rocket instrument designed to measure for the first time the linear
polarization of the hydrogen Lyman-α line (121.6 nm). The instrument
was successfully launched on 3 September 2015 and observations were
conducted at the solar disc center and close to the limb during the
five-minutes flight. In this article, the disc center observations are
used to provide an in-flight calibration of the instrument spurious
polarization. The derived in-flight spurious polarization is consistent
with the spurious polarization levels determined during the pre-flight
calibration and a statistical analysis of the polarization fluctuations
from solar origin is conducted to ensure a 0.014% precision on the
spurious polarization. The combination of the pre-flight and the
in-flight polarization calibrations provides a complete picture of
the instrument response matrix, and a proper error transfer method
is used to confirm the achieved polarization accuracy. As a result,
the unprecedented 0.1% polarization accuracy of the instrument in the
vacuum ultraviolet is ensured by the polarization calibration.
Title: Discovery of Scattering Polarization in the Hydrogen Lyα
Line of the Solar Disk Radiation
Authors: Kano, R.; Trujillo Bueno, J.; Winebarger, A.; Auchère, F.;
Narukage, N.; Ishikawa, R.; Kobayashi, K.; Bando, T.; Katsukawa, Y.;
Kubo, M.; Ishikawa, S.; Giono, G.; Hara, H.; Suematsu, Y.; Shimizu,
T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.; Goto, M.; Belluzzi, L.;
Štěpán, J.; Asensio Ramos, A.; Manso Sainz, R.; Champey, P.;
Cirtain, J.; De Pontieu, B.; Casini, R.; Carlsson, M.
Bibcode: 2017ApJ...839L..10K
Altcode: 2017arXiv170403228K
There is a thin transition region (TR) in the solar atmosphere where
the temperature rises from 10,000 K in the chromosphere to millions
of degrees in the corona. Little is known about the mechanisms that
dominate this enigmatic region other than the magnetic field plays a
key role. The magnetism of the TR can only be detected by polarimetric
measurements of a few ultraviolet (UV) spectral lines, the Lyα line
of neutral hydrogen at 121.6 nm (the strongest line of the solar UV
spectrum) being of particular interest given its sensitivity to the
Hanle effect (the magnetic-field-induced modification of the scattering
line polarization). We report the discovery of linear polarization
produced by scattering processes in the Lyα line, obtained with
the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) rocket
experiment. The Stokes profiles observed by CLASP in quiet regions of
the solar disk show that the Q/I and U/I linear polarization signals are
of the order of 0.1% in the line core and up to a few percent in the
nearby wings, and that both have conspicuous spatial variations with
scales of ∼10 arcsec. These observations help constrain theoretical
models of the chromosphere-corona TR and extrapolations of the
magnetic field from photospheric magnetograms. In fact, the observed
spatial variation from disk to limb of polarization at the line core
and wings already challenge the predictions from three-dimensional
magnetohydrodynamical models of the upper solar chromosphere.
Title: High-Reflectivity Coatings for a Vacuum Ultraviolet
Spectropolarimeter
Authors: Narukage, Noriyuki; Kubo, Masahito; Ishikawa, Ryohko;
Ishikawa, Shin-nosuke; Katsukawa, Yukio; Kobiki, Toshihiko; Giono,
Gabriel; Kano, Ryouhei; Bando, Takamasa; Tsuneta, Saku; Auchère,
Frédéric; Kobayashi, Ken; Winebarger, Amy; McCandless, Jim; Chen,
Jianrong; Choi, Joanne
Bibcode: 2017SoPh..292...40N
Altcode:
Precise polarization measurements in the vacuum ultraviolet (VUV)
region are expected to be a new tool for inferring the magnetic fields
in the upper atmosphere of the Sun. High-reflectivity coatings are key
elements to achieving high-throughput optics for precise polarization
measurements. We fabricated three types of high-reflectivity coatings
for a solar spectropolarimeter in the hydrogen Lyman-α (Lyα ; 121.567
nm) region and evaluated their performance. The first high-reflectivity
mirror coating offers a reflectivity of more than 80 % in Lyα
optics. The second is a reflective narrow-band filter coating that has
a peak reflectivity of 57 % in Lyα , whereas its reflectivity in the
visible light range is lower than 1/10 of the peak reflectivity (∼5
% on average). This coating can be used to easily realize a visible
light rejection system, which is indispensable for a solar telescope,
while maintaining high throughput in the Lyα line. The third is a
high-efficiency reflective polarizing coating that almost exclusively
reflects an s-polarized beam at its Brewster angle of 68° with a
reflectivity of 55 %. This coating achieves both high polarizing power
and high throughput. These coatings contributed to the high-throughput
solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP), which was launched on 3 September, 2015.
Title: High resolution observations of prominence rotation by Hinode
and IRIS
Authors: Okamoto, J.; Liu, W.; Tsuneta, S.
Bibcode: 2016AGUFMSH41E..05O
Altcode:
Fine structures of prominences, especially threads, and their dynamics
provide physical information about the magnetic configuration and
property in the corona. Here we report two events of prominence rotation
observed by the Hinode and IRIS satellites. In the first event, we found
transverse motions of brightening threads at speeds up to 55 km/s 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. At least 15
episodes of such motions occurred in two days, none associated with
any 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, spectral data taken by IRIS showed
strong blueshifts in the top portion of the prominence with a speed
of 30-40 km/s, while redshifts of similar speeds were detected at the
bottom. Line width of the bright threads were significantly larger
than those of stationary threads. These behaviors indicate rotations of
helical prominence threads. We interpreted the activations as evidence
of unwinding motions caused by magnetic reconnection between twisted
prominence fields and ambient coronal fields.
Title: Discovery of Ubiquitous Fast-Propagating Intensity Disturbances
by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP)
Authors: Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando,
T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.;
Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.;
Cirtain, J.; Champey, P.; Auchère, F.; Trujillo Bueno, J.; Asensio
Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu,
B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.
Bibcode: 2016ApJ...832..141K
Altcode:
High-cadence observations by the slit-jaw (SJ) optics system of the
sounding rocket experiment known as the Chromospheric Lyman Alpha
Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances
that recurrently propagate in either the chromosphere or the transition
region or both at a speed much higher than the speed of sound. The
CLASP/SJ instrument provides a time series of two-dimensional images
taken with broadband filters centered on the Lyα line at a 0.6 s
cadence. The multiple fast-propagating intensity disturbances appear in
the quiet Sun and in an active region, and they are clearly detected in
at least 20 areas in a field of view of 527″ × 527″ during the 5
minute observing time. The apparent speeds of the intensity disturbances
range from 150 to 350 km s-1, and they are comparable
to the local Alfvén speed in the transition region. The intensity
disturbances tend to propagate along bright elongated structures away
from areas with strong photospheric magnetic fields. This suggests
that the observed fast-propagating intensity disturbances are related
to the magnetic canopy structures. The maximum distance traveled by
the intensity disturbances is about 10″, and the widths are a few
arcseconds, which are almost determined by a pixel size of 1.″03. The
timescale of each intensity pulse is shorter than 30 s. One possible
explanation for the fast-propagating intensity disturbances observed
by CLASP is magnetohydrodynamic fast-mode waves.
Title: Helical Motions of Fine-structure Prominence Threads Observed
by Hinode and IRIS
Authors: Okamoto, Takenori J.; Liu, Wei; Tsuneta, Saku
Bibcode: 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-1 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-1. 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-1 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: Reflections on the Outstanding Contributions Charles Elachi
Has Made to Furthering Planetary Exploration through International
Cooperation
Authors: Tsuneta, Saku
Bibcode: 2016cosp...41E1945T
Altcode:
The presentation will recall Charles Elachi's accomplishments in
furthering space science in a wide context of international cooperation.
Title: Spectro-polarimetric observation in UV with CLASP to probe
the chromosphere and transition region
Authors: Kano, Ryouhei; Ishikawa, Ryohko; Winebarger, Amy R.; Auchère,
Frédéric; Trujillo Bueno, Javier; Narukage, Noriyuki; Kobayashi,
Ken; Bando, Takamasa; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
Shin-Nosuke; Giono, Gabriel; Hara, Hirohisa; Suematsu, Yoshinori;
Shimizu, Toshifumi; Sakao, Taro; Tsuneta, Saku; Ichimoto, Kiyoshi;
Goto, Motoshi; Cirtain, Jonathan W.; De Pontieu, Bart; Casini, Roberto;
Manso Sainz, Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi,
Luca; Carlsson, Mats
Bibcode: 2016SPD....4710107K
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a NASA
sounding-rocket experiment that was performed in White Sands in
the US on September 3, 2015. During its 5-minute ballistic flight,
CLASP successfully made the first spectro-polarimetric observation in
the Lyman-alpha line (121.57 nm) originating in the chromosphere and
transition region. Since the Lyman-alpha polarization is sensitive
to magnetic field of 10-100 G by the Hanle effect, we aim to infer
the magnetic field information in such upper solar atmosphere with
this experiment.The obtained CLASP data showed that the Lyman-alpha
scattering polarization is about a few percent in the wings and
the order of 0.1% in the core near the solar limb, as it had been
theoretically predicted, and that both polarization signals have a
conspicuous spatio-temporal variability. CLASP also observed another
upper-chromospheric line, Si III (120.65 nm), whose critical field
strength for the Hanle effect is 290 G, and showed a measurable
scattering polarization of a few % in this line. The polarization
properties of the Si III line could facilitate the interpretation of
the scattering polarization observed in the Lyman-alpha line.In this
presentation, we would like to show how the upper chromosphere and
transition region are seen in the polarization of these UV lines and
discuss the possible source of these complicated polarization signals.
Title: Development of a Precise Polarization Modulator for UV
Spectropolarimetry
Authors: Ishikawa, S.; Shimizu, T.; Kano, R.; Bando, T.; Ishikawa,
R.; Giono, G.; Tsuneta, S.; Nakayama, S.; Tajima, T.
Bibcode: 2015SoPh..290.3081I
Altcode: 2015arXiv150905716I; 2015SoPh..tmp..120I
We developed a polarization modulation unit (PMU) to rotate a
waveplate continuously in order to observe solar magnetic fields
by spectropolarimetry. The non-uniformity of the PMU rotation may
cause errors in the measurement of the degree of linear polarization
(scale error) and its angle (crosstalk between Stokes-Q and -U ),
although it does not cause an artificial linear polarization signal
(spurious polarization). We rotated a waveplate with the PMU to obtain
a polarization modulation curve and estimated the scale error and
crosstalk caused by the rotation non-uniformity. The estimated scale
error and crosstalk were <0.01 % for both. This PMU will be used as
a waveplate motor for the Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) rocket experiment. We confirm that the PMU performs and
functions sufficiently well for CLASP.
Title: CLASP: A UV Spectropolarimeter on a Sounding Rocket for
Probing theChromosphere-Corona Transition Regio
Authors: Ishikawa, Ryohko; Kano, Ryouhei; Winebarger, Amy; Auchere,
Frederic; Trujillo Bueno, Javier; Bando, Takamasa; Narukage,
Noriyuki; Kobayashi, Ken; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
Shin-nosuke; Giono, Gabriel; Tsuneta, Saku; Hara, Hirohisa; Suematsu,
Yoshinori; Shimizu, Toshifumi; Sakao, Taro; Ichimoto, Kiyoshi;
Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Manso Sainz,
Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi, Luca
Bibcode: 2015IAUGA..2254536I
Altcode:
The wish to understand the energetic phenomena of the outer solar
atmosphere makes it increasingly important to achieve quantitative
information on the magnetic field in the chromosphere-corona
transition region. To this end, we need to measure and model the
linear polarization produced by scattering processes and the Hanle
effect in strong UV resonance lines, such as the hydrogen Lyman-alpha
line. A team consisting of Japan, USA, Spain, France, and Norway has
been developing a sounding rocket experiment called the Chromospheric
Lyman-alpha Spectro-Polarimeter (CLASP). The aim is to detect the
scattering polarization produced by anisotropic radiation pumping in
the hydrogen Lyman-alpha line (121.6 nm), and via the Hanle effect to
try to constrain the magnetic field vector in the upper chromosphere
and transition region. In this talk, we will present an overview
of our CLASP mission, its scientific objectives, ground tests made,
and the latest information on the launch planned for the Summer of 2015.
Title: Photon Mean Free Paths, Scattering, and Ever-Increasing
Telescope Resolution
Authors: Judge, P. G.; Kleint, L.; Uitenbroek, H.; Rempel, M.;
Suematsu, Y.; Tsuneta, S.
Bibcode: 2015SoPh..290..979J
Altcode: 2014arXiv1409.7866J; 2015SoPh..tmp....3J
We revisit an old question: what are the effects of observing stratified
atmospheres on scales below a photon mean free path λ? The mean free
path of photons emerging from the solar photosphere and chromosphere
is ≈ 102 km. Using current 1 m-class telescopes, λ is
on the order of the angular resolution. But the Daniel K. Inoue Solar
Telescope will have a diffraction limit of 0.020″ near the atmospheric
cutoff at 310 nm, corresponding to 14 km at the solar surface. Even
a small amount of scattering in the source function leads to physical
smearing due to this solar "fog", with effects similar to a degradation
of the telescope point spread function. We discuss a unified picture
that depends simply on the nature and amount of scattering in the
source function. Scalings are derived from which the scattering in the
solar atmosphere can be transcribed into an effective Strehl ratio,
a quantity useful to observers. Observations in both permitted (e.g.,
Fe I 630.2 nm) and forbidden (Fe I 525.0 nm) lines will shed light on
both instrumental performance as well as on small-scale structures in
the solar atmosphere.
Title: Photospheric Flow Field Related to the Evolution of the Sun's
Polar Magnetic Patches Observed by Hinode Solar Optical Telescope
Authors: Kaithakkal, Anjali John; Suematsu, Y.; Kubo, M.; Iida, Y.;
Shiota, D.; Tsuneta, S.
Bibcode: 2015ApJ...799..139K
Altcode: 2014arXiv1412.8023K
We investigated the role of photospheric plasma motions in the formation
and evolution of polar magnetic patches using time-sequence observations
with high spatial resolution. The observations were obtained with
the spectropolarimeter on board the Hinode satellite. From the
statistical analysis using 75 magnetic patches, we found that they are
surrounded by strong converging, supergranulation associated flows
during their apparent lifetime and that the converging flow around
the patch boundary is better observed in the Doppler velocity profile
in the deeper photosphere. Based on our analysis, we suggest that the
like-polarity magnetic fragments in the polar region are advected and
clustered by photospheric converging flows, thereby resulting in the
formation of polar magnetic patches. Our observations show that, in
addition to direct cancellation, magnetic patches decay by fragmentation
followed by unipolar disappearance or unipolar disappearance without
fragmentation. It is possible that the magnetic patches of existing
polarity fragment or diffuse away into smaller elements and eventually
cancel out with opposite polarity fragments that reach the polar region
around the solar cycle maximum. This could be one of the possible
mechanisms by which the existing polarity decays during the reversal
of the polar magnetic field.
Title: Strategy for Realizing High-Precision VUV Spectro-Polarimeter
Authors: Ishikawa, R.; Narukage, N.; Kubo, M.; Ishikawa, S.; Kano,
R.; Tsuneta, S.
Bibcode: 2014SoPh..289.4727I
Altcode: 2014SoPh..tmp..116I
Spectro-polarimetric observations in the vacuum ultraviolet (VUV)
range are currently the only means to measure magnetic fields in the
upper chromosphere and transition region of the solar atmosphere. The
Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) aims to measure
linear polarization at the hydrogen Lyman-α line (121.6 nm). This
measurement requires a polarization sensitivity better than 0.1 %,
which is unprecedented in the VUV range. We here present a strategy with
which to realize such high-precision spectro-polarimetry. This involves
the optimization of instrument design, testing of optical components,
extensive analyses of polarization errors, polarization calibration
of the instrument, and calibration with onboard data. We expect that
this strategy will aid the development of other advanced high-precision
polarimeters in the UV as well as in other wavelength ranges.
Title: Precision VUV Spectro-Polarimetry for Solar Chromospheric
Magnetic Field Measurements
Authors: Ishikawa, R.; Bando, T.; Hara, H.; Ishikawa, S.; Kano, R.;
Kubo, M.; Katsukawa, Y.; Kobiki, T.; Narukage, N.; Suematsu, Y.;
Tsuneta, S.; Aoki, K.; Miyagawa, K.; Ichimoto, K.; Kobayashi, K.;
Auchère, F.; Clasp Team
Bibcode: 2014ASPC..489..319I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV
spectro-polarimeter optimized for measuring the linear polarization
of the Lyman-α line (121.6 nm) to be launched in 2015 with NASA's
sounding rocket (Ishikawa et al. 2011; Narukage et al. 2011; Kano et
al. 2012; Kobayashi et al. 2012). With this experiment, we aim to (1)
observe the scattering polarization in the Lyman-α line, (2) detect
the Hanle effect, and (3) assess the magnetic fields in the upper
chromosphere and transition region for the first time. The polarization
measurement error consists of scale error δ a (error in amplitude
of linear polarization), azimuth error Δφ (error in the direction
of linear polarization), and spurious polarization ɛ (false linear
polarization signals). The error ɛ should be suppressed below 0.1%
in the Lyman-α core (121.567 nm ±0.02 nm), and 0.5% in the Lyman-α
wing (121.567 nm ±0.05 nm), based on our scientific requirements shown
in Table 2 of Kubo et al. (2014). From scientific justification, we
adopt Δ φ<2° and δ a<10% as the instrument requirements. The
spectro-polarimeter features a continuously rotating MgF2
waveplate (Ishikawa et al. 2013), a dual-beam spectrograph with a
spherical grating working also as a beam splitter, and two polarization
analyzers (Bridou et al. 2011), which are mounted at 90 degree from
each other to measure two orthogonal polarization simultaneously. For
the optical layout of the CLASP instrument, see Figure 3 in Kubo et
al. (2014). Considering the continuous rotation of the half-waveplate,
the modulation efficiency is 0.64 both for Stokes Q and U. All the raw
data are returned and demodulation (successive addition or subtraction
of images) is done on the ground. We control the CLASP polarization
performance in the following three steps. First, we evaluate the
throughput and polarization properties of each optical component in
the Lyman-α line, using the Ultraviolet Synchrotron ORbital Radiation
Facility (UVSOR) at the Institute for Molecular Science. The second
step is polarization calibration of the spectro-polarimeter after
alignment. Since the spurious polarization caused by the axisymmetric
telescope is estimated to be negligibly small because of the symmetry
(Ishikawa et al. 2014), we do not perform end-to-end polarization
calibration. As the final step, before the scientific observation near
the limb, we make a short observation at the Sun center and verify
the polarization sensitivity, because the scattering polarization
is expected to be close to zero at the Sun center due to symmetric
geometry. In order to clarify whether we will be able to achieve the
required polarization sensitivity and accuracy via these steps, we
exercise polarization error budget, by investigating all the possible
causes and their magnitudes of polarization errors, all of which are not
necessarily verified by the polarization calibration. Based on these
error budgets, we conclude that a polarization sensitivity of 0.1% in
the line core, δ a<10% and Δ φ<2° can be achieved combined
with the polarization calibration of the spectro-polarimeter and the
onboard calibration at the Sun center(refer to Ishikawa et al. 2014,
for the detail). We are currently conducting verification tests
of the flight components and development of the UV light source for
the polarization calibration. From 2014 spring, we will begin the
integration, alignment, and calibration. We will update the error
budgets throughout the course of these tests.
Title: A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP)
Authors: Kubo, M.; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N.;
Ishikawa, R.; Tsuneta, S.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.;
Hara, H.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Goto, M.; Holloway,
T.; Winebarger, A.; Cirtain, J.; De Pontieu, B.; Casini, R.; Auchère,
F.; Trujillo Bueno, J.; Manso Sainz, R.; Belluzzi, L.; Asensio Ramos,
A.; Štěpán, J.; Carlsson, M.
Bibcode: 2014ASPC..489..307K
Altcode:
A sounding-rocket experiment called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is presently under development to measure
the linear polarization profiles in the hydrogen Lyman-alpha (Lyα)
line at 121.567 nm. CLASP is a vacuum-UV (VUV) spectropolarimeter to aim
for first detection of the linear polarizations caused by scattering
processes and the Hanle effect in the Lyα line with high accuracy
(0.1%). This is a fist step for exploration of magnetic fields in
the upper chromosphere and transition region of the Sun. Accurate
measurements of the linear polarization signals caused by scattering
processes and the Hanle effect in strong UV lines like Lyα are
essential to explore with future solar telescopes the strength
and structures of the magnetic field in the upper chromosphere and
transition region of the Sun. The CLASP proposal has been accepted by
NASA in 2012, and the flight is planned in 2015.
Title: Development of micro image slicer of integral field unit for
spaceborne solar spectrograph
Authors: Suematsu, Y.; Sukegawa, T.; Okura, Y.; Nakayasu, T.; Enokida,
Y.; Koyama, M.; Saito, K.; Ozaki, S.; Tsuneta, S.
Bibcode: 2014SPIE.9151E..1SS
Altcode:
We present an innovative optical design for image slicer integral field
unit (IFU) and manufacturing method which overcome optical limitation of
metallic mirrors. Our IFU consists of micro image slicer of 45 arrayed
highly-narrow flat metallic mirrors and a pseudo pupil mirror array
of off-axis conic aspheres forming three pseudo slits of re-arranged
slicer images. A prototype IFU demonstrates their optical quality high
enough for a visible light spectrograph. The each slicer mirror is 1.58
mm in length and 30μm in width with surface roughness < 1 nm rms,
edge sharpness < 0.1μm, etc. This IFU is small-sized and can be
implemented in a multi-slit spectrograph without any moving mechanism
and fore optics in which one slit is real and the others are of pseudo
slits from the IFU. Those properties are well suitable for space-borne
spectrograph to be aboard such as a next Japanese solar mission SOLAR-C.
Title: On the Inversion of the Scattering Polarization and the Hanle
Effect Signals in the Hydrogen Lyα Line
Authors: Ishikawa, R.; Asensio Ramos, A.; Belluzzi, L.; Manso Sainz,
R.; Štěpán, J.; Trujillo Bueno, J.; Goto, M.; Tsuneta, S.
Bibcode: 2014ApJ...787..159I
Altcode: 2014arXiv1404.0786I
Magnetic field measurements in the upper chromosphere and above,
where the gas-to-magnetic pressure ratio β is lower than unity,
are essential for understanding the thermal structure and dynamical
activity of the solar atmosphere. Recent developments in the theory and
numerical modeling of polarization in spectral lines have suggested
that information on the magnetic field of the chromosphere-corona
transition region could be obtained by measuring the linear polarization
of the solar disk radiation at the core of the hydrogen Lyα line at
121.6 nm, which is produced by scattering processes and the Hanle
effect. The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP)
sounding rocket experiment aims to measure the intensity (Stokes I)
and the linear polarization profiles (Q/I and U/I) of the hydrogen
Lyα line. In this paper, we clarify the information that the Hanle
effect can provide by applying a Stokes inversion technique based on
a database search. The database contains all theoretical Q/I and U/I
profiles calculated in a one-dimensional semi-empirical model of the
solar atmosphere for all possible values of the strength, inclination,
and azimuth of the magnetic field vector, though this atmospheric
region is highly inhomogeneous and dynamic. We focus on understanding
the sensitivity of the inversion results to the noise and spectral
resolution of the synthetic observations as well as the ambiguities and
limitation inherent to the Hanle effect when only the hydrogen Lyα is
used. We conclude that spectropolarimetric observations with CLASP can
indeed be a suitable diagnostic tool for probing the magnetism of the
transition region, especially when complemented with information on
the magnetic field azimuth that can be obtained from other instruments.
Title: Photospheric Properties of Warm EUV Loops and Hot X-Ray Loops
Authors: Kano, R.; Ueda, K.; Tsuneta, S.
Bibcode: 2014ApJ...782L..32K
Altcode:
We investigate the photospheric properties (vector magnetic fields and
horizontal velocity) of a well-developed active region, NOAA AR 10978,
using the Hinode Solar Optical Telescope specifically to determine
what gives rise to the temperature difference between "warm loops"
(1-2 MK), which are coronal loops observed in EUV wavelengths, and
"hot loops" (>3 MK), coronal loops observed in X-rays. We found
that outside sunspots, the magnetic filling factor in the solar network
varies with location and is anti-correlated with the horizontal random
velocity. If we accept that the observed magnetic features consist of
unresolved magnetic flux tubes, this anti-correlation can be explained
by the ensemble average of flux-tube motion driven by small-scale random
flows. The observed data are consistent with a flux tube width of ~77
km and horizontal flow at ~2.6 km s-1 with a spatial scale
of ~120 km. We also found that outside sunspots, there is no significant
difference between warm and hot loops either in the magnetic properties
(except for the inclination) or in the horizontal random velocity
at their footpoints, which are identified with the Hinode X-Ray
Telescope and the Transition Region and Coronal Explorer. The energy
flux injected into the coronal loops by the observed photospheric
motion of the magnetic fields is estimated to be 2 × 106
erg s-1 cm-2, which is the same for both warm and
hot loops. This suggests that coronal properties (e.g., loop length)
play a more important role in giving rise to temperature differences
of active-region coronal loops than photospheric parameters.
Title: UV spectropolarimeter design for precise polarization
measurement and its application to the CLASP for exploration of
magnetic fields in solar atmosphere
Authors: Narukage, Noriyuki; Katsukawa, Yukio; Hara, Hirohisa; Kubo,
Masahito; Auchere, Frederic; Ishikawa, Ryohko; Kano, Ryouhei; Bando,
Takamasa; Ishikawa, Shin-nosuke; Suematsu, Yoshinori; Tsuneta, Saku
Bibcode: 2014cosp...40E2232N
Altcode:
In order to measure the magnetic field in the region where the
hot plasma from 10 (4) K to 10 (6) K is occupied, e.g., for solar
atmosphere, the polarimetric measurements in ultra violet (UV)
with 0.1% accuracy are required. In this paper, we propose a new
UV spectropolarimeter design with 0.1% sensitivity in polarization
measurement. This spectropolarimeter has two devices for the 0.1%
accuracy. First, all optical components except the waveplate are the
reflective type ones that can be equipped with the high reflectivity
coating for the high throughput. Secondly, it equips the optically
symmetric dual channels to measure the orthogonal linear polarization
state simultaneously, using a concave diffraction grating as both the
spectral dispersion element and the beam splitter. These two devices
make the spurious polarizations caused by the photon noise, by the
intensity variation of the observation target, and, by the instrument
itself, enough small to achieve the 0.1% accuracy in polarization
measurement. The spectropolarimeter thus designed is currently under
fabrication for the sounding rocket project of Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP) that aims at the direct measurement of the
magnetic fields in solar atmosphere with Lyman-alpha line (121.6 nm)
for the first time.
Title: The Association of Polar Faculae with Polar Magnetic Patches
Examined with Hinode Observations
Authors: Kaithakkal, Anjali John; Suematsu, Y.; Kubo, M.; Shiota,
D.; Tsuneta, S.
Bibcode: 2013ApJ...776..122K
Altcode: 2013arXiv1311.0980K
The magnetic properties of the Sun's polar faculae are investigated with
spectropolarimetric observations of the north polar region obtained by
the Hinode satellite in 2007 September. Polar faculae are embedded in
nearly all magnetic patches with fluxes greater than 1018
Mx, while magnetic patches without polar faculae dominate in the flux
range below 1018 Mx. The faculae are considerably smaller
than their parent patches, and single magnetic patches contain single
or multiple faculae. The faculae in general have higher intrinsic
magnetic field strengths than the surrounding regions within their
parent patches. Less than 20% of the total magnetic flux contributed
by the large (>=1018 Mx) concentrations, which are known
to be modulated by the solar cycle, is accounted for by the associated
polar faculae.
Title: Saturation of Stellar Winds from Young Suns
Authors: Suzuki, Takeru K.; Imada, Shinsuke; Kataoka, Ryuho; Kato,
Yoshiaki; Matsumoto, Takuma; Miyahara, Hiroko; Tsuneta, Saku
Bibcode: 2013PASJ...65...98S
Altcode: 2012arXiv1212.6713S
We investigated mass losses via stellar winds from Sun-like
main-sequence stars with a wide range of activity levels. We performed
forward-type magnetohydrodynamical numerical experiments for Alfvén
wave-driven stellar winds with a wide range of input Poynting flux
from the photosphere. Increasing the magnetic field strength and
the turbulent velocity at the stellar photosphere from the current
solar level, the mass-loss rate rapidly at first increases, owing
to suppression of the reflection of the Alfvén waves. The surface
materials are lifted up by the magnetic pressure associated with
the Alfvén waves, and the cool dense chromosphere is intermittently
extended to 10%#8211;20% of the stellar radius. The dense atmospheres
enhance the radiative losses, and eventually most of the input Poynting
energy from the stellar surface escapes by radiation. As a result, there
is no more sufficient energy remaining for the kinetic energy of the
wind; the stellar wind saturates in very active stars, as observed in
Wood et al. (2002, ApJ, 574, 412; 2005, ApJ, 628, L143). The saturation
level is positively correlated with Br,0
f0, where Br,0 and f0
are the magnetic field strength and the filling factor of open flux
tubes at the photosphere. If Br,0 f0
is relatively large gtrsim 5 G, the mass-loss rate could be as high as
1000 times. If such a strong mass loss lasts for ∼ 1 billion years,
the stellar mass itself would be affected, which could be a solution to
the faint young Sun paradox. We derived a Reimers-type scaling relation
that estimates the mass-loss rate from an energetics consideration of
our simulations. Finally, we derived the evolution of the mass-loss
rates, dot;{M} ∝ t-1.23, of our simulations, combining
with an observed time evolution of X-ray flux from Sun-like stars,
which are shallower than dot;{M} ∝ t-2.33±0.55 in Wood
et al. (2005).
Title: Formation and disappearance of a filament
Authors: Zhou, G. P.; Wang, J. X.; Tsuneta, S.
Bibcode: 2013IAUS..294..593Z
Altcode:
A continuous observations near an small active region (AR) NOAA 10976
by the Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) on board
the Hinode satellite during Dec. 02 2007 from 15:50 UT to 19:59 UT. We
observed that: (a) the filament formed by merging parallel fibrils into
a twist structure. (b) the filament faded by reconnecting among its
own loop structures, or being stripped into pieces.These process are
always preceded by the brightening. (c) for the disappearance of the
filament, it has close correlation with the activity, like untwisting
or expanding, of its corresponding X-ray bright rope.
Title: Chromospheric Lyman Alpha SpectroPolarimeter: CLASP
Authors: Kobayashi, Ken; Kano, R.; Trujillo Bueno, J.; Winebarger,
A. R.; Cirtain, J. W.; Bando, T.; De Pontieu, B.; Ishikawa, R.;
Katsukawa, Y.; Kubo, M.; Narukage, N.; Sakao, T.; Tsuneta, S.;
Auchère, F.; Asensio Ramos, A.; Belluzzi, L.; Carlsson, M.; Casini,
R.; Hara, H.; Ichimoto, K.; Manso Sainz, R.; Shimizu, T.; Stepan,
J.; Suematsu, Y.; Holloway, T.
Bibcode: 2013SPD....44..142K
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV
spectropolarimeter optimized for measuring the linear polarization of
the Lyman-alpha line (121.6 nm). The Lyman-alpha line is predicted to
show linear polarization caused by atomic scattering in the chromosphere
and modified by the magnetic field through the Hanle effect. The
Hanle effect is sensitive to weaker magnetic fields than Zeeman
effect, and is not canceled by opposing fields, making it sensitive
to tangled or unresolved magnetic field structures. These factors make
the Hanle effect a valuable tool for probing the magnetic field in the
chromosphere above the quiet sun. To meet this goal, CLASP is designed
to measure linear polarization with 0.1% polarization sensitivity
at 0.01 nm spectral resolution and 10" spatial resolution. CLASP is
scheduled to be launched in 2015.
Title: The Hinode Spectro-Polarimeter
Authors: Lites, B. W.; Akin, D. L.; Card, G.; Cruz, T.; Duncan, D. W.;
Edwards, C. G.; Elmore, D. F.; Hoffmann, C.; Katsukawa, Y.; Katz, N.;
Kubo, M.; Ichimoto, K.; Shimizu, T.; Shine, R. A.; Streander, K. V.;
Suematsu, A.; Tarbell, T. D.; Title, A. M.; Tsuneta, S.
Bibcode: 2013SoPh..283..579L
Altcode:
The joint Japan/US/UK Hinode mission includes the first large-aperture
visible-light solar telescope flown in space. One component of the
Focal Plane Package of that telescope is a precision spectro-polarimeter
designed to measure full Stokes spectra with the intent of using those
spectra to infer the magnetic-field vector at high precision in the
solar photosphere. This article describes the characteristics of the
flight hardware of the HinodeSpectro-Polarimeter, and summarizes its
in-flight performance.
Title: Polar Field Reversal Observations with Hinode
Authors: Shiota, D.; Tsuneta, S.; Shimojo, M.; Sako, N.; Orozco Suarez,
D.; Ishikawa, R.
Bibcode: 2012AGUFMSH13C2274S
Altcode:
We have been monitoring yearly variation in the Sun's polar magnetic
fields with the Solar Optical Telescope aboard Hinode to record their
evolution and expected reversal near the solar maximum. All magnetic
patches in the magnetic flux maps are automatically identified to obtain
the number density and magnetic flux density as a function of the total
magnetic flux per patch. The detected magnetic flux per patch ranges
over four orders of magnitude (10^15 -- 10^20 Mx). The higher end of
the magnetic flux in the polar regions is about one order of magnitude
larger than that of the quiet Sun, and nearly that of pores. Almost
all large patches ( > 10^18 Mx) have the same polarity, while
smaller patches have a fair balance of both polarities. The polarity
of the polar region as a whole is consequently determined only by the
large magnetic concentrations. A clear decrease in the net flux of
the polar region is detected in the slow rising phase of the current
solar cycle. The decrease is more rapid in the north polar region than
in the south. The decrease in the net flux is caused by a decrease in
the number and size of the large flux concentrations as well as the
appearance of patches with opposite polarity at lower latitudes. In
contrast, we do not see temporal change in the magnetic flux associated
with the smaller patches ( < 10^18 Mx) and that of the horizontal
magnetic fields during the years 2008--2012.
Title: Next space solar observatory SOLAR-C: mission instruments
and science objectives
Authors: Katsukawa, Y.; Watanabe, T.; Hara, H.; Ichimoto, K.; Kubo,
M.; Kusano, K.; Sakao, T.; Shimizu, T.; Suematsu, Y.; Tsuneta, S.
Bibcode: 2012IAUSS...6E.207K
Altcode:
SOLAR-C, the fourth space solar mission in Japan, is under study with a
launch target of fiscal year 2018. A key concept of the mission is to
view the photosphere, chromosphere, and corona as one system coupled
by magnetic fields along with resolving the size scale of fundamental
physical processes connecting these atmospheric layers. It is especially
important to study magnetic structure in the chromosphere as an
interface layer between the photosphere and the corona. The SOLAR-C
satellite is equipped with three telescopes, the Solar UV-Visible-IR
Telescope (SUVIT), the EUV/FUV High Throughput Spectroscopic Telescope
(EUVS/LEMUR), and the X-ray Imaging Telescope (XIT). Observations
with SUVIT of photospheric and chromospheric magnetic fields make it
possible to infer three dimensional magnetic structure extending from
the photosphere to the chromosphere and corona.This helps to identify
magnetic structures causing magnetic reconnection, and clarify how
waves are propagated, reflected, and dissipated. Phenomena indicative
of or byproducts of magnetic reconnection, such as flows and shocks,
are to be captured by SUVIT and by spectroscopic observations using
EUVS/LEMUR, while XIT observes rapid changes in temperature distribution
of plasma heated by shock waves.
Title: Association of Polar Faculae with the Polar Magnetic Patches
as Revealed by Hinode
Authors: Kaithakkal, A. J.; Tsuneta, S.; Suematsu, Y.; Kubo, M.;
Shiota, D.; Shimojo, M.
Bibcode: 2012AGUFMSH13C2273K
Altcode:
Polar faculae are small bright features in the polar region of the
Sun. They are observed with concentrations of magnetic fields. Previous
studies have shown that the number of polar faculae at latitudes greater
than 50 degrees has 11-year periodicity like the sunspot cycle, but
becomes a maximum in the solar minimum period. The aim of this study is
to understand the magnetic properties of faculae, which are believed
to be associated with the polar magnetic patches. We analysed data of
the north polar region taken by the Hinode/SOT spectropolarimeter (SP)
in September 2007. Accurate measurements of vector magnetic fields
at high spatial resolution by Hinode/SP for the first time allow us
to compare polar faculae with polar magnetic fields in detail. The
continuum intensity map is corrected for limb darkening. There are many
patchy magnetic field structures in the polar region and thresholds on
both size and intensity for the patches are applied to automatically
choose faculae. The definition of magnetic patch is same as in Shiota et
al. (2012 ApJ). We find that magnetic patches are not uniformly bright
but contain smaller faculae inside. The following results describe
the properties of faculae associated with the majority polarity
patches. Our results show that a positive correlation exists between
total flux and average intensity contrast of faculae. On average the
contribution of polar faculae to the total flux of the patch is less
than 30% and the area occupied by polar faculae with in a patch is
roughly 20-25%. We find that there are patches without faculae and
their number is much larger than those with faculae. We also find
that faculae are present in all the patches with total flux ≥ 10^19
Mx. Our result show that faculae are polarity independent and hence are
associated with minority polarity patches as well. But the flux of these
minority polarity faculae is <10^18 Mx in most of the cases. These
results suggest that the magnetic patches and polar faculae do not
have a one-to-one spatial correspondence and have fine structure, and
may raise a fundamental question on our current understanding on the
formation of the faculae. Shiota et al. (2012 ApJ) report that there
are two classes of magnetic patches: small (< 10^18 Mx) and large
(≥10^18 Mx) of which the large patches contribute to the cyclic
variation of the polar magnetic flux. This is consistent with the
concept of faculae as a proxy of the majority polarity magnetic flux.
Title: LEMUR: Large European module for solar Ultraviolet
Research. European contribution to JAXA's Solar-C mission
Authors: Teriaca, Luca; Andretta, Vincenzo; Auchère, Frédéric;
Brown, Charles M.; Buchlin, Eric; Cauzzi, Gianna; Culhane, J. Len;
Curdt, Werner; Davila, Joseph M.; Del Zanna, Giulio; Doschek, George
A.; Fineschi, Silvano; Fludra, Andrzej; Gallagher, Peter T.; Green,
Lucie; Harra, Louise K.; Imada, Shinsuke; Innes, Davina; Kliem,
Bernhard; Korendyke, Clarence; Mariska, John T.; Martínez-Pillet,
Valentin; Parenti, Susanna; Patsourakos, Spiros; Peter, Hardi; Poletto,
Luca; Rutten, Robert J.; Schühle, Udo; Siemer, Martin; Shimizu,
Toshifumi; Socas-Navarro, Hector; Solanki, Sami K.; Spadaro, Daniele;
Trujillo-Bueno, Javier; Tsuneta, Saku; Dominguez, Santiago Vargas;
Vial, Jean-Claude; Walsh, Robert; Warren, Harry P.; Wiegelmann,
Thomas; Winter, Berend; Young, Peter
Bibcode: 2012ExA....34..273T
Altcode: 2011ExA...tmp..135T; 2011arXiv1109.4301T
The solar outer atmosphere is an extremely dynamic environment
characterized by the continuous interplay between the plasma and the
magnetic field that generates and permeates it. Such interactions play a
fundamental role in hugely diverse astrophysical systems, but occur at
scales that cannot be studied outside the solar system. Understanding
this complex system requires concerted, simultaneous solar observations
from the visible to the vacuum ultraviolet (VUV) and soft X-rays, at
high spatial resolution (between 0.1'' and 0.3''), at high temporal
resolution (on the order of 10 s, i.e., the time scale of chromospheric
dynamics), with a wide temperature coverage (0.01 MK to 20 MK,
from the chromosphere to the flaring corona), and the capability of
measuring magnetic fields through spectropolarimetry at visible and
near-infrared wavelengths. Simultaneous spectroscopic measurements
sampling the entire temperature range are particularly important. These
requirements are fulfilled by the Japanese Solar-C mission (Plan B),
composed of a spacecraft in a geosynchronous orbit with a payload
providing a significant improvement of imaging and spectropolarimetric
capabilities in the UV, visible, and near-infrared with respect to
what is available today and foreseen in the near future. The Large
European Module for solar Ultraviolet Research (LEMUR), described
in this paper, is a large VUV telescope feeding a scientific payload
of high-resolution imaging spectrographs and cameras. LEMUR consists
of two major components: a VUV solar telescope with a 30 cm diameter
mirror and a focal length of 3.6 m, and a focal-plane package composed
of VUV spectrometers covering six carefully chosen wavelength ranges
between 170 Å and 1270 Å. The LEMUR slit covers 280'' on the Sun with
0.14'' per pixel sampling. In addition, LEMUR is capable of measuring
mass flows velocities (line shifts) down to 2 km s - 1 or
better. LEMUR has been proposed to ESA as the European contribution
to the Solar C mission.
Title: Chromospheric Lyman-alpha spectro-polarimeter (CLASP)
Authors: Kano, Ryouhei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa,
Ryoko; Tsuneta, Saku; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
Shin-nosuke; Hara, Hirohisa; Shimizu, Toshifumi; Suematsu, Yoshinori;
Ichimoto, Kiyoshi; Sakao, Taro; Goto, Motoshi; Kato, Yoshiaki; Imada,
Shinsuke; Kobayashi, Ken; Holloway, Todd; Winebarger, Amy; Cirtain,
Jonathan; De Pontieu, Bart; Casini, Roberto; Trujillo Bueno, Javier;
Štepán, Jiří; Manso Sainz, Rafael; Belluzzi, Luca; Asensio Ramos,
Andres; Auchère, Frédéric; Carlsson, Mats
Bibcode: 2012SPIE.8443E..4FK
Altcode:
One of the biggest challenges in heliophysics is to decipher the
magnetic structure of the solar chromosphere. The importance of
measuring the chromospheric magnetic field is due to both the key role
the chromosphere plays in energizing and structuring the outer solar
atmosphere and the inability of extrapolation of photospheric fields to
adequately describe this key boundary region. Over the last few years,
significant progress has been made in the spectral line formation
of UV lines as well as the MHD modeling of the solar atmosphere. It
is found that the Hanle effect in the Lyman-alpha line (121.567 nm)
is a most promising diagnostic tool for weaker magnetic fields in
the chromosphere and transition region. Based on this groundbreaking
research, we propose the Chromospheric Lyman-Alpha Spectro-Polarimeter
(CLASP) to NASA as a sounding rocket experiment, for making the first
measurement of the linear polarization produced by scattering processes
and the Hanle effect in the Lyman-alpha line (121.567 nm), and making
the first exploration of the magnetic field in the upper chromosphere
and transition region of the Sun. The CLASP instrument consists
of a Cassegrain telescope, a rotating 1/2-wave plate, a dual-beam
spectrograph assembly with a grating working as a beam splitter, and
an identical pair of reflective polarization analyzers each equipped
with a CCD camera. We propose to launch CLASP in December 2014.
Title: The x-ray/EUV telescope for the Solar-C mission: science and
development activities
Authors: Sakao, Taro; Narukage, Noriyuki; Imada, Shinsuke; Suematsu,
Yoshinori; Shimojo, Masumi; Tsuneta, Saku; DeLuca, Edward E.; Watanabe,
Kyoko; Ishikawa, Shin-nosuke
Bibcode: 2012SPIE.8443E..0AS
Altcode:
We report science and development activities of the X-ray/EUV telescope
for the Japanese Solar-C mission whose projected launch around 2019. The
telescope consists of a package of (a) a normal-incidence (NI) EUV
telescope and (b) a grazing-incidence (GI) soft X-ray telescope. The NI
telescope chiefly provides images of low corona (whose temperature 1
MK or even lower) with ultra-high angular resolution (0.2-0.3"/pixel)
in 3 wavelength bands (304, 171, and 94 angstroms). On the other
hand, the GI telescope provides images of the corona with a wide
temperature coverage (1 MK to beyond 10 MK) with the highest-ever
angular resolution (~0.5"/pixel) as a soft X-ray coronal imager. The
set of NI and GI telescopes should provide crucial information for
establishing magnetic and gas-dynamic connection between the corona and
the lower atmosphere of the Sun which is essential for understanding
heating of, and plasma activities in, the corona. Moreover, we attempt
to implement photon-counting capability for the GI telescope with
which imaging-spectroscopy of the X-ray corona will be performed for
the first time, in the energy range from ~0.5 keV up to 10 keV. The
imaging-spectroscopic observations will provide totally-new information
on mechanism(s) for the generation of hot coronal plasmas (heated
beyond a few MK), those for magnetic reconnection, and even generation
of supra-thermal electrons associated with flares. An overview of
instrument outline and science for the X-ray photoncounting telescope
are presented, together with ongoing development activities in Japan
towards soft X-ray photoncounting observations, focusing on high-speed
X-ray CMOS detector and sub-arcsecond-resolution GI mirror.
Title: WISH for deep and wide NIR surveys
Authors: Yamada, Toru; Iwata, Ikuru; Ando, Makiko; Doi, Mamoru; Goto,
Tomotsugu; Ikeda, Yuji; Imanishi, Masatoshi; Inoue, Akio K.; Iwamura,
Satoru; Kawai, Nobuyuki; Kobayashi, Masakazu A. R.; Kodama, Tadayuki;
Komiyama, Yutaka; Kubo, Mariko; Matsuhara, Hideo; Mawatari, Ken;
Matsuoka, Yoshiki; Morokuma, Tomoki; Nakaya, Hidehiko; Ohta, Koji;
Okamoto, Atsushi; Oyabu, Shinki; Sato, Yohichi; Sugita, Hiroyuki;
Tsutsui, Ryo; Tokoku, Chihiro; Toshikawa, Jun; Tsuneta, Saku; Wada,
Takehiko; Yabe, Kiyoto; Yasuda, Naoki; Yonetoku, Daisuke
Bibcode: 2012SPIE.8442E..1AY
Altcode:
WISH, Wide-field Imaging Surveyor for High-redshiftt, is a space
mission concept to conduct very deep and widefield surveys at near
infrared wavelength at 1-5μm to study the properties of galaxies
at very high redshift beyond the epoch of cosmic reionization. The
concept has been developed and studied since 2008 to be proposed for
future JAXA/ISAS mission. WISH has a 1.5m-diameter primary mirror
and a wide-field imager covering 850 arcmin2. The pixel
scale is 0.155 arcsec for 18μm pitch, which properly samples the
diffraction-limited image at 1.5μm. The main program is Ultra Deep
Survey (UDS) covering 100 deg2 down to 28AB mag at least in
five broad bands. We expect to detect <104 galaxies at
z=8-9, 103-104 galaxies at z=11-12, and 50-100
galaxies at z<14, many of which can be feasible targets for deep
spectroscopy with Extremely Large Telescopes. With recurrent deep
observations, detection and light curve monitoring for type-Ia SNe in
rest-frame infrared wavelength is also conducted, which is another main
science goal of the mission. During the in-orbit 5 years observations,
we expect to detect and monitor <2000 type-Ia SNe up to z~2. WISH
also conducts Ultra Wide Survey, covering 1000deg2 down to
24-25AB mag as well as Extreme Survey, covering a limited number of
fields of view down to 29-30AB mag. We here report the progress of
the WISH project including the basic telescope and satellite design
as well as the results of the test for a proto-model of the flip-type
filter exchanger which works robustly near 100K.
Title: Fine Structure in Three Dimensional Magnetic Field in Polar
Region
Authors: Shiota, D.; Tsuneta, S.; Ito, H.; Kusano, K.; Nishikawa,
N.; Suzuki, T. K.
Bibcode: 2012ASPC..454..375S
Altcode:
In order to discuss the propagation of Alfvén wave in the real solar
atmosphere, we calculate three dimensional magnetic field using magnetic
field observation obtained with Hinode and a high resolution potential
field model. The modeled field reproduces fun out (canopy) structure
rooted to patchy concentrations of magnetic flux (kG-patches) in the
polar region. Combined with a atmosphere model, the model shows that
most of the Alfvén wave propagating along the magnetic field lines can
hardly pass through the transition region due to reflection there. The
model suggests that strong concentration of the magnetic field may
make retardation of Alfvén wave phase between neighboring field
lines rooted on the edge of the canopy. The situation may be potential
situation for Alfvén wave dissipation due to phase mixing process.
Title: Polar Field Reversal Observations with Hinode
Authors: Shiota, D.; Tsuneta, S.; Shimojo, M.; Sako, N.; Orozco
Suárez, D.; Ishikawa, R.
Bibcode: 2012ApJ...753..157S
Altcode: 2012arXiv1205.2154S
We have been monitoring yearly variation in the Sun's polar magnetic
fields with the Solar Optical Telescope aboard Hinode to record their
evolution and expected reversal near the solar maximum. All magnetic
patches in the magnetic flux maps are automatically identified to
obtain the number density and magnetic flux density as a function of
the total magnetic flux per patch. The detected magnetic flux per patch
ranges over four orders of magnitude (1015-1020
Mx). The higher end of the magnetic flux in the polar regions is about
one order of magnitude larger than that of the quiet Sun, and nearly
that of pores. Almost all large patches (>=1018 Mx) have
the same polarity, while smaller patches have a fair balance of both
polarities. The polarity of the polar region as a whole is consequently
determined only by the large magnetic concentrations. A clear decrease
in the net flux of the polar region is detected in the slow rising phase
of the current solar cycle. The decrease is more rapid in the north
polar region than in the south. The decrease in the net flux is caused
by a decrease in the number and size of the large flux concentrations
as well as the appearance of patches with opposite polarity at lower
latitudes. In contrast, we do not see temporal change in the magnetic
flux associated with the smaller patches (<1018 Mx)
and that of the horizontal magnetic fields during the years 2008-2012.
Title: The Chromospheric Lyman-Alpha SpectroPolarimeter: CLASP
Authors: Kobayashi, K.; Kano, R.; Trujillo-Bueno, J.; Asensio Ramos,
A.; Bando, T.; Belluzzi, L.; Carlsson, M.; De Pontieu, R. C. B.; Hara,
H.; Ichimoto, K.; Ishikawa, R.; Katsukawa, Y.; Kubo, M.; Manso Sainz,
R.; Narukage, N.; Sakao, T.; Stepan, J.; Suematsu, Y.; Tsuneta, S.;
Watanabe, H.; Winebarger, A.
Bibcode: 2012ASPC..456..233K
Altcode:
The magnetic field plays a crucial role in the chromosphere and the
transition region, and our poor empirical knowledge of the magnetic
field in the upper chromosphere and transition region is a major
impediment to advancing the understanding of the solar atmosphere. The
Hanle effect promises to be a valuable alternative to Zeeman effect
as a method of measuring the magnetic field in the chromosphere and
transition region; it is sensitive to weaker magnetic fields, and
also sensitive to tangled, unresolved field structures. CLASP
is a sounding rocket experiment that aims to observe the Hanle effect
polarization of the Lyman α (1215.67Å) line in the solar chromosphere
and transition region, and prove the usefulness of this technique in
placing constraints on the magnetic field strength and orientation
in the low plasma-β region of the solar atmosphere. The Ly-α line
has been chosen because it is a chromospheric/transition-region line,
and because the Hanle effect polarization of this line is predicted to
be sensitive to 10-250 Gauss, encompassing the range of interest. The
CLASP instrument is designed to measure linear polarization in the
Ly-α line with a polarization sensitivity of 0.1%. The instrument is
currently funded for development. The optical design of the instrument
has been finalized, and an extensive series of component-level tests
are underway to validate the design.
Title: Nanoflare Evidence from Analysis of the X-Ray Variability of
an Active Region Observed with Hinode/XRT
Authors: Terzo, S.; Reale, F.; Miceli, M.; Kano, R.; Tsuneta, S.;
Klimchuk, J. A.
Bibcode: 2012ASPC..455..245T
Altcode: 2012arXiv1201.5482T
The heating of the solar corona is one of the big questions in
astrophysics. Rapid pulses called nanoflares are among the best
candidate mechanisms. The analysis of the time variability of coronal
X-ray emission is potentially a very useful tool to detect impulsive
events. We analyze the small-scale variability of a solar active
region in a high cadence Hinode/XRT observation. The dataset allows
us to detect very small deviations of emission fluctuations from the
distribution expected for a constant rate. We discuss the deviations
in the light of the pulsed-heating scenario.
Title: Emergence of Twisted Flux in Prominence Observations
Authors: Okamoto, T. J.; Tsuneta, S.; Berger, T. E.; Lites, B. W.
Bibcode: 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: MHD waves in photosphere
Authors: Tsuneta, Saku
Bibcode: 2012decs.confE.100T
Altcode:
We report the observations of the magnetohydrodynamic (MHD) waves
propagating along magnetic flux tubes in the solar photosphere. We
identified multiple isolated strong peaks in the power spectra of
the line-of-sight (LOS) magnetic flux, the LOS velocity, and the
intensity for many different magnetic concentrations. The observation
is performed with the spectro-polarimeter of the Solar Optical Telescope
aboard the Hinode satellite. The oscillation periods are located in 3-9
minutes. These peaks correspond to the magnetic, the velocity, and the
intensity fluctuations. Phase differences between the LOS magnetic flux
and the LOS velocity have striking concentrations at around -90°. We
suggest that the observed fluctuations are due to the superposition
of the ascending wave and the descending longitudinal (sausage-mode)
and/or transverse (kink-mode) MHD waves reflected at chromosphere/corona
boundary (standing wave). Even with such reflected waves, the residual
leaky Poynting flux is estimated to be 2.7 × 10(6) erg cm(-2) s(-1).
Title: Ly-alpha polarimeter design for CLASP rocket experiment
Authors: Kubo, M.; Watanabe, H.; Narukage, N.; Ishikawa, R.; Bando,
T.; Kano, R.; Tsuneta, S.; Kobayashi, K.; Ichimoto, K.; Trujillo Bueno,
J.; Song, D.
Bibcode: 2011AGUFM.P11F1627K
Altcode:
A sounding-rocket program called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is proposed to be launched in the Summer
of 2014. CLASP will observe the upper solar chromosphere in Ly-alpha
(121.567 nm), aiming to detect the linear polarization signal produced
by scattering processes and the Hanle effect for the first time. The
CLASP needs a rotating half-waveplate and a polarization analyzer
working at the Ly-alpha wavelength to measure the linear polarization
signal. We select Magnesium Fluoride (MgF2) as a material of the
optical components because of its birefringent property and high
transparency at UV wavelength. We have confirmed that the reflection
at the Brewster's Angle of MgF2 plate is a good polarization analyzer
for the Ly-alpha line by deriving its ordinary refractive index and
extinction coefficient along the ordinary and extraordinary axes. These
optical parameters are calculated with a least-square fitting in such a
way that the reflectance and transmittance satisfy the Kramers-Kronig
relation. The reflectance and transmittance against oblique incident
angles for the s-polarized and the p-polarized light are measured
using the synchrotron beamline at the Ultraviolet Synchrotron Orbital
Radiation Facility (UVSOR). We have also measured a retardation of
a zeroth-order waveplate made of MgF2. The thickness difference of
the waveplate is 14.57 um.This waveplate works as a half-waveplate at
121.74 nm. From this measurement, we estimate that a waveplate with
the thickness difference of 15.71 um will work as a half-waveplate
at the Ly-alpha wavelength. We have developed a rotating waveplate -
polarization analyzer system called a prototype of CLASP polarimeter,
and input the perfect Stokes Q and U signals. The modulation patterns
that are consistent with the theoretical prediction are successfully
obtained in both cases.
Title: The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP)j
Authors: Kobayashi, K.; Tsuneta, S.; Trujillo Bueno, J.; Bando, T.;
Belluzzi, L.; Casini, R.; Carlsson, M.; Cirtain, J. W.; De Pontieu,
B.; Hara, H.; Ichimoto, K.; Ishikawa, R.; Kano, R.; Katsukawa, Y.;
Kim, T.; Kubo, M.; Manso Sainz, R.; Narukage, N.; Asensio Ramos,
A.; Robinson, B.; Sakao, T.; Shimizu, T.; Stepan, J.; Suematsu, Y.;
Watanabe, H.; West, E.; Winebarger, A. R.
Bibcode: 2011AGUFM.P14C..05K
Altcode:
We present an overview of the Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP) program. CLASP is a proposed sounding rocket
experiment currently under development as collaboration between Japan,
USA and Spain. The aim is to achieve the first measurement of magnetic
field in the upper chromosphere and transition region of the Sun
through the detection and measurement of Hanle effect polarization
of the Lyman alpha line. The Hanle effect (i.e. the magnetic field
induced modification of the linear polarization due to scattering
processes in spectral lines) is believed to be a powerful tool for
measuring the magnetic field in the upper chromosphere, as it is more
sensitive to weaker magnetic fields than the Zeeman effect, and also
sensitive to magnetic fields tangled at spatial scales too small to be
resolved. The Lyman-alpha (121.567 nm) line has been chosen because
it is a chromospheric/transition-region line, and because the Hanle
effect polarization of the Lyman-alpha line is predicted to be sensitive
to 10-250 Gauss, encompassing the range of interest. Hanle effect is
predicted to be observable as linear polarization or depolarization,
depending on the geometry, with a fractional polarization amplitude
varying between 0.1% and 1% depending on the strength and orientation of
the magnetic field. This quantification of the chromospheric magnetic
field requires a highly sensitive polarization measurement. The
CLASP instrument consists of a large aperture (287 mm) Cassegrain
telescope mated to a polarizing beamsplitter and a matched pair
of grating spectrographs. The polarizing beamsplitter consists
of a continuously rotating waveplate and a linear beamsplitter,
allowing simultaneous measurement of orthogonal polarizations and
in-flight self-calibration. Development of the instrument is underway,
and prototypes of all optical components have been tested using a
synchrotron beamline. The experiment is proposed for flight in 2014.
Title: Photon-counting soft x-ray telescope for the Solar-C mission
Authors: Sakao, Taro; Narukage, Noriyuki; Shimojo, Masumi; Tsuneta,
Saku; Suematsu, Yoshinori; Miyazaki, Satoshi; Imada, Shinsuke;
Nishizuka, Naoto; Watanabe, Kyoko; Dotani, Tadayasu; DeLuca, Edward
E.; Ishikawa, Shin-nosuke
Bibcode: 2011SPIE.8148E..0CS
Altcode: 2011SPIE.8148E..11S
We report instrument outline as well as science of the photon-counting
soft X-ray telescope that we have been studying as a possible scientific
payload for the Japanese Solar-C mission whose projected launch around
2019. Soft X-rays (~1- 10 keV) from the solar corona include rich
information on (1) possible mechanism(s) for heating the bright core of
active regions seen in soft X-rays (namely, the hottest portion in the
non-flaring corona), (2) dynamics and magnetohydrodynamic structures
associated with magnetic reconnection processes ongoing in flares,
and even (3) generation of supra-thermal distributions of coronal
plasmas associated with flares. Nevertheless, imaging-spectroscopic
investigation of the soft X-ray corona has so far remained unexplored
due to difficulty in the instrumentation for achieving this aim. With
the advent of recent remarkable progress in CMOS-APS detector
technology, the photon-counting X-ray telescope will be capable
of, in addition to conventional photon-integration type exposures,
performing imaging-spectroscopic investigation on active regions and
flares, thus providing, for example, detailed temperature information
(beyond the sofar- utilized filter-ratio temperature) at each spatial
point of the observing target. The photon-counting X-ray telescope will
emply a Wolter type I optics with a piece of a segmented mirror whose
focal length 4 meters, combined with a focal-plane CMOS-APS detector
(0.4-0.5"/pixel) whose frame read-out rate required to be as high as
1000 fps.
Title: Ly-alpha polarimeter design for CLASP rocket experiment
Authors: Watanabe, H.; Narukage, N.; Kubo, M.; Ishikawa, R.; Bando, T.;
Kano, R.; Tsuneta, S.; Kobayashi, K.; Ichimoto, K.; Trujillo-Bueno, J.
Bibcode: 2011SPIE.8148E..0TW
Altcode: 2011SPIE.8148E..25W; 2014arXiv1407.4577W
A sounding-rocket program called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is proposed to be launched in the summer of
2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567
nm), aiming to detect the linear polarization signal produced by
scattering processes and the Hanle effect for the first time. The
polarimeter of CLASP consists of a rotating half-waveplate, a beam
splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is
used for these optical components, because MgF2 exhibits birefringent
property and high transparency at ultraviolet wavelength. The
development and comprehensive testing program of the optical components
of the polarimeter is underway using the synchrotron beamline at the
Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). The first
objective is deriving the optical constants of MgF2 by the measurement
of the reflectance and transmittance against oblique incident angles
for the s-polarized and the p-polarized light. The ordinary refractive
index and extinction coefficient along the ordinary and extraordinary
axes are derived with a least-square fitting in such a way that the
reflectance and transmittance satisfy the Kramers-Krönig relation. The
reflection at the Brewster's Angle of MgF2 plate is confirmed to become
a good polarization analyzer at Ly-alpha. The second objective is the
retardation measurement of a zeroth-order waveplate made of MgF2. The
retardation of a waveplate is determined by observing the modulation
amplitude that comes out of a waveplate and a polarization analyzer. We
tested a waveplate with the thickness difference of 14.57 um. The 14.57
um waveplate worked as a half-waveplate at 121.74 nm. We derived that
a waveplate with the thickness difference of 15.71 um will work as a
half-waveplate at Ly-alpha wavelength. We developed a prototype of CLASP
polarimeter using the MgF2 half-waveplate and polarization analyzers,
and succeeded in obtaining the modulation patterns that are consistent
with the theoretical prediction. We confirm that the performance of
the prototype is optimized for measuring linear polarization signal
with the least effect of the crosstalk from the circular polarization.
Title: Overview of Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP)
Authors: Narukage, Noriyuki; Tsuneta, Saku; Bando, Takamasa; Kano,
Ryouhei; Kubo, Masahito; Ishikawa, Ryoko; Hara, Hirohisa; Suematsu,
Yoshinori; Katsukawa, Yukio; Watanabe, Hiroko; Ichimoto, Kiyoshi;
Sakao, Taro; Shimizu, Toshifumi; Kobayashi, Ken; Robinson, Brian; Kim,
Tony; Winebarger, Amy; West, Edward; Cirtain, Jonathan; De Pontieu,
Bart; Casini, Roberto; Trujillo Bueno, Javier; Stepan, Jiri; Manso
Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Carlsson, Mats
Bibcode: 2011SPIE.8148E..0HN
Altcode: 2011SPIE.8148E..16N
The solar chromosphere is an important boundary, through which all of
the plasma, magnetic fields and energy in the corona and solar wind
are supplied. Since the Zeeman splitting is typically smaller than
the Doppler line broadening in the chromosphere and transition region,
it is not effective to explore weak magnetic fields. However, this is
not the case for the Hanle effect, when we have an instrument with
high polarization sensitivity (~ 0.1%). "Chromospheric Lyman- Alpha
SpectroPolarimeter (CLASP)" is the sounding rocket experiment to detect
linear polarization produced by the Hanle effect in Lyman-alpha line
(121.567 nm) and to make the first direct measurement of magnetic
fields in the upper chromosphere and lower transition region. To
achieve the high sensitivity of ~ 0.1% within a rocket flight (5
minutes) in Lyman-alpha line, which is easily absorbed by materials,
we design the optical system mainly with reflections. The CLASP
consists of a classical Cassegrain telescope, a polarimeter and a
spectrometer. The polarimeter consists of a rotating 1/2-wave plate
and two reflecting polarization analyzers. One of the analyzer also
works as a polarization beam splitter to give us two orthogonal linear
polarizations simultaneously. The CLASP is planned to be launched in
2014 summer.
Title: The SOLAR-C mission: current status
Authors: Shimizu, Toshifumi; Tsuneta, Saku; Hara, Hirohisa; Ichimoto,
Kiyoshi; Kusano, Kanya; Sakao, Taro; Sekii, Takashi; Suematsu,
Yoshinori; Watanabe, Tetsuya
Bibcode: 2011SPIE.8148E..0BS
Altcode: 2011SPIE.8148E..10S
Two mission concepts (plan A: out-of-ecliptic mission and plan B:
high resolution spectroscopic mission) have been studied for the next
Japanese-led solar mission Solar-C, which will follow the scientific
success of the Hinode mission. The both mission concepts are concluded
as equally important and attractive for the promotion of space solar
physics. In the meantime we also had to make efforts for prioritizing
the two options, in order to proceed to next stage of requesting the
launch of Solar-C mission at the earliest opportunity. This paper
briefly describes the two mission concepts and the current status
on our efforts for prioritizing the two options. More details are
also described for the plan B option as the first-priority Solar-C
mission. The latest report from the Solar-C mission concept studies
was documented as "Interim Report on the Solar-C Mission Concept."
Title: Modeling and verification of the diffraction-limited visible
light telescope aboard the solar observing satellite HINODE
Authors: Katsukawa, Y.; Suematsu, Y.; Tsuneta, S.; Ichimoto, K.;
Shimizu, T.
Bibcode: 2011SPIE.8336E..0FK
Altcode: 2011SPIE.8336E..14K
HINODE, Japanese for "sunrise", is a spacecraft dedicated for
observations of the Sun, and was launched in 2006 to study the Sun's
magnetic fields and how their explosive energies propagate through the
different atmospheric layers. The spacecraft carries the Solar Optical
Telescope (SOT), which has a 50 cm diameter clear aperture and provides
a continuous series of diffraction-limited visible light images from
space. The telescope was developed through international collaboration
between Japan and US. In order to achieve the diffraction-limited
performance, thermal and structural modeling of the telescope was
extensively used in its development phase to predict how the optical
performance changes dependent on the thermal condition in orbit. Not
only the modeling, we devoted many efforts to verify the optical
performance in ground tests before the launch. The verification in
the ground tests helped us to find many issues, such as temperature
dependent focus shifts, which were not identified only through the
thermal-structural modeling. Another critical issue was micro-vibrations
induced by internal disturbances of mechanical gyroscopes and momentum
wheels for attitude control of the spacecraft. Because the structural
modeling was not accurate enough to predict how much the image quality
was degraded by the micro-vibrations, we measured their transmission
in a spacecraft-level test.
Title: Widespread Nanoflare Variability Detected with Hinode/X-Ray
Telescope in a Solar Active Region
Authors: Terzo, Sergio; Reale, Fabio; Miceli, Marco; Klimchuk, James
A.; Kano, Ryouhei; Tsuneta, Saku
Bibcode: 2011ApJ...736..111T
Altcode: 2011arXiv1105.2506T
It is generally agreed that small impulsive energy bursts called
nanoflares are responsible for at least some of the Sun's hot corona,
but whether they are the explanation for most of the multimillion-degree
plasma has been a matter of ongoing debate. We present here evidence
that nanoflares are widespread in an active region observed by the X-Ray
Telescope on board the Hinode mission. The distributions of intensity
fluctuations have small but important asymmetries, whether taken
from individual pixels, multipixel subregions, or the entire active
region. Negative fluctuations (corresponding to reduced intensity)
are greater in number but weaker in amplitude, so that the median
fluctuation is negative compared to a mean of zero. Using Monte Carlo
simulations, we show that only part of this asymmetry can be explained
by Poisson photon statistics. The remainder is explainable through
a tendency for exponentially decreasing intensity, such as would be
expected from a cooling plasma produced from a nanoflare. We suggest
that nanoflares are a universal heating process within active regions.
Title: The Relationship between Vertical and Horizontal Magnetic
Fields in the Quiet Sun
Authors: Ishikawa, Ryohko; Tsuneta, Saku
Bibcode: 2011ApJ...735...74I
Altcode: 2011arXiv1103.5556I
Vertical magnetic fields have been known for decades to exist
in the internetwork region of the Sun, while the properties of
horizontal magnetic fields have only recently been extensively
investigated with Hinode. Vertical and horizontal magnetic fields in
the internetwork region are considered to be separate entities and
have thus far not been investigated in a unified way. We discover
a clear positional association between the vertical and horizontal
magnetic fields in the internetwork region with Hinode. Essentially,
all of the horizontal magnetic patches are associated with the vertical
magnetic patches. Alternatively, half of the vertical magnetic patches
accommodate the horizontal magnetic patches. These horizontal patches
are located around the borders of the vertical patches. The intrinsic
magnetic field strength as obtained with the Stokes V line ratio
inside the horizontal patches is weak, and is in the subequipartition
field regime (B < 700 G), while the field strength outside the
horizontal patches ranges from weak to strong (kG) fields. Vertical
magnetic patches are known to be concentrated on mesogranular and
supergranular boundaries, while the horizontal magnetic patches are
found only on mesogranular boundaries. These observations provide us
with new information on the origin of the vertical and horizontal
internetwork magnetic fields, in a unified way. We conjecture that
internetwork magnetic fields are formed by the emergence of small-scale
flux tubes with bipolar footpoints, and the vertical magnetic fields
of the footpoints are intensified to kG fields due to convective
collapse. Resultant strong vertical fields are advected by the
supergranular flow, and eventually form the network fields.
Title: A Sounding Rocket Experiment for Spectropolarimetric
Observations with the Lyα Line at 121.6 nm (CLASP)
Authors: Ishikawa, R.; Bando, T.; Fujimura, D.; Hara, H.; Kano,
R.; Kobiki, T.; Narukage, N.; Tsuneta, S.; Ueda, K.; Wantanabe,
H.; Kobayashi, K.; Trujillo Bueno, J.; Manso Sainz, R.; Stepan, J.;
de Pontieu, B.; Carlsson, M.; Casini, R.
Bibcode: 2011ASPC..437..287I
Altcode:
A team consisting of Japan, USA, Spain, and Norway is developing a
high-throughput Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP),
which is proposed to fly with a NASA sounding rocket in 2014. CLASP will
explore the magnetism of the upper solar chromosphere and transition
region via the Hanle effect of the Lyα line for the first
time. This experiment requires spectropolarimetric observations with
high polarimetric sensitivity (∼0.1%) and wavelength resolution
(0.1 Å). The final spatial resolution (slit width) is being discussed
taking into account the required high signal-to-noise ratio. We have
demonstrated the performance of the Lyα polarimeter by
extensively using the Ultraviolet Synchrotron ORbital Radiation Facility
(UVSOR) at the Institute for Molecular Sciences. In this contribution,
we report these measurements at UVSOR together with the current status
of the CLASP project.
Title: Coronal-Temperature-Diagnostic Capability of the Hinode/
X-Ray Telescope Based on Self-Consistent Calibration
Authors: Narukage, N.; Sakao, T.; Kano, R.; Hara, H.; Shimojo, M.;
Bando, T.; Urayama, F.; DeLuca, E.; Golub, L.; Weber, M.; Grigis,
P.; Cirtain, J.; Tsuneta, S.
Bibcode: 2011SoPh..269..169N
Altcode: 2010arXiv1011.2867N; 2011SoPh..tmp....1N
The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray
imager that observes the solar corona with unprecedentedly high angular
resolution (consistent with its 1″ pixel size). XRT has nine X-ray
analysis filters with different temperature responses. One of the most
significant scientific features of this telescope is its capability
of diagnosing coronal temperatures from less than 1 MK to more than
10 MK, which has never been accomplished before. To make full use
of this capability, accurate calibration of the coronal temperature
response of XRT is indispensable and is presented in this article. The
effect of on-orbit contamination is also taken into account in the
calibration. On the basis of our calibration results, we review the
coronal-temperature-diagnostic capability of XRT.
Title: Hinode "A new solar observatory in space"
Authors: Tsuneta, Saku
Bibcode: 2011ASInC...2....1T
Altcode:
The road to Hinode is briefly reviewed. Some science highlights of
the Hinode mission are described, and the plan following Hinode is
presented.
Title: The Chromospheric Lyman Alpha SpectroPolarimeter (CLASP)
Authors: Kobayashi, K.; Tsuneta, S.; Trujillo Bueno, J.; Cirtain,
J. W.; Bando, T.; Kano, R.; Hara, H.; Fujimura, D.; Ueda, K.; Ishikawa,
R.; Watanabe, H.; Ichimoto, K.; Sakao, T.; de Pontieu, B.; Carlsson,
M.; Casini, R.
Bibcode: 2010AGUFMSH11B1632K
Altcode:
Magnetic fields in the solar chromosphere play a key role in the
energy transfer and dynamics of the solar atmosphere. Yet a direct
observation of the chromospheric magnetic field remains one of the
greatest challenges in solar physics. While some advances have been
made for observing the Zeeman effect in strong chromospheric lines,
the effect is small and difficult to detect outside sunspots. The
Hanle effect offers a promising alternative; it is sensitive to weaker
magnetic fields (e.g., 5-500 G for Ly-Alpha), and while its magnitude
saturates at stronger magnetic fields, the linear polarization signals
remain sensitive to the magnetic field orientation. The Hanle effect
is not only limited to off-limb observations. Because the chromosphere
is illuminated by an anisotropic radiation field, the Ly-Alpha line is
predicted to show linear polarization for on-disk, near-limb regions,
and magnetic field is predicted to cause a measurable depolarization. At
disk center, the Ly-Alpha radiation is predicted to be negligible
in the absence of magnetic field, and linearly polarized to an order
of 0.3% in the presence of an inclined magnetic field. The proposed
CLASP sounding rocket instrument is designed to detect 0.3% linear
polarization of the Ly-Alpha line at 1.5 arcsecond spatial resolution
(0.7’’ pixel size) and 10 pm spectral resolution. The instrument
consists of a 30 cm aperture Cassegrain telescope and a dual-beam
spectropolarimeter. The telescope employs a ``cold mirror’’ design
that uses multilayer coatings to reflect only the target wavelength
range into the spectropolarimeter. The polarization analyzer consists of
a rotating waveplate and a polarizing beamsplitter that comprises MgF2
plates placed at Brewster’s Angle. Each output beam of the polarizing
beamsplitter, representing two orthogonal linear polarizations, is
dispersed and focused using a separate spherical varied-line-space
grating, and imaged with a separate 512x512 CCD camera. Prototypes
of key optical components have been fabricated and tested. Instrument
design is being finalized, and the experiment will be proposed for a
2014 flight aboard a NASA sounding rocket.
Title: A rising cool column associated with formation of prominence
and coronal cavity
Authors: Okamoto, T. J.; Tsuneta, S.; Berger, T. E.
Bibcode: 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: Spatial and Temporal Distributions of Transient Horizontal
Magnetic Fields with Deep Exposure
Authors: Ishikawa, Ryohko; Tsuneta, Saku
Bibcode: 2010ApJ...718L.171I
Altcode: 2011arXiv1103.5812I
We obtained a long-exposure vector magnetogram of the quiet Sun
photosphere at the disk center with a wide field of view of 51''
× 82''. The observation was performed at Fe I 525.0 nm with the
shutterless mode of the Narrow Band Filter Imager of the Solar Optical
Telescope (SOT) on board the Hinode satellite. We summed the linear
polarization (LP) maps taken with a time cadence of 60 s for 2 hr to
obtain a map with as long of an exposure as possible. The polarization
sensitivity would be more than 4.6 (21.2 in exposure time) times the
standard observation with the SOT Spectropolarimeter. The LP map shows
a cellular structure with a typical scale of 5''-10''. We find that
the enhanced LP signals essentially consist of the isolated sporadic
transient horizontal magnetic fields (THMFs) with a lifetime of 1-10
minutes and are not contributed by long-duration weak horizontal
magnetic fields. The cellular structure coincides in position with the
negative divergence of the horizontal flow field, i.e., mesogranular
boundaries with downflows. Azimuth distribution appears to be random
for the scale size of the mesogranules. Some pixels have two separate
appearances of THMFs, and the measured time intervals are consistent
with the random appearance. THMFs tend to appear at the mesogranular
boundaries, but appear randomly in time. We discuss the origin of
THMFs based on these observations.
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.
Bibcode: 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
~104 K plasma develops from the lower atmosphere during
the observations. The apparent ascent speed of the column is 2 km
s-1, while the fine structures of the column exhibit much
faster motion of up to 20 km s-1. 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-1. 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-1 and the higher one of 20 km s-1 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: Is the Polar Region Different from the Quiet Region of the Sun?
Authors: Ito, Hiroaki; Tsuneta, Saku; Shiota, Daikou; Tokumaru,
Munetoshi; Fujiki, Ken'ichi
Bibcode: 2010ApJ...719..131I
Altcode: 2010arXiv1005.3667I
Observations of the polar region of the Sun are critically important for
understanding the solar dynamo and the acceleration of solar wind. We
carried out precise magnetic observations on both the north polar
region and the quiet Sun at the east limb with the spectropolarimeter
of the Solar Optical Telescope aboard Hinode to characterize the
polar region with respect to the quiet Sun. The average area and the
total magnetic flux of the kilo-Gauss magnetic concentrations in the
polar region appear to be larger than those of the quiet Sun. The
magnetic field vectors classified as vertical in the quiet Sun have
symmetric histograms around zero in the strengths, showing balanced
positive and negative fluxes, while the histogram in the north polar
region is clearly asymmetric, showing a predominance of the negative
polarity. The total magnetic flux of the polar region is larger than
that of the quiet Sun. In contrast, the histogram of the horizontal
magnetic fields is exactly the same for both the polar region and the
quiet Sun. This is consistent with the idea that a local dynamo process
is responsible for the horizontal magnetic fields. A high-resolution
potential field extrapolation shows that the majority of magnetic
field lines from the kG-patches in the polar region are open with a
fanning-out structure very low in the atmosphere, while in the quiet
Sun, almost all the field lines are closed.
Title: WISH: wide-field imaging surveyor at high redshift
Authors: Yamada, Toru; Doi, Mamoru; Goto, Tomotsugu; Ikeda, Yuji;
Imanishi, Masatoshi; Inoue, Akio; Iwamura, Satoru; Iwata, Ikuru;
Kawai, Nobuyuki; Kobayashi, Masakazu A. R.; Kodama, Tadayuki; Komiyama,
Yutaka; Matsuhara, Hideo; Matsuoka, Yoshiki; Morokuma, Tomoki; Ohta,
Kouji; Oyabu, Shinki; Sato, Yoichi; Sugita, Hiroyuki; Tsutsui, Ryo;
Tokoku, Chihiro; Tsuneta, Saku; Wada, Takehiko; Yabe, Kiyoto; Yasuda,
Naoki; Yonetoku, Daisuke
Bibcode: 2010SPIE.7731E..1QY
Altcode: 2010SPIE.7731E..49Y
WISH is a new space science mission concept whose primary goal is
to study the first galaxies in the early universe. We will launch a
1.5m telescope equipped with 1000 arcmin2 wide-field NIR camera by
late 2010's in order to conduct unique ultra-deep and wide-area sky
surveys at 1-5 micron. The primary science goal of WISH mission is
pushing the high-redshift frontier beyond the epoch of reionization
by utilizing its unique imaging capability and the dedicated survey
strategy. We expect to detect ~104 galaxies at z=8-9,
~3-6x103 galaxies at z=11-12, and ~50-100 galaxies at
z=14-17 within about 5 years of the planned mission life time. It is
worth mentioning that a large fraction of these objects may be bright
enough for the spectroscopic observations with the extremely large
telescopes. By adopting the optimized strategy for the recurrent
observations to reach the depth, we also use the surveys to detect
transient objects. Type Ia Supernova cosmology is thus another important
primary goal of WISH. A unique optical layout has been developed to
achieve the diffraction-limited imaging at 1-5micron over the required
large area. Cooling the mirror and telescope to ~100K is needed to
achieve the zodiacal light limited imaging and WISH will achieve
the required temperature by passive cooling in the stable thermal
environment at the orbit near Sun-Earth L2. We are conducting the
conceptual studies and development for the important components of
WISH including the exchange mechanism for the wide-field filters as
well as the primary mirror fixation.
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.
Bibcode: 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: Three-Dimensional View of Transient Horizontal Magnetic Fields
in the Photosphere
Authors: Ishikawa, Ryohko; Tsuneta, Saku; Jurčák, Jan
Bibcode: 2010ApJ...713.1310I
Altcode: 2010arXiv1003.1376I
We infer the three-dimensional magnetic structure of a transient
horizontal magnetic field (THMF) during its evolution through
the photosphere using SIRGAUS inversion code. The SIRGAUS code
is a modified version of SIR (Stokes Inversion based on Response
function), and allows for retrieval of information on the magnetic and
thermodynamic parameters of the flux tube embedded in the atmosphere
from the observed Stokes profiles. Spectropolarimetric observations of
the quiet Sun at the disk center were performed with the Solar Optical
Telescope on board Hinode with Fe I 630.2 nm lines. Using repetitive
scans with a cadence of 130 s, we first detect the horizontal field
that appears inside a granule, near its edge. On the second scan,
vertical fields with positive and negative polarities appear at both
ends of the horizontal field. Then, the horizontal field disappears
leaving the bipolar vertical magnetic fields. The results from the
inversion of the Stokes spectra clearly point to the existence of
a flux tube with magnetic field strength of ~400 G rising through
the line-forming layer of the Fe I 630.2 nm lines. The flux tube is
located at around log τ500 ~ 0 at Δt = 0 s and around log
τ500 ~ -1.7 at Δt = 130 s. At Δt = 260 s, the horizontal
part is already above the line-forming region of the analyzed lines. The
observed Doppler velocity is maximally 3 km s-1, consistent
with the upward motion of the structure as retrieved from the SIRGAUS
code. The vertical size of the tube is smaller than the thickness of
the line-forming layer. The THMF has a clear Ω-shaped loop structure
with the apex located near the edge of a granular cell. The magnetic
flux carried by this THMF is estimated to be 3.1 × 1017 Mx.
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.
Bibcode: 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: Is the Polar Region Different from the Quiet Region of the Sun?
Authors: Ito, Hiroaki; Tsuneta, Saku; Shiota, Daikou; Tokumaru,
Munetoshi; Fujiki, Ken'ichi
Bibcode: 2010AIPC.1216...88I
Altcode:
No abstract at ADS
Title: Orientation of X-Ray Bright Points in the Quiet Sun
Authors: Ueda, K.; Kano, R.; Tsuneta, S.; Shibahashi, H.
Bibcode: 2010SoPh..261...77U
Altcode:
Thanks to the high-resolution images from the X-ray telescope (XRT)
aboard the Hinode satellite, X-ray bright points (XBPs) in the quiet
region of the Sun are resolved and can be seen to have complex loop-like
structures. We measure the orientation of such loop structures for 488
XBPs picked up in 26 snapshot X-ray images near the disk center. The
distribution of the orientation is slightly but clearly biased to
the east - west direction: the random distribution is rejected with a
significance level of 1% by the χ2-test. The distribution
is similar to the orientation distribution for the bipolar magnetic
fields. The XBP orientation is, however, much more random than that
of the bipolar magnetic fields with similar size. 24% of the XBPs are
due to emerging bipoles, while the remaining 76% are due to chance
encounters of opposite polarities.
Title: Analysis of the X-ray variability of an active region observed
with Hinode/XRT for investigation of coronal heating
Authors: Terzo, Sergio; Tsuneta, Saku; Kano, Ryouhei; Miceli, Marco;
Reale, Fabio
Bibcode: 2010cosp...38.2898T
Altcode: 2010cosp.meet.2898T
Impulsive mechanisms of solar and stellar coronal heating are under
investigation. The analysis of the time variability of coronal emission
is one of the useful tools. We analyze the small-scale variability of a
solar active region in a high cadence Hinode/XRT observation. We compare
measured fluctuation intensity distributions with the distribution
expected for Poisson noise and look for possible signatures of
nanoflaring activity, which might be extrapolated to stellar coronae.
Title: EUV Solar Instrument Development at the Marshall Space
Flight Center
Authors: Kobayashi, K.; Cirtain, J. W.; Davis, J. M.; West, E.; Golub,
L.; Korreck, K. E.; Tsuneta, S.; Bando, T.
Bibcode: 2009AGUFMSH33B1500K
Altcode:
The three sounding rocket instrument programs currently underway at
the NASA Marshall Space Flight Center represent major advances in solar
observations, made possible by improvements in EUV optics and detector
technology. The Solar Ultraviolet Magnetograph Instrument (SUMI) is an
EUV spectropolarimeter designed to measure the Zeeman splitting of two
chromospheric EUV lines, the 280 nm MgII and 155 nm CIV lines. SUMI
directly observes the magnetic field in the low-beta region where
most energetic phenomena are though to originate. In conjunction with
visible-light magnetographs, this observation allows us to track the
evolution of the magnetic field as it evolves from the photosphere to
the upper chromosphere. SUMI incorporates a normal incidence Cassegrain
telescope, a MgF2 double-Wollaston polarizing beam splitter and two TVLS
(toroidal varied line space) gratings, and is capable of observing two
orthogonal polarizations in two wavelength bands simultaneously. SUMI
has been fully assembled and tested, and currently scheduled for
launch in summer of 2010. The High-resolution Coronal Imager is a
normal-incidence EUV imaging telescope designed to achieve 0.2 arcsecond
resolution, with a pixel size of 0.1 arcsecond. This is a factor of
25 improvement in aerial resolution over the Transition Region And
Coronal Explorer (TRACE). Images obtained by TRACE indicate presence of
unresolved structures; higher resolution images will reveal the scale
and topology of structures that make up the corona. The telescope
mirrors are currently being fabricated, and the instrument has been
funded for flight. In addition, a Lyman alpha spectropolarimeter is
under development in collaboration with the National Astronomical
Observatory of Japan. This aims to detect the linear polarization in
the chromosphere caused by the Hanle effect. Horizontal magnetic fields
in the chromosphere are expected to be detectable as polarization near
disk center, and off-limb observations will reveal the magnetic field
structure of filaments and prominences. Laboratory tests of candidate
optical components are currently underway.
Title: Service-Mode Observations for Ground-Based Solar Physics
Authors: Reardon, K. P.; Rimmele, T.; Tritschler, A.; Cauzzi, G.;
Wöger, F.; Uitenbroek, H.; Tsuneta, S.; Berger, T.
Bibcode: 2009ASPC..415..332R
Altcode: 2009arXiv0909.1522R
There are significant advantages in combining Hinode observations
with ground-based instruments that can observe additional spectral
diagnostics at higher data rates and with greater flexibility. However,
ground-based observations, because of the random effects of weather
and seeing as well as the complexities data analysis due to changing
instrumental configurations, have traditionally been less efficient
than satellite observations in producing useful datasets. Future large
ground-based telescopes will need to find new ways to optimize both
their operational efficiency and scientific output. We have begun
experimenting with service-mode or queue-mode observations at the Dunn
Solar Telescope using the Interferometric Bidimensional Spectrometer
(IBIS) as part of joint Hinode campaigns. We describe our experiences
and the advantag es of such an observing mode for solar physics.
Title: Internetwork Horizontal Magnetic Fields in the Quiet Sun
Chromosphere: Results from a Joint Hinode/VTT Study
Authors: Lagg, A.; Ishikawa, R.; Merenda, L.; Wiegelmann, T.; Tsuneta,
S.; Solanki, S. K.
Bibcode: 2009ASPC..415..327L
Altcode:
We present results from a joint Hinode/VTT campaign (May
2008). Spectropolarimetric data of a quiet Sun super-granular network
cell at a heliocentric angle of 28° in the He I 10830 Å line were
analyzed using an inversion code incorporating Hanle and Zeeman effects
(HeLIx^+) to retrieve magnetic field strength and direction in the upper
chromosphere. Simultaneously recorded Hinode SOT/SP data reveal the
photospheric magnetic field morphology, clearly showing magnetic flux
concentrations in the internetwork. The photospheric magnetic field
maps are used to feed potential field extrapolations similar to the
work by Schrijver & Title (2003). The extrapolated magnetic field
structure is compared with the magnetic field configuration resulting
from the He 10830 inversions. These inversions also reveal horizontal
magnetic structures extending over a length of up to 20 Mm above the
internetwork, indicative of the presence of a magnetic canopy. The
photospheric magnetic flux concentrations in the internetwork are
obviously not sufficiently strong to prevent the formation of a canopy
at chromospheric heights.
Title: Properties of Transient Horizontal Magnetic Fields
Authors: Ishikawa, R.; Tsuneta, S.
Bibcode: 2009ASPC..415..132I
Altcode:
We present statistical properties of the transient horizontal magnetic
field (THMF) observed by the spectropolarimeter (SP) aboard Hinode. The
topics to be reported here include (1) locations of their appearance
and disappearance in terms of granular structure, (2) size and lifetime
distribution, (3) spatial relationship between vertical and horizontal
magnetic fields, (4) azimuth orientation of the horizontal field vector,
(5) PDF (probability distribution function) of the intrinsic magnetic
field strength. An extensive statistical survey reveals numbers of so
far unknown unique and remarkable properties of THMFs, leading us to
conclude that a local dynamo processes is responsible for THMFs.
Title: The Relation Between Magnetic Fields and Coronal Activities
in the Polar Coronal Hole
Authors: Shimojo, Masumi; Tsuneta, Saku
Bibcode: 2009ApJ...706L.145S
Altcode:
We investigated the relation between polar magnetic fields and
polar coronal activities based on Stokes maps of photospheric and
chromospheric lines, simultaneous X-ray and EUV images. These images are
taken with Hinode and Solar and Heliospheric Observatory. With careful
co-alignment between these images, we found that the X-ray jets, the
X-ray bright points, and the coronal loops in the polar coronal hole
appear around the relatively large magnetic concentrations near the
kG-patches with minority polarity. The magnetic concentrations have
magnetic polarity opposite to that of kG-patches, and they are clearly
identified in the Stokes-V maps of the Na I line. We also found that
such minority magnetic concentrations emerge from below the photosphere
in the polar region. Our results suggest that the coronal activities
and structures in the polar coronal hole can be used as a tracer of
the appearance of the minority polarities in the polar region.
Title: A Nanoflare Heating Model and Comparison with Observations
Authors: Sakamoto, Yasushi; Tsuneta, Saku; Vekstein, Grigory
Bibcode: 2009ApJ...703.2118S
Altcode:
A nanoflare-heated coronal loop model is developed based on the model
of Vekstein & Katsukawa. We performed numerical simulations based
on the model, and then compared the results with the Yohkoh/Soft X-ray
Telescope (SXT) and Transition Region and Coronal Explorer (TRACE)
observations. We found that the most significant difference between
hot (>2 MK) SXT loops and cool (~1 MK) TRACE loops is the energy
of nanoflares and the magnetic field strength. Energy of individual
nanoflares is 1024-25 erg for SXT loops, and 1023
erg for TRACE loops. This is derived from the observed intensity
fluctuations. To observed mean intensities, we require the model SXT
loops to have a stronger magnetic field than the TRACE loops, 40 G and
8 G, respectively. The model predicts two characteristic properties of
nanoflare-heated coronal loops: (1) the SXT and TRACE light curves of a
coronal loop show weak cross-correlation with a lag time corresponding
to the cooling timescale. (2) SXT loops have a smaller volumetric
filling factor than TRACE loops. We consider that this difference in
the filling factor makes SXT loops look more diffuse than TRACE loops.
Title: Properties of Magnetohydrodynamic Waves in the Solar
Photosphere Obtained with Hinode
Authors: Fujimura, D.; Tsuneta, S.
Bibcode: 2009ApJ...702.1443F
Altcode: 2009arXiv0907.3025F
We report the observations of the magnetohydrodynamic (MHD) waves
propagating along magnetic flux tubes in the solar photosphere. We
identified 20 isolated strong peaks (8 peaks for pores and 12 peaks
for intergranular magnetic structure) in the power spectra of the
line-of-sight (LOS) magnetic flux, the LOS velocity, and the intensity
for 14 different magnetic concentrations. The observation is performed
with the spectro-polarimeter of the Solar Optical Telescope aboard
the Hinode satellite. The oscillation periods are located in 3-6
minutes for the pores and in 4-9 minutes for the intergranular magnetic
elements. These peaks correspond to the magnetic, the velocity, and the
intensity fluctuation in time domain with root-mean-square amplitudes
of 4-17 G (0.3%-1.2%), 0.03-0.12 km s-1, and 0.1%-1%,
respectively. Phase differences between the LOS magnetic flux (phi
B ), the LOS velocity (phi v ), the intensities of
the line core (phi I,core), and the continuum intensity
(phi I,cont) have striking concentrations at around -90°
for phi B - phi v and phi v
- phi I,core, around 180° for phi I,core
- phi B , and around 10° for phi I,core -
phi I,cont. Here, for example, phi B - phi
v ~ -90° means that the velocity leads the magnetic field by a
quarter of cycle. The observed phase relation between the magnetic and
the photometric intensity fluctuations would not be consistent with
that caused by the opacity effect, if the magnetic field strength
decreases with height along the oblique LOS. We suggest that the
observed fluctuations are due to longitudinal (sausage-mode) and/or
transverse (kink-mode) MHD waves. The observed phase relation between
the fluctuations in the magnetic flux and the velocity is consistent
with the superposition of the ascending wave and the descending wave
reflected at chromosphere/corona boundary (standing wave). Even with
such reflected waves, the residual upward Poynting flux is estimated to
be 2.7 × 106 erg cm-2 s-1 for a case
of the kink wave. Seismology of the magnetic flux tubes is possible
to obtain various physical parameters from the observed period and
amplitude of the oscillations.
Title: A New View of Fine Scale Dynamics and Magnetism of Sunspots
Revealed by Hinode/SOT
Authors: Ichimoto, K.; Suematsu, Y.; Katsukawa, Y.; Tsuneta, S.;
Shimojo, M.; Shimizu, T.; Shine, R. A.; Tarbell, T. D.; Berger, T.;
Title, A. M.; Lites, B. W.; Kubo, M.; Yokoyama, T.; Nagata, S.
Bibcode: 2009ASPC..405..167I
Altcode:
The Solar Optical Telescope on-board Hinode is providing a new view of
the fine scale dynamics in sunspots with its high spatial resolution and
unprecedented image stability. We present three features related to the
Evershed flow each of which raises a new puzzle in sunspot dynamics;
i.e., twisting appearance of penumbral filaments, the source and sink
of individual Evershed flow channels, and the net circular polarization
in penumbrae with its spatial relation to the Evershed flow channels.
Title: Has Hinode Revealed the Missing Turbulent Flux of the
Quiet Sun?
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A. M.; Ichimoto, K.; Katsukawa,
Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2009ASPC..405..173L
Altcode:
The Hinode Spectro-Polarimeter has revealed the presence of surprisingly
strong horizontal magnetic fields nearly everywhere in the quiet
solar atmosphere. These horizontal fields, along with measures of the
vertical fields, may be the signature of the ``hidden turbulent flux''
of the quiet Sun. The measured horizontal fields average at least to
55 Gauss: nearly 5 times that of the measured longitudinal apparent
flux density. The nature of these fields are reviewed, and discussed
in the light of recent magneto-convection numerical simulations of
the quiet Sun.
Title: Hinode Observation of the Magnetic Fields in a Sunspot Light
Bridge Accompanied by Long-Lasting Chromospheric Plasma Ejections
Authors: Shimizu, Toshifumi; Katsukawa, Yukio; Kubo, Masahito; Lites,
Bruce W.; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Tsuneta, Saku;
Nagata, Shin'ichi; Shine, Richard A.; Tarbell, Theodore D.
Bibcode: 2009ApJ...696L..66S
Altcode:
We present high-resolution magnetic field measurements of a sunspot
light bridge (LB) that produced chromospheric plasma ejections
intermittently and recurrently for more than 1 day. The observations
were carried out with the Hinode Solar Optical Telescope on 2007
April 29 and 30. The spectro-polarimeter reveals obliquely oriented
magnetic fields with vertical electric current density higher than
100 mA m-2 along the LB. The observations suggest that
current-carrying highly twisted magnetic flux tubes are trapped below
a cusp-shaped magnetic structure along the LB. The presence of trapped
current-carrying flux tubes is essential for causing long-lasting
chromospheric plasma ejections at the interface with pre-existing
vertically oriented umbral fields. A bidirectional jet was clearly
detected, suggesting magnetic reconnections occurring at very low
altitudes, slightly above the height where the vector magnetic fields
are measured. Moreover, we found another strong vertical electric
current on the interface between the current-carrying flux tube
and pre-existing umbral field, which might be a direct detection
of the currents flowing in the current sheet formed at the magnetic
reconnection sites.
Title: Hinode ``a new solar observatory in space''
Authors: Tsuneta, S.; Harra, L. K.; Masuda, S.
Bibcode: 2009cwse.conf...63T
Altcode:
Since its launch in September 2006, the Japan-US-UK solar physics
satellite, Hinode, has continued its observation of the sun, sending
back solar images of unprecedented clarity every day. Hinode is equipped
with three telescopes, a visible light telescope, an X-ray telescope,
and an extreme ultraviolet imaging spectrometer. The Hinode optical
telescope has a large primary mirror measuring 50 centimeters in
diameter and is the world's largest space telescope for observing the
sun and its vector magnetic fields. The impact of Hinode as an optical
telescope on solar physics is comparable to that of the Hubble Space
Telescope on optical astronomy. While the optical telescope observes
the sun's surface, the Hinode X-ray telescope captures images of the
corona and the high-temperature flares that range between several
million and several tens of millions of degrees. The telescope has
captured coronal structures that are clearer than ever. The Hinode
EUV imaging spectrometer possesses approximately ten times the
sensitivity and four times the resolution of a similar instrument on
the SOHO satellite. The source of energy for the sun is in the nuclear
fusion reaction that takes place at its core. Here temperature drops
closer to the surface, where the temperature measures about 6,000
degrees. Mysteriously, the temperature starts rising again above the
surface, and the temperature of the corona is exceptionally high,
several millions of degrees. It is as if water were boiling fiercely
in a kettle placed on a stove with no fire, inconceivable as it may
sound. The phenomenon is referred to as the coronal heating problem, and
it is one of the major astronomical mysteries. The Hinode observatory
was designed to solve this mystery. It is expected that Hinode would
also provide clues to unraveling why strong magnetic fields are formed
and how solar flares are triggered. An overview on the initial results
from Hinode is presented. Dynamic video pictures captured by Hinode
can be viewed on the website of the National Astronomical Observatory
of Japan (NAOJ) at http://hinode.nao.ac.jp/index_e.shtml
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.
Bibcode: 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: Small-Scale Solar Magnetic Fields
Authors: de Wijn, A. G.; Stenflo, J. O.; Solanki, S. K.; Tsuneta, S.
Bibcode: 2009SSRv..144..275D
Altcode: 2008SSRv..tmp..190D; 2008SSRv..tmp..191D; 2008arXiv0812.4465D
As we resolve ever smaller structures in the solar atmosphere,
it has become clear that magnetism is an important component of
those small structures. Small-scale magnetism holds the key to many
poorly understood facets of solar magnetism on all scales, such as the
existence of a local dynamo, chromospheric heating, and flux emergence,
to name a few. Here, we review our knowledge of small-scale photospheric
fields, with particular emphasis on quiet-sun field, and discuss the
implications of several results obtained recently using new instruments,
as well as future prospects in this field of research.
Title: Coronal Nonthermal Velocity Following Helicity Injection
Before an X-Class Flare
Authors: Harra, L. K.; Williams, D. R.; Wallace, A. J.; Magara, T.;
Hara, H.; Tsuneta, S.; Sterling, A. C.; Doschek, G. A.
Bibcode: 2009ApJ...691L..99H
Altcode:
We explore the "pre-flare" behavior of the corona in a three-day
period building up to an X-class flare on 2006 December 13 by analyzing
EUV spectral profiles from the Hinode EUV Imaging Spectrometer (EIS)
instrument. We found an increase in the coronal spectral line widths,
beginning after the time of saturation of the injected helicity as
measured by Magara & Tsuneta. In addition, this increase in line
widths (indicating nonthermal motions) starts before any eruptive
activity occurs. The Hinode EIS has the sensitivity to measure changes
in the buildup to a flare many hours before the flare begins.
Title: Comparison of transient horizontal magnetic fields in a plage
region and in the quiet Sun
Authors: Ishikawa, R.; Tsuneta, S.
Bibcode: 2009A&A...495..607I
Altcode: 2008arXiv0812.1631I
Aims: The properties of transient horizontal magnetic fields (THMFs)
in both plage and quiet Sun regions are obtained and compared.
Methods: Spectro-polarimetric observations with the Solar Optical
Telescope (SOT) on the Hinode satellite were carried out with a cadence
of about 30 s for both plage and quiet regions located near the disk
center. We selected THMFs that have net linear polarization (LP) higher
than 0.22%, and an area larger than or equal to 3 pixels, and compared
their occurrence rates and distribution of magnetic field azimuth. We
obtained probability density functions (PDFs) of magnetic field strength
and inclination for both regions.
Results: The occurrence rate in
the plage region is the same as for the quiet Sun. The vertical magnetic
flux in the plage region is ~8 times more than in the quiet Sun. There
is essentially no preferred orientation for the THMFs in either region;
however, THMFs in the plage region with higher LP have a preferred
direction consistent with that of the plage-region's large-scale
vertical field pattern. PDFs show that there is no difference in the
distribution of field strength of horizontal fields between the quiet
Sun and the plage regions when we avoid the persistent vertical flux
concentrations for the plage region.
Conclusions: The similarity
between the PDFs and the occurrence rates in plage and quiet regions
suggests that a local dynamo process due to the granular motion may
generate THMFs all over the Sun. The preferred orientation for higher
LP in the plage indicates that the THMFs may be somewhat influenced
by the larger-scale magnetic field pattern of the plage. A movie
is only available in electronic form at http://www.aanda.org
Title: Commission 10: Solar Activity
Authors: Klimchuk, James A.; van Driel-Gesztelyi, Lidia; Schrijver,
Carolus J.; Melrose, Donald B.; Fletcher, Lyndsay; Gopalswamy,
Natchimuthuk; Harrison, Richard A.; Mandrini, Cristina H.; Peter,
Hardi; Tsuneta, Saku; Vršnak, Bojan; Wang, Jing-Xiu
Bibcode: 2009IAUTA..27...79K
Altcode: 2008arXiv0809.1444K
Commission 10 deals with solar activity in all of its forms,
ranging from the smallest nanoflares to the largest coronal mass
ejections. This report reviews scientific progress over the roughly
two-year period ending in the middle of 2008. This has been an exciting
time in solar physics, highlighted by the launches of the Hinode and
STEREO missions late in 2006. The report is reasonably comprehensive,
though it is far from exhaustive. Limited space prevents the inclusion
of many significant results. The report is divided into the following
sections: Photosphere and chromosphere; Transition region; Corona and
coronal heating; Coronal jets; flares; Coronal mass ejection initiation;
Global coronal waves and shocks; Coronal dimming; The link between low
coronal CME signatures and magnetic clouds; Coronal mass ejections in
the heliosphere; and Coronal mass ejections and space weather. Primary
authorship is indicated at the beginning of each section.
Title: A New View of the Sun with Hinode Mission
Authors: Sakao, Taro; Tsuneta, Saku; Shimojo, Masumi; Narukage,
Noriyuki; Kano, Ryouhei; Obara, Takahiro; Watari, Shinichi; Hinode Team
Bibcode: 2009TrSpT...7Tr215S
Altcode:
We present highlights of observations of the Sun with Japanese Hinode
mission launched by JAXA in September 2006. The scientific objective
of Hinode mission is to observe, in an unprecedented detail, a wide
variety of plasma activities in the Sun's corona together with magnetic
activities on the photosphere and in the chromosphere, utilizing a suite
of three state-of-the-art telescopes; Solar Optical Telescope (SOT),
X-Ray Telescope (XRT), and EUV Imaging Spectrometer (EIS). Since the
beginning of the observations late in October 2006, Hinode has been
providing ample information on activities of magnetized plasmas in the
solar atmosphere some of which are totally new to us. In this article,
we present an overview of the Hinode mission as well as some highlights
of the observations.
Title: Quiet Sun magnetism and Alfven waves as observed with Hinode
Authors: Tsuneta, S.
Bibcode: 2009iac..talk..193T
Altcode: 2009iac..talk...48T
No abstract at ADS
Title: Small-Scale Solar Magnetic Fields
Authors: de Wijn, A. G.; Stenflo, J. O.; Solanki, S. K.; Tsuneta, S.
Bibcode: 2009odsm.book..275D
Altcode:
As we resolve ever smaller structures in the solar atmosphere,
it has become clear that magnetism is an important component of
those small structures. Small-scale magnetism holds the key to many
poorly understood facets of solar magnetism on all scales, such as the
existence of a local dynamo, chromospheric heating, and flux emergence,
to name a few. Here, we review our knowledge of small-scale photospheric
fields, with particular emphasis on quiet-sun field, and discuss the
implications of several results obtained recently using new instruments,
as well as future prospects in this field of research.
Title: Is the polar region different from the quiet region of the Sun?
Authors: Ito, H.; Tsuneta, S.; Shiota, D.; Tokumaru, M.; Fujiki, K.
Bibcode: 2008AGUFMSH41B1622I
Altcode:
We present the magnetic landscape of the polar region of the
Sun as observed with Hinode (Tsuneta et al 2008). We found many
vertically-oriented magnetic flux tubes with field strength as strong
as 1 kG that are scattered in the whole polar region. They all have
the same polarity. Probability distribution function, that is number of
pixels as a function of the magnetic field strength, for the unsigned
vertical field strength is exactly the same as that for the quiet
Sun. Uni-polarity of the polar region differentiates it from the quiet
Sun, which has mixed polarity. Difference and similarity between the
quiet sun and the polar regions are summarized (Ito and Tsuneta, 2008),
and its implication for the solar wind acceleration will be discussed.
Title: The Magnetic Landscape of the Sun's Polar Region
Authors: Tsuneta, S.; Ichimoto, K.; Katsukawa, Y.; Lites, B. W.;
Matsuzaki, K.; Nagata, S.; Orozco Suárez, D.; Shimizu, T.; Shimojo,
M.; Shine, R. A.; Suematsu, Y.; Suzuki, T. K.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2008ApJ...688.1374T
Altcode: 2008arXiv0807.4631T
We present observations of the magnetic landscape of the polar region
of the Sun that are unprecedented in terms of spatial resolution,
field of view, and polarimetric precision. They were carried out with
the Solar Optical Telescope aboard Hinode. Using a Milne-Eddington
inversion, we find many vertically oriented magnetic flux tubes
with field strengths as strong as 1 kG scattered in latitude between
70° and 90°. They all have the same polarity, consistent with the
global polarity of the polar region. The field vectors are observed to
diverge from the centers of the flux elements, consistent with a view
of magnetic fields that are expanding and fanning out with height. The
polar region is also found to have ubiquitous horizontal fields. The
polar regions are the source of the fast solar wind, which is channeled
along unipolar coronal magnetic fields whose photospheric source is
evidently rooted in the strong-field, vertical patches of flux. We
conjecture that vertical flux tubes with large expansion around the
photospheric-coronal boundary serve as efficient chimneys for Alfvén
waves that accelerate the solar wind.
Title: Observational Appearance of Nanoflares with SXT and TRACE
Authors: Sakamoto, Yasushi; Tsuneta, Saku; Vekstein, Grigory
Bibcode: 2008ApJ...689.1421S
Altcode:
We quantitatively investigate intensity fluctuations observed
with the Yohkoh SXT, which is sensitive to hot (>2 MK) plasma,
and TRACE, which is sensitive to cool (~1 MK) plasma. We find that
the TRACE light curves contain fluctuations that are significantly
larger than the photon noise and that TRACE is more sensitive to the
emission from nanoflare heating than is the SXT. We discover that the
standard deviation of the fluctuation (the photon noise is removed)
is proportional to the mean intensity for both the SXT and TRACE
loops. We also analyze the autocorrelation functions in order to obtain
the duration of the intensity fluctuations. While the duration of the
intensity fluctuations for the SXT loops is relatively short because
of the significant photon noise, that for the TRACE loops agrees well
with the characteristic cooling timescale. This is evidence that
coronal loops are continuously heated by impulsive nanoflares. We
estimate the energy of nanoflares to be 1025 ergs for SXT
loops and 1023 ergs for TRACE loops. The occurrence rate of
nanoflares is about 0.4 and 30 nanoflares s-1 in a typical
SXT loop and a typical TRACE loop, respectively.
Title: Hinode's Observational Result on the Saturation of Magnetic
Helicity Injected into the Solar Atmosphere and Its Relation to the
Occurrence of a Solar Flare
Authors: Magara, Tetsuya; Tsuneta, Saku
Bibcode: 2008PASJ...60.1181M
Altcode:
This paper is intended to present key features of the evolution
toward the onset of a solar flare, using Hinode's observations on
the photospheric magnetic field. Hinode can provide the temporal
development of the photospheric field as a vector quantity, which shows
that magnetic shear is initially developed in a flare-productive active
region (AR 10930), and then decreases toward the onset of an X-class
flare. The magnetic helicity in this active region first increases
rapidly, while it become saturated in the late phase. We explain
the physical origin of these features in terms of the emergence of
a magnetic flux tube into the solar atmosphere, and investigate how
they relate to the occurrence of a flare. We also discuss how the
magnetic helicity evolves in different types of flares, showing that
its evolution can be used for flare prediction.
Title: New Form of Emerging Magnetic Fields in Plage Regions
Authors: Ishikawa, R.; Tsuneta, S.
Bibcode: 2008ASPC..397...21I
Altcode:
Using the Solar Optical Telescope aboard Hinode we have discovered
a new form of emerging magnetic fields. In this article we briefly
outline our results and their possible implications.
Title: Magnetic Fields in the Solar Polar Region
Authors: Tsuneta, S.
Bibcode: 2008ASPC..397...19T
Altcode:
The solar polar regions occupy a unique place in solar studies. Here
we outline the first results from these important regions obtained
by Hinode.
Title: Magnetic Fields of the Quiet Sun: A New Quantitative
Perspective From Hinode
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa, Y.;
Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ASPC..397...17L
Altcode:
This article summarizes results of studies presented in two papers
already published: Lites et al. (2007a); Lites et al. (2007b). Please
see these for further details.
Title: On-orbit Performance of the Solar Optical Telescope aboard
Hinode
Authors: Ichimoto, K.; Katsukawa, Y.; Tarbell, T.; Shine, R. A.;
Hoffmann, C.; Berger, T.; Cruz, T.; Suematsu, Y.; Tsuneta, S.; Shimizu,
T.; Lites, B. W.
Bibcode: 2008ASPC..397....5I
Altcode: 2008arXiv0804.3248I
On-orbit performance of the Solar Optical Telescope (SOT) aboard Hinode
is described with some attention to its unpredicted aspects. In general,
SOT reveals an excellent performance and has been providing outstanding
data. Some unexpected features exist, however, in behaviours of the
focus position, throughput and structural stability. Most of them are
recovered by the daily operation i.e., frequent focus adjustment,
careful heater setting and corrections in data analysis. The
tunable filter contains air bubbles which degrade the data quality
significantly. Schemes for tuning the filter without disturbing the
bubbles have been developed and tested, and some useful procedures
to obtain Dopplergrams and magnetograms are now available. October
and March, when the orbit of satellite becomes nearly perpendicular
to the direction towards the Sun, provide a favourable condition for
continuous runs of the narrow-band filter imager.
Title: Evolution of Magnetic Field and Flow in NOAA 10930 Obtained
by Hinode Observations
Authors: Magara, T.; Katsukawa, Y.; Ichimoto, K.; Tsuneta, S.;
Yokoyama, T.; Nagata, S.; Inoue, S.
Bibcode: 2008ASPC..397..135M
Altcode:
We here present an initial result of investigations into the evolution
of NOAA 10930 obtained by the Solar Optical Telescope on board
Hinode. The fine-scale G-band images associated with three components of
the magnetic field provide useful information on the characteristics
of this active region. We derived three phases characterizing the
evolution of magnetic field toward producing an X-class flare. We
also study the nature of a rapid flow found in this active region by
investigating the configuration of the magnetic field and flow.
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.
Bibcode: 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: Evolution of Magnetic Fields at the Boundary of the Penumbra
Authors: Kubo, M.; Ichimoto, K.; Shimizu, T.; Lites, B. W.; Tsuneta,
S.; Suematsu, Y.; Katsukawa, Y.; Nagata, S.; Tarbell, T.; Shine,
R. A.; Title, A. M.
Bibcode: 2008ASPC..397...79K
Altcode:
The formation of moving magnetic features (MMFs) separating from the
penumbra were successfully observed with the Solar Optical Telescope
(SOT) aboard the Hinode satellite. We find that bright features in
the outer penumbra are located at the penumbral spines, which have
magnetic fields more vertical than the surroundings, or located at the
MMFs separating from the spines. This suggests that convection in the
outer penumbra is related to the disintegration of the sunspot.
Title: The Hinode Mission
Authors: Tsuneta, S.
Bibcode: 2008ASPC..397....3T
Altcode:
This article contains a brief overview of the Hinode Mission. For a
more extensive discussion please see Kosugi et al. (2007).
Title: Observational Evidence for Nanoflares Heating the Solar Corona
Authors: Vekstein, G.; Sakamoto, Y.; Tsuneta, S.
Bibcode: 2008ESPM...12.3.31V
Altcode:
We investigated intensity and small fluctuations of the X-ray and EUV
coronal emission by using simultaneous Solar Active region observations
with the Soft X-ray Telescope (SXT) of the Yohkoh mission, and with the
Transition Region and Coronal Explorer (TRACE). It is found that the
TRACE light curves exhibit fluctuations which are significantly larger
than the estimated photon noise and other instrumental effects. This is
considered as a clear signature of the underlying discrete impulsive
coronal heating events (nanoflares). Comparison of these data
with the theoretical predictions obtained from the forward modelling
of the nanoflare heating yields an estimate of about 10 24 erg for
the energy of individual nanoflares in the Active Region of the Sun.
Title: Balloon-Borne Hard X-Ray Spectrometer Using CdTe Detectors
Authors: Kobayashi, K.; Tsuneta, S.; Tamura, T.; Kumagai, K.;
Katsukawa, Y.; Kubo, M.; Sakamoto, Y.; Kohara, N.; Yamagami, T.;
Saito, Y.; Mori, K.
Bibcode: 2008SoPh..250..431K
Altcode: 2008SoPh..tmp..132K
Spectroscopic observation of solar flares in the hard X-ray energy
range, particularly the 20 ∼ 100 keV region, is an invaluable tool
for investigating the flare mechanism. This paper describes the design
and performance of a balloon-borne hard X-ray spectrometer using CdTe
detectors developed for solar flare observation. The instrument is a
small balloon payload (gondola weight 70 kg) with sixteen 10×10×0.5
mm CdTe detectors, designed for a 1-day flight at 41 km altitude. It
observes in an energy range of 20−120 keV and has an energy resolution
of 3 keV at 60 keV. The second flight on 24 May 2002 succeeded in
observing a class M1.1 flare.
Title: Erratum: The Analysis of Penumbral Fine Structure Using an
Advanced Inversion Technique
Authors: Jurcák, Jan; Bellot Rubio, Luis; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi;
Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.; Tsuneta,
Saku
Bibcode: 2008PASJ...60..933J
Altcode:
In the article [PASJ 59, S601-S606 (2007)], the word ''CSIC'' was
omitted from the affiliation of Dr. Luis Bellot Rubio. The correct
affiliation is : 2Instituto de Astrofísica de Andalucía
(CSIC), Apdo. de Correos 3004, 18080 Granada, Spain
Title: Vertical Temperature Structures of the Solar Corona Derived
with the Hinode X-Ray Telescope
Authors: Kano, Ryouhei; Sakao, Taro; Narukage, Noriyuki; Tsuneta,
Saku; Kotoku, Jun'ichi; Bando, Takamasa; Deluca, Edward; Lundquist,
Loraine; Golub, Leon; Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo,
Masumi; Shibasaki, Kiyoto; Shimizu, Toshifumi; Nakatani, Ichiro
Bibcode: 2008PASJ...60..827K
Altcode:
We obtained temperature structures in faint coronal features
above and near the solar limb with the X-Ray Telescope aboard the
Hinode satellite by accurately correcting the scattered X-rays
from surrounding bright regions with occulted images during
the solar eclipses. Our analysis yields a polar coronal hole
temperature of about 1.0MK and an emission measure in the range of
1025.5-1026.0cm-5. In addition,
our methods allow us to measure the temperature and emission
measure of two distinct quiet-Sun structures: radial (plume-like)
structures near the boundary of the coronal-hole and diffuse quiet
Sun regions at mid-latitudes. The radial structures appear to have
increasing temperature with height during the first 100Mm, and
constant temperatures above 100Mm. For the diffuse quiet-Sun region
the temperatures are the highest just above the limb, and appear
to decrease with height. These differences may be due to different
magnetic configurations.
Title: Disintegration of Magnetic Flux in Decaying Sunspots as
Observed with the Hinode SOT
Authors: Kubo, M.; Lites, B. W.; Ichimoto, K.; Shimizu, T.; Suematsu,
Y.; Katsukawa, Y.; Tarbell, T. D.; Shine, R. A.; Title, A. M.; Nagata,
S.; Tsuneta, S.
Bibcode: 2008ApJ...681.1677K
Altcode: 2008arXiv0806.0415K
Continuous observations of sunspot penumbrae with the Solar Optical
Telescope aboard Hinode clearly show that the outer boundary of the
penumbra fluctuates around its averaged position. The penumbral outer
boundary moves inward when granules appear in the outer penumbra. We
discover that such granules appear one after another while moving
magnetic features (MMFs) are separating from the penumbral "spines"
(penumbral features that have fields that are stronger and more vertical
than those of their surroundings). These granules that appear in the
outer penumbra often merge with bright features inside the penumbra
that move with the spines as they elongate toward the moat region. This
suggests that convective motions around the penumbral outer boundary are
related to the disintegration of magnetic flux in the sunspot. We also
find that dark penumbral filaments frequently elongate into the moat
region in the vicinity of MMFs that detach from penumbral spines. Such
elongating dark penumbral filaments correspond to nearly horizontal
fields extending from the penumbra. Pairs of MMFs with positive and
negative polarities are sometimes observed along the elongating dark
penumbral filaments. This strongly supports the notion that such
elongating dark penumbral filaments have magnetic fields with a "sea
serpent"-like structure. Evershed flows, which are associated with the
penumbral horizontal fields, may be related to the detachment of the
MMFs from the penumbral spines, as well as to the formation of the MMFs
along the dark penumbral filaments that elongate into the moat region.
Title: Polarization Calibration of the Solar Optical Telescope
onboard Hinode
Authors: Ichimoto, K.; Lites, B.; Elmore, D.; Suematsu, Y.; Tsuneta,
S.; Katsukawa, Y.; Shimizu, T.; Shine, R.; Tarbell, T.; Title, A.;
Kiyohara, J.; Shinoda, K.; Card, G.; Lecinski, A.; Streander, K.;
Nakagiri, M.; Miyashita, M.; Noguchi, M.; Hoffmann, C.; Cruz, T.
Bibcode: 2008SoPh..249..233I
Altcode: 2008SoPh..tmp...69I
The Solar Optical Telescope (SOT) onboard Hinode aims to obtain vector
magnetic fields on the Sun through precise spectropolarimetry of
solar spectral lines with a spatial resolution of 0.2 - 0.3 arcsec. A
photometric accuracy of 10−3 is achieved and, after the
polarization calibration, any artificial polarization from crosstalk
among Stokes parameters is required to be suppressed below the level
of the statistical noise over the SOT's field of view. This goal was
achieved by the highly optimized design of the SOT as a polarimeter,
extensive analyses and testing of optical elements, and an end-to-end
calibration test of the entire system. In this paper we review both
the approach adopted to realize the high-precision polarimeter of the
SOT and its final polarization characteristics.
Title: Image Stabilization System for Hinode (Solar-B) Solar Optical
Telescope
Authors: Shimizu, T.; Nagata, S.; Tsuneta, S.; Tarbell, T.; Edwards,
C.; Shine, R.; Hoffmann, C.; Thomas, E.; Sour, S.; Rehse, R.; Ito,
O.; Kashiwagi, Y.; Tabata, M.; Kodeki, K.; Nagase, M.; Matsuzaki,
K.; Kobayashi, K.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2008SoPh..249..221S
Altcode:
The Hinode Solar Optical Telescope (SOT) is the first space-borne
visible-light telescope that enables us to observe magnetic-field
dynamics in the solar lower atmosphere with 0.2 - 0.3 arcsec spatial
resolution under extremely stable (seeing-free) conditions. To achieve
precise measurements of the polarization with diffraction-limited
images, stable pointing of the telescope (<0.09 arcsec, 3σ) is
required for solar images exposed on the focal plane CCD detectors. SOT
has an image stabilization system that uses image displacements
calculated from correlation tracking of solar granules to control
a piezo-driven tip-tilt mirror. The system minimizes the motions
of images for frequencies lower than 14 Hz while the satellite and
telescope structural design damps microvibration in higher frequency
ranges. It has been confirmed from the data taken on orbit that
the remaining jitter is less than 0.03 arcsec (3σ) on the Sun. This
excellent performance makes a major contribution to successful precise
polarimetric measurements with 0.2 - 0.3 arcsec resolution.
Title: The Solar Optical Telescope for the Hinode Mission: An Overview
Authors: Tsuneta, S.; Ichimoto, K.; Katsukawa, Y.; Nagata, S.; Otsubo,
M.; Shimizu, T.; Suematsu, Y.; Nakagiri, M.; Noguchi, M.; Tarbell,
T.; Title, A.; Shine, R.; Rosenberg, W.; Hoffmann, C.; Jurcevich,
B.; Kushner, G.; Levay, M.; Lites, B.; Elmore, D.; Matsushita, T.;
Kawaguchi, N.; Saito, H.; Mikami, I.; Hill, L. D.; Owens, J. K.
Bibcode: 2008SoPh..249..167T
Altcode: 2008SoPh..tmp...74T; 2007arXiv0711.1715T
The Solar Optical Telescope (SOT) aboard the Hinode satellite
(formerly called Solar-B) consists of the Optical Telescope Assembly
(OTA) and the Focal Plane Package (FPP). The OTA is a 50-cm
diffraction-limited Gregorian telescope, and the FPP includes the
narrowband filtergraph (NFI) and the broadband filtergraph (BFI), plus
the Stokes Spectro-Polarimeter (SP). The SOT provides unprecedented
high-resolution photometric and vector magnetic images of the
photosphere and chromosphere with a very stable point spread function
and is equipped with an image-stabilization system with performance
better than 0.01 arcsec rms. Together with the other two instruments
on Hinode (the X-Ray Telescope (XRT) and the EUV Imaging Spectrometer
(EIS)), the SOT is poised to address many fundamental questions about
solar magnetohydrodynamics. This paper provides an overview; the
details of the instrument are presented in a series of companion papers.
Title: Frequent Occurrence of High-Speed Local Mass Downflows on
the Solar Surface
Authors: Shimizu, T.; Lites, B. W.; Katsukawa, Y.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Nagata, S.; Kubo, M.; Shine, R. A.; Tarbell,
T. D.
Bibcode: 2008ApJ...680.1467S
Altcode: 2008arXiv0804.1167S
We report on new spectropolarimetric measurements with simultaneous
filter imaging observation, revealing the frequent appearance of
polarization signals indicating high-speed, probably supersonic,
downflows that are associated with at least three different
configurations of magnetic fields in the solar photosphere. The
observations were carried out with the Solar Optical Telescope on
board the Hinode satellite. High-speed downflows are excited when a
moving magnetic feature is newly formed near the penumbral boundary of
sunspots. Also, a new type of downflows is identified at the edge of
sunspot umbra that lack accompanying penumbral structures. These may
be triggered by the interaction of magnetic fields swept by convection
with well-concentrated magnetic flux. Another class of high-speed
downflows are observed in quiet Sun and sunspot moat regions. These are
closely related to the formation of small concentrated magnetic flux
patches. High-speed downflows of all types are transient time-dependent
mass motions. These findings suggest that the excitation of supersonic
mass flows are one of the key observational features of the dynamical
evolution occurring in magnetic-field fine structures on the solar
surface.
Title: Cooperative Observation of Ellerman Bombs between the Solar
Optical Telescope aboard Hinode and Hida/Domeless Solar Telescope
Authors: Matsumoto, Takuma; Kitai, Reizaburo; Shibata, Kazunari;
Nagata, Shin'ichi; Otsuji, Kenichi; Nakamura, Tahei; Watanabe, Hiroko;
Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu,
Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.; Lites, Bruce W.;
Shine, Richard A.; Title, Alan M.
Bibcode: 2008PASJ...60..577M
Altcode:
High-resolution CaIIH broad-band filter images of NOAA10933 on 2007
January 5 were obtained by the Solar Optical Telescope aboard the Hinode
satellite. Many small-scale (∼1") bright points were observed outside
the sunspot and inside the emerging flux region. We identified some of
these bright points with Ellerman bombs (EBs) by using Hα images taken
by the Domeless Solar Telescope at Hida observatory. The sub-arcsec
structures of two EBs seen in CaIIH were studied in detail. Our
observation showed the following two aspects: (1) The CaIIH bright
points identified with EBs were associated with the bipolar magnetic
field structures, as reported by previous studies. (2)The structure
of the CaIIH bright points turned out to consist of the following two
parts: a central elongated bright core (0.7" × 0.5") located along
the magnetic neutral line and a diffuse halo (1.2"×1.8").
Title: The Hinode X-Ray Telescope (XRT): Camera Design, Performance
and Operations
Authors: Kano, R.; Sakao, T.; Hara, H.; Tsuneta, S.; Matsuzaki, K.;
Kumagai, K.; Shimojo, M.; Minesugi, K.; Shibasaki, K.; DeLuca, E. E.;
Golub, L.; Bookbinder, J.; Caldwell, D.; Cheimets, P.; Cirtain, J.;
Dennis, E.; Kent, T.; Weber, M.
Bibcode: 2008SoPh..249..263K
Altcode:
The X-ray Telescope (XRT) aboard the Hinode satellite is a grazing
incidence X-ray imager equipped with a 2048×2048 CCD. The XRT has
1 arcsec pixels with a wide field of view of 34×34 arcmin. It is
sensitive to plasmas with a wide temperature range from < 1 to 30
MK, allowing us to obtain TRACE-like low-temperature images as well as
Yohkoh/SXT-like high-temperature images. The spacecraft Mission Data
Processor (MDP) controls the XRT through sequence tables with versatile
autonomous functions such as exposure control, region-of-interest
tracking, flare detection, and flare location identification. Data are
compressed either with DPCM or JPEG, depending on the purpose. This
results in higher cadence and/or wider field of view for a given
telemetry bandwidth. With a focus adjust mechanism, a higher resolution
of Gaussian focus may be available on-axis. This paper follows the
first instrument paper for the XRT (Golub et al., Solar Phys.243, 63,
2007) and discusses the design and measured performance of the X-ray
CCD camera for the XRT and its control system with the MDP.
Title: The Solar Optical Telescope of Solar-B ( Hinode): The Optical
Telescope Assembly
Authors: Suematsu, Y.; Tsuneta, S.; Ichimoto, K.; Shimizu, T.; Otsubo,
M.; Katsukawa, Y.; Nakagiri, M.; Noguchi, M.; Tamura, T.; Kato, Y.;
Hara, H.; Kubo, M.; Mikami, I.; Saito, H.; Matsushita, T.; Kawaguchi,
N.; Nakaoji, T.; Nagae, K.; Shimada, S.; Takeyama, N.; Yamamuro, T.
Bibcode: 2008SoPh..249..197S
Altcode: 2008SoPh..tmp...26S
The Solar Optical Telescope (SOT) aboard the Solar-B satellite (Hinode)
is designed to perform high-precision photometric and polarimetric
observations of the Sun in visible light spectra (388 - 668 nm)
with a spatial resolution of 0.2 - 0.3 arcsec. The SOT consists of
two optically separable components: the Optical Telescope Assembly
(OTA), consisting of a 50-cm aperture Gregorian with a collimating lens
unit and an active tip-tilt mirror, and an accompanying Focal Plane
Package (FPP), housing two filtergraphs and a spectro-polarimeter. The
optomechanical and optothermal performance of the OTA is crucial to
attain unprecedented high-quality solar observations. We describe in
detail the instrument design and expected stable diffraction-limited
on-orbit performance of the OTA, the largest state-of-the-art solar
telescope yet flown in space.
Title: The intensity contrast of solar granulation: comparing Hinode
SP results with MHD simulations
Authors: Danilovic, S.; Gandorfer, A.; Lagg, A.; Schüssler, M.;
Solanki, S. K.; Vögler, A.; Katsukawa, Y.; Tsuneta, S.
Bibcode: 2008A&A...484L..17D
Altcode: 2008arXiv0804.4230D
Context: The contrast of granulation is an important quantity
characterizing solar surface convection.
Aims: We compare the
intensity contrast at 630 nm, observed using the Spectro-Polarimeter
(SP) aboard the Hinode satellite, with the 3D radiative MHD simulations
of Vögler & Schüssler (2007, A&A, 465, L43).
Methods:
A synthetic image from the simulation is degraded using a theoretical
point-spread function of the optical system, and by considering other
important effects.
Results: The telescope aperture and the
obscuration by the secondary mirror and its attachment spider, reduce
the simulated contrast from 14.4% to 8.5%. A slight effective defocus
of the instrument brings the simulated contrast down to 7.5%, close to
the observed value of 7.0%.
Conclusions: A proper consideration
of the effects of the optical system and a slight defocus, lead to
sufficient degradation of the synthetic image from the MHD simulation,
such that the contrast reaches almost the observed value. The remaining
small discrepancy can be ascribed to straylight and slight imperfections
of the instrument, which are difficult to model. Hence, Hinode SP data
are consistent with a granulation contrast which is predicted by 3D
radiation MHD simulations.
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.
Bibcode: 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: Photospheric Signature of Penumbral Microjets
Authors: Katsukawa, Y.; Jurcak, J.; Ichimoto, K.; Suemtasu, Y.;
Tsuneta, S.; Shimizu, T.; Berger, T. E.; Shine, R. A.; Tarbell, T. D.;
Lites, B. W.
Bibcode: 2008AGUSMSP53A..03K
Altcode:
HINODE Solar Optical Telescope (SOT) discovered ubiquitous occurrence
of fine-scale jetlike activities in penumbral chromospheres, which
are referred to as penumbral microjets. The microjets' small width
of 400 km and short duration of less than 1 min make them difficult
to identify in existing ground-based observations. The apparent
rise velocity is faster than 50km/s and is roughly comparable to
the Alfven speed in the sunspot chromosphere. These properties of
penumbral microjets suggest that magnetic reconnection in uncombed
magnetic field configuration is the most possible cause of penumbral
microjets. In order to understand magnetic configuration associated with
penumbral microjets and prove the chromospheric magnetic reconnection
hypothesis, we investigated relationship between penumbral microjets
seen in CaIIH images and photospheric magnetic fields measured by
the HINODE spectro-polarimeter. We found the inclination angles of
penumbral microjets measured in CaII H images are roughly consistent
with inclination angles of relatively vertical magnetic field
component in uncombed magnetic field configuration. In addition,
strong and transient downflows are observed in the photosphere near
the boundary of a horizontal flux tube associated with a penumbral
microjet. The size of the downflow region is about 300km, which is
close to the width of penumbral microjets seen in CaII H images. The
downflow velocity of several km/s might be a result of an outflow of
chromospheric magnetic reconnection and suffer deceleration due to
the higher density in the photosphere.
Title: Properties of transient horizontal magnetic field and its
implication to a local dynamo process
Authors: Ishikawa, R.; Tsuneta, S.
Bibcode: 2008AGUSMSP23A..01I
Altcode:
Hinode discovered granular-sized "transient horizontal magnetic fields"
(THMFs) on the photosphere. They are ubiquitous in a plage region as
well as in the quiet Sun, and they attract a lot of attention due to
their apparent unique properties. Spectro-polarimetric observations with
the Solar Optical Telescope (SOT) are analyzed to compare the properties
of THMFs in both plage and quiet Sun regions near solar disc center. The
distribution of magnetic field strengths inferred from Milne-Eddington
inversions of the data are remarkably similar. A majority of the THMFs
have field strengths smaller than the equipartition field strength
for average local convective flow. The occurrence rate in plage is
only two times that in the quiet Sun, while the vertical magnetic
flux in the plage region is 8 times larger than in the quiet Sun. The
similarity in the field strength distributions and the occurrence rates
suggests that a common local dynamo process generates THMFs all over
the sun. THMFs in the plage region selected for their higher degree
of linear polarization appear to have preferred direction which is
consistent with that of the plage-region's large-scale vertical field
pattern. This fact and the slightly higher occurrence rate in the plage
suggest that the THMFs are influenced by the larger-scale magnetic
field pattern of the plage. These unique properties of the horizontal
magnetic fields are presented. We also plan to clarify a connection
between the horizontal magnetic fields and chromospheric activities.
Title: The SOLAR-C Mission
Authors: Tsuneta, S.
Bibcode: 2008AGUSMSP54A..04T
Altcode:
The solar physics community in Japan has so far developed three
solar missions over the past 25 years with strong NASA and UK
participation. With the success of the Hinode (SOLAR-B) mission, a
SOLAR-C working group was officially approved by ISAS/JAXA in December
2007 to develop a mission plan. Two plans are being considered. The
Plan A mission performs out-of-ecliptic magnetic and helio-seismic
observations to investigate the internal structure and dynamo mechanism
of the Sun. The spacecraft maintains an orbit approximately 1AU from the
Sun with inclination up to 60 degrees, so that the spacecraft observes
both polar regions as well as equatorial regions in each year. The Plan
B mission pursues high resolution observations that Hinode initiated by
enhancing the spectroscopic and spectro-polarimetric capability and by
extending the wavelength coverage to the UV. The plan B mission covers
the entire solar atmosphere from photosphere to corona, including the
chromosphere and transition layer, with a suite of telescopes with high
spatial, temporal and spectral resolutions. We request a launch date in
the mid 2010s. ISAS/JAXA expects the working group to propose a single
mission plan after one year of study. The solar physics community and
related disciplines in Japan strongly desire and endorse the SOLAR-C
mission to be realized in mid 2010s. The JAXA SOLAR-C working group
invites US and European participation in the SOLAR-C program, following
our remarkable history of collaboration.
Title: Disintegration of Magnetic Flux in Decaying Sunspots as
Observed with the Hinode/SOT
Authors: Kubo, M.; Lites, B. W.; Ichimoto, K.; Shimizu, T.; Suematsu,
Y.; Katsukawa, Y.; Tarbell, T. D.; Shine, R. A.; Title, A. M.; Nagata,
S.; Tsuneta, S.
Bibcode: 2008AGUSMSP31B..01K
Altcode:
Continuous observations of sunspot penumbrae with the Solar Optical
Telescope aboard Hinode clearly show that the outer boundary of the
penumbra fluctuates around its averaged position. The penumbral outer
boundary moves inward when granules appear in the outer penumbra. We
discover that such granules appear one after another while moving
magnetic features (MMFs) are separating from the penumbral "spines"
(penumbral features having fields that are stronger and more vertical
than their surroundings). These granules that appear in the outer
penumbra often merge with bright features inside the penumbra that move
with spines as they elongate toward the moat region. This suggests that
convective motions around the penumbral outer boundary are related to
disintegration of magnetic flux in the sunspot. We also find that dark
penumbral filaments frequently elongate into the moat region in the
vicinity of MMFs that detach from penumbral spines. Such elongating
dark penumbral filaments correspond to nearly horizontal fields
extending from the penumbra. Pairs of MMFs with positive and negative
polarities are sometimes observed along the elongating dark penumbral
filaments. This strongly supports the notion that such elongating dark
penumbral filaments have magnetic fields with a "sea serpent"-like
structure. Evershed flows, which are associated with the penumbral
horizontal fields, may be related to detachment of the MMFs from the
penumbral spines, as well as to the formation of the MMFs along the
dark penumbral filaments that elongate into the moat region.
Title: Quiescent Prominence Structure and Dynamics: a new View From
the Hinode/SOT
Authors: Berger, T.; Okamoto, J.; Slater, G.; Magara, T.; Tarbell,
T.; Tsuneta, S.; Hurlburt, N.
Bibcode: 2008AGUSMSP53A..01B
Altcode:
To date the Hinode/Solar Optical Telescope (SOT) has produced over a
dozen sub-arcsecond, multi-hour movies of quiescent solar prominences
in both the Ca II 396.8~nm H-line and the H-alpha 656.3~nm line. These
datasets have revealed new details of the structure and dynamics of
quiescent prominences including a new form of mass transport in the
form of buoyant plume upflows from the chromosphere. We review the
SOT prominence datasets to show that quiescent prominences appear in
two major morphological categories: "vertically" and "horizontally"
structured. The vertically structured prominences all show ubiquitous
downflows in 400--700~km wide "streams" with velocities of approximately
10~km~s-1. Most of the vertically structured prominences also show
episodic upflows in the form of dark turbulent plumes with typical
velocities of 20~km~s-1. Large-scale oscillations are frequently
seen in vertical prominences with periods on the order of 10 min and
upward propagation speeds of approximately 10~km~s-1. In addition,
"bubble" events in which large voids 10--30~Mm across inflate and
then burst are seen in some of the vertical prominences. In contrast,
the horizontally structured quiescent prominences exhibit only limited
flows along the horizontal filaments. We speculate on the origin of
the distinction between the vertically and horizontally structured
prominences, taking into account viewing angle and the underlying
photospheric magnetic flux density. We also discuss the nature of the
mysterious dark plumes and bubble expansions and their implications
for prominence mass balance in light of recent models of prominence
magnetic structure that find vertical flows along some field lines.
Title: Magnetic field emergence in quiet Sun granules
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; del Toro Iniesta,
J. C.; Tsuneta, S.
Bibcode: 2008A&A...481L..33O
Altcode: 2007arXiv0712.2663O
Aims:We describe a new form of small-scale magnetic flux emergence in
the quiet Sun. This process seems to take vertical magnetic fields
from subsurface layers to the photosphere, where they appear above
granular convection cells.
Methods: High-cadence time series
of spectropolarimetric measurements obtained by Hinode in a quiet
region near disk center are analyzed. We extract line parameters from
the observed Stokes profiles and study their evolution with time.
Results: The circular polarization maps derived from the observed Fe
I 630 nm lines show clear magnetic signals emerging at the center of
granular cells. We do not find any evidence for linear polarization
signals associated with these events. The magnetic flux patches grow
with time, occupying a significant fraction of the granular area. The
signals then fade until they disappear completely. The typical lifetime
of these events is of the order of 20 min. No significant changes in
the chromosphere are seen to occur in response to the emergence, as
revealed by co-spatial Ca II H filtergrams. The Stokes I and V profiles
measured in the emerging flux concentrations show strong asymmetries
and Doppler shifts.
Conclusions: The origin of these events is
unclear at present, but we suggest that they may represent the emergence
of vertical fields lines from the bottom of the photosphere, possibly
dragged by the convective upflows of granules. Preliminary inversions
of the Stokes spectra indicate that this scenario is compatible with
the observations, although the emergence of vertical field lines is
not free from conceptual problems.
Title: Formation of Solar Magnetic Flux Tubes with Kilogauss Field
Strength Induced by Convective Instability
Authors: Nagata, Shin'ichi; Tsuneta, Saku; Suematsu, Yoshinori;
Ichimoto, Kiyoshi; Katsukawa, Yukio; Shimizu, Toshifumi; Yokoyama,
Takaaki; Tarbell, Theodore D.; Lites, Bruce W.; Shine, Richard A.;
Berger, Thomas E.; Title, Alan M.; Bellot Rubio, Luis R.; Orozco
Suárez, David
Bibcode: 2008ApJ...677L.145N
Altcode:
Convective instability has been a mechanism used to explain
the formation of solar photospheric flux tubes with kG field
strength. However, the turbulence of the Earth's atmosphere has
prevented ground-based observers from examining the hypothesis
with precise polarimetric measurement on the subarcsecond scale
flux tubes. Here we discuss observational evidence of this scenario
based on observations with the Solar Optical Telescope (SOT) aboard
Hinode. The cooling of an equipartition field strength flux tube
precedes a transient downflow reaching 6 km s-1 and the
intensification of the field strength to 2 kG. These observations
agree very well with the theoretical predictions.
Title: Transient horizontal magnetic fields in solar plage regions
Authors: Ishikawa, R.; Tsuneta, S.; Ichimoto, K.; Isobe, H.; Katsukawa,
Y.; Lites, B. W.; Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu,
Y.; Tarbell, T. D.; Title, A. M.
Bibcode: 2008A&A...481L..25I
Altcode: 2008arXiv0802.1769I
Aims:We report the discovery of isolated, small-scale emerging
magnetic fields in a plage region with the Solar Optical Telescope
aboard Hinode.
Methods: Spectro-polarimetric observations were
carried out with a cadence of 34 s for the plage region located near
disc center. The vector magnetic fields are inferred by Milne-Eddington
inversion.
Results: The observations reveal widespread occurrence
of transient, spatially isolated horizontal magnetic fields. The
lateral extent of the horizontal magnetic fields is comparable to
the size of photospheric granules. These horizontal magnetic fields
seem to be tossed about by upflows and downflows of the granular
convection. We also report an event that appears to be driven by the
magnetic buoyancy instability. We refer to buoyancy-driven emergence
as type 1 and convection-driven emergence as type 2. Although both
events have magnetic field strengths of about 600 G, the filling
factor of type 1 is a factor of two larger than that of type 2.
Conclusions: Our finding suggests that the granular convection in
the plage regions is characterized by a high rate of occurrence of
granular-sized transient horizontal fields.
Title: Net circular polarization of sunspots in high spatial
resolution
Authors: Ichimoto, K.; Tsuneta, S.; Suematsu, Y.; Katsukawa, Y.;
Shimizu, T.; Lites, B. W.; Kubo, M.; Tarbell, T. D.; Shine, R. A.;
Title, A. M.; Nagata, S.
Bibcode: 2008A&A...481L...9I
Altcode:
Context: Net circular polarization (NCP) of spectral lines in
sunspots has been most successfully explained by the presense of
discontinuities in the magnetic field inclination and flow velocity
along the line-of-sight in the geometry of the embedded flux tube model
of penumbrae (Δγ-effect).
Aims: The fine scale structure of
NCP in a sunspot is examined with special attention paid to spatial
relations of the Evershed flow to confirm the validity of the present
interpretation of the NCP of sunspots.
Methods: High resolution
spectro-polarimetric data of a positive-polarity sunspot obtained
by the Solar Optical Telescope aboard Hinode are analysed.
Results: A positive NCP is associated with the Evershed flow
channels in both limb-side and disk center-side penumbrae and with
upflows in the penumbra at disk center. The negative NCP in the disk
center-side penumbra is generated in inter-Evershed flow channels.
Conclusions: The first result is apparently inconsistent with the
current explanation of NCP with the Δγ-effect but rather suggests a
positive correlation between the magnetic field strength and the flow
velocity as the cause of the NCP. The second result serves as strong
evidence for the presence of gas flows in inter-Evershed flow channels.
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
Bibcode: 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-1,
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-1
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.
Bibcode: 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: Hinode results on the solar magnetic fields
Authors: Tsuneta, Saku
Bibcode: 2008cosp...37.3234T
Altcode: 2008cosp.meet.3234T
Since its launch in September 2006, solar physics satellite, the
Hinode, has continued its observation of the sun, sending back solar
images of unprecedented clarity every day. The impact of the Hinode
solar optical telescope on solar physics is comparable to that of the
Hubble Space Telescope on optical astronomy. In particular, Hinode
demonstrates, for the first time, the importance of spectroscopic and
spectro-polarimetric observations from space. High spatial, temporal,
and spectral observations combined with imaging capabilities with
Hinode Solar Optical Telescope are bringing us with continuous flow of
discoveries. I will present a few selected topics on the solar magnetic
fields that might affect whole solar and plasma astrophysics. The
topics include (1) properties of newly-discovered ubiquitous transient
horizontal fields and its implication to Chromospheric heating,
(2) emergence of horizontal flux rope along the polarity inversion
line as discovered with Hinode, and its potential relationship with
the randomlyoriented transient horizontal magnetic fields, and (3)
convective collapse confirmed for the first time with Hinode.
Title: The Horizontal Magnetic Flux of the Quiet-Sun Internetwork
as Observed with the Hinode Spectro-Polarimeter
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa, Y.;
Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ApJ...672.1237L
Altcode:
Observations of very quiet Sun using the Solar Optical
Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft
reveal that the quiet internetwork regions are pervaded by horizontal
magnetic flux. The spatial average horizontal apparent flux density
derived from wavelength-integrated measures of Zeeman-induced linear
polarization is BTapp = 55 Mx cm -2, as
compared to the corresponding average vertical apparent flux density of
| BLapp| = 11 Mx cm -2. Distributions
of apparent flux density are presented. Magnetic fields are organized on
mesogranular scales, with both horizontal and vertical fields showing
"voids" of reduced flux density of a few granules spatial extent. The
vertical fields are concentrated in the intergranular lanes, whereas the
stronger horizontal fields are somewhat separated spatially from the
vertical fields and occur most commonly at the edges of the bright
granules. High-S/N observations from disk center to the limb help
to constrain possible causes of the apparent imbalance between |
BLapp| and BTapp, with
unresolved structures of linear dimension on the surface smaller by at
least a factor of 2 relative to the SOT/SP angular resolution being one
likely cause of this discrepancy. Other scenarios for explaining this
imbalance are discussed. The horizontal fields are likely the source of
the "seething" fields of the quiet Sun discovered by Harvey et al. The
horizontal fields may also contribute to the "hidden" turbulent flux
suggested by studies involving Hanle effect depolarization of scattered
radiation.
Title: New Views of the Sun: STEREO and Hinode
Authors: Luhmann, Janet G.; Tsuneta, Saku; Bougeret, J. -L.; Galvin,
Antoinette; Howard, R. A.; Kaiser, Michael; Thompson, W. T.
Bibcode: 2008cosp...37.1840L
Altcode: 2008cosp.meet.1840L
The twin-spacecraft STEREO mission has now been in orbit for 1.5
years. Although the main scientific objective of STEREO is the origin
and evolution of Coronal Mass Ejections (CMEs) and their heliospheric
consequences, the slow decline of the previous solar cycle has provided
an extraordinary opportunity for close scrutiny of the quiet corona and
solar wind, including suprathermal and energetic particles. However,
STEREO has also captured a few late cycle CMEs that have given us
a taste of the observations and analyses to come. Images from the
SECCHI investigation afforded by STEREO's separated perspectives and
the heliospheric imager have already allowed us to visibly witness the
origins of the slow solar wind and the Sun-to-1 AU transit of ICMEs. The
SWAVES investigation has monitored the transit of interplanetary shocks
in 3D while the PLASTIC and IMPACT in-situ measurements provide the
'ground truth' of what is remotely sensed. New prospects for space
weather forecasting have been demonstrated with the STEREO behind
spacecraft, a successful proof-of-concept test for future space
weather mission designs. The data sets for the STEREO investigations
are openly available through a STEREO Science Center web interface
that also provides supporting information for potential users from
all communities. Comet observers and astronomers, interplanetary
dust researchers and planetary scientists have already made use
of this resource. The potential for detailed Sun-to-Earth CME/ICME
interpretations with sophisticated modeling efforts are an upcoming
STEREO-Hinode partnering activity whose success we can only anticipate
at this time. Since its launch in September 2006, Hinode has sent back
solar images of unprecedented clarity every day. The primary purpose
of this mission is a systems approach to understanding the generation,
transport and ultimate dissipation of solar magnetic fields with a
well-coordinated set of advanced telescopes. Hinode is equipped with
three telescopes: a visible light telescope, an X-ray telescope, and
an extreme ultraviolet imaging spectrometer. The optical telescope
has a large primary mirror measuring 50 centimeters in diameter, and
is the world's largest space telescope for observing the sun and its
vector magnetic fields. The impact of the Hinode optical telescope on
solar physics is comparable to that of the Hubble Space Telescope on
optical astronomy. Its X-ray telescope captures coronal structures
in exceptional detail. The EUV imaging spectrometer possesses about
ten times the sensitivity and four times the resolution of similar
instruments on previous satellites. With the synergy of Hinode and
STEREO, we are able to witness the entire life cycle of the solar
magnetic field; namely helio-seismic observations of the subsurface flux
tubes, vector magnetic observations of flux emergence and evolution by
the optical telescope, flaring activity on various scales and eventual
eruption in the inner corona observed by the X-ray telescope and the
EUV imaging spectrometer, and their consequences in the heliosphere
observed with the STEREO instruments. We look forward to the upcoming
solar maximum with great expectations for a much improved understanding
of how the Sun works and how it influences Earth's environment in the
solar system.
Title: Hinode Observations of Flux Emergence in Quiet and Active
Regions
Authors: Lites, B. W.; Centeno, R.; Kubo, M.; Socas-Navarro, H. Berger,
T.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.;
Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ASPC..383...71L
Altcode:
We review briefly the observational understanding of emergence of
flux in both the quiet Sun and active regions in the light of first
results from the joint Japan/US/UK Hinode mission. That spacecraft
is now providing us with our first continuous, high resolution
measurements of the photospheric vector magnetic field, along with
high resolution observations of the thermal and dynamic properties
of the chromosphere and corona. This review is intended to present a
few very early results and to highlight the potential for discovery
offered by this extraordinary new mission. The discovery of ubiquitous
horizontal magnetic flux in the quiet internetwork regions is presented.
Title: Recent results from Hinode
Authors: Tsuneta, Saku
Bibcode: 2008cosp...37.3235T
Altcode: 2008cosp.meet.3235T
The Hinode is equipped with three telescopes, visible light telescope,
X-ray telescope, and extreme ultraviolet imaging spectrometer. These
suites of telescopes are able to observe generation and emergence
of solar magnetic fields through their eventual dissipation. Hinode
has been revolutionizing our understating of the Sun. Highlights of
the Hinode include (1) discovery of ubiquitous horizontal fields and
its implication to a local dynamo process and chromospheric heating,
(2) emergence of horizontal flux rope along the polarity inversion
line and its relationship to prominence formation and solar dynamo,
(3) observational confirmation of long-thought convective collapse,
which is related to formation of kG elemental flux tubes and
eventual formation of sunspots, (4) discovery of kG polar fields, (5)
discovery of penumbral micro-jets, (6) high chromospheric activity
such as chromospheric fountain and jets, (7) discovery of waves in
prominence and spicules, (8) discovery of high coronal turbulence around
foot-points of coronal loops, (9) new observations on the origin of
slow and fast solar winds, and (10) high magnetic fluctuation on the
photosphere, etc etc. I will present some of these topics relevant to
the session.
Title: Hinode observations of polar fields
Authors: Tsuneta, Saku
Bibcode: 2008cosp...37.3232T
Altcode: 2008cosp.meet.3232T
The Sun's polar magnetic fields are the direct extension of the global
poloidal field, which serves as seed fields for the toroidal fields
forming active regions and sunspots. The polar regions are also the
source of fast solar wind, and are the final destination of pole-ward
meridional flows. We present spectro-polarimetric maps of the vector
magnetic fields in the polar region of the Sun that are unprecedented in
terms of high spatial resolution, large field of view, and polarimetric
precision. These observations were carried out with the Solar Optical
Telescope aboard Hinode. More than 100 canopy-like vertical magnetic
structures as strong as 1-1.2 kG are scattered in heliographic latitude
of 70-90o . They all have the same polarity, consistent with the global
polar fields. The temporal-spatial evolution of these kG patches,
which are crucial to understanding of their origin, will be reported. In
addition to the vertical fields, the polar region appears to be covered
with ubiquitous horizontal fields. Chromospheric observations with
Hinode indicate that substantial amount of the horizontal fields reach
chromosphere. Our observations describe the magnetic landscape of this
poorly known region of the solar atmosphere. The polar regions are the
source of the fast solar wind channelled along unipolar coronal-hole
magnetic fields. We conjecture that the fast solar wind emanates only
from the vertical flux tubes (canopies), which also seem to serve as
efficient chimneys for Alfven waves to accelerate the solar wind.
Title: Contribution of Yohkoh observations to our current
understanding of solar flares
Authors: Tsuneta, Saku
Bibcode: 2008cosp...37.3233T
Altcode: 2008cosp.meet.3233T
Yohkoh mission brought us with considerable progress in our
understanding on the sporadic energy release of magnetized coronal
plasma with photospheric agitation. Observations of long duration flare
events suggest the existence of the slow shocks and Petschek-type
magnetic reconnection. Loop-top hard X-ray source is found with the
Yohkoh hard X-ray telescope at the position where it should be in the
global Petschek magnetic configuration: the loop-top hard X-ray source
consists of either super hot plasma or confined accelerated electrons
due to the fast shock in the locally super Alfvenic outflow. Ubiquitous
micro flares would also be due to magnetic reconnection. Soft X-ray
light curves exhibit fluctuations larger than the estimated photon
noise, suggesting signature of the underlying discrete impulsive
nanoflares. Therefore, observations with the Yohkoh satellite point to
magnetic reconnection as a necessary ingredient for sporadic coronal
heating on various scales from major flares to ubiquitous nano-bursts,
and we now know that magnetic fields do dissipate. Nevertheless,
the specific mechanisms of coronal and chromospheric heating remain
essentially unknown, and many important issues such as mechanism for
MHD destabilization leading to the formation of Petschek configuration
are not understood. These are fascinating topics left for the missions
following Yohkoh.
Title: Non-Linear Force-Free Modeling of AR NOAA 10930 Based on
Vector Magnetogram Observation with Hinode/SOT
Authors: Inoue, S.; Kusano, K.; Masuda, S.; Miyoshi, T.; Magara, T.;
Yamamoto, T.; Sakurai, T.; Tsuneta, S.; Yokoyama, T.
Bibcode: 2007AGUFMSH53A1048I
Altcode:
Since the detection of three-dimensional (3D) magnetic field in active
regions is crucially important to understand the trigger mechanism
of solar flares, the methodologies to reconstruct the 3D magnetic
field from magnetgram observation is quickly developed recently. In
this study, we have developed a new Non-linear Force-Free (NLFF)
field extrapolation method, based on the extended magnetofrictional
model and the divergence field cleaning technique, and applied it onto
the magnetograms of Active Region NOAA10930, which were observed by
Hinode/SOT. The data covers the time span before and after the X-class
flare arising on December 13, 2006 in this active region, and Hinode
satellite clearly observed the typical features of flare; two ribbon
and post flare loop structures by SOT, and sigmoidal structure before
the onset and the cusp loop structures after that by XRT. As a result
of the NLFF extrapolation, we found that, before the onset of flare,
strong sheared structures were formed on the neutral line, whereas the
field overlying magnetic neutral line was potential-like. Furthermore,
we revealed that a sigmoid structure was not formed of a single sheared
loop, but was composed of strong multiple sheared fields. It is also
detected that, after the flare, elongated magnetic flux is partially
formed but a part of magnetic shear was released. The results indicate
that the NLFF relaxes towards the potential field on average during
the flaring phase, although some sigmoidal structure remains. Also,
the long term evolution of the active region and the storage process
of magnetic energy and helicity in the active region are investigated.
Title: Mangetic field properties at the footpoints of solar
microflares (active-region transient brightenings)
Authors: Shimizu, T.; Kano, R.; Katsukawa, Y.; Kubo, M.; Deluca, E.;
Ichimoto, K.; Lites, B.; Nagata, S.; Sakao, T.; Shine, R.; Suematsu,
Y.; Tarbell, T.; Title, A.; Tsuneta, S.
Bibcode: 2007AGUFMSH52C..06S
Altcode:
Solar active regions produce numerous numbers of small-scale explosive
energy releases, i.e., microflares, which are captured by imaging
observations in soft X-rays as transient brightenings of small-scale
coronal loops. Thanks to advanced performance of X-Ray Telescope (XRT)
onboard the Hinode satellite, we can investigate finer structure
of the brightening X-ray sources in more details than we did with
Yohkoh data. One of important questions on microflares is what causes
microflares. The simultaneous visible-light observations by the Solar
Optical Telescope (SOT) allow us to explore magnetic activities
and magnetic field configuration at the photospheric footpoints
of brightening loops, giving key observations to investigate the
question. For our investigations of corona-photosphere magnetic
coupling, we have established co-alignment between SOT and XRT
with accuracy better than 1 arcsec (Shimizu et al. 2007, PASJ in
press). It turns out that Ca II H observations are very useful
to identify the exact positions of footpoints of X-ray transient
brightening loops. Small "Kernels" are sometimes observed in Ca II H
and they may be signature of highly accelerated non-thermal particles
impinging on chromosphere. As already shown in Shimizu et al.(2002),
frequent transient brightenings are observed at the locations where
emerging activities are on going. However, another type of brightening
triggering mechanism should exist to explain some observed multiple-loop
brightenings. In the multiple-loop brightenings, multiple loops are
magnetically in parallel with each other and no apparent magnetic
activities, such as emerging and canceling, are observed at and near
the footpoints. This paper will present SOT observations of some
microflares observed with XRT.
Title: Small-Scale Jetlike Features in Penumbral Chromospheres
Authors: Katsukawa, Y.; Berger, T. E.; Ichimoto, K.; Lites, B. W.;
Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.;
Title, A. M.; Tsuneta, S.
Bibcode: 2007Sci...318.1594K
Altcode:
We observed fine-scale jetlike features, referred to as penumbral
microjets, in chromospheres of sunspot penumbrae. The microjets
were identified in image sequences of a sunspot taken through a Ca II
H-line filter on the Solar Optical Telescope on board the Japanese solar
physics satellite Hinode. The microjets’ small width of 400 kilometers
and short duration of less than 1 minute make them difficult to identify
in existing observations. The microjets are possibly caused by magnetic
reconnection in the complex magnetic configuration in penumbrae and
have the potential to heat the corona above a sunspot.
Title: Chromospheric Alfvénic Waves Strong Enough to Power the
Solar Wind
Authors: De Pontieu, B.; McIntosh, S. W.; Carlsson, M.; Hansteen,
V. H.; Tarbell, T. D.; Schrijver, C. J.; Title, A. M.; Shine, R. A.;
Tsuneta, S.; Katsukawa, Y.; Ichimoto, K.; Suematsu, Y.; Shimizu, T.;
Nagata, S.
Bibcode: 2007Sci...318.1574D
Altcode:
Alfvén waves have been invoked as a possible mechanism for the heating
of the Sun's outer atmosphere, or corona, to millions of degrees and
for the acceleration of the solar wind to hundreds of kilometers per
second. However, Alfvén waves of sufficient strength have not been
unambiguously observed in the solar atmosphere. We used images of
high temporal and spatial resolution obtained with the Solar Optical
Telescope onboard the Japanese Hinode satellite to reveal that the
chromosphere, the region sandwiched between the solar surface and
the corona, is permeated by Alfvén waves with strong amplitudes on
the order of 10 to 25 kilometers per second and periods of 100 to
500 seconds. Estimates of the energy flux carried by these waves and
comparisons with advanced radiative magnetohydrodynamic simulations
indicate that such Alfvén waves are energetic enough to accelerate
the solar wind and possibly to heat the quiet 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.
Bibcode: 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: Twisting Motions of Sunspot Penumbral Filaments
Authors: Ichimoto, K.; Suematsu, Y.; Tsuneta, S.; Katsukawa, Y.;
Shimizu, T.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Lites, B. W.;
Kubo, M.; Nagata, S.
Bibcode: 2007Sci...318.1597I
Altcode:
The penumbra of a sunspot is composed of numerous thin, radially
extended, bright and dark filaments carrying outward gas flows
(the Evershed flow). Using high-resolution images obtained by the
Solar Optical Telescope aboard the solar physics satellite Hinode, we
discovered a number of penumbral bright filaments revealing twisting
motions about their axes. These twisting motions are observed only
in penumbrae located in the direction perpendicular to the symmetry
line connecting the sunspot center and the solar disk center, and
the direction of the twist (that is, lateral motions of intensity
fluctuation across filaments) is always from limb side to disk-center
side. Thus, the twisting feature is not an actual twist or turn of
filaments but a manifestation of dynamics of penumbral filaments with
three-dimensional radiative transfer effects.
Title: Evidence for Alfvén Waves in Solar X-ray Jets
Authors: Cirtain, J. W.; Golub, L.; Lundquist, L.; van Ballegooijen,
A.; Savcheva, A.; Shimojo, M.; DeLuca, E.; Tsuneta, S.; Sakao, T.;
Reeves, K.; Weber, M.; Kano, R.; Narukage, N.; Shibasaki, K.
Bibcode: 2007Sci...318.1580C
Altcode:
Coronal magnetic fields are dynamic, and field lines may misalign,
reassemble, and release energy by means of magnetic reconnection. Giant
releases may generate solar flares and coronal mass ejections and,
on a smaller scale, produce x-ray jets. Hinode observations of polar
coronal holes reveal that x-ray jets have two distinct velocities:
one near the Alfvén speed (~800 kilometers per second) and another
near the sound speed (200 kilometers per second). Many more jets were
seen than have been reported previously; we detected an average of
10 events per hour up to these speeds, whereas previous observations
documented only a handful per day with lower average speeds of 200
kilometers per second. The x-ray jets are about 2 × 103 to
2 × 104 kilometers wide and 1 × 105 kilometers
long and last from 100 to 2500 seconds. The large number of events,
coupled with the high velocities of the apparent outflows, indicates
that the jets may contribute to the high-speed solar wind.
Title: Continuous Plasma Outflows from the Edge of a Solar Active
Region as a Possible Source of Solar Wind
Authors: Sakao, Taro; Kano, Ryouhei; Narukage, Noriyuki; Kotoku,
Jun'ichi; Bando, Takamasa; DeLuca, Edward E.; Lundquist, Loraine L.;
Tsuneta, Saku; Harra, Louise K.; Katsukawa, Yukio; Kubo, Masahito;
Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo, Masumi; Bookbinder, Jay
A.; Golub, Leon; Korreck, Kelly E.; Su, Yingna; Shibasaki, Kiyoto;
Shimizu, Toshifumi; Nakatani, Ichiro
Bibcode: 2007Sci...318.1585S
Altcode:
The Sun continuously expels a huge amount of ionized material into
interplanetary space as the solar wind. Despite its influence on the
heliospheric environment, the origin of the solar wind has yet to
be well identified. In this paper, we report Hinode X-ray Telescope
observations of a solar active region. At the edge of the active region,
located adjacent to a coronal hole, a pattern of continuous outflow of
soft-x-ray emitting plasmas was identified emanating along apparently
open magnetic field lines and into the upper corona. Estimates of
temperature and density for the outflowing plasmas suggest a mass
loss rate that amounts to ~1/4 of the total mass loss rate of the
solar wind. These outflows may be indicative of one of the solar wind
sources at the Sun.
Title: Magnetic and velocity fluctuations of solar magnetic fields
observed with Hinode
Authors: Tsuneta, S.
Bibcode: 2007AGUFMSH34A..02T
Altcode:
Solar Optical Telescope aboard Hinode satellite has a filter instrument
and spectro-polarimetric instrument. The filter instrument provides us
with high resolution high cadence images with line-of-sight Dopplergram,
while the spectropolarimter gives precise magnetic and velocity maps
with lower time resolution. The quality of the data is unprecedented. We
will present relevant data in terms of fluctuations.
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.
Bibcode: 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.
Bibcode: 2007Sci...318.1577O
Altcode: 2008arXiv0801.1958O
Solar prominences are cool 104 kelvin plasma clouds
supported in the surrounding 106 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: Quiet-Sun Internetwork Magnetic Fields from the Inversion of
Hinode Measurements
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; del Toro Iniesta,
J. C.; Tsuneta, S.; Lites, B. W.; Ichimoto, K.; Katsukawa, Y.; Nagata,
S.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2007ApJ...670L..61O
Altcode: 2007arXiv0710.1405O
We analyze Fe I 630 nm observations of the quiet Sun at disk center
taken with the spectropolarimeter of the Solar Optical Telescope aboard
the Hinode satellite. A significant fraction of the scanned area,
including granules, turns out to be covered by magnetic fields. We
derive field strength and inclination probability density functions from
a Milne-Eddington inversion of the observed Stokes profiles. They show
that the internetwork consists of very inclined, hG fields. As expected,
network areas exhibit a predominance of kG field concentrations. The
high spatial resolution of Hinode's spectropolarimetric measurements
brings to an agreement the results obtained from the analysis of
visible and near-infrared lines.
Title: Center-to-Limb Variation of Stokes V Asymmetries in Solar
Pores Observed with the Hinode Spectro-Polarimeter
Authors: Morinaga, Shuji; Nagata, Shin'ichi; Ichimoto, Kiyoshi;
Suematsu, Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimizu,
Toshifumi; Shine, Richard A.; Tarbell, Theodore D.; Title, Alan M.;
Lites, Bruce; Kubo, Masahito; Sakurai, Takashi
Bibcode: 2007PASJ...59S.613M
Altcode:
Here we present spectro-polarimetric measurements of several pores
and the surrounding regions taken with the Solar Optical Telescope
aboard Hinode at various viewing angles. We analyzed the Stokes V
area asymmetry, and confirmed that it is depressed at the center of
the pores, while it shows large positive values (a blue lobe larger
than a red lobe) in the surrounding area; this is consistent with a
previous report. In addition to this ring of positive asymmetry, we
found regions of alternating positive and negative area asymmetries
when weak V regions were observed near the solar limb. The positive
asymmetry occurs on the disk-center side and the negative asymmetry
on the limb side of the magnetic concentrations. These center-to-limb
variations of the Stokes V area asymmetry can be interpreted as being
a systematic inflow of plasma into the magnetic concentrations from
their surroundings.
Title: Initial Results on Line-of-Sight Field Calibrations of SP/NFI
Data Taken by SOT/Hinode
Authors: Chae, Jongchul; Moon, Yong-Jae; Park, Young-Deuk; Ichimoto,
Kiyoshi; Sakurai, Takashi; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Shimizu, Toshifumi; Shine, Richard A.; Tarbell,
Theodore D.; Title, Alan M.; Lites, Bruce; Kubo, Masahito; Nagata,
Shin'ichi; Yokoyama, Takaaki
Bibcode: 2007PASJ...59S.619C
Altcode:
We present initial results on the line-of-sight field calibration
of the two kinds of Stokes I and V data taken by the Solar Optical
Telescope on the satellite Hinode: spectral profiles of Stokes I and V
parameters recorded on the Spectro-polarimeter (SP), and monochromatic
images of the same parameters recorded on the Narrow-band Filter Imager
(NFI). By applying the center-of-gravity method to the SP data of
AR10930 taken on 2006 December 11, we determined the line-of-sight field
at every location in the active region. As a result, we found that the
line-of-sight field strength ranges up to 2kG in plages, even without
taking into account the filling factor, and up to 3.5kG or higher values
inside the umbra of the major sunspot. We calibrated the NFI data in
reference to the field determined from the SP data. In regions outside
the sunspots and the penumbral regions, we adopted a linear relation,
B|| = βV / I, between the circular polarization, V / I,
and the line-of-sight field strength, B||, and obtained β =
23.5kG in regions outside the sunspots, and β = 12.0kG in penumbral
regions. In umbral regions of sunspots, a first-order polynomial was
adopted to model the reversal of the polarization signal over the
field strength.
Title: Response of the Solar Atmosphere to Magnetic Flux Emergence
from Hinode Observations
Authors: Li, Hui; Sakurai, Takashi; Ichimito, Kiyoshi; Suematsu,
Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimizu, Toshifumi; Shine,
Richard A.; Tarbell, Theodore D.; Title, Alan M.; Lites, Bruce; Kubo,
Masahito; Nagata, Shin'ichi; Kotoku, Jun; Shibasaki, Kiyoto; Saar,
Steven H.; Bobra, Monica
Bibcode: 2007PASJ...59S.643L
Altcode:
No abstract at ADS
Title: Initial Helioseismic Observations by Hinode/SOT
Authors: Sekii, Takashi; Kosovichev, Alexander G.; Zhao, Junwei;
Tsuneta, Saku; Shibahashi, Hiromoto; Berger, Thomas E.; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
Bibcode: 2007PASJ...59S.637S
Altcode: 2007arXiv0709.1806S
Results from initial helioseismic observations by the Solar Optical
Telescope on-board Hinode are reported. It has been demonstrated
that intensity oscillation data from the Broadband Filter Imager
can be used for various helioseismic analyses. The k - ω power
spectra, as well as the corresponding time-distance cross-correlation
function, which promise high-resolution time-distance analysis below
the 6-Mm travelling distance, were obtained for G-band and CaII-H
data. Subsurface supergranular patterns were observed from our first
time-distance analysis. The results show that the solar oscillation
spectrum is extended to much higher frequencies and wavenumbers, and
the time-distance diagram is extended to much shorter travel distances
and times than were observed before, thus revealing great potential
for high-resolution helioseismic observations from Hinode.
Title: Magnetic Feature and Morphological Study of X-Ray Bright
Points with Hinode
Authors: Kotoku, Jun'ichi; Kano, Ryouhei; Tsuneta, Saku; Katsukawa,
Yukio; Shimizu, Toshifumi; Sakao, Taro; Shibazaki, Kiyoto; Deluca,
Edward E.; Korreck, Kelly E.; Golub, Leon; Bobra, Monica
Bibcode: 2007PASJ...59S.735K
Altcode:
We observed X-ray bright points (XBPs) in a quiet region of the Sun
with the X-Ray Telescope (XRT) aboard the Hinode satellite on 2006
December 19. XRT's high-resolution X-ray images revealed many XBPs with
complicated structure and evolving dramatically with time. Almost all
of the dynamic eruptions in the quiet region were composed of XBPs,
and they had either loop or multiloop shapes, as is observed in larger
flares. Brightening XBPs had strong magnetic fields with opposite
polarities near their footpoints. While we have found a possible
example of associated magnetic cancellation, other XBPs brighten and
fade without any associated movement of the photospheric magnetic field.
Title: Hinode Observations of Horizontal Quiet Sun Magnetic Flux
and the ``Hidden Turbulent Magnetic Flux''
Authors: Lites, Bruce; Socas-Navarro, Hector; Kubo, Masahito; Berger,
Thomas; Frank, Zoe; Shine, Richard A.; Tarbell, Theodore D.; Title,
Alan M.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Tsuneta, Saku; Suematsu,
Yoshinori; Shimizu, Toshifumi
Bibcode: 2007PASJ...59S.571L
Altcode:
We present observations of magnetic fields of the very quiet Sun
near disk center using the Spectro-Polarimeter of the Solar Optical
Telescope aboard the Hinode satellite. These observations reveal for
the first time the ubiquitous presence of horizontal magnetic fields in
the internetwork regions. The horizontal fields are spatially distinct
from the vertical fields, demonstrating that they are not arising mainly
from buffeting of vertical flux tubes by the granular convection. The
horizontal component has an average ``apparent flux density'' of
55Mxcm-2 (assuming the horizontal field structures are
spatially resolved), in contrast to the average apparent vertical flux
density of 11Mxcm-2. The vertical fields reside mainly in
the intergranular lanes, whereas the horizontal fields occur mainly
over the bright granules, with a preference to be near the outside
edge of the bright granules. The large apparent imbalance of vertical
and horizontal flux densities is discussed, and several scenarios are
presented to explain this imbalance.
Title: A Study of Polar Jet Parameters Based on Hinode XRT
Observations
Authors: Savcheva, Antonia; Cirtain, Jonathan; Deluca, Edward E.;
Lundquist, Loraine L.; Golub, Leon; Weber, Mark; Shimojo, Masumi;
Shibasaki, Kiyoto; Sakao, Taro; Narukage, Noriyuki; Tsuneta, Saku;
Kano, Ryouhei
Bibcode: 2007PASJ...59S.771S
Altcode:
Hinode/SOHO campaign 7197 is the most extensive study of polar jet
formation and evolution from within both the north and south polar
coronal holes so far. For the first time, this study showed that the
appearance of X-ray jets in the solar coronal holes occurs at very high
frequency - about 60 jets d-1 on average. Using observations
collected by the X-Ray Telescope on Hinode, a number of physical
parameters from a large sample of jets were statistically studied. We
measured the apparent outward velocity, the height, the width and
the lifetime of the jets. In our sample, all of these parameters show
peaked distributions with maxima at 160kms-1 for the outward
velocity, 5 × 104 km for the height, 8 × 103
km for the width, and about 10min for the lifetime of the jets. We
also present the first statistical study of jet transverse motions,
which obtained transverse velocities of 0-35kms-1. These
values were obtained on the basis of a larger (in terms of frequency)
and better sampled set of events than what was previously statistically
studied (Shimojo et al. 1996, PASJ, 48, 123). The results were made
possible by the unique characteristics of XRT. We describe the methods
used to determine the characteristics and set some future goals. We
also show that despite some possible selection effects, jets preferably
occur inside the polar coronal holes.
Title: Strategy for the Inversion of Hinode Spectropolarimetric
Measurements in the Quiet Sun
Authors: Orozco Suárez, David; Bellot Rubio, Luis R.; Del Toro
Iniesta, Jose Carlos; Tsuneta, Saku; Lites, Bruce; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.
Bibcode: 2007PASJ...59S.837O
Altcode: 2007arXiv0709.2033O
In this paper we propose an inversion strategy for the analysis of
spectropolarimetric measurements taken by Hinode in the quiet Sun. The
Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode records
the Stokes spectra of the FeI line pair at 630.2nm with unprecendented
angular resolution, high spectral resolution, and high sensitivity. We
discuss the need to consider a local stray-light contamination to
account for the effects of telescope diffraction. The strategy is
applied to observations of a wide quiet Sun area at disk center. Using
these data we examine the influence of noise and initial guess models
in the inversion results. Our analysis yields the distributions of
magnetic field strengths and stray-light factors. They show that quiet
Sun internetwork regions consist mainly of hG fields with stray-light
contamination of about 0.8.
Title: Hinode Calibration for Precise Image Co-Alignment between
SOT and XRT (2006 November-2007 April)
Authors: Shimizu, Toshifumi; Katsukawa, Yukio; Matsuzaki, Keiichi;
Ichimoto, Kiyoshi; Kano, Ryohei; Deluca, Edward E.; Lundquist,
Loraine L.; Weber, Mark; Tarbell, Theodore D.; Shine, Richard A.;
Sôma, Mitsuru; Tsuneta, Saku; Sakao, Taro; Minesugi, Kenji
Bibcode: 2007PASJ...59S.845S
Altcode: 2007arXiv0709.4098S
To understand the physical mechanisms for activity and heating in
the solar atmosphere, the magnetic coupling from the photosphere
to the corona is an important piece of information from the Hinode
observations, and therefore precise positional alignment is required
among the data acquired by different telescopes. The Hinode spacecraft
and its onboard telescopes were developed to allow us to investigate
magnetic coupling with co-alignment accuracy better than 1". Using
the Mercury transit observed on 2006 November 8 and co-alignment
measurements regularly performed on a weekly basis, we have determined
the information necessary for precise image co-alignment, and have
confirmed that co-alignment better than 1" can be realized between
Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) with our
baseline co-alignment method. This paper presents results from the
calibration for precise co-alignment of CCD images from SOT and XRT.
Title: Hinode Observations of a Vector Magnetic Field Change
Associated with a Flare on 2006 December 13
Authors: Kubo, Masahito; Yokoyama, Takaaki; Katsukawa, Yukio; Lites,
Bruce; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu,
Toshifumi; Nagata, Shin'ichi; Tarbell, Theodore D.; Shine, Richard A.;
Title, Alan M.; Elmore David
Bibcode: 2007PASJ...59S.779K
Altcode: 2007arXiv0709.2397K
Continuous observations of the flare productive active region 10930
were successfully carried out with the Solar Optical Telescope aboard
the Hinode spacecraft during 2006 December 6 to 19. We focused on the
evolution of photospheric magnetic fields in this active region, and the
magnetic field properties at the site of the X3.4 class flare, using
a time series of vector field maps with high spatial resolution. The
X3.4 class flare occurred on 2006 December 13 at the apparent
collision site between the large, opposite polarity umbrae. Elongated
magnetic structures with alternatingly positive and negative polarities
resulting from flux emergence appeared one day before the flare in the
collision site penumbra. Subsequently, the polarity inversion line
at the collision site became very complicated. The number of bright
loops in CaII H increased during the formation of these elongated
magnetic structures. Flare ribbons and bright loops evolved along
the polarity inversion line and one footpoint of the bright loop was
located in a region having a large departure of the field azimuth angle
with respect to its surroundings. SOT observations with high spatial
resolution and high polarization precision revealed temporal change in
the fine structure of magnetic fields at the flare site: some parts of
the complicated polarity inversion line then disappeared, and in those
regions the azimuth angle of the photospheric magnetic field changed by
about 90°, becoming more spatially uniform within the collision site.
Title: The Analysis of Penumbral Fine Structure Using an Advanced
Inversion Technique
Authors: Jurcák, Jan; Bellot Rubio, Luis; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi;
Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.; Tsuneta,
Saku
Bibcode: 2007PASJ...59S.601J
Altcode: 2007arXiv0707.1560J
We present a method to study the penumbral fine structure using data
obtained by the spectropolarimeter on board Hinode. For the first
time, the penumbral filaments can be considered as being resolved in
spectropolarimetric measurements. This enables us to use inversion
codes with only one-component model atmospheres, and thus to assign
the obtained stratifications of the plasma parameters directly to the
penumbral fine structure. This approach was applied to the limb-side
part of the penumbra in the active region NOAA10923. Preliminary results
show a clear dependence of the plasma parameters on the continuum
intensity in the inner penumbra, i.e., a weaker and horizontal magnetic
field along with an increased line-of-sight velocity are found in the
low layers of the bright filaments. The results in the mid penumbra
are ambiguous, and future analyses are necessary to unveil the magnetic
field structure and other plasma parameters there.
Title: Fine-Scale Structures of the Evershed Effect Observed by the
Solar Optical Telescope aboard Hinode
Authors: Ichimoto, Kiyoshi; Shine, Richard A.; Lites, Bruce; Kubo,
Masahito; Shimizu, Toshifumi; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Tarbell, Theodore D.; Title, Alan M.; Nagata,
Shin'ichi; Yokoyama, Takaaki; Shimojo, Masumi
Bibcode: 2007PASJ...59S.593I
Altcode:
The small-scale structure of the Evershed effect is being studied
using data obtained by the Spectropolarimeter and the Broadband Filter
Imager of the Solar Optical Telescope aboard Hinode. We find that the
Evershed flow starts at the leading edge of inwardly migrating bright
penumbral grains, and turns to nearly a horizontal flow preferentially
in the dark lanes of the penumbra. A number of small elongated regions
that have an upward motion of ∼ 1kms-1 are found in the
deep photosphere distributed over the penumbra. They are cospatial
with bright grains and have relatively horizontal magnetic fields. A
number of patches having a strong downward motion associated with the
opposite magnetic polarity from the sunspot are also found in the mid
and outer penumbra. They could be identified as foot points of the
Evershed flow channels, though the identification of individual pairs
is not straightforward. Our results provide strong support for some
recent findings from ground-based high-resolution observations, and
are in general agreement with the well-known picture of the uncombed
structure of the penumbra, in which the penumbrae consist of rising
flux tubes carrying nearly horizontal Evershed flows embedded in more
vertical background magnetic fields.
Title: Flare Ribbons Observed with G-band and FeI 6302Å, Filters
of the Solar Optical Telescope on Board Hinode
Authors: Isobe, Hiroaki; Kubo, Masahito; Minoshima, Takashi; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Tarbell, Theodore D.; Tsuneta, Saku; Berger,
Thomas E.; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Title, Alan M.
Bibcode: 2007PASJ...59S.807I
Altcode: 2007arXiv0711.3946I
The Solar Optical Telescope (SOT) on board the Hinode satellite observed
an X3.4 class flare on 2006 December 13. A typical two-ribbon structure
was observed, not only in the chromospheric CaII H line, but also in
the G-band and FeI 6302Å line. The high-resolution, seeing-free images
achieved by SOT revealed, for the first time, sub-arcsec fine structures
of the ``white light'' flare. The G-band flare ribbons on sunspot
umbrae showed a sharp leading edge, followed by a diffuse inside,
as well as a previously known core-halo structure. The underlying
structures, such as umbral dots, penumbral filaments, and granules,
were visible in the flare ribbons. Assuming that the sharp leading
edge was directly heated by a particle beam and the diffuse parts were
heated by radiative back-warming, we estimated the depth of the diffuse
flare emission using an intensity profile of the flare ribbon. We found
that the depth of the diffuse emission was about 100km or less from
the height of the source of radiative back-warming. The flare ribbons
were also visible in the Stokes-V images of FeI 6302Å, as a transient
polarity reversal. This is probably related to a ``magnetic transient''
reported in the literature. The intensity increase in Stokes-I images
indicates that the FeI 6302Å line was significantly deformed by the
flare, which may cause such a magnetic transient.
Title: Small-Scale Magnetic-Flux Emergence Observed with Hinode
Solar Optical Telescope
Authors: Otsuji, Kenichi; Shibata, Kazunari; Kitai, Reizaburo; Ueno,
Satoru; Nagata, Shin'ichi; Matsumoto, Takuma; Nakamura, Tahei;
Watanabe, Hiroko; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto,
Kiyoshi; Shimizu, Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.;
Lites, Bruce; Shine, Richard A.; Title Alan M.
Bibcode: 2007PASJ...59S.649O
Altcode: 2007arXiv0709.3207O
We observed small-scale magnetic-flux emergence in a sunspot moat region
by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We
analyzed filtergram images observed at wavelengths of Fe 6302Å, G band,
and CaII H. In Stokes I images of Fe 6302Å, emerging magnetic flux was
recognized as dark lanes. In the G band, they showed to be their shapes
almost the same as in Stokes I images. These magnetic fluxes appeared
as dark filaments in CaII H images. Stokes V images of Fe 6302Å showed
pairs of opposite polarities at footpoints of each filament. These
magnetic concentrations were identified to correspond to bright points
in G band/CaII H images. From an analysis of time-sliced diagrams, we
derived the following properties of emerging flux, which are consistent
with those of previous studies: (1) Two footpoints separate each other
at a speed of 4.2kms-1 during the initial phase of evolution,
and decrease to about 1kms-1 10minutes later. (2) CaII H
filaments appear almost simultaneously with the formation of dark lanes
in Stokes I in an observational cadence of 2minutes. (3) The lifetime
of the dark lanes in the Stokes I and G band is 8minutes, while that
of Ca filament is 12minutes. An interesting phenomena was observed,
that an emerging flux tube expanded laterally in the photosphere with a
speed of 3.8kms-1. A discussion on the horizontal expansion
of the flux tube is given with refernce to previous simulation studies.
Title: Observations of Sunspot Oscillations in G Band and CaII H
Line with Solar Optical Telescope on Hinode
Authors: Nagashima, Kaori; Sekii, Takashi; Kosovichev, Alexander G.;
Shibahashi, Hiromoto; Tsuneta, Saku; Ichimoto, Kiyoshi; Katsukawa,
Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.
Bibcode: 2007PASJ...59S.631N
Altcode: 2007arXiv0709.0569N
Exploiting high-resolution observations made by the Solar Optical
Telescope on board Hinode, we investigate the spatial distribution
of the power spectral density of the oscillatory signal in and around
the active region NOAA 10935. The G-band data show that in the umbra
the oscillatory power is suppressed in all frequency ranges. On
the other hand, in CaII H intensity maps oscillations in the umbra,
so-called umbral flashes, are clearly seen with the power peaking around
5.5mHz. The CaII H power distribution shows the enhanced elements with
the spatial scale of the umbral flashes over most of the umbra, but
there is a region with suppressed power at the center of the umbra. The
origin and property of this node-like feature remain unexplained.
Title: Hinode SP Vector Magnetogram of AR10930 and Its
Cross-Comparison with MDI
Authors: Moon, Yong-Jae; Kim, Yeon-Han; Park, Young-Deuk; Ichimoto,
Kiyoshi; Sakurai, Takashi; Chae, Jongchul; Cho, Kyung Suk; Bong,
Suchan; Suematsu, Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimojo,
Masumi; Shimizu, Toshifumi; Shine, Richard A.; Tarbell, Theodore D.;
Title, Alan M.; Lites, Bruce; Kubo, Masahito; Nagata, Shin'ichi;
Yokoyama, Takaaki
Bibcode: 2007PASJ...59S.625M
Altcode:
We present one Hinode Spectropolarimeter (SP) magnetogram of AR 10930
that produced several major flares. The inversion from Stokes profiles
to magnetic field vectors was made using the standard Milne-Eddington
code. We successfully applied the Uniform Shear Method for resolving
the 180° ambiguity to the magnetogram. The inversion gave very strong
magnetic field strengths (near 4500 gauss) for a small portion of area
in the umbra. Considering that the observed V-profile of 6301.5Å was
well-fitted as well as a direct estimation of the Zeeman splitting
results in 4300-4600 gauss, we think that the field strengths
should not be far from the actual value. A cross-comparison of the
Hinode SP and SOHO MDI high resolution flux densities shows that the
MDI flux density could be significantly underestimated by about a
factor of two. In addition, it has a serious negative correlation
(the so-called Zeeman saturation effect) with the Hinode SP flux
density for umbral regions. Finally, we could successfully obtain
a recalibrated MDI magnetogram that has been corrected for the
Zeeman saturation effect using not only a pair of MDI intensity and
magnetogram data simultaneously observed, but also the relationship
from the cross-comparison between the Hinode SP and MDI flux densities.
Title: Formation Process of a Light Bridge Revealed with the Hinode
Solar Optical Telescope
Authors: Katsukawa, Yukio; Yokoyama, Takaaki; Berger, Thomas E.;
Ichimoto, Kiyoshi; Kubo, Masahito; Lites, Bruce; Nagata, Shin'ichi;
Shimizu, Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell,
Theodore D.; Title, Alan M.; Tsuneta, Saku
Bibcode: 2007PASJ...59S.577K
Altcode: 2007arXiv0709.2527K
The Solar Optical Telescope (SOT) on-board Hinode successfully and
continuously observed the formation process of a light bridge in a
matured sunspot of the NOAA active region 10923 for several days with
high spatial resolution. During its formation, many umbral dots were
observed to be emerging from the leading edges of penumbral filaments,
and rapidly intruding into the umbra. The precursor of the light bridge
formation was also identified as a relatively slow inward motion of
the umbral dots, which emerged not near the penumbra, but inside the
umbra. The spectro-polarimeter on SOT provided physical conditions in
the photosphere around the umbral dots and the light bridges. We found
that the light bridges and the umbral dots had significantly weaker
magnetic fields associated with upflows relative to the core of the
umbra, which implies that there was hot gas with weak field strength
penetrating from the subphotosphere to near the visible surface inside
those structures. There needs to be a mechanism to drive the inward
motion of the hot gas along the light bridges. We suggest that the
emergence and the inward motion are triggered by a buoyant penumbral
flux tube as well as subphotospheric flow crossing the sunspot.
Title: Umbral Fine Structures in Sunspots Observed with Hinode Solar
Optical Telescope
Authors: Kitai, Reizaburo; Watanabe, Hiroko; Nakamura, Tahei; Otsuji,
Ken-ichi; Matsumoto, Takuma; UeNo, Satoru; Nagata, Shin'ichi; Shibata,
Kazunari; Muller, Richard; Ichimoto, Kiyoshi; Tsuneta, Saku; Suematsu,
Yoshinori; Katsukawa, Yukio; Shimizu, Toshifumi; Tarbell, Theodore D.;
Shine, Richard A.; Title, Alan M.; Lites, Bruce
Bibcode: 2007PASJ...59S.585K
Altcode: 2007arXiv0711.3266K
A high resolution imaging observation of a sunspot umbra was made with
the Hinode Solar Optical Telescope. Filtergrams at wavelengths of the
blue and green continua were taken during three consecutive days. The
umbra consisted of a dark core region, several diffuse components,
and numerous umbral dots. We derived basic properties of umbral dots
(UDs), especially their temperatures, lifetimes, proper motions,
spatial distribution, and morphological evolution. The brightness
of UDs is confirmed to depend on the brightness of their surrounding
background. Several UDs show fission and fusion. Thanks to the stable
condition of the space observation, we could for the first time follow
the temporal behavior of these events. The derived properties of the
internal structure of the umbra are discussed from the viewpoint of
magnetoconvection in a strong magnetic field.
Title: On Connecting the Dynamics of the Chromosphere and Transition
Region with Hinode SOT and EIS
Authors: Hansteen, Viggo H.; de Pontieu, Bart; Carlsson, Mats;
McIntosh, Scott; Watanabe, Tetsuya; Warren, Harry P.; Harra, Louise K.;
Hara, Hirohisa; Tarbell, Theodore D.; Shine, Dick; Title, Alan M.;
Schrijver, Carolus J.; Tsuneta, Saku; Katsukawa, Yukio; Ichimoto,
Kiyoshi; Suematsu, Yoshinori; Shimizu, Toshifumi
Bibcode: 2007PASJ...59S.699H
Altcode: 2007arXiv0711.0487H
We use coordinated Hinode SOT/EIS observations that include
high-resolution magnetograms, chromospheric, and transition region
(TR) imaging, and TR/coronal spectra in a first test to study how
the dynamics of the TR are driven by the highly dynamic photospheric
magnetic fields and the ubiquitous chromospheric waves. Initial
analysis shows that these connections are quite subtle and require a
combination of techniques including magnetic field extrapolations,
frequency-filtered time-series, and comparisons with synthetic
chromospheric and TR images from advanced 3D numerical simulations. As a
first result, we find signatures of magnetic flux emergence as well as
3 and 5mHz wave power above regions of enhanced photospheric magnetic
field in both chromospheric, transition region, and coronal emission.
Title: Can High Frequency Acoustic Waves Heat the Quiet Sun
Chromosphere?
Authors: Carlsson, Mats; Hansteen, Viggo H.; de Pontieu, Bart;
McIntosh, Scott; Tarbell, Theodore D.; Shine, Dick; Tsuneta, Saku;
Katsukawa, Yukio; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Shimizu,
Toshifumi; Nagata, Shin'ichi
Bibcode: 2007PASJ...59S.663C
Altcode: 2007arXiv0709.3462C
We use Hinode/SOT Ca II H-line and blue continuum broadband observations
to study the presence and power of high frequency acoustic waves at
high spatial resolution. We find that there is no dominant power at
small spatial scales; the integrated power using the full resolution of
Hinode (0.05'' pixels, 0.16'' resolution) is larger than the power in
the data degraded to 0.5'' pixels (TRACE pixel size) by only a factor
of 1.2. At 20 mHz the ratio is 1.6. Combining this result with the
estimates of the acoustic flux based on TRACE data of Fossum &
Carlsson (2006), we conclude that the total energy flux in acoustic
waves of frequency 5-40 mHz entering the internetwork chromosphere of
the quiet Sun is less than 800 W m$^{-2}$, inadequate to balance the
radiative losses in a static chromosphere by a factor of five.
Title: Formation of Moving Magnetic Features and Penumbral Magnetic
Fields with Hinode/SOT
Authors: Kubo, Masahito; Ichimoto, Kiyoshi; Shimizu, Toshifumi;
Tsuneta, Saku; Suematsu, Yoshinori; Katsukawa, Yukio; Nagata,
Shin'ichi; Tarbell, Theodore D.; Shine, Richard A.; Title, Alan M.;
Frank, Zoe A.; Lites, Bruce; Elmore, David
Bibcode: 2007PASJ...59S.607K
Altcode: 2007arXiv0709.1853K
Vector magnetic fields of moving magnetic features (MMFs) were well
observed with the Solar Optical Telescope (SOT) aboard the Hinode
satellite. We focused on the evolution of three MMFs with the SOT in
this study. We found that an MMF having relatively vertical fields
with the same polarity as the sunspot was detached from the penumbra
around the granules appearing in the outer penumbra. This suggests
that granular motions in the outer penumbra are responsible for
disintegration of the sunspot. Two MMFs with polarity opposite to
the sunspot are located around the outer edge of horizontal fields
extending from the penumbra. This is evidence that the MMFs with
polarity opposite to the sunspot are the prolongation of penumbral
horizontal fields. Redshifts larger than the sonic velocity in the
photosphere are detected for some of the MMFs with polarity opposite
to the sunspot.
Title: A Tale of Two Spicules: The Impact of Spicules on the Magnetic
Chromosphere
Authors: de Pontieu, Bart; McIntosh, Scott; Hansteen, Viggo H.;
Carlsson, Mats; Schrijver, Carolus J.; Tarbell, Theodore D.; Title,
Alan M.; Shine, Richard A.; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Nagata,
Shin'ichi
Bibcode: 2007PASJ...59S.655D
Altcode: 2007arXiv0710.2934D
We use high-resolution observations of the Sun in CaIIH (3968Å)
from the Solar Optical Telescope on Hinode to show that there are
at least two types of spicules that dominate the structure of the
magnetic solar chromosphere. Both types are tied to the relentless
magnetoconvective driving in the photosphere, but have very different
dynamic properties. ``Type-I'' spicules are driven by shock waves
that form when global oscillations and convective flows leak into
the upper atmosphere along magnetic field lines on 3--7minute
timescales. ``Type-II'' spicules are much more dynamic: they form
rapidly (in ∼ 10s), are very thin (≤ 200 km wide), have lifetimes
of 10-150s (at any one height), and seem to be rapidly heated to
(at least) transition region temperatures, sending material through
the chromosphere at speeds of order 50--150kms-1. The
properties of Type II spicules suggest a formation process that is
a consequence of magnetic reconnection, typically in the vicinity
of magnetic flux concentrations in plage and network. Both types of
spicules are observed to carry Alfvén waves with significant amplitudes
of order 20kms-1.
Title: Fine Structures of Solar X-Ray Jets Observed with the X-Ray
Telescope aboard Hinode
Authors: Shimojo, Masumi; Narukage, Noriyuki; Kano, Ryohei; Sakao,
Taro; Tsuneta, Saku; Shibasaki, Kiyoto; Cirtain, Jonathan W.;
Lundquist, Loraine L.; Reeves, Katherine K.; Savcheva, Antonia
Bibcode: 2007PASJ...59S.745S
Altcode:
The X-Ray Telescope (XRT) aboard Hinode has revealed the fine structure
of solar X-ray jets. One of the fine structures observed by XRT is an
expanding loop. The loop appeared near the footpoint of the jet when
footpoint brightening was observed. Additionally, we have found that the
X-ray jets began just after the expanding loop ``breaks''. Other fine
structures discovered by XRT are thread-like features along the axis
of the jets. XRT has shown that these thread structures compose the
cross-section of jets. The fine structures and their motions strongly
support an X-ray jet model based on magnetic reconnection, and also
suggest that we must consider the three-dimensional configuration of the
magnetic field to understand the jet phenomenon. We also investigated
the reverse jet associated with the X-ray jet in the quiet Sun, and
propose that the reverse jet is produced by heat conduction, or a MHD
wave subsequent to the main jet.
Title: The Solar-B Science Center in Japan
Authors: Shimojo, M.; Tsuneta, S.
Bibcode: 2007ASPC..369...59S
Altcode:
We are proposing to establish the Solar-B Science Center (SBSC) at
NAOJ. The concept of the proposal is that SBSC be a platform for joint
research to maximize scientific return from Solar-B. The concept was
accepted both by NAOJ and JAXA. The computer system of SBSC includes
the PC-cluster for the inversion of the vector magnetogram and the
local helioseismology. The mass-storage system at NAO is mainly
for the higher-level data, while JAXA/ISAS maintains lower-level
data. We plan to provide methodology to make DVD Movie disc etc for
simultaneous browse of SOT, XRT and EIS data. We are discussing with
JAXA/ISAS for the easy-to-use data search system based on the existing
ISAS DARTS data archive system. We recognize that these plans are
ambitious. SBSC invites both domestic and international visitors, and
provide scientifically comfortable environment for joint data analysis.
Title: Estimate on SOT Light Level in Flight with Throughput
Measurements in SOT Sun Tests
Authors: Shimizu, T.; Kubo, M.; Tarbell, T. D.; Berger, T. E.;
Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Miyashita, M.; Noguchi,
M.; Nakagiri, M.; Tsuneta, S.; Elmore, D. F.; Lites, B. W.
Bibcode: 2007ASPC..369...51S
Altcode:
The SOT (Solar Optical Telescope, e.g., Shimizu 2004) optical
system consists of 50cm-aperture optical telescope (OTA) and focal
plane instrument (FPP). The solar light into the telescope penetrates
through many optical elements located in OTA and FPP before illuminating
CCDs. Natural solar light was fed to the integrated SOT in sun tests for
verifying various optical aspects including the confirmation of photon
throughput. CCD exposures provide the number of photons accumulated
in an exposure duration with a clean-room test condition. To estimate
the absolute intensity of the solar light at the telescope entrance
in the clean-room test condition, we developed a pinhole-PSD sensor
for simultaneous monitoring the solar light outside the clean room
and measured the transmission of light through two flat mirrors of
the heliostat and clean-room entrance window glass as a function of
wavelength. The PSD sensor was pre-calibrated with continuous monitoring
the solar light in a day long under a clear constant sky condition,
determining the earth atmospheric attenuation and the PSD output for
the solar light on orbit. These throughput measurements have provided
an estimate on photon throughput for the SOT flight model. The results
confirm suitable number of photons without saturation for proper CCD
exposures in flight.
Title: Performance Characteristics of the Solar-B Spectro-Polarimeter
Authors: Lites, B. W.; Elmore, D. F.; Streander, K. V.; Hoffmann,
C. M.; Tarbell, T. D.; Title, A. M.; Shine, R. A.; Ichimoto, K.;
Tsuneta, S.; Shimizu, T.; Suematsu, Y.
Bibcode: 2007ASPC..369...55L
Altcode:
The Focal Plane Package (FPP) of the Solar Optical Telescope (SOT)
includes the first precision Spectro-Polarimeter (SP) for solar space
observations. The FPP/SP will provide high precision measures of
the vector magnetic field in the solar photosphere. Here we present
some as-built performance specifications for the entire system of
telescope + polarimeter. The FPP-SP system represents significant
gains in several aspects over existing spectro-polarimetric systems;
notably, angular resolution, polarimetric accuracy, spectral purity,
and most importantly, temporal continuity of stable, high angular
resolution. In this short summary of the poster, a few of the
performance characteristics of the SP are presented.
Title: Calibration of the SOT Polarization
Authors: Ichimoto, K.; Suematsu, Y.; Shimizu, T.; Katsukawa, Y.;
Noguchi, M.; Nakagiri, M.; Miyashita, M.; Tsuneta, S.; Tarbell, T. D.;
Shine, R. A.; Hoffmann, C. M.; Cruz, T.; Lites, B. W.; Elmore, D. F.
Bibcode: 2007ASPC..369...39I
Altcode:
Calibration of SOT polarization property was performed using natural
sunlight and well calibrated sheet polarizer (linear and circular)
placed on the entrance of the telescope. The polarimeter response
matrices were determined for the spectropolarimeter (SP) and the
narrowband filter imager (NFI), and it is shown that they are well
behave as predicted and constant over the field of view. The crosstalk
between I,Q,U,V will be suppressed to the negligible level at the
photometric accuracy of 10^{-3} after the calibration with the obtained
matrices. The sensitivity of SOT on linear and circular polarizations
at each wavelength observed by NFI are also obtained.
Title: Calibration of SOT Dopplergrams
Authors: Katsukawa, Y.; Ichimoto, K.; Sekii, T.; Suematsu, Y.; Tsuneta,
S.; Shine, R. A.; Tarbell, T. D.
Bibcode: 2007ASPC..369...43K
Altcode:
Narrow-band Filter Imager on SOT provides Dopplergrams (DGs) which
are images of Doppler (line- of-sight) velocities. Observations with
DGs are critically important in studies of photospheric dynamics and
helioseismology. The primary photospheric line used for DGs is Fe I 5576
Å which is a line insensitive to Zeeman effect. We made a calibration
function for the 5576 Å DGs to get actual Doppler velocities from
velocity indexes using an atlas spectrum and simulated transmission
profiles for the tunable filter (TF) on SOT. Using data sets taken
in the natural sun-light test, we quantitatively evaluated accuracy
of the DGs by comparing the rotational speed of the Sun measured
with DGs with the expected one. There was a little systematic error
in the velocity obtained by SOT, but the error was less than 20 %
of the predicted velocities.
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.
Bibcode: 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: Vector Spectropolarimetry of Dark-cored Penumbral Filaments
with Hinode
Authors: Bellot Rubio, L. R.; Tsuneta, S.; Ichimoto, K.; Katsukawa,
Y.; Lites, B. W.; Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu,
Y.; Tarbell, T. D.; Title, A. M.; del Toro Iniesta, J. C.
Bibcode: 2007ApJ...668L..91B
Altcode: 2007arXiv0708.2791B
We present spectropolarimetric measurements of dark-cored penumbral
filaments taken with Hinode at a resolution of 0.3". Our observations
demonstrate that dark-cored filaments are more prominent in polarized
light than in continuum intensity. Far from disk center, the Stokes
profiles emerging from these structures are very asymmetric and show
evidence for magnetic fields of different inclinations along the
line of sight, together with strong Evershed flows of at least 6-7 km
s-1. In sunspots closer to disk center, dark-cored penumbral
filaments exhibit regular Stokes profiles with little asymmetries due
to the vanishing line-of-sight component of the horizontal Evershed
flow. An inversion of the observed spectra indicates that the magnetic
field is weaker and more inclined in the dark cores as compared with
the surrounding bright structures. This is compatible with the idea
that dark-cored filaments are the manifestation of flux tubes carrying
hot Evershed flows.
Title: Relationships between magnetic foot points and G-band bright
structures
Authors: Ishikawa, R.; Tsuneta, S.; Kitakoshi, Y.; Katsukawa, Y.;
Bonet, J. A.; Vargas Domínguez, S.; Rouppe van der Voort, L. H. M.;
Sakamoto, Y.; Ebisuzaki, T.
Bibcode: 2007A&A...472..911I
Altcode: 2008arXiv0802.1765I
Aims:Magnetic elements are thought to be described by flux tube models,
and are well reproduced by MHD simulations. However, these simulations
are only partially constrained by observations. We observationally
investigate the relationship between G-band bright points and magnetic
structures to clarify conditions, which make magnetic structures
bright in G-band.
Methods: The G-band filtergrams together with
magnetograms and dopplergrams were taken for a plage region covered
by abnormal granules as well as ubiquitous G-band bright points,
using the Swedish 1-m Solar Telescope (SST) under very good seeing
conditions.
Results: High magnetic flux density regions are
not necessarily associated with G-band bright points. We refer to the
observed extended areas with high magnetic flux density as magnetic
islands to separate them from magnetic elements. We discover that G-band
bright points tend to be located near the boundary of such magnetic
islands. The concentration of G-band bright points decreases with inward
distance from the boundary of the magnetic islands. Moreover, G-band
bright points are preferentially located where magnetic flux density is
higher, given the same distance from the boundary. There are some bright
points located far inside the magnetic islands. Such bright points have
higher minimum magnetic flux density at the larger inward distance from
the boundary. Convective velocity is apparently reduced for such high
magnetic flux density regions regardless of whether they are populated
by G-band bright points or not. The magnetic islands are surrounded by
downflows.
Conclusions: These results suggest that high magnetic
flux density, as well as efficient heat transport from the sides or
beneath, are required to make magnetic elements bright in G-band.
Title: Emergence of Small-Scale Magnetic Loops in the Quiet-Sun
Internetwork
Authors: Centeno, R.; Socas-Navarro, H.; Lites, B.; Kubo, M.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Tsuneta, S.;
Katsukawa, Y.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2007ApJ...666L.137C
Altcode: 2007arXiv0708.0844C
We study the emergence of magnetic flux at very small spatial
scales (less than 2") in the quiet-Sun internetwork. To this aim,
a time series of spectropolarimetric maps was taken at disk center
using the instrument SP/SOT on board Hinode. The LTE inversion of
the full Stokes vector measured in the Fe I 6301 and 6302 Å lines
allows us to retrieve the magnetic flux and topology in the region
of study. In the example presented here, the magnetic flux emerges
within a granular structure. The horizontal magnetic field appears
prior to any significant amount of vertical field. As time goes on,
the traces of the horizontal field disappear, while the vertical dipoles
drift-carried by the plasma motions-toward the surrounding intergranular
lanes. These events take place within typical granulation timescales.
Title: The Hinode (Solar-B) Mission: An Overview
Authors: Kosugi, T.; Matsuzaki, K.; Sakao, T.; Shimizu, T.; Sone,
Y.; Tachikawa, S.; Hashimoto, T.; Minesugi, K.; Ohnishi, A.; Yamada,
T.; Tsuneta, S.; Hara, H.; Ichimoto, K.; Suematsu, Y.; Shimojo, M.;
Watanabe, T.; Shimada, S.; Davis, J. M.; Hill, L. D.; Owens, J. K.;
Title, A. M.; Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Golub, L.
Bibcode: 2007SoPh..243....3K
Altcode:
The Hinode satellite (formerly Solar-B) of the Japan Aerospace
Exploration Agency's Institute of Space and Astronautical Science
(ISAS/JAXA) was successfully launched in September 2006. As the
successor to the Yohkoh mission, it aims to understand how magnetic
energy gets transferred from the photosphere to the upper atmosphere
and results in explosive energy releases. Hinode is an observatory
style mission, with all the instruments being designed and built to
work together to address the science aims. There are three instruments
onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer
(EIS), and the X-Ray Telescope (XRT). This paper provides an overview
of the mission, detailing the satellite, the scientific payload, and
operations. It will conclude with discussions on how the international
science community can participate in the analysis of the mission data.
Title: The X-Ray Telescope (XRT) for the Hinode Mission
Authors: Golub, L.; DeLuca, E.; Austin, G.; Bookbinder, J.; Caldwell,
D.; Cheimets, P.; Cirtain, J.; Cosmo, M.; Reid, P.; Sette, A.; Weber,
M.; Sakao, T.; Kano, R.; Shibasaki, K.; Hara, H.; Tsuneta, S.; Kumagai,
K.; Tamura, T.; Shimojo, M.; McCracken, J.; Carpenter, J.; Haight,
H.; Siler, R.; Wright, E.; Tucker, J.; Rutledge, H.; Barbera, M.;
Peres, G.; Varisco, S.
Bibcode: 2007SoPh..243...63G
Altcode:
The X-ray Telescope (XRT) of the Hinode mission provides an
unprecedented combination of spatial and temporal resolution in solar
coronal studies. The high sensitivity and broad dynamic range of XRT,
coupled with the spacecraft's onboard memory capacity and the planned
downlink capability will permit a broad range of coronal studies over
an extended period of time, for targets ranging from quiet Sun to
X-flares. This paper discusses in detail the design, calibration, and
measured performance of the XRT instrument up to the focal plane. The
CCD camera and data handling are discussed separately in a companion
paper.
Title: Chromospheric Micro-jets Discovered Above Sunspot Penumbrae
Authors: Katsukawa, Yukio; Tsuneta, S.; Suematsu, Y.; Ichimoto, K.;
Shimizu, T.; Kubo, M.; Nagata, S.; Berger, T.; Tarbell, T.; Shine,
R.; Title, A.
Bibcode: 2007AAS...210.9413K
Altcode: 2007BAAS...39..219K
The Solar Optical Telescope (SOT) aboard HINODE allows us to observe
dynamical activities in the solar photosphere and the chromosphere
with high and stable image quality of 0.2 arcseconds. This superior
performance of SOT provides new findings of fine-scale transient
activities occurring in the chromosphere. In this paper, we report
discovery of fine-scale jet-like phenomena ubiquitously observed
above sunspot penumbrae. The jets are identified in image sequences
of a sunspot taken through a Ca II H line filter at 3968A. The Ca II
H line is sensitive to about 10^4 K plasma in the chromosphere. Their length is typically between 3000 and 10000km, and their
width is smaller than 500km. It is notable that their lifetime
is shorter than 1 minute. Those small spatial and temporal scale
possibly makes it difficult to identify the phenomena in existing
ground-based observations. The jets are easily identified when a
sunspot is located far from the disk center, and motion of the bright
features suggests that mass is erupted from lower chromosphere to upper
atmosphere. Velocities of the motion are estimated to be 50 to 100 km/s
from their lateral motion of intensity patterns. The velocities are much
faster than sound speeds in the chromosphere. A possible cause of such
high-speed jets is magnetic reconnection at the lower chromosphere
resulted from fluted magnetic configuration in penumbrae which is
suggested by vector magnetic field measurements in the photosphere.
Title: Hinode Data Calibration For Precise Image Co-alignment:
XRT vs. SOT
Authors: Shimizu, Toshifumi; DeLuca, E. E.; Lundquist, L.; Sakao,
T.; Kubo, M.; Narukage, N.; Kano, R.; Katsukawa, Y.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Tarbell, T.; Shine, D.; Hinode Team
Bibcode: 2007AAS...210.9417S
Altcode: 2007BAAS...39Q.220S
From late October in 2006, Hinode solar optical telescope (SOT) has
started to produce series of 0.2-0.3 arcsec visible-light images,
revealing dynamical behaviors of solar magnetic fields on the
solar surface. Simultaneously, Hinode X-ray telescope (XRT) has been
providing 1 arcsec resolution X-ray images of the solar corona, giving
the location of heating and dynamics occuring in the corona. Precise
image co-alignment of SOT data on XRT data with sub-arcsec accuracy is
required to provide new information regarding connecting the corona to
the photosphere. This presentation will give an introduction of Hinode
between-telescopes' image co-alignment to SPD participants. For active
region observations with sunspots, sunspots can be used as fiducial to
co-align the data from the two telescopes each other. Satellite jitter
in order of 1 arcsec or less is included in the series of XRT data,
whereas image stabilization system (correlation tracker) removes the
satellite jitter from the series of SOT images. Telescope pointings show
orbital variation in order of a few arcsec, which can be well predicted
from Hinode orbit information. Modeling co-alignment is under study
and it is the only precise method for quiet Sun and limb observations.
Title: Magnetic Patches in Internetwork Quiet Sun
Authors: De Wijn, Alfred; Lites, B.; Berger, T.; Shine, R.; Title,
A.; Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Hinode Team
Bibcode: 2007AAS...210.9412D
Altcode: 2007BAAS...39Q.219D
We study strong flux elements in the quiet sun in the context of
the nature of quiet-sun magnetism, its coupling to chromospheric,
transition-region and coronal fields, and the nature of a local
turbulent dynamo. Strong, kilogauss flux elements show up intermittently
as small bright points in G-band and Ca II H images. Although
bright points have been extensively studied in the magnetic network,
internetwork magnetism has only come under scrutiny in recent years. A
full spectrum of field strengths seems to be ubiquitously present in
the internetwork at small spatial scales, with the stronger elements
residing in intergranular lanes. De Wijn et al. (2005) found that bright
points in quiet sun internetwork areas appear recurrently with varying
intensity and horizontal motion within long-lived patches that outline
cell patterns on mesogranular scales. They estimate that the "magnetic
patches" have a mean lifetime of nine hours, much longer than granular
timescales. We use multi-hour sequences of G-band and Ca II H images
as well as magnetograms recorded by the Hinode satellite to follow up
on their results. The larger field of view, the longer sequences, the
addition of magnetograms, and the absence of atmospheric seeing allows
us to better constrain the patch lifetime, to provide much improved
statistics on IBP lifetime, to compare IBPs to network bright points,
and to study field polarity of IBPs in patches and between nearby
patches. Hinode is an international project supported by JAXA,
NASA, PPARC and ESA. We are grateful to the Hinode team for all their
efforts in the design, build and operation of the mission.
Title: Hinode/SOT Observations Of Apparent "Thermal Plume" Motions
In A Solar Prominence
Authors: Berger, Thomas; Tarbell, T.; Slater, G.; Tsuneta, S.;
Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Shimizu, T.; Kubo, M.;
Nagata, S.
Bibcode: 2007AAS...210.9433B
Altcode: 2007BAAS...39..222B
We present 396.8 nm Ca II H-line observations of a large
hedgerow, or "sheet", prominence seen on the solar western limb
on 30-November-2006. The 16 second cadence observations show dark
channels rising vertically at speeds of approximately 10 km/sec to
heights of about 15 Mm above the limb. Many of the motions end in
vortical overturning near the top of the sheet . Bright downflows of
similar speed are also seen within the sheet, often in association
with a dark channel that has risen to the top of the sheet. The dark
channels are suggestive of hot material rising in thermal plumes
within the prominence sheet. Similarly, the bright material motions
appear to be density enhanced regions of turbulent downflow. Current
models of sheet prominences do not include the observed dynamics. In
these models, the prominence plasma is in a low-beta state and is
constrained to move only along magnetic field lines. However the
motions observed here are extremely complex, implying either that the
magnetic field lines are undergoing turbulent motion, thus tangling
and reconnecting constantly, or that the plasma is not constrained
by the field and is in a high-beta convective state. We measure the
motion of several representative "plumes" and downflows, estimate the
density and temperature of the prominence plasma, and suggest several
avenues for further investigation. This work was supported by
NASA under the Hinode/SOT contract NNM07AA01C.
Title: A Study of Polar Jet Parameters Based on Solar-B XRT
Observations
Authors: Savcheva, Antonia; Cirtain, J.; Lundquist, L. L.; DeLuca,
E. E.; Shimojo, M.; Tsuneta, S.
Bibcode: 2007AAS...210.9116S
Altcode: 2007BAAS...39T.206S
SoHO/Hinode campaign 7197 studied polar jet formation from within
both the north and south polar coronal holes. Using the observations
collected by the X-Ray Telescope on Hinode, a number of physical
parameters of the jets have been characterized. We will show the
results for velocity, emission measure, length, width, lifetime, and
spatial distribution. These observational results will be compared to
models such as the Shibata-type reconnection model and correlations
to estimates of the theoretical model will be compared to the observations.
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.
Bibcode: 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: Hinode/SOT Observation of Fine Structure of the Evershed Flow
Authors: Ichimoto, Kiyoshi; Suematsu, Y.; Tsuneta, S.; Katsukawa, Y.;
Shimojo, M.; Kubo, M.; Shimizu, T.; Shine, R.; Tarbell, T.; Title,
A.; Lites, B.; Elmore, D.; Yokoyama, T.; Nagaka, S.
Bibcode: 2007AAS...210.9408I
Altcode: 2007BAAS...39..218I
Small scale structure of the Evershed effect was studied using the
Spectropolarimeter (SP) and Broadband Filter Imager (BFI) of SOT aboard
Hinode. SP maps and high cadence continuum images of BFI coverting
entire sunspots are used to investigate the spatial distribution of
the flow field, brightness and magnetic fields. It is revealed that the
Evershed flow starts at the front edge of inwardly migrating penumbral
grains with an upward velocity component and turns to nearly holizontal
flow preferentially in dark lanes (or dark core of filaments) of the
penumbra. Our results are in general agreement with the well known
uncombed penumbral concept in which the Evershed flow takes place
in nearly holizontal field channels. We discovered a number of tiny
elongated regions in deep photosphere in which there is an obvious
upward motion of 1-1.5km/s distributing over the penumbra. They
could be identified as the 'foot points' of the individual Evershed
flow channels. Cross-correlation among the flow speed, intensity,
magnetic field strength and inclination, and distribution of string
down flows in and around the penumbra will also be discussed.
Title: Coronal Temperature Diagnostics With Hinode X-ray Telescope
Authors: Narukage, Noriyuki; Sakao, T.; Kano, R.; Shimojo, M.; Tsuneta,
S.; Kosugi, T.; Deluca, E. E.; Golub, L.; Weber, M.; Cirtain, J.;
Japan-US X-Ray Telescope Team
Bibcode: 2007AAS...210.6304N
Altcode: 2007BAAS...39..172N
An X-ray telescope (XRT) on board HINODE satellite observes the Sun
in X-rays with high special resolution (1arcsec 730km on solar the
disk). This telescope has 9 X-ray filters with different temperature
responses. Using these filters, the XRT can detect the coronal
plasma with a wide temperature range from less than 1MK to more
than 10MK. Moreover, based on observations with more than 2 filters,
we can estimate the coronal temperature. In this paper, we use the
filter ratio method for coronal temperature diagnostics. Using this
method, we can easily estimate the averaged temperature of the coronal
plasma along the line-of-sight. This method has been used frequently
in the past, but the high quality XRT data give us temperature maps
with unprecedented accuracy and resolution. The XRT usually takes
the full Sun images with 2 kinds of filters 4 times a day. Using this
data and filter ratio method, we can obtain full Sun temperature maps
with high special resolution. In our analysis, we can derive reliable
temperatures not only in active regions but also in quiet regions and
coronal holes. This map can be created with the data set of one synoptic
observation. This means that we can obtain 4 maps a day. The result is
a full Sun temperature movie that gives us an unprecedented view of the
time evolution of solar temperature. In this meeting, we will show the
full Sun temperature movie and our coronal temperature analysis results.
Title: Continuous Upflow of Plasmas at the Edge of an Active Region
as Revealed by the X-ray Telescope (XRT) aboard Hinode
Authors: Sakao, Taro; Kano, R.; Narukage, N.; Kotoku, J.; Bando, T.;
DeLuca, E. E.; Lundquist, L. L.; Golub, L.; Kubo, M.; Katsukawa, Y.;
Tsuneta, S.; Hara, H.; Matsuzaki, K.; Shimojo, M.; Shibasaki, K.;
Shimizu, T.; Nakatani, I.
Bibcode: 2007AAS...210.7205S
Altcode: 2007BAAS...39Q.179S
We present X-ray imaging observations with Hinode X-Ray Telescope (XRT)
of an active region NOAA AR 10942 made in the period of 20-22 February
2007. A prominent feature that drew our particular attention is that
there revealed continuous upflow of soft-X-ray-emitting plasmas along
apparently-open field lines towards the outer corona emanating from the
edge of the active region. The field lines are originated from
an ensamble of small spots of following polarity, and are located at
a border between the active region and an adjacent equatorial coronal
hole(s) located to the east. The upflow was observed to be continuous
throughout the three days of observation intervals with projected
velocity of 140 km/s, accompanied with undulating motion of the field
lines. We assert that these upflowing plasmas would be a possible
source of slow solar wind material, which supports a foresighted
notion which grew out of interplanetary scintillation observations
that slow solar wind most likely has its origin in the vicinity of
active regions with large flux expansion (Kojima et al. 1999). A
preliminaty analysis indicates that the temperature of the upflowing
material near the base of the field lines is 1.3 MK with number density
of 2 × 109 /cm3. Assuming that all the material
is to escape to the interplanetary space, this leads to a mass loss
rate of 2 × 1011 g/s which amounts to a good fraction of
the total mass loss rate for solar wind. It is noteworthy that, even
apart from this unique upflow, we see continuous (up)flows of plasmas
anywhere around (surrounding) the active region. Details of the
upflow will be presented and their possible implication to slow solar
wind discussed.
Title: Magnetic Flux Emergence In The Quiet Sun Photosphere
Authors: Centeno, Rebecca; Lites, B.; Socas-Navarro, H.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Tsuneta, S.;
Katsukawa, Y.; Suematsu, Y.; Kubo, M.; Shimizu, T.
Bibcode: 2007AAS...210.9406C
Altcode: 2007BAAS...39..218C
We study the emergence of magnetic flux at very small spacial scales
(less than 1 arcsec) in the quiet Sun internetwork. To this aim, several
time series of spectropolarimetric maps were taken at disk center using
the instrument SP/SOT on board Hinode. The LTE inversion of the full
Stokes vector measured in the Fe I 6301 and 6302 lines will allow us
to retrieve the magnetic flux and topology in the region of study. We
find that the magnetic flux emerges typically within the granular
structures. In many cases, the horizontal magnetic field appears
prior to any significant amount of vertical field. As time goes on,
the traces of the horizontal field dissapear while the the vertical
dipoles drift -carried by the plasma motions- towards the surrounding
intergranular lanes. Sometimes they stay trapped there for a while
but they eventually either disappear by disgregation/cancelation
or agregate to other magnetic field concentrations giving rise to
larger flux elements. The time scale of these events is of the order
of 10-20 minutes.
Title: Formation of Moving Magnetic Features and Penumbral Magnetic
Fields
Authors: Kubo, Masahito; Ichimoto, K.; Shimizu, T.; Tsuneta, S.;
Suematsu, Y.; Katsukawa, Y.; Nagata, S.; Lites, B. W.; Frank, Z.;
Tarbell, T. D.; Shine, R. A.; Title, A. M.
Bibcode: 2007AAS...210.9410K
Altcode: 2007BAAS...39..218K
We investigate the formation process of Moving Magnetic Features
(MMFs) observed with Hinode/SOT. Moving magnetic features are small
magnetic elements moving outward in the moat region surrounding
mature sunspots. We derive vector magnetic fields of MMFs around
simple sunspots near the disk center. Most of MMFs with polarity
opposite to the sunspot have large redshift around the penumbral outer
boundary. We find that some of them have Doppler velocities of about
10 km/s and such large Doppler motion is observed only in the Stokes
V profile. The Stokes Q and U profiles in the same pixel do not have
any significant Doppler motions. Horizontal magnetic fields of the
penumbra frequently extend to the moat region and the MMFs having
horizontal fields with polarity same as the sunspot are formed. The
MMFs with polarity opposite to the sunspot appear around the outer
edge of the extending penumbral fields. We also find penumbral spines,
which have more vertical magnetic fields than the surroundings, branch
off at their outer edge and MMFs having relatively vertical fields
with polarity same as the sunspot are detached from the outer edge
of the branch. The branch of penumbral spine is formed when granular
cells in the moat region go into the penumbra.
Title: Ubiquitous Horizontal Magnetic Fields in the Quiet Solar
Photosphere as Revealed by HINODE Meaurements
Authors: Lites, Bruce W.; Socas Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa,
Y.; Tsuneta, S.; Suematsu, Y.; Kubo, M.; Shimizu, T.; Nagata, S.;
Hinode Team
Bibcode: 2007AAS...210.6303L
Altcode: 2007BAAS...39..171L
Measurements with the HINODE Spectro-Polarimeter (SP) of the quiet
Sun allow characterization of the weak, mixed-polarity magnetic
flux at the highest angular resolution to date (0.3"), and with good
polarimetric sensitivity(0.025% relative to the continuum). The image
stabilization of the HINODE spacecraft allows long integrations with
degradation of the image quality only by the evolution of the solar
granulation. From the Stokes V profile measurements we find an average
solar "Apparent Flux Density" of 14 Mx cm-2, with significant Stokes V
signals at every position on the disk at all times. However, there are
patches of meso-granular size (5-15") where the flux is very weak. At
this high sensitivity, transverse fields produce measurable Stokes
Q,U linear polarization signals over a majority of the area, with
apparent transverse flux densities in the internetwork significantly
larger than the corresponding longitudinal flux densities. When viewed
at the center of the solar disk, the Stokes V signals (longitudinal
fields) show a preference for occurrence in the intergranular lanes,
and the Q,U signals occur preferably over the granule interiors,
but neither association is exclusive. Hinode is an international
project supported by JAXA, NASA, PPARC and ESA. We are grateful to the
Hinode team for all their efforts in the design, build and operation
of the mission.
Title: The Solar Optical Telescope on Hinode: Performance and
Capabilities
Authors: Tarbell, Theodore D.; Tsuneta, S.; SOT Team
Bibcode: 2007AAS...210.9401T
Altcode: 2007BAAS...39..217T
The Hinode (Solar B) satellite includes the Solar Optical Telescope
(SOT) with its 50 cm diameter Optical Telescope Assembly (OTA) and
Focal Plane Package (FPP), for near UV and visible observations of
the photosphere and chromosphere at very high (diffraction limited)
angular resolution. The FPP has a Spectropolarimeter (SP) for precision
measurements of photospheric vector magnetic fields over a 160 x
320 arcsecond field of view; a Narrowband Filter Imager (NFI) with
a tunable birefringent filter for magnetic, Doppler, and intensity
maps over the same field of view; and a Broadband Filter Imager (BFI)
for highest resolution images in six wavelengths (G band, Ca II H,
continua, etc.) over two thirds of that field of view. A polarization
modulator in the telescope allows measurement of Stokes parameters at
all wavelengths in the SP and NFI. This poster gives examples of SOT
observables from the performance verification and initial observing
phases of the mission. The SP routinely collects Stokes profiles with
spatial resolution 0.16 arc seconds (pixel) and rms noise less than
0.001. Initially the NFI only made magnetograms in Fe I 6302.5 with
rms noise less than 0.002; more recently it has begun to observe
the other photospheric and chromospheric lines available. The BFI
movies have unprecedented uniformity and stability for such high
spatial resolution; cadence can be 4 seconds or less. All images are
stabilized to 0.01 arc seconds by a tip tilt mirror and correlation
tracker. The process for requesting Hinode observations is described,
along with guidelines for SOT observing programs. Starting in May, 2007,
the Hinode data policy becomes completely open, with all data available
to the community immediately after receipt and reformatting at ISAS. Hinode is an international cooperative mission between JAXA/ISAS of
Japan, NASA of the United States, PPARC of the United Kingdom, and ESA.
Title: First Results from the Solar Optical Telescope on Hinode
Authors: Title, Alan M.; Tarbell, T.; Tsuneta, S.; SOT Team
Bibcode: 2007AAS...210.6301T
Altcode: 2007BAAS...39..171T
The Solar Optical Telescope (SOT) is a joint project of the National
Observatory of Japan and the Lockheed Martin Solar and Astrophysical
Laboratory. SOT consists of a 50 cm Gregorian telescope optimized to
reduce instrumental polarization and the Focal Plane Package (FPP). FPP
contains a version of the Advanced Stokes Polarimeters developed by
the High Altitude Observatory, a broadband filter system, and a tunable
birefringent filter. A correlation tracker in the FPP sends a control
signal to an active mirror in the telescope. Both the telescope and the
active mirror were developed by the National Astronomical Observatory
of Japan. The correlation tracking system reduces image motion in the
focal planes to +/- 0.02 arcseconds. The diffraction limited performance
of the SOT coupled with large format CCD’s and high data rates have
allowed the construction of high resolution line of sight and vector
magnetograms and imaging of phenomena on solar surface and off the
solar limb. This data are providing new insights into the processes
of flux emergence and disappearance from the scale of granulation to
active regions. High cadence observations of filaments, prominences,
and spicules have revealed surprising evolutionary features that include
alfven waves, current systems, and rapid reconnection. Movies of many
of these phenomena will be shown.
Title: Attempt to detect Aflven waves with Solar Optical Telescope
aboard Hinode
Authors: Tsuneta, Saku; Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.;
Shimizu, T.; Nagata, S.; Orozco Suárez, D.; Lites, B.; Shine, D.;
Tarbell, T.; Title, A.
Bibcode: 2007AAS...210.9428T
Altcode: 2007BAAS...39..222T
Flux tube on the sun may carry linear and torsional Alfven waves
generated by photospheric motion. Photospheric motion of 2 km/s would
provide magnetic fluctuation of 40G for 1KG tube and for the Alfven
speed of 50km/s. This may be close to the detection limit of the Stokes
Q and U signals for flux tubes located in the sun center. However,
for flux tubes located near the limb, the fluctuation would be seen in
the Stokes V signal, and can be detectable. We also may be able
to confirm the 90 degree phase shift between magnetic fluctuation and
velocity fluctuation, which is easier to observe for flux tubes near
the limb. Detection of waves would be important in terms of coronal
heating and solar wind acceleration. An attempt to detect waves along
flux tubes will be reported.
Title: Temperature Structures Above Coronal Hole and Quiet Sun
Authors: Kano, Ryouhei; Sakao, T.; Narukage, N.; Kotoku, J.; Bando,
T.; DeLuca, E. E.; Lundquist, L.; Golub, L.; Tsuneta, S.; Hara, H.;
Shibasaki, K.; Shimojo, M.
Bibcode: 2007AAS...210.9436K
Altcode: 2007BAAS...39..223K
The X-ray Telescope (XRT) on board Hinode satelite has the capability
to derive the temperature structure in the solar corona. We present
the hieght dependence of the temperature above the limb. Because X-ray
intensity above the limb is so faint, it is important to estimate the
scattered light from disk corona. The eclipses happened on February 17
and March 19 in 2007 at Hinode orbit. On February 17, we took X-ray
images above the south polar coronal hole, while Moon passed it. On
March 19, we took the data for quiet Sun in the same way. We
can estimated the scattered light from the eclipse data, and derived
the scatter-free X-ray images above the solar limb. In this meeting,
we will present the temperatures above coronal hole and quiet Sun,
based on the eclipse data.
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.
Bibcode: 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: Discovery Of Small-scale Horizontal Magnetic Structures On
The Solar Photosphere
Authors: Ishikawa, Ryohko; Tsuneta, S.; Suematsu, Y.; Ichimoto, K.;
Katsukawa, Y.; Nagata, S.; Ishobe, H.; Tarbell, T.; Lites, B. W.;
Title, A.
Bibcode: 2007AAS...210.9404I
Altcode: 2007BAAS...39..217I
We discover two different types of episodes on the appearance
of horizontal magnetic fields with Solar Optical Telescope aboard
Hinode. The first episode is an emergence of strong thin horizontal
magnetic fields associated with separating vertical components on
both ends. Its size is about two granules. We also detect strong area
asymmetry of the environment Stokes Vprofile for the bout 8 minutes
before the first emergence of the horizontal component. One of the
footpoints has very strong downflows (several km/s), while the region
with strong linear polarization signal has small blue shift, indicating
an upward-moving horizontal flux. The second episode appears to be
more ubiquitous. Linear polarization signals appear inside granules (not
in inter-granules). Their size is smaller than granules, and lifetime
is longer than several minutes. We will summarize the nature of the
two types of the horizontal magnetic fluxes, and discuss their origin.
Title: Hinode/SOT Observations of Sunspot Penumbral Dynamics and
Evolution
Authors: Shine, Richard A.; Hagenaar, M.; Tarbell, T.; Title, A.;
Lites, B.; Ichimoto, K.; Tsuneta, S.; Katsakawa, Y.; Suematsu, Y.;
Nagata, S.; Kubo, M.; Shimizu, T.
Bibcode: 2007AAS...210.9407S
Altcode: 2007BAAS...39..218S
The Solar Optical Telescope (SOT) on the Hinode satellite (launched
October 2006) has obtained long and nearly continuous time series of
several large sunspots including those in NOAA AR's 10923, 10925,
and 10930. Here we use high resolution movies taken primarily with
the broad band Ca II (396.8nm) and G band (430.5nm) channels and
magnetograms taken with the 630.2nm narrow band channel to study
the details and short term evolution of penumbral fine structures
as well as the long term evolution of the sunspots. We compute flow
maps and use space/time slices to track motions of Evershed clouds,
penumbral grains, and visualize oscillations. The data contain examples
of penumbral formation and disintegration including "orphan" penumbra
(i.e., penumbra without an obvious umbra). There is also an interesting
instance of "colliding" penumbra in AR 10930 as two sunspots of opposite
polarity converged. The zone of apparent shear was associated with
several flares. This work was supported by NASA contract NNM07AA01C
Title: Optical Performance of the Solar Optical Telescope aboard
HINODE
Authors: Suematsu, Yoshinori; Ichimoto, K.; Katsukawa, Y.; Otsubo,
M.; Tsuneta, S.; Nakagiri, M.; Noguchi, M.; Tamura, T.; Kato, Y.;
Hara, H.; Miyashita, M.; Shimizu, T.; Kubo, M.; Sakamoto, Y.
Bibcode: 2007AAS...210.9402S
Altcode: 2007BAAS...39Q.217S
The Solar Optical Telescope (SOT) carried by HINODE was designed
to perform a high-precision polarimetric observation of the Sun
in visible light spectra with a spatial resolution of 0.2 - 0.3
arcseconds. The SOT is a sophistcated instrument and consists of two
separate optical parts; the Optical Telescope Assembly (OTA) which is
50 cm aperture Gregorian telescope feeding the light into following
observing instruments which is called the focal plane package (FPP)
made of two filtergraphs and a spectro-polarimeter. The performance
of the OTA is important because a spatial resolution and its temporal
stability is mainly determined by this component. To keep the OTA in
moderate temperature and optical thermal deformation small, it equipped
newly designed components such as a heat dump and a secondary field stop
aluminum mirror with high reflectivity silver coating and a temperature
low-sensitive apochromatic collimataing lens unit with a UV/IR cut
coating on the first surface. In addition, the SOT has an active image
stabilization system consisting of correlation tracker, tip-tilt mirror
and its controller against satellite pointing jitter. It was confirmed
that this system freezes residual motion to the 0.01 arcsecond level
on orbit. The image of sub-arcsecond G-band (430.5 nm) bright points
clearly indicates that the SOT achieves the diffraction-limit on orbit;
this is also confirmed using a phase diversity method. In this paper,
we describe details of the design and on-orbit performance of the OTA.
Title: The Statistics of Polar Coronal Jets using XRT/Hinode
Authors: Cirtain, Jonathan W.; Lundquist, L. L.; DeLuca, E. E.;
Savcheva, A.; Shimojo, M.; Tsuneta, S.
Bibcode: 2007AAS...210.9432C
Altcode: 2007BAAS...39..222C
Recent observations of the polar coronal holes using the X-Ray Telescope
on Hinode revealed how frequent x-ray jets occur. Previous observations
were limited by cadence, spatial resolution and continuity. However,
with XRT operations successfully underway, multiple weeks of polar
observations can be used to provide improved statistics of some
fundamental physical parameters of the jets. In particular, we will
present results for the radial and transverse velocities, observed
length and width, duration, and spatial distribution of some of the
more than 200 jets XRT has observed to date. The observed changes in
the structure of the region where the jets are formed seems to be well
characterized by the Shibata-type reconnection model. Examples will
be provided.
Title: Magnetic Landscape Of Solar Polar Region With Solar Optical
Telescope Aboard Hinode
Authors: Tsuneta, Saku; Suematsu, Y.; Ichimoto, K.; Shimizu, T.;
Katsukawa, Y.; Nagata, S.; Orozco Suárez, D.; Lites, B.; Shine, D.;
Tarbell, T.; Title, A.
Bibcode: 2007AAS...210.9405T
Altcode: 2007BAAS...39..218T
Solar polar region is the final destination for remnant magnetic
fields due to meridional flow and granular diffusion, and is very
important for the global solar dynamo. Hinode satellite carried out
high-resolution spectro-polarimetric observations for the Northern
pole on 2006 November 22 as a part of its performance verification
program. We find ubiquitous isolated (positive and negative) patches
in the Stokes V map (i.e. fields horizontal to local surface) all over
the Arctic circle. The Q (vertical to local surface) map indicates
scattered vertical flux tubes, which have bipolar feature in the U and
V maps. This suggests canopy-like structure of the strong isolated flux
tubes. This will be compared with equatorial landscape with similar
distance from the sun center. Strong flux tube and weaker ubiquitous
horizontal fields as represented by Stokes V would have implication
to the current understanding of the global and local dynamo.
Title: Vector Magnetic Fields of Moving Magnetic Features and Flux
Removal from a Sunspot
Authors: Kubo, M.; Shimizu, T.; Tsuneta, S.
Bibcode: 2007ApJ...659..812K
Altcode:
Moving magnetic features (MMFs) are small photospheric magnetic
elements moving outward in the zone (moat region) surrounding mature
sunspots. Vector magnetic fields and horizontal motion of the classical
MMFs (called isolated MMFs hereafter) are investigated using coordinated
ASP and MDI observations. Their magnetic and velocity properties
are compared to nearby magnetic features, including moat fields
surrounding the isolated MMFs and penumbral uncombed structure. The
moat fields are defined as nonisolated MMFs because they also move
outward from sunspots. The nonisolated MMFs have nearly horizontal
magnetic fields of both polarities. We find that the isolated MMFs
located on the lines extrapolated from the horizontal component of the
uncombed structure have magnetic fields similar to the nonisolated
MMFs. This suggests that the MMFs with nearly horizontal fields are
intersections of horizontal fields extended from the penumbra with the
photospheric surface. We find clear evidence that the isolated MMFs
located on the lines extrapolated from the vertical component of the
uncombed structure have vertical field lines with polarity same as the
sunspot. This correspondence shows that such MMFs are detached from
the spine (vertical) component of the penumbra. We estimate that the
magnetic flux carried by the vertical MMFs is about 1-3 times larger
than the flux loss of the sunspot. We suggest that the isolated vertical
MMFs alone can transport sufficient magnetic flux and are responsible
for the disappearance and disintegration of the sunspot.
Title: Development of a Correlation Tracker and a Tip-Tilt Mirror
System for SOLAR-B
Authors: Kodeki, Kazuhide; Kashiwagi, Yasuhiro; Miki, Shiro; Endoh,
Makoto; Itoh, Osamu; Shimizu, Toshihumi; Matsuzaki, Keiichi; Nagata,
Shinichi; Ichimoto, Kiyoshi; Tsuneta, Saku
Bibcode: 2007JSASS..55...57K
Altcode:
The solar observation satellite “SOLAR-B,” which is being developed
under the joint cooperation of JAXA and NAOJ with the U.S.A. (NASA)
and the U.K. (PPARC), will be launched in summer 2006. SOLAR-B requires
very high pointing stability for its three telescopes. In particular,
the Solar Optical Telescope (SOT), which has the highest resolution
and narrowest field of view among these telescopes, requires 0.06
[arcsec]<SUB>3σ</SUB> of short-term (10[s]) stability to
meet the observation demands. However, it is very difficult to achieve
such levels of stability by only using the satellite attitude control
system due to disturbance from the observation equipment. Therefore,
we propose using the Correlation Tracker and tip-tilt Mirror package
(CTM), which stabilizes the sun observation image. CTM consists of
a correlation tracker and a piezo-based tip-tilt mirror with servo
control electronics. This paper describes the mechanism and the control
and determination methods of the control gain of CTM as well as the
results of experiments conducted to clarify its capability.
Title: Magnetic Field Diagnostic Capability of Solar-B/SOT:
Filtergraph Instrument
Authors: Ichimoto, K.; Suematsu, Y.; Shimizu, T.; Katsukawa, Y.;
Tsuneta, S.; Tarbell, T. D.; Shine, R. A.; Hoffmann, C. M.; Title,
A. M.; Lites, B. W.; Elmore, D. F.; Streander, K. V.
Bibcode: 2006ASPC..358..189I
Altcode:
The Narrowband Filter Instrument (NFI) of the Solar Optical Telescope
onboard Solar-B provides 2D magnetograms/Dopplergrams with a tunable
Lyot filter (width ∼ 0.1 Å) in 6 selected wavelength bands, and
spatial sampling of 0.08 arcsec/px. The Zeeman-effect sensitivity of
NFI and the detection limits of weak magnetic fields are evaluated for
2 photospheric and 3 chromospheric lines. Magnetic-field retrievability
from the NFI observables is studied using synthetic Stokes profiles
of Fe I 5250 Å. We find that, with optimized wavelength sampling at 4
positions, the inferred magnetic field is sufficiently accurate under
the hypothesis of constant magnetic field and velocity along the LOS.
Title: Hard X-Ray Spectral Observation of a High-Temperature
Thermal Flare
Authors: Kobayashi, Ken; Tsuneta, Saku; Tamura, Tomonori; Kumagai,
Kazuyoshi; Katsukawa, Yukio; Kubo, Masahito; Sakamoto, Yasushi;
Kohara, Naoki; Yamagami, Takamasa; Saito, Yoshitaka
Bibcode: 2006ApJ...648.1239K
Altcode:
We report on the analysis of a thermal flare observed by a newly
developed balloon-borne hard X-ray spectrometer. This instrument uses
CdTe detectors and can observe the 20-120 keV hard X-ray range, with
3.0 keV energy resolution at 60 keV. During the 2002 May 24 flight,
it successfully observed a class M1.1 flare. This flare observation
shows no detectable flux above 35 keV, and its spectrum is consistent
with a superhot thermal source with the temperature varying from 44
to 20 MK. Partial observation of the flare by the RHESSI satellite is
consistent with this result. The Nobeyama Radio Polarimeters (NORP)
observation of this flare shows no detectable polarization. The NORP
light curves show impulsive features at 3.75 GHz that can be explained
as thermal gyrosynchrotron emission, and this flux is consistent with
observed X-ray spectra if a magnetic field of 275 G is assumed. Slower
varying features seen in the NORP data are consistent with the
lower temperature (``hot'') thermal source of 10-15 MK seen in soft
X-rays. We conclude that this flare shows no observable signature of
nonthermal electrons, and all observed features are consistent with
a purely thermal event. This serves as a strong indication that a
nonthermal electron beam is not always the dominant energy source of
plasma heating in solar flares.
Title: Tolerance test of a sample filter for use in space
Authors: Hayashi, Masao; Tanaka, Mikito; Komiyama, Yutaka; Okamura,
Sadanori; Tsuneta, Saku; Noguchi, Motokazu; Nakagiri, Masao; Kano,
Ryouhei; Kimura, Toshihiko
Bibcode: 2006PNAOJ...9...21H
Altcode:
We report the result of a tolerance test of a sample filter for the
planned Very Wide Field Imager on board the Hubble Origin Probe. We
investigated whether the properties of the filter and its components,
i.e., color glass, synthetic quartz, short-wavelength-pass coating
and long-wavelength-pass coating, changed after they were put in a
vacuum, after they were subjected to a thermal cycle, and after they
were exposed to γ ray. Results are shown mostly in graphical form. No
significant change of the properties was observed for the filter and
any of the components before and after the tests, except for the color
glass which was exposed to strong γ ray.
Title: Probing coronal heating with variability of solar X-ray
emission
Authors: Vekstein, G.; Jain, R.; Katsukawa, Y.; Tsuneta, S.
Bibcode: 2006cosp...36...65V
Altcode: 2006cosp.meet...65V
If the mechanism responsible for creating hot solar corona is a
magnetic one the resulting coronal heating events are likely to be
highly fragmented in space and in time This makes the nanoflare
heating scenario where both these features are at the heart of
the concept a strong candidate The major problem is to find out
how to test this theory while individual nanoflares remain beyond
observational recognition Here we discuss a possibility of probing
nanoflares with variability of the coronal X-ray emission We present
results of the numerical simulation of X-ray coronal loops that mimics
a sporadic nature of the nanoflare heating The aim is to investigate
how an imposed power-law energy spectrum of heating events nanoflares
translates into fluctuations in the intensity of the X-ray emission
which can be detected observationally as X-ray and EUV brightenings
These theoretical predictions are compared with a recently reported
analysis of observed fluctuations of the solar X-ray emission and
we discuss their implications on the deduced energy and spectrum of
nanoflares A future study envisaged with the upcoming Solar-B mission
is also discussed
Title: High resolution solar physics with Solar-B
Authors: Tsuneta, S.
Bibcode: 2006cosp...36.3642T
Altcode: 2006cosp.meet.3642T
SOLAR-B satellite carries three advanced solar telescopes solar
optical telescope SOT X-ray telescope and EUV imaging spectrometer
In particular SOT provides us with continuous 24hrs high cadence
diffraction-limited 0 2 stable images with fully-calibrated high
polarimetric sensitivity Solar-B will be launched on September 2006
Current status of the mission preparation is excellent due to hard work
of the international Solar-B team including NASA and UK PPARC over 6
years With SOLAR-B we are able to reach or be closer to the Promised
Land of solar magneto-hydrodynamics where elemental magnetic fields
higher convective flows higher electric-currents sharp distribution
of magnetic and non-magnetic atmospheres various forms of MHD waves
interplay each other For instance the Yohkoh and TRACE images show
spatially-exclusive hot and cool quasi-steady loops With ASP we
found clear difference in magnetic filling factor which was aerial
fraction of magnetic atmosphere between hot and cool loops Katsukawa
Tsuneta 2004 With Solar-B introduction of the filling factor may be no
longer needed and is replaced with observations on real interactions
of flow and fields the result of which would be coronal heating Parker
proposed that coronal heating is due to reconnection of magnetic fields
entangled by photospheric motion Whether this concept is true or not
will be observationally answered by the long-term stable Lagrangian
tracking of individual magnetic elements and G-band bright points from
its creation through
Title: Contamination evaluation and thermal vacuum bakeout for
SOLAR-B visible-light and X-ray telescope
Authors: Tamura, Tomonori; Hara, Hirohisa; Tsuneta, Saku; Ichimoto,
Kiyoshi; Kumagai, Kazuyoshi; Nakagiri, Masao; Shimizu, Toshifumi;
Sakao, Taro; Kano, Ryouhei
Bibcode: 2005RNAOJ...8...21T
Altcode:
In the development of space telescopes, we are concerned about molecular
outgassing materials from telescope components. In particular, for
solar telescopes in space, the deposition of the outgassing materials
may lead to the increase of solar absorptance at a mirror surface
and it causes the thermal distortion due to the resultant temperature
increase. The mirror reflectivity at vacuum ultraviolet wavelengths
is very sensitive to molecular contamination. We have extensively
evaluated reflectance at 121.6nm (Lyman-alpha) of the contamination
witness mirrors exposed to the telescope testing environments in the
SOLAR-B visible-light telescope program. Thermal vacuum bakeout of
flight components is very effective process to reduce the outgassing
rate. We have severe contamination control program during the assembly
and testing of the SOLAR-B telescope up to launch of the satellite.
Title: Development of Heater control equipment for the Solar-B XRT
thermal vacuum test
Authors: Kumagai, Kazuyoshi; Kano, Ryohei; Hara, Hirohisa; Tamura,
Tomonori; Sawa, Masaki; Tsuneta, Saku; Sakao, Taro; Matsuzaki, Keiichi
Bibcode: 2005RNAOJ...8...29K
Altcode:
The thermal vacuum test of the X-ray Telescope (XRT) aboard the
Solar-B satellite was carried out at NASA/Goddard Space Flight Center
(GSFC) since January 2004. For this thermal test, we developed the
Heater Sensor GSE (HS-GSE). It is an equipment to record flight
temperature sensors in the X-ray camera and to control flight camera
heaters. During the GSFC thermal test, the HS-GSE successfully recorded
the camera temperatures every 10 seconds, and controlled the heaters
automatically. We report the system of the HS-GSE successfully recorded
the camera temperatures every 10 seconds, and controlled the heaters
automatically. We report the system of the HS-GSE with the results in
the thermal test.
Title: Magnetic Properties at Footpoints of Hot and Cool Loops
Authors: Katsukawa, Yukio; Tsuneta, Saku
Bibcode: 2005ApJ...621..498K
Altcode:
Observations of the solar corona with Yohkoh, the Solar and Heliospheric
Observatory, and the Transition Region and Coronal Explorer (TRACE)
have revealed that individual coronal loops of active regions have their
own temperatures from 1 to 5 MK. The hot (2-5 MK) Soft X-Ray Telescope
(SXT) loops appear to require more heating energy than the cool (1-2 MK)
EUV loops. We investigate the photospheric magnetic signature for the
hot and cool loops with the Advanced Stokes Polarimeter. In contrast to
the cool loops, the hot loops observed with the SXT are usually diffuse,
resulting in ambiguous identification of their footpoint locations. We
use TRACE ``moss'' structure, which we confirm is low-lying EUV emission
at the footpoints of the hot loops. Footpoints of both loops have
magnetic fields whose strength is 1.2-1.3 kG, and the orientation is
almost vertical to the surface. A significant difference is discovered
in the magnetic filling factor, which is defined by the fraction of
a pixel filled with a magnetized atmosphere. The footpoints of the
hot loops have a lower filling factor than the footpoints of the cool
loops. We suggest that braiding of coronal magnetic fields is more
efficient at the footpoints of the hot loops than at the footpoints
of the cool loops as a result of the combination of the lower filling
factor and higher horizontal velocity.
Title: Completion of Solar-B/Optical Telescope flight model
Authors: Suematsu, Yoshinori; Ichimoto, Kiyosi; Shimizu, Toshifumi;
Otsubo, Masashi; Nakagiri, Masao; Noguchi, Motokazu; Tamura, Tomonori;
Katsukawa, Yukio; Kato, Yoshihiro; Hara, Hirohisa; Miyashita, Masakuni;
Tsuneta, Saku; Kubo, Masahito; Sakamoto, Yasushi
Bibcode: 2005ARAOJ...7...52S
Altcode:
No abstract at ADS
Title: Observation of solar flare hard X-ray spectra using CdTe
detectors
Authors: Kobayashi, Ken; Tsuneta, Saku; Tamura, Tomonori; Kumagai,
Kazuyoshi; Katsukawa, Yukio; Kubo, Masahito; Sakamoto, Yasushi;
Kohara, Naoki; Yamagami, Takamasa; Saito, Yoshitaka; Mori, Kunishiro;
Kato, Genzo
Bibcode: 2005naoj.book...33K
Altcode:
No abstract at ADS
Title: Solar-B/Optical Telescope flight model is coming up
Authors: Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu, Toshifumi;
Otsubo, Masashi; Nakagiri, Masao; Noguchi, Motokazu; Tamura, Tomonori;
Kato, Yoshihiro; Hara, Hirohisa; Miyashita, Masakuni; Tsuneta, Saku;
Katsukawa, Yukio; Kubo, Masahito; Sakamoto, Yasushi
Bibcode: 2005naoj.book....4S
Altcode:
No abstract at ADS
Title: New clean room for space instrumentation
Authors: Noguchi, Motokazu; Nakagiri, Masao; Suematsu, Yoshinori;
Tsuneta, Saku; Kubo, Masahito
Bibcode: 2005naoj.book...37N
Altcode:
No abstract at ADS
Title: Magnetic properties at the footpoints of hot and cool loops
Authors: Katsukawa, Yukio; Tsuneta, Saku
Bibcode: 2005naoj.book...27K
Altcode:
No abstract at ADS
Title: Development of ultra light weight mirror for space and ground
based telescopes
Authors: Kohara, Naoki; Otsubo, Masashi; Tsuneta, Saku; Ozaki,
Tsuyoshi; Takeya, Hajime; Kume, Masami
Bibcode: 2005naoj.book...32K
Altcode:
No abstract at ADS
Title: The first build-up of the Solar-B flight models
Authors: Hara, Hirohisa; Ichimoto, Kiyoshi; Otsubo, Masashi; Katsukawa,
Yukio; Kato, Yoshihiro; Kano, Ryohei; Kumagai, Kazuyoshi; Shibasaki,
Kiyoto; Shimizu, Toshifumi; Shimojo, Masumi; Suematsu, Yoshinori;
Tamura, Tomonori; Tsuneta, Saku; Noguchi, Motokazu; Nakagiri, Masao;
Miyashita, Masakuni; Watanabe, Tesuya; Kosuchi, Takeo; Sakao, Taro;
Matsuzaki, Keiichi; Kitakoshi, Yasunori; Kubo, Masahito; Sakamoto,
Yasushi
Bibcode: 2005ARAOJ...7...46H
Altcode:
No abstract at ADS
Title: Hard X-Ray Spectral Observation of a High-Temperature
Thermal Flare
Authors: Kobayashi, K.; Katsukawa, Y.; Kubo, M.; Sakamoto, Y.; Kohara,
N.; Tsuneta, S.; Tamura, T.; Kumagai, K.; Yamagami, T.; Saito, Y.
Bibcode: 2004ASPC..325..353K
Altcode:
No abstract at ADS
Title: Multi-Temperature Corona and the Photospheric Magnetic Fields
Authors: Katsukawa, Y.; Tsuneta, S.
Bibcode: 2004ASPC..325..281K
Altcode:
No abstract at ADS
Title: Coronal Heating with Sweet-Parker Picoflares
Authors: Tsuneta, S.; Katsukawa, Y.
Bibcode: 2004ASPC..325..289T
Altcode:
Katsukawa & Tsuneta (2001) found an excess fluctuation in soft
X-rays coming from active regions, and proposed that the fluctuation
was attributed to ubiquitous tiny bursts. They estimated the energy
range of individual bursts to be 1020--1022
erg. There appears to be a big desert, the void in which no burst
occurs for 3--6 orders of magnitudes in energy from the pico-flare
range to the observed micro-flare range, indicating that a separate
physical mechanism is responsible for the picoflares. We propose that
the picoflares are due to Sweet-Parker reconnection, which is presumably
easier to occur than the Petschek reconnection responsible for larger
flares. We point out the critical importance of the simultaneous
observations with SolarB X-ray/EUV and visible-light telescopes.
Title: SolarB X-Ray Telescope (XRT)
Authors: Kano, R.; Hara, H.; Shimojo, M.; Tsuneta, S.; Sakao, T.;
Matsuzaki, K.; Kosugi, T.; Golub, L.; Deluca, E. E.; Bookbinder,
J. A.; Cheimets, P.; Owens, J. K.; Hill, L. D.
Bibcode: 2004ASPC..325...15K
Altcode:
The Soft X-ray Telescope (XRT) aboard SolarB is a grazing incidence
X-ray telescope equipped with 2k × 2k CCD. XRT has 1 arcsec resolution
with wide field-of-view of 34 × 34 arcmin. It is sensitive to
<1 MK to 30 MK, allowing us to obtain TRACE-like low temperature
images as well. Co-alignment with SOT and EIS is realized through
the XRT visible light telescope and with temperature overlap with
EIS. Spacecraft mission data processor (MDP) controls XRT through
the sequence tables with versatile autonomous functions such as
exposure control, region-of-interest tracking, flare detection and
flare location identification. Data are compressed either with DPCM or
JPEG, depending on the purpose. This results in higher cadence and/or
wider field-of-view for given telemetry bandwidth. With focus adjust
mechanism, higher resolution of Gaussian focus may be available on-axis.
Title: Very Wide Field Imager(VWFI) for the Hubble Origins Probe(HOP)
Authors: Tsuneta, S.; Miyazaki, S.; Nakaya, H.; Yamada, T.; Iye, M.;
Kaifu, N.; Taniguchi, Y.; Doi, M.; Okamura, S.; Ikeda, Y.; Takeyama,
N.; Kaido, N.; Yamaguchi, K.; Norman, C.; Ford, H.; Kruk, J.; Ouchi,
M.; Woodruff, R.
Bibcode: 2004AAS...20510003T
Altcode: 2004BAAS...36Q1509T
High-resolution high-throughput multi-color wide-field imaging from
space allows us to: (1) study origins of galaxy morphology (z=1-2);
(2) to map the post-reionization universe of z=5-10; (3) to investigate
the nature of dark energy through an efficient search for distant
type Ia SNe; and (4) to map the distribution of dark matter and to
measure cosmological parameters with weak gravitational lensing. These
science drivers can be carried out by the Very Wide Field Imager
(VWFI) aboard the Hubble Origins Probe (HOP) with the other onboard
science instruments COS and WFC3. VWFI consists of > 40 2K x
2K CCDs occupying >2 quadrants of the HOP focal plane with off-axis
aberration corrector optics. The astigmatism corrector optics consists
of a pair of simple fused-silica prisms optimized and dedicated to
each CCD. The FOV of VWFI is >170 square-arcmin, and the HOP OTA
with the corrector delivers stable and high Strehl-ratio images with
a 0.05 arcsec CCD pixel size over the wide field of view. CCDs are
cooled down to -80 degree C with a mechanical cooling system and an
external dedicated radiator. The fully-depleted CCDs to be provided
by Hamamatsu Photonics have a demonstrated capability of high quantum
efficiency approx. 0.7 at 1 micron. The very high efficiency at red
wavelengths makes VWFI exceptionally qualified to pursue the above
science drivers. Multiple optimized filters either allocated to each
CCDs or with the mechanical filter wheels allow multi-color imaging. VWFI is currently being studied with US-Japan working group under
the auspices of the NASA Origins Probes Study. VWFI is expected to be
primarily provided by Japan.
Title: Nanoflares and Coronal X-Ray Variability
Authors: Jain, R.; Katsukawa, Y.; Tsuneta, S.; Vekstein, G.
Bibcode: 2004ASPC..325..271J
Altcode:
A possibility of probing nanoflares with variability in the coronal
X-ray emission is discussed. We present results of numerical simulation
of X-ray coronal loops by using a Monte Carlo code, which mimics a
sporadic nature of the nanoflare heating. The aim is to investigate how
the imposed power-law energy spectrum of heating events (nanoflares)
translates into fluctuations in the intensity of the X-ray emission,
which can be detected observationally as X-ray and EUV brightenings. It
was found that probability distribution of these fluctuations is
very sensitive to the power-law index α of the energy spectrum of
nanoflares. If α > 3, intensity fluctuations have a noise-like
nature with a Gaussian distribution originating from interference of
many small nanoflares. For spectral indices 2 < α ≤ 3, histograms
of the intensity deviation from the mean value show positive skewness
indicating significant role of bigger events. Comparison of these
results with the analysis of small fluctuations of coronal X-ray
intensity observed with Yohkoh SXT telescope yields an estimate of
1023 erg for the energy of nanoflares in the active region.
Title: Hubble Origins Probe(HOP): Science Overview
Authors: Norman, C.; Bianchi, L.; Ford, H.; Heckman, T.; Moos,
W.; Giavalisco, M.; Nota, A.; Riess, A.; Sahu, K.; Somerville, R.;
Stiavelli, M.; Baum, S.; Crocker, J.; Woodruff, R.; Ebbets, D.; Green,
J.; Shull, M.; Steidel, C.; Silk, J.; Hutchings, J.; Tsuneta, S.;
Freeman, K.; Bacon, R.; de Zeeuw, T.
Bibcode: 2004AAS...20510002N
Altcode: 2004BAAS...36R1508N
The HOP core instruments COS and WFC3 as well as the additionally
proposed Very Wide-Field Imager(VWFI) and Integral Field Spectrograph
(IFS) allow us to study the redshift range z=0->3 where the majority
of star and planet formation, heavy element production,black hole
growth, and galaxy assembly took place. We will be able to study in
detail the dark energy via SN Ia and the dark matter distribution
using weak lensing. With a field of view (FOV) of greater 20 times
the ACS FOV we can perform vast surveys of the universe in the range
z=0->6. The COS UV spectrograph will study the cosmic web of baryons
in the WHIM including its density and temperature. We expect to see
thousands of planetary transits per year and, using microlensing,
we also expect to detect earth-like planets. Using the IFS we will
complete a major survey of black hole dynamics in the central regions
of galaxies. We will also study the dynamics of assembly of massive
galaxies at redshifts greater than unity. This study is supported in
part by a NASA Origins Probes study grant NNG04GQ04G.
Title: The Hubble Origins Probe (HOP): Mission Overview
Authors: Ford, H.; Bianchi, L.; Heckman, T.; Moos, W.; Norman, C.;
Baum, S.; Giavalisco, M.; Nota, A.; Riess, A.; Sahu, K.; Somerville,
R.; Stiavelli, M.; Crocker, J.; Woodruff, R.; Bacon, R.; Ebbetts, D.;
Freeman, K.; Green, J.; Shull, M.; Hutchings, J.; Silk, J.; Steidel,
C.; Tsuneta, S.; de Zeeuw, T.
Bibcode: 2004AAS...20510001F
Altcode: 2004BAAS...36.1508F
A no-new-technology HST-class observatory with COS and WFC3 as its core
instruments can be launched to LEO on a Delta IV H or Atlas 541 long
fairing by 2010 with an estimated cost of \1 Billion. Considerable
cost savings are achieved by drawing from a large inventory of HST
spare parts. Technology developed and perfected since HST was built 25
years ago allows us to build HOP with a much lighter mirror and OTA than
those in HST. HOP will be unaberrated, making the telescope much easier
to test on the ground than an intentionally aberrated telescope. In
addition to replacing the aberration-correcting optics in COS and WFC3,
we will extend the wavelength range of COS down to 110 nm and modify the
filter complement of the WFC3. Our Japanese partners are leading
the development of a high throughput, Very Wide Field Imager (VWFI)
that achieves a field of view approximately 17 times larger than the
ACS by tiling one half of the unaberrated focal plane with CCDs. An
accompanying poster describes a novel optical solution for correcting
the astigmatism and field curvature in HOP's HST-like wide field of
view Ritchey-Chretein design. The thick, deep depletion Hamamatsu CCDs
in the VWFI are optimized for the near infrared, and have \sim90%
QE at 900 nm and \sim$70% QE at 1000 nm. We are exploring with
our European partners the concept of an Integral Field Spectrograph
operating from 200 nm to 1000 nm. The IFS would replace STIS's moderate
resolution capability in the near-UV and optical, and simultaneously
provide a spectrograph that is up to 30 times faster than STIS when
observing extended objects. This work was supported in part by
NASA grant NNG04GQ04G.
Title: Image stabilization system on SOLAR-B Solar Optical Telescope
Authors: Shimizu, Toshifumi; Nagata, Shin'ichi; Edwards, Chris;
Tarbell, Theodore; Kashiwagi, Yasuhiro; Kodeki, Kazuhide; Ito,
Osamu; Miyagawa, Hiroyuki; Nagase, Masayuki; Inoue, Syunsaku; Kaneko,
Kazumasa; Sakamoto, Yasushi; Ichimoto, Kiyoshi; Tsuneta, Saku; Miki,
Shiro; Endo, Makoto; Tabata, Masaki; Nakaoji, Toshitaka; Matsuzaki,
Keiichi; Kobayashi, Ken; Otsubo, Masashi; Suematsu, Yoshinori; Kumagai,
Kazuyoshi; Noguchi, Motokazu; Tamura, Tomonori; Nakagiri, Masao
Bibcode: 2004SPIE.5487.1199S
Altcode:
Extremely stable pointing of the telescope is required for images on the
CCD cameras to accurately measure the nature of magnetic field on the
sun. An image stabilization system is installed to the Solar Optical
Telescope onboard SOLAR-B, which stabilizes images on the focal plane
CCD detectors in the frequency range lower than about 20Hz. The system
consists of a correlation tracker and a piezo-based tip-tilt mirror with
servo control electronics. The correlation tracker is a high speed CCD
camera with a correlation algorithm on the flight computer, producing
a pointing error from series of solar granule images. Servo control
electronics drives three piezo actuators in the tip-tilt mirror. A
unique function in the servo control electronics can put sine wave
form signals in the servo loop, allowing us to diagnose the transfer
function of the servo loop even on orbit. The image stabilization
system has been jointly developed by collaboration of National
Astronomical Observatory of Japan/Mitsubishi Electronic Corp. and
Lockheed Martin Advanced Technology Center Solar and Astrophysics
Laboratory. Flight model was fabricated in summer 2003, and we measured
the system performance of the flight model on a laboratory environment
in September 2003, confirming that the servo stability within 0-20 Hz
bandwidth is 0.001-0.002 arcsec rms level on the sun.
Title: Focal plane CCD camera for the X-Ray Telescope (XRT) aboard
SOLAR-B
Authors: Sakao, Taro; Kano, Ryouhei; Hara, Hirohisa; Matsuzaki,
Keiichi; Shimojo, Masumi; Tsuneta, Saku; Kosugi, Takeo; Shibasaki,
Kiyoto; Kumagai, Kazuyoshi; Sawa, Masaki; Tamura, Tomonori; Iwamura,
Satoru; Nakano, Mitsuhiko; Du, Zhangong; Hiyoshi, Kenji; Horii,
Michihiro; Golub, Leon; Bookbinder, Jay A.; Cheimets, Peter C.; Hill,
Lawrence D.; Owens, Jerry K.
Bibcode: 2004SPIE.5487.1189S
Altcode:
We present scientific as well as engineering overview of the X-Ray
Telescope (XRT) aboard the Japanese Solar-B mission to be launched in
2006, with emphasis on the focal plane CCD camera that employs a 2k
x 2k back-thinned CCD. Characterization activities for the flight CCD
camera made at the National Astronomical Observatory of Japan (NAOJ)
are discussed in detail with some of the results presented.
Title: The Solar Optical Telescope onboard the Solar-B
Authors: Ichimoto, Kiyoshi; Tsuneta, Saku; Suematsu, Yoshinori;
Shimizu, Toshifumi; Otsubo, Masashi; Kato, Yoshihiro; Noguchi,
Motokazu; Nakagiri, Masao; Tamura, Tomonori; Katsukawa, Yukio; Kubo,
Masahito; Sakamoto, Yasushi; Hara, Hirohisa; Minesugi, Kenji; Ohnishi,
Akira; Saito, Hideo; Kawaguchi, Noboru; Matsushita, Tadashi; Nakaoji,
Toshitaka; Nagae, Kazuhiro; Sakamoto, Joji; Hasuyama, Yoshihiro;
Mikami, Izumi; Miyawaki, Keizo; Sakurai, Yasushi; Kaido, Nobuaki;
Horiuchi, Toshihida; Shimada, Sadanori; Inoue, Toshio; Mitsutake,
Masaaki; Yoshida, Norimasa; Takahara, Osamu; Takeyama, Norihide;
Suzuki, Masaharu; Abe, Shunichi
Bibcode: 2004SPIE.5487.1142I
Altcode:
The solar optical telescope onboard the Solar-B is aimed to perform a
high precision polarization measurements of the solar spectral lines
in visible wavelengths to obtain, for the first time, continuous
sets of high spatial resolution (~0.2arcsec) and high accuracy
vector-magnetic-field map of the sun for studying the mechanisms
driving the fascinating activity phenomena occurring in the solar
atmosphere. The optical telescope assembly (OTA) is a diffraction
limited, aplanatic Gregorian telescope with an aperture of Φ500mm. With
a collimating lens unit and an active folding mirror, the OTA provides
a pointing-stabilized parallel beam to the focal plane package (FPP)
with a field of view of about 360x200arcsec. In this paper we identify
the key technical issues of OTA for achieving the mission goal and
describe the basic concepts in its optical, mechanical and thermal
designs. The strategy to verify the in-orbit performance of the
telescope is also discussed.
Title: Development of ultra-light-weight mirror with carbon/carbon
composites for optical-IR astronomy
Authors: Takeya, Hajime; Kume, Masami; Hahn, Steven; Ozaki, Tsuyoshi;
Kohara, Naoki; Otsubo, Masashi; Tsuneta, Saku
Bibcode: 2004SPIE.5487.1084T
Altcode:
Future large aperture telescope projects will require very
lightweight mirrors that can be produced at significantly lower cost
and faster production times than currently possible. Tailorable,
low thermal expansion composite materials offer an attractive path
to achieve these goals. Application of carbon/carbon composites
is particularly attractive as these materials do not exhibit the
moisture-absorption-related expansion problems observed in typical resin
matrix composites. The National Astronomical Observatory of Japan and
Mitsubishi Electric Corporation are collaborating to develop materials
and surface finishing technologies to enable future carbon/carbon
composite mirror applications. Material processing techniques for
improved substrate surface finish have been developed. An innovative
surface finish approach involving high precision machining of a metal
layer applied to the mirror surface has also been developed. As a
result, 150mm diameter C/C spherical mirror with honeycomb sandwich
structure was successfully demonstrated.
Title: Design and Performance of Tip-Tilt Mirror System for Solar
Telescope
Authors: Kodeki, Kazuhide; Fukushima, Kazuhiko; Hara, Hirohisa; Inoue,
Masao; Kano, Ryouhei; Kashiwase, Toshio; Nagata, Shin'ichi; Sakao,
Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi
Bibcode: 2004JSpRo..41..868K
Altcode:
No abstract at ADS
Title: Observation of solar flare hard X-ray spectra using CdTe
detectors
Authors: Kobayashi, K.; Tsuneta, S.; Tamura, T.; Kumagai, K.;
Katsukawa, Y.; Kubo, M.; Sakamoto, Y.; Kohara, N.; Yamagami, T.;
Saito, Y.; Mori, K.
Bibcode: 2004AdSpR..33.1786K
Altcode:
We present the design and initial flight results of a balloon-borne
hard X-ray spectrometer for observing solar flares. The instrument
is designed for quantitative observation of nonthermal and thermal
components of solar flare hard X-ray emission, and has an energy range
of 15-120 keV and an energy resolution of 3 keV. The instrument is
a small (gondola weight 70 kg) system equipped with sixteen 10 ×
10 × 0.5 mm CdTe detectors, and designed for a 1-day flight at 41
km altitude. Detector temperature of -15 °C was achieved through
radiative cooling alone. Pre-flight tests confirmed that all detectors
exceeded the target 3 keV resolution. No flares were observed during
the 2001 flight, but the second flight on May 24, 2002 succeeded
in observing a class M1.1 flare. Preliminary analysis indicates the
observed spectrum is consistent with a purely thermal plasma at an
unusually high temperature of 47 mK.
Title: Science with Solar-B solar optical telescope
Authors: Tsuneta, S.; Title, A.
Bibcode: 2004cosp...35.4418T
Altcode: 2004cosp.meet.4418T
SOLAR-B to be launched in the summer of 2006 will carry optical, EUV
and X-ray telescopes. The prime purpose is to track the sub-surface
generation and transport of magnetic fields and its eventual dissipation
in the corona. Solar Optical Telescope (SOT) is a 50cm telescope (0.2
arcsec resolution at 0.5micron, wavelengths: 380nm-670nm, FOV: 328
x 164 arcsec) with spectro-polarimeter (0.16 arcsec pixel) and with
filtergraph for high spatial and temporal observations (0.08 arcsec
pixel). SOT is a combination of the flying Advanced Stokes Polarimeter
and the flying Swedish solar telescope (with lesser spatial resolution)
with 24 hour coverage. Polarimetric and helioseismic approaches allow
us to simultaneously observe the magnetic fields on and below the
photosphere. Configuration of sub-surface and emergent magnetic flux
tubes, emergence, submergence, and cancellation of magnetic fields,
disintegration and transport of sunspot fields, direct detection
of various MHD waves, role of magnetic helicity and flows, nature
of elemental flux tubes are among the massive topics to be pursued
with SOT. SOT also brings fusion of observations and numerical MHD
simulation. Time-dependent boundary-data of magnetic and velocity fields
may be directly fed to the MHD system in the computer to predict its
evolution, that is compared with the X-ray and EUV data.
Title: Development of the Solar-B X-ray telescope focal plane camera
Authors: Kano, Ryouhei; Hara, Hirohisa; Kumagai, Kazuyoshi; Sawa,
Masaki; Tsuneta, Saku; Sakao, Taro; Matsuzaki, Keiichi
Bibcode: 2004naoj.book....5K
Altcode:
No abstract at ADS
Title: The evoluton of vector magnetic fields in an emerging flux
region
Authors: Kubo, Masahito; Shimizu, Toshifumi; Tsuneta, Saku; Lites,
B. W.
Bibcode: 2004naoj.book...41K
Altcode:
No abstract at ADS
Title: Observation of solar flare hard X-ray spectra using CdTe
detectors
Authors: Kobayashi, Ken; Tsuneta, Saku; Tamura, Tomonori; Kumagai,
Kazuyoshi; Katsukawa, Yukio; Kubo, Masahito; Sakamoto, Yasushi;
Kohara, Naoki; Yamagami, Takamasa; Saito, Yoshitaka; Mori, Kunishiro;
Kato, Genzo
Bibcode: 2004naoj.book...38K
Altcode:
No abstract at ADS
Title: What determines the coronal heating rate in the photosphere?
Authors: Katsukawa, Y.; Tsuneta, S.
Bibcode: 2004cosp...35.2233K
Altcode: 2004cosp.meet.2233K
Observations of the solar corona with Yohkoh/SXT, SOHO/EIT and TRACE
have revealed that individual loops of active region corona have their
own temperatures from 1 MK to 5 MK. The most significant difference
between hot (2 - 5 MK) SXT loops and cool (1 - 2 MK) EUV ones is that
heat input to maintain the hot loops is about one order of magnitude
larger than that for the cool loops. We investigate the photospheric
magnetic signature for the hot and cool loops with the Advanced Stokes
Polarimeter (ASP) to clarify what makes such a large difference in the
heat input. Footpoints of both loops have magnetic fields whose strength
is 1.2 - 1.3 kG and the orientation is almost vertical to the surface. A
significant difference is discovered in the magnetic filling factor,
which is defined by the fraction of a pixel filled with a magnetized
atmosphere. The footpoints of the hot loops have significantly lower
filling factor than the footpoints of the cool loops. If we interpret
the lower filing factor as multiple granular magnetic elements in
an ASP pixel, those elemental magnetic footpoints combined with
photospheric motion would provide enhanced coronal heating, leading
to the hot loops. Solar-B and STEREO will provide an opportunity to
perform direct investigation of the correlation between the photospheric
motion of magnetic elements and the coronal temperature.
Title: Thermo-optical testing of the solar optical telescope of
the Solar-B
Authors: Ichimoto, Kiyoshi; Nakagiri, Masao; Suematsu, Yoshinori;
Tamura, Tomonori; Tsuneta, Saku; Noguchi, Motokazu; Kato, Yoshihiro;
Otsubo, Seiji; Katsukawa, Yukio; Kubo, Masahito
Bibcode: 2004naoj.book....6I
Altcode:
No abstract at ADS
Title: The Focal Plane Package for Solar B
Authors: Title, A.; Tsuneta, S.
Bibcode: 2004cosp...35.1299T
Altcode: 2004cosp.meet.1299T
The Focal Plane Package (FPP) of the JAXA Solar B Solar Optical
Telescope (SOT) combines an advanced version of Stokes Polarimeter, a
tunable birefringent filter, and a set of narrow spectral filters. The
Stokes Polarimeter and the filter systems can operate simultaneously
allowing the construction of precise vector magnetograms and images
in a range of spectral lines. Both the Stokes Polarimeter and the
filter systems have controllable fields of view and cadence. A local
correlation tracker in the FFP operates a high speed tip-tilt mirror
to stabilize the image in all focal planes. The time sequences of
precise vector magnetic maps uncompromised by seeing will enable new
understanding of how flux emerges through and disappears from the solar
surface. The tunable filter can measure the flows in the atmosphere
from the lower photosphere through the Chromosphere enabling new
insights in the magneto-hydrodynamics of magnetic evolution.
Title: Development and flight performance of the sun sensor for
balloon observation
Authors: Tamura, Tomonori; Kobayashi, Ken; Tsuneta, Saku; Kubo,
Masahito; Katsukawa, Yukio
Bibcode: 2003RNAOJ...6..117T
Altcode:
We developed a sun-sensor for the balloon mission to observe solar
flare hard X-ray spectra using CdTe detectors. The sensor utilizes a
position-sensitive detector (PSD) with a pinhole, and has 60 degrees ×
60 degrees field-of-view with a 1 degree resolution. The sun-sensor
operated nominally during the two flights. We report the design,
ground calibration, and flight performance.
Title: Spatial and Temporal Properties of Hot and Cool Coronal Loops
Authors: Nagata, Shin'ichi; Hara, Hirohisa; Kano, Ryouhei; Kobayashi,
Ken; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi;
Gurman, Joseph B.
Bibcode: 2003ApJ...590.1095N
Altcode:
A suite of images from the XUV Doppler Telescope (XDT), the Yohkoh Soft
X-ray Telescope (SXT), and the Extreme-Ultraviolet Imaging Telescope
(EIT) on the Solar and Heliospheric Observatory (SOHO) allow us to
see the whole (T>1 MK) temperature evolution of coronal loops. The
detailed morphological comparison of an active region shows that hot
loops seen in SXT (T>3 MK) and cool loops seen in the the EIT 195
Å band (T~1.5 MK) are located in almost alternating manner. The
anticoincidence of the hot and the cool loops is conserved for a
duration much longer than the estimated cooling timescale. However, both
hot and cool loops have counterparts in the intermediate-temperature
images. The cross-correlation coefficients are higher for neighboring
temperature pairs and lower for pairs with larger temperature
differences. These results suggest that loops are not isothermal but
rather have a differential emission measure distribution of modest but
finite width that peaks at different temperatures for different loops.
Title: Balloon-borne hard x-ray spectrometer for flare observations
Authors: Kobayashi, Ken; Tsuneta, Saku; Tamura, Tomonori; Kumagai,
Kazuyoshi; Katsukawa, Yukio; Kubo, Masahito; Yamagami, Takamasa;
Saito, Yoshitaka
Bibcode: 2003SPIE.4851.1009K
Altcode:
We present the design and initial flight results of a balloon-borne
hard X-ray detector system for observing high-resolution spectra of
solar flares. The instrument is designed to achieve a 3 keV energy
resolution over the energy range of 15-120 keV. The instrument uses
sixteen 10×10×0.5mm cadmium telluride (CdTe) detectors with indium
electrodes that act as Schottky barriers. Pre-flight tests confirmed
that all detectors exceeded the target 3 keV resolution. The detector
system is designed to optimize radiative cooling in order to achieve
the operating temperature of 0°C without refrigeration mechanisms. The
first flight took place on August 29, 2001 and while no major flares
were observed, the instrument operation was verified and a detector
temperature of -13° C was achieved. The second flight took place on
May 24, 1974 and during the 8 hours of level flight at an altitude of
41km, we succeeded in observing a class M1.1 solar flare.
Title: Development of the Solar-B spacecraft
Authors: Tsuneta, Saku; Ichimoto, Kiyoshi; Suematsu, Yoshinori;
Shimizu, Toshifumi; Hara, Hirohisa; Kano, Ryohei; Nagata, Shin'ichi;
Tamura, Tomonori; Nakagiri, Masao; Noguchi, Motokazu; Kato, Yoshihiro;
Watanabe, Tetsuya; Hanaoka, Yoichiro; Sawa, Masaki; Otsubo, Masashi;
Kosugi, Takeo; Yamada, Takahiro; Sakao, Taro; Matsuzaki, Keiichi;
Minesugi, Kenji; Onishi, Akira; Katsukawa, Yukio; Kobayashi, Ken;
Kubo, Masahito
Bibcode: 2003naoj.book....3T
Altcode:
No abstract at ADS
Title: Development of Solar-B solar optical telescope
Authors: Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu, Toshifumi;
Nagata, Shin'ichi; Tamura, Tomonori; Tsuneta, Saku; Noguchi, Motokazu;
Kato, Yoshihiro; Nakagiri, Masao; Otsubo, Masashi; Hanaoka, Yoichiro;
Katsukawa, Yukio; Kobayashi, Ken; Kubo, Masahito
Bibcode: 2003naoj.book....5S
Altcode:
No abstract at ADS
Title: Development of image stabilization system for solar optical
telescope onboard Solar-B satellite
Authors: Nagata, Shinichi; Shimizu, Toshifumi; Ichimoto, Kiyoshi;
Tsuneta, Saku; Matsuzaki, Keiichi; Kobayashi, Ken
Bibcode: 2003naoj.book....8N
Altcode:
No abstract at ADS
Title: Small fluctuation of coronal X-ray intensity: possibility of
nanoflare heating
Authors: Katsukawa, Yukio; Tsuneta, Saku
Bibcode: 2003naoj.book...41K
Altcode:
No abstract at ADS
Title: Contamination evaluation and control for SOLAR-B optical
telescope
Authors: Tamura, Tomonori; Hara, Hirohisa; Tsuneta, Saku; Ichimoto,
Kiyoshi; Kumagai, Kazuyoshi
Bibcode: 2002RNAOJ...6...49T
Altcode:
In space telescopes, the deposition of molecular outgassing from its
component parts may degrade the mirror reflectivity. In the case of the
SOLAR-B visible light telescope, the molecular contamination is even
more threatening since the deposited contaminants, when illuminated by
the ultraviolet light from the sun, not only blacken but also promote
further deposition. We thus started an extensive program to measure
outgassing from all the non-metal material candidates to be used
of the SOLAR-B telescope and to evaluate various chemical-cleaning
(de-oil) procedures for the metal parts. The evaluation is based on
NASA-MSFC-SPEC-1238 specification, and Thermoelectric Quartz Crystal
Microbalance is the primary apparatus for the measurement. We are
able to select the best possible adhesives and de-oil procedures for
the flight model, whenever there are multiple choices. Conditions
for the flight-model vacuum bakeout will also be established based on
the measurements. The program significantly mitigates the risk due to
molecular contamination the SOLAR-B program.
Title: Yohkoh Satellite Findings on Solar Flares and Coronal Heating
Authors: Tsuneta, Saku
Bibcode: 2002APS..APRK12002T
Altcode:
Solar corona has sporadic energy release with energies over 7 orders of
magnitudes. Occasional larger events are called flares, and ubiquitous
smaller one discovered with Yohkoh are called micro-flares or transient
brightening. The mechanism of the solar flares has been enigma over
the years. Soft and hard X-ray imaging telescopes aboard Yohkoh for
the first time demonstrates that these sporadic energy releases are
in general attributed to magnetic reconnection (annihilation). Pieces
of observational evidence indicates that the reconnection site has an
infinitesimal diffusion region with pairs of large-scale MHD slow-mode
shocks and bipolar fast Alfvenic outflows as Petschek predicted years
ago. In particular, soft X-ray imaging data shows clear signature
of the slow-shock heating. Hard X-ray imaging telescope discovered an
isolated hard source near the reconnection site in addition to the usual
double foot-point hard X-ray sources. The so-called loop-top hard X-ray
source is emitted from confined non-thermal electrons or from 100-200
MK super-hot plasma with lesser possibility. Fast mode shock due to
the collision of the outflow and the reconnected loops appears to be
responsible for the electron acceleration. A key open issue is how the
solar corona, with continuous agitation from the sub-surface convective
layer in terms of energy and helicity, evolves to a configuration with
neutral sheet (X-point), where magnetic reconnection is ready to take
place. There has been an intriguing possibility that stationary corona,
which is more energetically dominant than total contribution of all
the observed transients, is heated by farther small transients, nano
or pico flares as Parker discussed. We find that coronal soft X-ray
emission contains random fluctuation signal in addition to photon
shot-noise. We discuss the possibility that pico-flares are responsible
for the fluctuation and heat the stationary corona.
Title: Balloon-Borne Hard X-ray Spectrometer for Flare Observations
Authors: Kobayashi, K.; Tsuneta, S.; Tamura, T.; Kumagai, K.;
Katsukawa, Y.; Kubo, S.; Yamagami, T.; Saitoh, Y.
Bibcode: 2002mwoc.conf..429K
Altcode:
We present an overview of a balloon-borne hard X-ray detector system
designed for high spectral resolution observation of solar flares. The
goal is to achieve a 3-keV energy resolution over an energy range of
15--100 keV, to observe both non-thermal and thermal components of the
solar flare hard X-ray emission. We achieve this by using an array of
16 CdTe detectors, each with a 10 times 10 times 0.5 mm size. These
detectors use an Indium electrode on one side which act as a Shottky
barrier, reducing leak current and improving energy resolution compared
to conventional CdTe detectors. The detectors are passively shielded by
2 mm of lead. The detectors are installed in a pressurized enclosure to
prevent coronal discharge. In order to maximize passive cooling, thermal
shields are installed around the detector housing to block sunlight and
infrared emission from the ground. Thermal math models indicate that
the detectors will be cooled to below 0circC. The signal
from the 16 detectors are processed by independent preamplifiers and
amplifiers, and a custom-designed 16 channel multichannel analyzer
acquires the signal and constructs 16 independent spectra. These are
read every 0.56 seconds and transmitted by telemetry. A 0.14 second
resolution counter is used to correct for dead time. The instrument
is currently undergoing testing and calibration, and first flight is
scheduled for September 2001 from an ISAS (Institute of Space and
Astronautical Science) facility in Sanriku, Japan. The flight will
last one day at an altitude of 42 km.
Title: Observation of solar flare hard x-ray spectra using CdTe
detectors
Authors: Kobayashi, K.; Tsuneta, S.; Tamura, T.; Kumagai, K.;
Katsukawa, Y.; Kubo, M.; Sakamoto, Y.; Yamagami, T.; Saito, Y.;
Mori, K.
Bibcode: 2002cosp...34E1971K
Altcode: 2002cosp.meetE1971K
We present the design and flight results of a balloon-borne hard
X-ray detector system for observing high-resolution spectra of solar
flares. The instrument is designed to achieve a 3 keV energy resolution
over the energy range of 15-120 keV. The instrument uses sixteen 10 ×
10 × 0.5 mm cadmium telluride (CdTe) detectors with indium electrodes
that act as Schottky barriers to minimize leak current and allow a high
bias voltage. Pre-flight tests confirmed that all detectors exceeded
the target 3 keV resolution. The pressurized detector vessel uses
a low-density (0.1 g/cm^2) CFRP/Rohacell window. The detectors are
passively shielded by 2 mm of lead, and field of view is constrained
with a graded-Z collimator. The vertical angle of the detectors are
fixed at 45 degrees, and the azimuth angle of the entire gondola
is controlled using a signal from a sun position sensor. Specially
developed electronics accumulate a 128 channel spectrum for each
detector, which is read through telemetry every 0.54 seconds. These
detectors need to be cooled down to 0 degrees C for optimal performance;
due to weight constraints this was achieved purely by radiative cooling,
using the detector enclosure surface as a radiator and by placing
shields that minimize radiative heat input from the sun and earth while
maximizing heat loss to the sky. The first flight of the instrument
took place on August 29, 2001 and while no major flares were observed,
we succeeded in detecting a small brightening (microflare). Detector
temperature of -13 degrees C was achieved, and all systems performed
as expected. The instrument was recovered successfully after the flight
and a second flight is planned for May 2002.
Title: Small Fluctuation of Coronal X-Ray Intensity and a Signature
of Nanoflares
Authors: Katsukawa, Yukio; Tsuneta, Saku
Bibcode: 2001ApJ...557..343K
Altcode:
If small energy events (nanoflares) contribute to the heating of the
solar corona, they may be too small to be recognized as independent
events. We create a simple histogram of the X-ray intensity fluctuation
around the mean intensity and find that the histogram consists of a
central Gaussian component and a wing component. The Gaussian component
corresponds to random fluctuation around the mean intensity. The width
of this component becomes broader with increasing intensity and is
larger than the predicted photon noise distribution. We suggest that
nanoflares produce the observed fluctuation of the X-ray intensity. The
energy of nanoflares is estimated to be less than 1022 ergs
to explain the observed fluctuation for active regions. It is estimated
that if the energy of nanoflares is 1020 ergs, then these
nanoflares must occur at a rate of 106 s-1 in a
single active region (~1020 cm2) to supply the
required energy (~5×107 ergs cm-2 s-1)
to maintain the corona.
Title: On the Detection of Solar Coronal High-Velocity Fields Using
the XUV Doppler Telescope
Authors: Kobayashi, Ken; Hara, Hirohisa; Kano, Ryohei; Nagata,
Shin'ichi; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida,
Tsuyoshi; Harrison, Richard
Bibcode: 2000PASJ...52.1165K
Altcode:
The XUV Doppler Telescope (XDT) is a sounding rocket experiment
designed to detect flows in the solar corona using filter ratios. The
XDT, successfully launched on 1998 January 31, is a normal incidence
telescope composed of narrow-bandpass multilayer mirrors and capable
of obtaining images 2 Å\ above and 2 Å\ below the Fe XIV 211 Å\
(T = 1.7 MK) emission line. It has the potential to make a velocity map
of the entire solar disk with just a few minutes of observation. The
image ratio maps show features that translate to Doppler shifts of
200 km s-1 or more, including several `redshift' features
located near footpoints of coronal loops. However, no corresponding
velocity features were seen by the Solar and Heliospheric Observatory
(SOHO) Coronal Diagnostic Spectrometer (CDS) in the Mg IX 368 Å (T =
1 MK) line, suggesting that the features are not caused by Doppler
shift. Instead, the features seem to be related to contamination
of lower temperature (T < 1 MK) emission lines and the nearby
density-sensitive Fe XIII lines. We conclude that while no flows were
positively identified by the XDT, this observing technique is capable
of detecting flows of 1000 km s^{-1} independently, and 200 km s^{-1}$
when combined with simultaneous plasma diagnostic observation.
Title: Yohkoh
Authors: Tsuneta, S.
Bibcode: 2000eaa..bookE1991T
Altcode:
The Yohkoh satellite was launched by Japan's INSTITUTE OF SPACE AND
ASTRONAUTICAL SCIENCE (ISAS) on 30 August 1991 for observations
of solar FLARES and the solar CORONA in x-ray and gamma-ray
wavelengths. Excellent observations have been made over the last nine
years (see figure 1 and figure 2). The satellite has experienced the
entire transition from the maximum to the minimum of the last SOLAR ...
Title: Initial Results from the XUV Doppler Telescope
Authors: Kano, R.; Hara, H.; Kobayashi, K.; Kumagai, K.; Nagata, S.;
Sakao, T.; Shimizu, T.; Tsuneta, S.; Yoshida, T.
Bibcode: 2000AdSpR..25.1739K
Altcode:
We developed a unique telescope to obtain simultaneous XUV images and
the velocity maps by measuring the line-of-sight Doppler shifts of the
Fe XIV 211A&ring line (T = 1.8 MK): the Solar XUV Doppler Telescope
(hereafter XDT). The telescope was launched by the Institute of Space
and Astronautical Science with the 22nd S520 rocket on January 31,
1998, and took 14 XUV whole sun images during 5 minutes. Simultaneous
observations of XDT with Yohkoh (SXT), SOHO (EIT, CDS, LASCO and MDI)
were successfully carried out. The images taken with EIT, XDT and SXT
are able to cover the wide temperature ranging from 1 to 10 MK, and
clearly show the multi-temperature nature of the solar corona. Indeed,
we notice that both the cool (1-2 MK) loops observed with EIT and
XDT, and the hot (>3 MK) loops observed with SXT exist in the same
active regions but in a spatially exclusive way. The XDT red-blue ratio
between longer- and shorter-wavelength bands of Fe XIV 211A&ring
line indicates a possible down-flow of 1.8 MK plasma near the footpoints
of multiple cool loops
Title: Narrow-Bandpass Multilayer Mirrors for an Extreme-Ultraviolet
Doppler Telescope
Authors: Hara, Hirohisa; Nagata, Shin'ichi; Kano, Ryouhei; Kumagai,
Kazuyoshi; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida,
Tsuyoshi; Ishiyama, Wakana; Oshino, Tetsuya; Murakami, Katsuhiko
Bibcode: 1999ApOpt..38.6617H
Altcode:
No abstract at ADS
Title: Erratum: Temperature Distributions and Energy Scaling Law of
Solar Coronal Loops Obtained with Yohkoh
Authors: Kano, Ryouhei; Tsuneta, Saku
Bibcode: 1999PASJ...51..569K
Altcode:
No abstract at ADS
Title: The XUV Doppler Telescope (XDT)
Authors: Sakao, T.; Tsuneta, S.; Hara, H.; Shimizu, T.; Kano, R.;
Kumagai, K.; Yoshida, T.; Nagata, S.; Kobayashi, K.
Bibcode: 1999SoPh..187..303S
Altcode:
We present an overview and instrumental details of the solar XUV Doppler
Telescope (XDT) launched in January 1998 with the S520CN-22 sounding
rocket of the Institute of Space and Astronautical Science. The XDT
observes nearly single-temperature solar corona at 1.8 MK with angular
resolution of ≈ 5'' pixel size, together with the ability to detect
the coronal velocity field with a full-Sun field of view. By use of
normal incidence optics whose primary and secondary mirrors are coated
with multilayer materials in two sectors, the XDT takes images of the
Sun in a set of shorter and longer wavelength bands around the Fe xiv
211.3 Å emission line. Summation of a pair of images in the two bands
provides an image of the 1.8 MK-corona while the difference between
the two provides velocity images of the Fe xiv-emitting plasma. A brief
description on the observation sequence together with the flight result
is also given.
Title: Development and flight performance of tip-tilt mirror system
for a sounding rocket observation of the Sun.
Authors: Shimizu, T.; Yoshida, T.; Tsuneta, S.; Sakao, T.; Kano,
R.; Hara, H.; Nagata, S.; Kodeki, K.; Inoue, M.; Fukushima, K.;
Kashiwase, T.
Bibcode: 1999RNAOJ...4...43S
Altcode: 1999RNOAJ...4...43S
A tip-tilt mirror (TTM) system was developed for the XUV Doppler
telescope (XDT) on board an ISAS sounding rocket. The spatial resolution
of the telescope is about 5″ whereas the pointing stability is
only ±0.3° with the rocket pointing control system. To achieve
better than 5″stability on the focal plane of the telescope, the
TTM system controls the tilt of the secondary mirror with fixed-coil
magnetic actuators. The control signal to stabilize focal-plane images
is supplied by the position-sensitive detector (PSD) of a pin-hole
telescope equipped inside XDT. Closed-loop controls are made with
the on-board software on the DSP processor. The sounding rocket was
successfully launched on 31 January 1998 from the Kagoshima Space
Center of ISAS. TTM worked perfectly during the flight, and achieved
better than 5″stability on the focal plane during CCD exposures.
Title: Development of the tip-tilt mirror system for the solar
XUV telescope
Authors: Kodeki, Kazuhide; Fukushima, Kazuhiko; Kashiwase, Toshio;
Inoue, Masao; Shimizu, Toshifumi; Yoshida, Tsuyoshi; Sakao, Taro;
Hara, Hirohisa; Nagata, Shin'ichi; Kano, Ryouhei; Tsuneta, Saku
Bibcode: 1998SPIE.3356..922K
Altcode:
This paper describes the design and prelaunch performance of the
tip-tilt mirror (TTM) system developed for the XUV Cassegrain telescope
aboard the ISAS sounding rocket experiment. The spatial resolution
of the telescope is about 5 arcsec, whereas the rocket pointing is
only controlled to be within +/- 0.5 degree around the target without
stability control. The TTM is utilized to stabilize the XUV image
on the focal planes by tilting the secondary mirror with two-axes
fixed-coil type actuators. The two position- sensitive detectors in
the telescope optics and in the TTM mechanical structure from the
normal and local closed-loop modes. The TTM has four grain modes with
automatic transition among the modes. The low gain mode is used in
the initial acquisition, and in case the TTM loses the tracking. The
high gain mode is used in the normal tracking mode. This arrangement
provides us with the wide initial acquisition angle with single TTM
system as well as the high pointing accuracy once the tracking is
established. The TTM has a launch-lock mechanism against the launch
vibration of 16G. The closed-loop control with command and telemetry
interface is done by the flight software against the launch vibration
of 16G. The closed-loop control with command and telemetry interface
is done by the flight software on the DSP processor. The use of the
fast processor brings in the significant reduction in the weight and
size of the control- electronics, more flexible control system, and
shorter design and testing period.
Title: Fermi Acceleration at the Fast Shock in a Solar Flare and
the Impulsive Loop-Top Hard X-Ray Source
Authors: Tsuneta, Saku; Naito, Tsuguya
Bibcode: 1998ApJ...495L..67T
Altcode: 1998astro.ph..1109T
Because of its high injection energy, Fermi acceleration has not been
considered to be viable to explain nonthermal electrons (20-100 keV)
produced in solar flares. Here we propose that nonthermal electrons
are efficiently accelerated by the first-order Fermi process at the
fast shock, as a natural consequence of the new magnetohydrodynamic
picture of the flaring region revealed with Yohkoh. An oblique fast
shock is naturally formed below the reconnection site and boosts the
acceleration to significantly decrease the injection energy. The slow
shocks attached to the reconnection X-point heat the plasma up to 10-20
MK, exceeding the injection energy. The combination of the oblique
shock configuration and the preheating by the slow shock allows bulk
electron acceleration from the thermal pool. The accelerated electrons
are trapped between the two slow shocks due to the magnetic mirror
downstream of the fast shock, thus explaining the impulsive loop-top
hard X-ray source discovered with Yohkoh. The acceleration timescale
is ~0.3-0.6 s, which is consistent with the timescale of impulsive
bursts. When these electrons stream away from the region enclosed
by the fast shock and the slow shocks, they are released toward the
footpoints and may form the simultaneous double-source hard X-ray
structure at the footpoints of the reconnected field lines.
Title: Radiation testing of optical glasses and crystals for Solar-B
optical instruments.
Authors: Nishino, Y.; Suematsu, Y.; Tsuneta, S.; Ichimoto, K.; Kobiki,
T.; Takeyama, N.
Bibcode: 1998RNAOJ...3..145N
Altcode: 1998RNOAJ...3..145N
This report gives some results of γ-ray irradiation (Co60
source) testing on optical glasses and crystals which may be used
in the next Japanese solar space mission Solar-B. Ordinary optical
glasses darken when exposed to high-energy radiation which is present
in natural space environment. In case of Solar-B, whose orbit will be
polar-sun-synchronous, the satellite will undergo the total dose of
more than 1000 krad in five years. Hence it is very crucial for the
success of the mission to know the feasibility of transmitting optical
elements in space. The authors tested two kinds of fused silica, a
fluorite, and ten kinds of UV transmitting glasses. Calcite was also
tested. It was found that the fused silica is radiation-resistant but
the other glasses and the fluorite are nonresistant and become quite
opaque in UV and visible wavelength regions after the irradiation.
Title: XUV Doppler Telescope Aboard Sounding Rocket
Authors: Yoshida, T.; Kano, R.; Nagata, S.; Hara, H.; Sakao, T.;
Shimizu, T.; Tsuneta, S.
Bibcode: 1998ASSL..229..383Y
Altcode: 1998opaf.conf..383Y
No abstract at ADS
Title: Magnetic Loops in the Hot Universe
Authors: Tsuneta, S.; Makishima, K.
Bibcode: 1998ASSL..229..121T
Altcode: 1998opaf.conf..121T
No abstract at ADS
Title: Deep Survey of Solar Nano-Flares with YOHKOH
Authors: Shimizu, T.; Tsuneta, S.
Bibcode: 1998ASSL..229...27S
Altcode: 1998opaf.conf...27S
No abstract at ADS
Title: Deep Survey of Solar Nanoflares with Yohkoh
Authors: Shimizu, Toshifumi; Tsuneta, Saku
Bibcode: 1997ApJ...486.1045S
Altcode:
Short timescale variability fainter than transient brightenings
(microflares) is found in the solar position-dependent light curves
observed with the Yohkoh Soft X-Ray Telescope. The time variability is
found almost everywhere in active regions and X-ray bright points,
while no significant variability is found in quiet regions. An
intensity correlation is found between the magnitudes of the time
variability and the intensities of the persistent corona. The time
variability is apparently related to the heating mechanism of the
persistent active-region corona. The intensity correlation can be
explained with the idea that the persistent corona is made of extremely
numerous nanoflares, larger ones of which are observed as the time
variability. The alternative explanation is that a common parameter
controls both the persistent corona and the time variability.
Title: Moving Plasmoid and Formation of the Neutral Sheet in a
Solar Flare
Authors: Tsuneta, Saku
Bibcode: 1997ApJ...483..507T
Altcode:
A spectacular erupting feature with a plasmoid-like structure is
observed before and during the solar flare that occurred on the limb on
1991 December 2 with the Yohkoh soft X-ray telescope. The rise of a loop
structure starts ~10 min before the flare, evolving to a plasmoid-like
structure in the impulsive phase of the flare. The speed of the rising
loop (plasmoid) is almost constant (~96 km s-1) throughout
the observation. A clear X-shaped structure is formed underneath the
rising plasmoid, and a bright soft X-ray loop is formed below the
X-point. The X-shaped structure indicates a magnetic neutral point
with a large-scale magnetic separatrix structure. Inverse-V-shaped
high-temperature ridges are located above the soft X-ray loop and
below the X-point. We interpret these as reconnected loops heated
by slow shocks. A moving high-temperature (15 MK) source is found,
coincident in position with the rising structure above the X-point. A
hard X-ray source (33-53 keV) is located at the top of the soft X-ray
flare loop. These two compact high-temperature sources located above and
below the X-point would be formed by fast shocks due to the symmetric
reconnection outflows both upward and downward from the X-point.
Title: Critical issues for understanding particle acceleration in
impulsive solar flares
Authors: Miller, James A.; Cargill, Peter J.; Emslie, A. Gordon;
Holman, Gordon D.; Dennis, Brian R.; LaRosa, T. N.; Winglee, Robert
M.; Benka, Stephen G.; Tsuneta, S.
Bibcode: 1997JGR...10214631M
Altcode: 1997JGR...102.1463M
This paper, a review of the present status of existing models for
particle acceleration during impulsive solar flares, was inspired by
a week-long workshop held in the Fall of 1993 at NASA Goddard Space
Flight Center. Recent observations from Yohkoh and the Compton Gamma
Ray Observatory, and a reanalysis of older observations from the
Solar Maximum Mission, have led to important new results concerning
the location, timing, and efficiency of particle acceleration in
flares. These are summarized in the first part of the review. Particle
acceleration processes are then discussed, with particular emphasis on
new developments in stochastic acceleration by magnetohydrodynamic
waves and direct electric field acceleration by both sub- and
super-Dreicer electric fields. Finally, issues that arise when these
mechanisms are incorporated into the large-scale flare structure
are considered. Stochastic and super-Dreicer acceleration may occur
either in a single large coronal reconnection site or at multiple
``fragmented'' energy release sites. Sub-Dreicer acceleration requires
a highly filamented coronal current pattern. A particular issue that
needs to be confronted by all theories is the apparent need for large
magnetic field strengths in the flare energy release region.
Title: XUV Doppler telescope with multilayer optics
Authors: Hara, Hirohisa; Kano, Ryouhei; Nagata, Shin'ichi; Sakao, Taro;
Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi; Kosugi, Takeo
Bibcode: 1997SPIE.3113..420H
Altcode:
We present an overview of a sounding-rocket experiment, which is
scheduled to be launched by the Institute of Space and Astronautical
Science (ISAS) in January 1998, the rising phase of the 11-year activity
cycle of the sun. The purpose of this experiment is (1) to obtain
whole-sun images taken in an XUV emission line, Fe XIV 211 angstrom,
using the normal incidence multilayer optics with a high spectral
resolution of (lambda) /(Delta) (lambda) approximately equals 40, and
(2) to carry out the velocity-field measurement with detection limit
as high as 100 km/s.
Title: Development of multilayer mirrors for the XUV Doppler telescope
Authors: Nagata, Shin'ichi; Hara, Hirohisa; Sakao, Taro; Shimizu,
Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi; Ishiyama, Wakana;
Murakami, Katsuhiko; Oshino, Tetsuya
Bibcode: 1997SPIE.3113..193N
Altcode:
We present the development status of the normal incidence XUV multilayer
mirrors for XUV Doppler telescope, which observes coronal velocity
fields of the whole sun. The telescope has two narrow band-pass
multilayer mirrors tuned to slightly longer and shorter wavelengths
around the Fe XIV line at 211.3 Angstrom. From the intensity difference
of the images taken with these two bands, we can obtain Dopplergram of
1.8 MK plasma of the whole sun. It is required that the multilayer has
high wavelength-resolution ((lambda) /(Delta) (lambda) approximately
30 per mirror), anti-reflection coating for intense He II 304 angstrom
emission line and high d-spacing uniformity of approximately 1%.
Title: Hot and Superhot Plasmas above an Impulsive Flare Loop
Authors: Tsuneta, Saku; Masuda, Satoshi; Kosugi, Takeo; Sato, Jun
Bibcode: 1997ApJ...478..787T
Altcode:
We report the discovery of a high-temperature source above the soft
X-ray loop of the impulsive limb flare on 1992 January 13 with the
Yohkoh Soft X-ray Telescope (SXT). The hot source coincides in position
with the loop-top impulsive hard X-ray source and continues to sit
above the soft X-ray flare loop throughout the flare. The single
high-temperature source in the initial phase evolves to the two
high-temperature (15-20 MK) ridge structures in the peak and decay
phases, and the compact hard X-ray source appears to be located in
between the high-temperature ridges. We assume that the loop-top hard
X-ray source is of thermal origin (superhot source). The loop-top hard
X-ray source has an effective temperature of 100-150 MK and a total
emission measure of ~10-4 of the hot source. The geometrical
relationship between the superhot and the hot sources indicates that (1)
the hot source is heated by the slow shocks associated with magnetic
reconnection and that (2) the superhot source is heated with the fast
bow shock owing to the collision of the supersonic downward outflow with
the reconnected flux tube. The small emission measure of the superhot
source indicates a narrow outflow jet in between the slow shocks. These
observations suggest that there is no essential difference between
the compact-loop (impulsive) and long-duration event (LDE) flares. The
time coincidence of the loop-top hard X-ray source with the footpoint
sources indicates that nonthermal electron acceleration is causally
related to the formation of the fast shock rather than the slow shocks.
Title: The Dynamic Solar Corona in X-Rays with YOHKOH
Authors: Tsuneta, S.
Bibcode: 1997xisc.conf..521T
Altcode:
No abstract at ADS
Title: New high-thermal-conductivity composite material for
high-precision space optics
Authors: Ozaki, Tsuyoshi; Ikeda, Chihiro; Isoda, Minoru; Tsuneta, Saku
Bibcode: 1996SPIE.2804...22O
Altcode:
This paper reports on the newly developed graphite-cyanate composite
pipes for high-precision space optics such as the Solar-B optical
telescope. Fundamental mechanical, thermal, and hygroscopic properties
of unidirectional graphite- cyanate laminates were evaluated,
first. The orientation of fibers in the pipe was designed to minimize
longitudinal thermal deformation. Model pipes were fabricated based on
the design, and have conducted a series of measurements to evaluate the
thermal expansion behavior, the hygroscopic performance, the thermal
conductivity, and the long-term stability. Excellent performance of
the pipe was successfully verified and the material was found to be
the most promising candidate for space optics structures.
Title: Japanese sounding rocket experiment with the solar XUV
Doppler telescope
Authors: Sakao, Taro; Tsuneta, Saku; Hara, Hirohisa; Kano, Ryouhei;
Yoshida, Tsuyoshi; Nagata, Shin'ichi; Shimizu, Toshifumi; Kosugi,
Takeo; Murakami, Katsuhiko; Wasa, Wakuna; Inoue, Masao; Miura,
Katsuhiro; Taguchi, Koji; Tanimoto, Kazuo
Bibcode: 1996SPIE.2804..153S
Altcode:
We present an overview of an ongoing Japanese sounding rocket project
with the Solar XUV Doppler telescope. The telescope employs a pair
of normal incidence multilayer mirrors and a back-thinned CCD, and is
designed to observe coronal velocity field of the whole sun by measuring
line- of-sight Doppler shifts of the Fe XIV 211 angstroms line. The
velocity detection limit is estimated to be better than 100 km/s. The
telescope will be launched by the Institute of Space and Astronautical
Science in 1998, when the solar activity is going to be increasing
towards the cycle 23 activity maximum. Together with the overview of
the telescope, the current status of the development of each telescope
components including multilayer mirrors, telescope structure, image
stabilization mechanism, and focal plane assembly, are reviewed. The
observation sequence during the flight is also briefly described.
Title: Structure and Dynamics of Magnetic Reconnection in a Solar
Flare: Erratum
Authors: Tsuneta, Saku
Bibcode: 1996ApJ...464.1055T
Altcode:
No abstract at ADS
Title: Temperature Distributions and Energy Scaling Law of Solar
Coronal Loops Obtained with YOHKOH
Authors: Kano, Ryouhei; Tsuneta, Saku
Bibcode: 1996PASJ...48..535K
Altcode:
We derived the temperature distributions along the 16 steady loops
observed with the Yohkoh Soft X-ray Telescope. We have found that the
temperature and emission measure (pressure) are the highest around
the loop top, and decrease towards the footpoints. Some of the loops
have a plateau in the temperature distribution at around the loop
top (``trapezoidal'' temperature distribution). The other loops, on
the other hand, have a sharp peak in the temperature distributions
(``triangular'' temperature distribution). This triangular temperature
distribution suggests that the energy input is concentrated at the
peak. We have estimated the thermal conductive fluxes downward to the
footpoints from the gradients of the temperature distributions. The
flux ranges from 1 times 10(7) to 2 times 10(8) [erg s(-1) cm(-2)
]. We derived the total energy loss {cal L}_T, which is the sum of the
conductive and radiative losses: {cal L}_T= 2 times 10(7) --3 times
10(8) [erg s(-1) cm(-2) ]. We discovered a good correlation between
the total energy loss and the gas pressure p_g for the steady loops:
{cal L}_T = 1.2 times 10(7) p_g({0.99+/-) 0.12}. The correlation
is consistent with the theoretical energy scaling law for the steady
loops: {cal L}_T = 4.0 -- 5.1 times 10(3) * (p_g * T_m(1/2) ), where
T_m is the maximum temperature (T_m ~ 6 times 10(6) [K] for all the
loops analyzed here). } % % Key word %
Title: Observations of Coronal Depletion and Ejection
Authors: Lemen, J. R.; Hudson, H.; Webb, D.; Tsuneta, S.
Bibcode: 1996AAS...188.7007L
Altcode: 1996BAAS...28..939L
We present the analysis of the Yohkoh/SXT observations of a long-decay
event that was observed on 1992 February 21. This event, previously
reported by Tsuneta et al. \ 1992, had a clearly observed compact
ejection at its onset. There is also evidence for a depletion
of material in the corona above the flare site (coronal dimming)
accompanying the onset of flare brightening. We find a lower limit of
3 x 10(14) g for this mass depletion. This event was observed near the
limb as an arcade viewed almost end-on. Its morphology resembles the
classical reconnection model for a solar flare. Here we describe the
early phase of this event when the outward motions as observed in the
SXT images are interpreted as the X-ray signature of a coronal mass
ejection (no white-light images are available). The coronal depletion
marks the beginning of the outward motion and occurs simultaneously
with hard X-ray emission. If this marks the beginning of a CME, then
this event provides support for a close connection between of X-ray
flares and coronal mass ejections.
Title: Coordinated SPDE rocket, YOHKOH and ground observations of
an emerging flux region and a filament
Authors: Damé, L.; Martic, M.; Brown, W. A.; Bruner, M. E.; Strong,
K.; Suematsu, Y.; Tsuneta, S.; Schmieder, B.
Bibcode: 1996AdSpR..17d.189D
Altcode: 1996AdSpR..17..189D
During the first flight of the Solar Plasma Diagnostic Experiment
(SPDE), May 12, 1992, we obtained UV filtergrams at high resolution
(full Sun 0.82'' spatial resolution in the 160 nm continuum, the
CIV lines and Lyman alpha) with the Ultraviolet Filtergrap Camera
(UVFC). Closely coordinated observations were obtained with the Soft
X-ray Telescope (SXT) of the Yohkoh satellite and from dedicated ground
programs in particular at Sacramento Peak, La Palma and Pic-du-Midi
observatories. With this unique set of data we cover the solar
atmosphere as a whole, from the temperature minimum to the high corona
with essential steps in the chromosphere and transition region. After
the necessary calibrations of the data set, we present the first results
of the multitemperature development of an emerging flux region and of
a filament that rapidly changed right during the rocket short lifetime.
Title: A high-temperature component in coronal holes observed with
YOHKOH SXT
Authors: Hara, H.; Tsuneta, S.; Acton, L. W.; Bruner, M. E.; Lemen,
J. R.; Ogawara, Y.
Bibcode: 1996AdSpR..17d.231H
Altcode: 1996AdSpR..17..231H
Temperatures of coronal holes are estimated from several sets of soft
X-ray images taken through various broad-band filters with the Soft
X-ray Telescope (SXT) aboard Yohkoh. The effect of scattered X-rays from
bright regions surrounding a temperature determination area, especially
those from nearby active regions, is carefully removed with the point
spread function derived from the post-launch data. An isothermal
approximation is applied to thus corrected data. The temperatures of
coronal holes near the disk center are found to be 1.8 - 2.4 x 10^6
K, which is almost the same as those derived for quiet regions. The
emission measures in coronal holes are estimated to be 10^25.5-26.2
cm^-5, about ten times smaller than in quiet regions. We conclude that
temperatures in coronal holes do not differ from those in quiet regions,
and that the depression in soft X-ray intensity of coronal hole regions
results from a lower density by a factor of 3 than quiet regions. We
propose that the coronal hole component observed with the SXT is not
the same one which is observed with the Skylab EUV instrument. An
X-ray intensity from a coronal hole is independently confirmed by the
eclipse observation on 1993 November 13, and consistent with intensities
derived from the scattering correction.
Title: Temperature Structure of Solar Active Regions
Authors: Yoshida, Tsuyoshi; Tsuneta, Saku
Bibcode: 1996ApJ...459..342Y
Altcode:
We obtain high-quality temperature maps of solar active regions observed
by the Yohkoh Soft X-ray Telescope. The temperatures of active region
structures range from 3 MK to 10 MK. The bright X-ray loops do not
necessarily have high temperatures, and faint structures sometimes
have temperatures as high as 6 MK. The loop structures with shorter
lifetimes (less than a few hours) generally have higher temperatures
(5-8 MK) than the loops with longer lifetimes (3-4 MK). The plasma
with temperature reaching 6-7 MK has cusp structures like solar flares
(mini-cusp) or has multiple loop structures in the temperature maps in
most cases. The 6-7 MK plasma is transiently heated either by magnetic
reconnection at the neutral sheet above the cusp structures, or by
magnetic reconnection of multiple loops. The 3-5 MK plasma is more
steadily and uniformly heated. Two different mechanisms are apparently
involved in the coronal heating.
Title: Discovery of a loop-top hard X-ray source in impulsive
solar flares
Authors: Masuda, S.; Kosugi, T.; Tsuneta, S.; Hara, H.
Bibcode: 1996AdSpR..17d..63M
Altcode: 1996AdSpR..17...63M
Observations of a solar flare on 13 January, 1992 (17:25 UT) with the
Hard X-ray Telescope (HXT; /1/) and the Soft X-ray Telescope (SXT;
/2/) aboard Yohkoh /3/ clearly show an impulsive hard X-ray source well
above a soft X-ray flaring loop. This source reveals that the primary
energy release, maybe the magnetic reconnection, occurs well above the
soft X-ray flaring loop. It is most plausible that this ``loop-top''
hard X-ray source represents the site where the downward plasma outflow,
ejected from a reconnection point located above the hard X-ray source,
collides with an underlying closed magnetic loop. This observation thus
shows for the first time where the high-energy electrons are energized.
Title: Structure and Dynamics of Magnetic Reconnection in a Solar
Flare
Authors: Tsuneta, Saku
Bibcode: 1996ApJ...456..840T
Altcode:
We report a detailed analysis of the temperature structure of a
prototypical flare that occurred on 1992 February 21. In the decay
phase of this flare, the outer loops systematically have higher
temperatures, reaching the peak (12 MK) far outside the apparent bright
X-ray loop where the X-ray intensity is only 2%-5% of the peak. In
between the high-temperature ridges, a distinct vertical channel with
temperature as low as 8-10 MK is seen at the loop top. In the model
presented here, these high-temperature ridges are heated by standing
isothermal slow shocks attached to a reconnection point higher in
the corona. The cool channel would be formed by conduction cooling
as the hot reconnection outflow (12-13 MK) traverses with Mach speed
∼1 (800 km s-1) from the slow-shock region to the loop
top. The reconnection point is located 8-18 x 104 km above
the apparent top of the flare loop (6 x 104 km), and the
inflow speed is estimated to be ∼56 km s-1 (Alfvén Mach
number ∼0.07). The bright soft X-ray loops are the reconnected flux
tubes subsequently filled with evaporated plasma.
Title: Hot and Super-Hot Plasmas above an Impulsive-Flare Loop
Authors: Tsuneta, S.; Kosugi, T.; Sato, J.; Masuda, S.
Bibcode: 1996ASPC..111..155T
Altcode: 1997ASPC..111..155T
No abstract at ADS
Title: Temperature Structure of Solar Active Regions
Authors: Yoshida, T.; Tsuneta, S.
Bibcode: 1996mpsa.conf...41Y
Altcode: 1996IAUCo.153...41Y
No abstract at ADS
Title: Interacting Active Regions in the Solar Corona
Authors: Tsuneta, Saku
Bibcode: 1996ApJ...456L..63T
Altcode:
We report an episode from the Yohkoh soft X-ray observations during
which antiparallel coronal magnetic fields from two separate active
regions, located in opposite hemispheres, reconnect and form new
transequatorial coronal loops. Strong evidence for magnetic reconnection
consists of the following: (1) Transequatorial connections not
previously observed are newly created, (2) an X-point and separatrix
structure are clearly seen in the soft X-ray images, and (3) the
plasma temperature of the downstream side of reconnection is ~4--7
MK, whereas that of the upstream side is ~2 MK. The quiet coronal
plasma is significantly heated over a few days, and the overall
magnetic structure of the region is completely changed as a result
of magnetic reconnection. This observation suggests that magnetic
reconnection occurs also in the quiet corona in a less explosive way
than in solar flares and that it may contribute to the overall heating
of the quiet corona.
Title: Temperature and Heating Distributions along the Steady
Coronal Loops
Authors: Kano, R.; Tsuneta, S.
Bibcode: 1996mpsa.conf...43K
Altcode: 1996IAUCo.153...43K
No abstract at ADS
Title: Magnetic Reconnection: Open Issues
Authors: Tsuneta, Saku
Bibcode: 1996ASPC..111..409T
Altcode: 1997ASPC..111..409T
Yohkoh observations establish that magnetic reconnection plays a vital
physical role in the transient heating of the solar corona. There are,
however, some critical quantitative tests that need to be done with
the Yohkoh data for further confirmation of magnetic reconnection as
an engine to convert magnetic energy to plasma kinetic and thermal
energies. The Yohkoh observations also raise numbers of new questions
about the physics of magnetic reconnection.
Title: Evidence of Magnetic Reconnection in Solar Flares
Authors: Tsuneta, S.
Bibcode: 1996mpsa.conf..161T
Altcode: 1996IAUCo.153..161T
No abstract at ADS
Title: Polar X-ray Arcade Formation and Giant Cusp
Authors: Fujisaki, K.; Okubo, H.; Uchida, Y.; Hirose, S.; Cable, S.;
Tsuneta, S.
Bibcode: 1996mpsa.conf..495F
Altcode: 1996IAUCo.153..495F
No abstract at ADS
Title: The dynamic solar corona in X-rays with Yohkoh.
Authors: Tsuneta, S.
Bibcode: 1996ASIC..481...85T
Altcode:
Yohkoh is revolutionizing the understanding of the solar corona and
the behavior of magnetized plasmas in general. It appears that all the
transient heating, including solar flares, which have times scales of
10 - 100 Alfvén transit times, is due to magnetic reconnection. This
transient heating is sometimes associated with global structural
changes in the coronal magnetic fields. Magnetic reconnection with its
associated slow shocks is a powerful engine to convert magnetic energy
to plasma kinetic and thermal energies. The Yohkoh observations also
show the existence of steadily heated plasmas with temperature of 2 -
4 MK, both in active regions and in the quiet Sun. The mechanism of
the steady heating has not yet been understood.
Title: Scaling Law of Solar Coronal Loops Obtained with YOHKOH
Authors: Kano, Ryouhei; Tsuneta, Saku
Bibcode: 1995ApJ...454..934K
Altcode:
We find a clear correlation among the maximum temperature
Tmax (K), the pressure p (dyn cm-2) and the
length L (cm) of 32 steady coronal loop structures observed with
Yohkoh Soft X-Ray Telescope: Tmax = 3.8 × 104
(pL)1/(5.1±0.5). The best-fit equation, however,
systematically deviates from the theoretical scaling law Tmax
= 1.4 × 103 (pL)1/3 derived by Rosner, Tucker,
& Vaiana. We examine various possibilities for the cause of the
discrepancy.
Title: Hard X-Ray Sources and the Primary Energy-Release Site in
Solar Flares
Authors: Masuda, Satoshi; Kosugi, Takeo; Hara, Hirohisa; Sakao, Taro;
Shibata, Kazunari; Tsuneta, Saku
Bibcode: 1995PASJ...47..677M
Altcode:
Accurately coaligned hard and soft X-ray images, taken simultaneously
with the Hard X-ray Telescope (HXT) and the Soft X-ray Telescope
(SXT) aboard Yohkoh, of impulsive solar flares on 1992 January 13
(17:29 UT), 1992 October 4 (22:21 UT), and 1993 February 17 (10:35
UT), occurring near the limb, clearly reveal that, in addition to
double-footpoint sources, a hard X-ray source exists well above the
corresponding soft X-ray loop structure around the peak time of the
impulsive phase. This hard X-ray source shows an intensity variation
similar to double-footpoint sources and a spectrum that is relatively
hard compared with that of loop-top gradual source which appeared later
in the flare. We believe that this is the first clear evidence that
magnetic reconnection, which is responsible for the primary flare energy
release, is under progress above the soft X-ray flaring loop. Maybe
this ``loop-top'' hard X-ray source represents the reconnection site
itself or the site where the downward plasma stream, ejected from
the reconnection point far above the hard X-ray source, collides with
the underlying closed magnetic loop. The characteristics of this hard
X-ray source are quantitatively discussed in the schemes of thermal
(T >~ 10(8) K) and nonthermal interpretations of hard X-ray emission.
Title: Hot-Plasma Ejections Associated with Compact-Loop Solar Flares
Authors: Shibata, K.; Masuda, S.; Shimojo, M.; Hara, H.; Yokoyama,
T.; Tsuneta, S.; Kosugi, T.; Ogawara, Y.
Bibcode: 1995ApJ...451L..83S
Altcode:
Masuda et al. found a hard X-ray source well above a soft X-ray loop
in impulsive compact-loop flares near the limb. This indicates that
main energy release is going on above the soft X-ray loop, and suggests
magnetic reconnection occurring above the loop, similar to the classical
model for two ribbon flares. If the reconnection hypothesis is correct,
a hot plasma (or plasmoid) ejection is expected to be associated
with these flares. Using the images taken by the soft X-ray telescope
aboard Yohkoh, we searched for such plasma ejections in eight impulsive
compact-loop flares near the limb, which are selected in an unbiased
manner and include also the Masuda flare, 1992 January 13 flare. We
found that all these flares were associated with X-ray plasma ejections
high above the soft X-ray loop and the velocity of ejections is within
the range of 50--400 km s-1. This result gives further support for
magnetic reconnection hypothesis of these impulsive compact-loop flares.
Title: Particle Acceleration and Magnetic Reconnection in Solar Flares
Authors: Tsuneta, Saku
Bibcode: 1995PASJ...47..691T
Altcode:
Yohkoh soft X-ray observations show that magnetic reconnection with
attached slow shock heats reconnected flux tubes, and that these
reconnected loops are subsequently filled with evaporated plasmas that
are seen as soft X-ray loops. Hard X-ray observations show that hard
X-ray (> 40--50 keV) sources are located at the footpoints of the
soft X-ray loop, suggesting non-thermal electron acceleration in the
loops. From these two key observations we propose a model in which
a fast downflow from the reconnection site collides with the loop,
and that the resulting small-scale time-varying shear flow (vortices)
at the loop top drives an oppositely directed field-aligned current
(channels). The field-aligned current then generates a voltage drop (
~ 100 keV) along the magnetic fields, generating runaway electrons. If
the size of the vortices is sufficiently small, the energy and number of
runaway electrons, and the time scale of acceleration, are consistent
with the observations. The line broadening observed with soft X-ray
crystal spectrometers would be due to vortices at the loop top rather
than chromospheric evaporation.
Title: The Possible Ascent of a Closed Magnetic System through
the Photosphere
Authors: Lites, B. W.; Low, B. C.; Martinez Pillet, V.; Seagraves,
P.; Skumanich, A.; Frank, Z. A.; Shine, R. A.; Tsuneta, S.
Bibcode: 1995ApJ...446..877L
Altcode:
We present a comprehensive interpretation of the evolution of a small
magnetic region observed during its entire disk passage. The vector
magnetic field measurements from the Advanced Stokes Polarimeter,
along with Hα and magnetogram measurements from the Lockheed SOUP
instrument operating at the Swedish Solar Observatory on La Palma,
and soft X-ray images from the Yohkoh satellite support the hypothesis
that we have observed the passage of a nearly closed magnetic system
through the photosphere into the corona. The observations suggest that
as the magnetic flux begins to emerge into the photosphere it shows a
rather simple geometry, but it subsequently develops a small δ-sunspot
configuration with a highly sheared vector field along the polarity
inversion line running through it. At that stage, the vector field is
consistent with a concave upward magnetic topology, indicative of strong
electric currents above the photosphere. An Hα prominence is found
above this inversion line when the δ-sunspot is fully formed. These
observed features and the sequence of events are interpreted in terms
of a nearly closed magnetic system that rises through the photosphere
into the corona as a result of magnetic buoyancy. The magnetic system
persists in the corona well after the dark δ-sunspot has disappeared
in the photosphere We suggest that this coronal structure is in
quasi-static equilibrium with its buoyancy partially countered by
the weight of the plasma trapped at the bottom of closed magnetic
loops. The plausibility of such a scenario is demonstrated by a
three-dimensional magnetostatic model of the emergence of a closed,
spheroidal magnetic system in the corona, in which the Lorentz force
arising from cross-field currents is balanced by the gravitational
and pressure forces. This theoretical model carries many features in
common with the observed morphology of our active region.
Title: The Dynamical Characteristics of a Disappearing-Filament
Associated Interplanetary Disturbance Observed in 1992 Early May
Authors: Kozuka, Yukio; Watanabe, Takashi; Kojima, Masayoshi; Ohyama,
Masamitsu; Tsuneta, Saku; Khan, Josef I.; Watari, Shin-Ichi
Bibcode: 1995PASJ...47..377K
Altcode:
The dynamical properties of an interplanetary disturbance related
to the sudden commencement of a geomagnetic storm at 15h41m UT on
1992 May 9 are discussed based on solar-wind data obtained by the
interplanetary scintillation technique and soft X-ray images taken with
the Soft X-ray Telescope on board Yohkoh. It is suggested here that the
sudden commencement was associated with the disappearance of a quiescent
filament, which took place in the south-east quadrant of the solar disk
at about 07h UT on 1992 May 7. An associated shock wave propagated at
approximately a constant speed of about 1000 km s(-1) up to about 0.3
AU from the Sun, then showed a blast-wave like deceleration. If this
was the case, the duration of the ``driven-like phase" of the shock
was about 12 hr. According to Yohkoh soft X-ray images, a transient
coronal hole was formed near to the disappearing filament. The lifetime
of this coronal hole, about 17 hr, was comparable to the duration of
the driven phase of the shock wave. A close connection between the
dynamical characteristics of the shock wave and the formation of the
transient coronal hole is suggested.
Title: Temperature Structure of the Solar Corona: Comparison of the
NIXT and YOHKOH X-Ray Images
Authors: Yoshida, Tsuyoshi; Tsuneta, Saku; Golub, Leon; Strong, Keith;
Ogawara, Yoshiaki
Bibcode: 1995PASJ...47L..15Y
Altcode:
Solar soft X-ray images taken simultaneously by the Yohkoh and the
Normal Incidence X-ray Telescope (NIXT) reveal significantly different
coronal structures. Coronal loops are more clearly seen in the Yohkoh
images, and the isolated island-like structures seen in the NIXT image
have been found to correspond to the footpoints of the Yohkoh loops. The
difference is due to the difference in the temperature response of the
telescopes: NIXT is sensitive to temperatures ranging from 0.9 to 3
MK, while Yohkoh is more sensitive to temperatures above 2.5 MK. The
morphological differences reflect the multi-temperature (1--5 MK)
nature of the solar coronal plasmas.
Title: The Bright Knots at the Tops of Soft X-Ray Loops: Quantitative
Results from YOHKOH
Authors: Doschek, G. A.; Strong, K. T.; Tsuneta, S.
Bibcode: 1995ApJ...440..370D
Altcode:
Soft X-ray Telescope (SXT) observations from the Japanese Yohkoh
spacecraft have shown that confined bright regions are common features
at the tops of flare loops throughout most of the duration of the
flares. In this paper we present quantitative results for these
flare knots, in relation to other flare regions, for four relatively
'simple' flares. Emission measure distributions, electron temperatures,
and electron densities are derived from SXT and Yohkoh Bragg Crystal
Spectrometer (BCS) observations. The four flares selected are dominated
by what appear to be single-loop structures, with bright knots at
the loop tops. The flares are neither long-duration nor impulsive
events. The spatial distributions of brightness and emission measure
in the flares are found to be quite similar for all four events, even
though there are significant differences in dynamical behavior between
at least two of the events. Temperatures and densities calculated for
these flares are consistent with previous results from many solar
experiments. An investigation of intensity correlations between
adjacent pixels at the tops of the loops suggests the existence of
local disturbances in the magnetic loops that occur on spatial scales
less than the radii of the loops.
Title: Comparison of Synoptic Maps of Solar Soft X-Ray Features,
Photospheric Magnetic Fields, and Helium 1083 NM
Authors: Harvey, J.; Slater, G.; Nitta, N.; Shibata, K.; Tsuneta,
S.; Sakurai, T.; Hara, H.
Bibcode: 1994AAS...18512308H
Altcode: 1994BAAS...26Q1523H
We studied the wealth of structural features visible in Yohkoh/SXT
and NSO/KP synoptic maps of the Sun that cover Carrington rotations
1847 through 1879. In order to do this comparison, various methods to
reduce soft X-ray maps to simple structural elements were explored. In
the end, the best way of comparing the various data sets turned out to
be to filter the X-ray maps to emphasize high-spatial frequencies and
then to either simply blink the various images or to make colorized
composite maps that distinctively assign different colors to various
quantities. Among the results are: 1. Active regions exhibit normal or
"anemone" (fountain-like) X-ray loop structure tendency depending on
whether the surrounding large-scale unipolarity of the magnetic field
is small or large. 2. There is a systematic twist of the coronal loops
around magnetic concentrations in the southern hemisphere and vice-versa
in the north. The sense is the same as one would expect from the action
of differential rotation. 3. Dark lanes in the X-ray images are centered
over large-scale polarity patterns of one sign or the other. 4. The
X-ray loops at the boundaries between large-scale opposite polarity
patterns are frequently strongly sheared. The presence or absence of
a filament in these locations may be related in a complicated way to
the amount of shear. 5. At the resolution of the synoptic maps, the
footpoints of X-ray loops are almost always rooted in locally strong
magnetic concentrations and also in extra-dark 1083 nm elements.
Title: A loop-top hard X-ray source in a compact solar flare as
evidence for magnetic reconnection
Authors: Masuda, S.; Kosugi, T.; Hara, H.; Tsuneta, S.; Ogawara, Y.
Bibcode: 1994Natur.371..495M
Altcode:
SOLAR flares are thought to be the result of magnetic reconnection
— the merging of antiparallel magnetic fields and the consequent
release of magnetic energy. Flares are classified into two
types1: compact and two-ribbon. The two-ribbon flares,
which appear as slowly-developing, long-lived large loops, are
understood theoretically2-6 as arising from an eruption
of a solar prominence that pulls magnetic field lines upward into
the corona. As the field lines form an inverted Y-shaped structure
and relax, the reconnection of the field lines takes place. This view
has been supported by recent observations7-10. A different
mechanism seemed to be required, however, to produce the short-lived,
impulsive compact flares. Here we report observations made with the
Yohkoh11 Hard X-ray Telescope12 and Soft X-ray
Telescope13, which show a compact flare with a geometry
similar to that of a two-ribbon flare. We identify the reconnection
region as the site of particle acceleration, suggesting that the
basic physics of the reconnection process (which remains uncertain)
may be common to both types of flare.
Title: Temperatures of Coronal Holes Observed with the YOHKOH SXT
Authors: Hara, Hirohisa; Tsuneta, Saku; Acton, Loren W.; Bruner,
Marilyn E.; Lemen, James R.; Ogawara, Yoshiaki
Bibcode: 1994PASJ...46..493H
Altcode:
Temperatures of coronal holes have been estimated from several sets
of soft X-ray images taken through various broad-band filters with the
Soft X-ray Telescope (SXT) aboard Yohkoh. Since coronal holes are dark
areas, a detailed examination of the telescope point spread function,
which is slightly dependent on the X-ray wavelength, is of crucial
importance. The calibration is made using post-launch data, and the
effect of scattered X-rays from bright regions surrounding coronal
holes, especially those from nearby active regions, is carefully
removed. An isothermal approximation is applied to the thus-corrected
data. The temperatures of coronal holes near the disk center are found
to be 1.8--2.4 times 10(6) K, which is almost the same as those derived
for quiet regions not including active regions. The emission measures
in coronal holes are estimated to be 10(25.5--26.2) cm(-5) , about ten
times smaller than those of quiet regions. We conclude that temperatures
in coronal holes do not differ from those in quiet regions, and that
the depression in the soft X-ray intensity of coronal hole regions
results from a lower density by a factor of 3 than quiet regions.
Title: H_alpha and X-ray Signatures of Chromospheric Heating Observed
in Solar Flares
Authors: Wuelser, J. -P.; Canfield, R. C.; Sakao, T.; Masuda, S.;
Kosugi, T.; Tsuneta, S.
Bibcode: 1994kofu.symp..195W
Altcode:
We have studied the spatial and temporal relationship between
thermal and non-thermal energy transport, and the chromospheric
response in solar flares. H_alpha imaging spectra from Mees Solar
Observatory provided the information on the heating and dynamics in the
chromosphere, soft X-ray images from Yohkoh provided the conditions
of the thermal plasma in the corona, and hard X-ray data from Yohkoh
provided the diagnostics of the non-thermal particles. We present
some preliminary results for several large flares, and discuss their
implications for the chromospheric flare heating mechanism.
Title: Observations of Enhanced Coronal Heating in Sheared MAgnetic
Fields
Authors: Moore, R. T.; Porter, J.; Roumeliotis, G.; Tsuneta, S.;
Shimizu, T.; Sturrock, P. A.; Acton, L. W.
Bibcode: 1994kofu.symp...89M
Altcode:
From superposition of Yohkoh SXT images on MSFC vector magnetograms of
two active regions, we find: (1) coronal heating is enhanced at sites of
strong magnetic shear, and (2) this heating is produced by microflares.
Title: Morphology of the 10 Million Degree Plasma in Solar Flares
and the Failure of the Chromospheric Evaporation Model
Authors: Seely, J. F.; Feldman, U.; Doschek, G. A.; Strong, K. T.;
Acton, L. W.; Uchida, Y.; Tsuneta, S.
Bibcode: 1994kofu.symp..177S
Altcode:
The SXT images of over fifty C, M, and X type flares which occurred
between October 1991 and February 1993 were analyzed. For each flare,
the 10 million degree emitting region was typically found to be located
at the loop top in the first well-exposed flare image recorded during
the rise phase (within 1 to 2 minutes after flare onset), in images
recorded near the intensity peak, and in images recorded during most of
the decay phase. For the November 2 1992 limb flare, the loop top was
bright for 24 hours. For a few flares, the brightness of the footpoints
in the onset images was comparable to the brightness of the loop top,
but the loop top brightness rapidly increased relative to the footpoints
and remained intense for the duration of the flare. The brightest region
at the loop top was very small throughout the flare, often as small as
a single pixel (1800x1800 km). The conclusions are that the energy is
deposited in a small volume at the top of the flaring loop structure,
the heating mechanism acts over a period of up to tens of hours, and
the hot plasma is confined at the top of the loop structure. These
results are not explained by the traditional chromospheric evaporation
model of solar flares.
Title: Microflaring at the Feet of Large Active Region Loops
Authors: Porter, J.; Moore, R. T.; Roumeliotis, G.; Shimizu, T.;
Tsuneta, S.; Sturrock, P. A.; Acton, L. W.
Bibcode: 1994kofu.symp...65P
Altcode:
By superposing Yohkoh SXT images on an MSFC magnetogram of an active
region, we find that the brightest loops in the bipolar magnetic
envelope spanning the active region are rooted near a compact site
of mixed polarity and microflaring. Apparently, the enhanced coronal
heating in these high loops is a consequence of the microflaring and/or
related magnetic activity at this end site.
Title: Electric Currents and Coronal Heating in NOAA Active Region
6952
Authors: Metcalf, T. R.; Canfield, R. C.; Hudson, H. S.; Mickey,
D. L.; Wulser, J. -P.; Martens, P. C. H.; Tsuneta, S.
Bibcode: 1994ApJ...428..860M
Altcode:
We examine the spatial and temporal relationship between coronal
structures observed with the soft X-ray telescope (SXT) on board the
Yohkoh spacecraft and the vertical electric current density derived from
photospheric vector magnetograms obtained using the Stokes Polarimeter
at the Mees Solar Observatory. We focus on a single active region:
AR 6952 which we observed on 7 days during 1991 December. For 11
independent maps of the vertical electric current density co-aligned
with non-flaring X-ray images, we search for a morphological
relationship between sites of high vertical current density in the
photosphere and enhanced X-ray emission in the overlying corona. We
find no compelling spatial or temporal correlation between the sites of
vertical current and the bright X-ray structures in this active region.
Title: Multispectral Observations of Chromospheric Evaporation in
the 1991 November 15 X-Class Solar Flare
Authors: Wuelser, Jean-Pierre; Canfield, Richard C.; Acton, Loren W.;
Culhane, J. Leonard; Phillips, Andrew; Fludra, Andrzej; Sakao, Taro;
Masuda, Satoshi; Kosugi, Takeo; Tsuneta, Saku
Bibcode: 1994ApJ...424..459W
Altcode:
We analyze simultaneous H(alpha) images and spectra (from Mees
Solar Observatory), and soft and hard X-ray images and spectra (from
YOHKOH) during the early phase of an X1.5/3B flare. We investigate
the morphological relationship between chromospheric downflows,
coronal upflows, and particle precipitation sites, and the energetic
relationship between conductive heating, nonthermal particle heating,
and the chromospheric response. We find that the observations
consistently fit the chromospheric evaporation model. In particular,
we demonstrate that the observed upflowing coronal and downflowing
chromospheric plasma components originate in the same locations,
and we show that our unique set of optical and X-ray observations
can clearly distinguish between conductively driven and electron beam
driven evaporation.
Title: The Morphology of the 10 7 K Plasma in Solar
Flares. I. Nonimpulsive Flares
Authors: Feldman, U.; Seely, J. F.; Doschek, G. A.; Strong, K. T.;
Acton, L. W.; Uchida, Y.; Tsuneta, S.
Bibcode: 1994ApJ...424..444F
Altcode:
In this paper we have analyzed images of 48 C-, M-, and X-type
flares which occurred between 1991 October and 1993 February. The
images were recorded by the soft X-ray telescope (SXT) flown on the
Japanese Yohkoh spacecraft. The spatial resolution of the recorded
images is about 2.5 sec. In each of the recorded flares the brightest
regions emitting the 107 K radiation were analyzed and
evaluate. The 107 K emitting region was found to be located
at loop tops in the first well-exposed flare image recorded during the
rise phase (within 1-2 minutes after flare onset), in images recorded
near intensity peak, and in those recorded during most of the decay
phase. Occasionally, in the begining of the event when the total
flare intensity is low, the brightness of the footpoints may rival the
brightness of the loop top. However, in these cases it is expected that
the temperature of the loop top is considerably higher. The emitting
region, even during flare peak, is very small (often smaller than a
single SXT pixel 1800 x 1800 km).
Title: Morphology of Active Region Transient Brightenings with the
YOHKOH Soft X-Ray Telescope
Authors: Shimizu, Toshifumi; Tsuneta, Saku; Acton, Loren W.; Lemen,
James R.; Ogawara, Yoshiaki; Uchida, Yutaka
Bibcode: 1994ApJ...422..906S
Altcode:
Frequent transient X-ray brightenings occur in solar active regions. The
Yohkoh Soft X-ray Telescope observed 142 transient brightenings
during an interval of time in late 1991 October. We classify them
in terms of morphology and time evolution: (1) simultaneous multiple
loop brightenings are more often seen than brightenings of single and
pointlike structures; (2) for multiple-loop brightenings, the loops
tend to brighten from their footpoints and/or the apparent contact
point in the initial phase of transient brightenings, followed by
the brightening of the entire loops; (3) more than one-half of the
multiple-loop brightenings have Y-type configurations in which the
apparent contact points are located close to their footpoints. Though
transient brightenings show great variety in morphology, these
results suggest that most of them are due to the magnetic interaction
of multiple loops. X-ray emission from the footpoints in the early
phase suggests that the hot plasma in the brightening loops comes from
chromospheric matter or low-temperature coronal matter present around
the bases of the coronal loops prior to the brightening. Enhanced X-ray
emission at the contact points implies local plasma heating by magnetic
interaction. The predominance of the Y-type configuration suggests that
the interaction of coronal loops tends to occur near the footpoints.
Title: Rotational Reversing Model and Triple Dipole Model as
Substantiated by YOHKOH SXT Data
Authors: Satio, T.; Kozuka, Y.; Tsuneta, S.; Minami, S.
Bibcode: 1994xspy.conf..211S
Altcode:
No abstract at ADS
Title: Non-Uniform Spatial Distribution of X-Ray Bright Points
Authors: Takami, M.; Tsuneta, S.; Takahashi, Te.; Strong, K. T.;
Slater, G. L.; Harvey, K. L.
Bibcode: 1994xspy.conf..237T
Altcode:
No abstract at ADS
Title: Optical and SXT Observations of the x9 Flare of Nov. 1992
Authors: Ichimoto, K.; Sakurai, T.; Nishino, Y.; Noguchi, M.; Shinoda,
K.; Yamaguchi, A.; Kumagai, K.; Hirayama, T.; Tsuneta, S.; Acton, L.
Bibcode: 1994xspy.conf..259I
Altcode:
No abstract at ADS
Title: Magnetic Reconnection in the Solar Corona
Authors: Tsuneta, Saku
Bibcode: 1994ASPC...68..338T
Altcode: 1994sare.conf..338T
No abstract at ADS
Title: Interplanetary Consequences of Transient Coronal Events
Authors: Watanabe, Ta.; Kojima, M.; Kozuka, Y.; Tsuneta, S.; Lemen,
J. R.; Hudson, H.; Joselyn, J. A.; Klimchuk, J. A.
Bibcode: 1994xspy.conf..207W
Altcode:
No abstract at ADS
Title: X-Ray Active Nests
Authors: Takahashi, Te.; Tsuneta, S.; Hayashi, K.; Yoshimura, H.
Bibcode: 1994xspy.conf..293T
Altcode:
No abstract at ADS
Title: Are X-Ray Bright Points the Signature of Magnetic Field
Reconnection?
Authors: Harvey, Karen L.; Strong, Keith S.; Nitta, Nariaki; Tsuneta,
Saku
Bibcode: 1994ASPC...68..377H
Altcode: 1994sare.conf..377H
No abstract at ADS
Title: Eruptive-Prominence Related Coronal Disturbances Observed
with YOHKOH SXT
Authors: Watanabe, T.; Kozuka, Y.; Ohyama, M.; Kojima, M.; Yamaguchi,
K.; Watari, S.; Tsuneta, S.; Joselyn, J. A.; Harvey, K. L.; Acton,
L. W.; Klimchuk, J. A.
Bibcode: 1994step.conf...85W
Altcode:
No abstract at ADS
Title: Transient Brightenings of Soft X-Ray Loops in Emerging
Flux Regions
Authors: Kurokawa, H.; Kawai, G.; Tsuneta, S.; Ogawara, Y.
Bibcode: 1994xspy.conf...59K
Altcode:
No abstract at ADS
Title: The Relationship of X-Ray Bright Points to the Photospheric
Magnetic Fields
Authors: Harvey, K. L.; Nitta, N.; Strong, K. T.; Tsuneta, S.
Bibcode: 1994xspy.conf...21H
Altcode:
No abstract at ADS
Title: Temperature of Coronal Holes Measured by YOHKOH SXT
Authors: Hara, H.; Tsuneta, S.; Acton, L. W.; Lemen, J. R.; Ogawara, Y.
Bibcode: 1994xspy.conf..217H
Altcode:
No abstract at ADS
Title: Coronal/Interplanetary Disturbances Associated with a Solar
Filament Disappearance on September 28, 1991
Authors: Watanabe, T.; Kozuka, Y.; Ohyama, M.; Kojima, M.; Yamaguchi,
K.; Watari, S.; Tsuneta, S.; Joselyn, J. A.; Harvey, K. L.; Acton,
L. W.; Klimchuk, J. A.
Bibcode: 1994step.conf...89W
Altcode:
No abstract at ADS
Title: Temperature and Density Structure of a Solar Flare Observed
by the YOHKOH SXT and HXT
Authors: McTiernan, J.; Kane, S.; Loran, J.; Lemen, J.; Acton, L.;
Hara, H.; Tsuneta, S.; Kosugi, T.
Bibcode: 1994xspy.conf..255M
Altcode:
No abstract at ADS
Title: A Simple Circuit Model for the December 2 1991 Flare
Authors: Martens, P. C. H.; Tsuneta, S.
Bibcode: 1994xspy.conf..327M
Altcode:
No abstract at ADS
Title: Large-Scale Coronal and Solar-Wind Structures
Authors: Kozuka, Y.; Watanabe, Ta.; Kojima, M.; Ohyama, M.; Tsuneta,
S.; Saito, T.; Watari, S.
Bibcode: 1994xspy.conf..301K
Altcode:
No abstract at ADS
Title: Observation of a Large Eruptive Hα Prominence with Soft
X-Rays on 30-31 July 1992
Authors: Miyazaki, H.; Miyasita, M.; Yamaguchi, A.; Ichimoto, K.;
Kumagai, K.; Hirayama, T.; Tsuneta, S.
Bibcode: 1994xspy.conf..277M
Altcode:
No abstract at ADS
Title: Non-Thermal Effects in Slow Solar Flares
Authors: Hudson, H. S.; Acton, L. W.; Sterling, A. C.; Tsuneta, S.;
Fishman, J.; Meegan, C.; Paciesas, W.; Wilson, R.
Bibcode: 1994xspy.conf..143H
Altcode:
No abstract at ADS
Title: Prominence Eruption in NOAA7125 on April 6, 1992
Authors: Kitai, R.; Kawai, G.; Anwar, B.; Kurokawa, H.; Funakoshi,
Y.; Nakai, Y.; Tsuneta, S.
Bibcode: 1994xspy.conf..287K
Altcode:
No abstract at ADS
Title: Electric Currents and Coronal Structures in NOAA Active
Region 6952
Authors: Metcalf, T. R.; Canfield, R. C.; Hudson, H. S.; Mickey,
D. L.; Wülser, J. -P.; Tsuneta, S.
Bibcode: 1994xspy.conf...51M
Altcode:
No abstract at ADS
Title: Solar Flares as Ongoing Magnetic Reconnection
Authors: Tsuneta, S.
Bibcode: 1994xspy.conf..115T
Altcode:
No abstract at ADS
Title: Rapid Sunspot Motion during a Major Solar Flare
Authors: Anwar, B.; Acton, L. W.; Hudson, H. S.; Makita, M.; McClymont,
A. N.; Tsuneta, S.
Bibcode: 1993SoPh..147..287A
Altcode:
A major solar flare on 15 November, 1991 produced a striking
perturbation in the position and shape of the sunspot related most
closely to the flare. We have studied these perturbations by use of the
aspect-sensor images from the Soft X-ray Telescope on board YOHKOH,
and with ground-based data from the Mees Solar Observatory. The
perturbation occurred during the impulsive phase of the flare, with
a total displacement on the order of 1 arc sec. The apparent velocity
of approximately 2 km s−1 exceeds that typically reported
for sunspot proper motions even in flare events. We estimate that the
magnetic energy involved in displacing the sunspot amounted to less
than 4 × 1030 ergs, comparable to the radiant energy from
the perturbed region. Examination of the Mees Observatory data shows
that the spot continued moving at lower speed for a half-hour after
the impulsive phase. The spot perturbation appears to have been a
result of the coronal restructuring and flare energy release, rather
than its cause.
Title: The 1992 January 5 Flare at 13.3 UT: Observations from YOHKOH
Authors: Doschek, G. A.; Strong, K. T.; Bentley, R. D.; Brown, C. M.;
Culhane, J. L.; Fludra, A.; Hiei, E.; Lang, J.; Mariska, J. T.;
Phillips, K. J. H.; Pike, C. D.; Sterling, A. C.; Watanabe, T.; Acton,
L. W.; Bruner, M. E.; Hirayama, T.; Tsuneta, S.; Rolli, E.; Kosugi,
T.; Yoshimori, M.; Hudson, H. S.; Metcalf, T. R.; Wuelser, J. -P.;
Uchida, Y.; Ogawara, Y.
Bibcode: 1993ApJ...416..845D
Altcode:
We discuss X-ray spectra and soft X-ray images of an M1.9 flare that
occurred on 1992 January 5 near 13.3 UT. These data were obtained
with instrumentation on the Japanese Yohkoh spacecraft. They cover
the entire rise phase of the flare. To supplement these data we have
ground-based magnetograms and Hα spectroheliograms. We calculate
the electron temperature and emission measure of the flare as a
function of time during the early rise phase using X-ray spectral
line intensities and line ratios. Using spectral line widths, line
profile asymmetries, and wavelength shifts due to the Doppler effect,
we calculate the dynamical properties of the flare. The time development
of the morphology of the flare, as revealed by the soft X-ray images
and the Hα spectroheliograms, and the physical quantities inferred
from the X-ray spectra, are compared with chromospheric evaporation
models. There is an enhancement of blueshifted emission that is closely
correlated with the hard X-ray bursts. Heating of one loop in the flare
is consistent with a conduction-evaporation model, but heating is found
in several structures that do not appear to be physically associated
with each other. No standard evaporation model can adequately explain
all of the observations.
Title: Temperature and Density Structure of the 1991 November 2 Flare
Observed by the YOHKOH Soft X-Ray Telescope and Hard X-Ray Telescope
Authors: McTiernan, James M.; Kane, Sharad R.; Loran, Jon M.; Lemen,
James R.; Acton, Loren W.; Hara, Hirohisa; Tsuneta, Saku; Kosugi, Takeo
Bibcode: 1993ApJ...416L..91M
Altcode:
No abstract at ADS
Title: Lifetimes and distribution of coronal bright points observed
with Yohkoh
Authors: Harvey, K. L.; Strong, K. T.; Nitta, N.; Tsuneta, S.
Bibcode: 1993AdSpR..13i..27H
Altcode: 1993AdSpR..13...27H
X-ray imaging from Skylab and various sounding rockets has established
the existence of and begun the characterization of coronal X-ray bright
points (XBPs). With the launch of Yohkoh, the Soft X-ray Telescope (SXT)
provides a new opportunity to observe these small-scale structures
with higher temporal resolution, improved dynamic range, and greater
sensitivity. We present the results from the analysis of SXT full-disk
images showing the location and detailed evolution of XBPs. We derive
correlations of XBPs with magnetic bipoles, He I 10830-Å dark points,
and other coronal features. From the evolution of 518 XBPs presented in
this initial study, we derive a mean lifetime of about 12 hours, with
some XBPs lasting as long as 5 days and others less than 10 minutes. A
comprehensive study of the relationship between XBP lifetime, X-ray
output, size, location, and variability may well lead to a re-evaluation
of the nature and definition of XBPs.
Title: Invited Talk: (Highlights of the Initial Results from the
Yohkoh Mission)
Authors: Tsuneta, S.
Bibcode: 1993BAAS...25.1177T
Altcode:
No abstract at ADS
Title: Electric Currents and Coronal Structures in NOAA Active
Region 6952
Authors: Metcalf, T. R.; Canfield, R. C.; Hudson, H. S.; Mickey,
D. L.; Martens, P. C. H.; Tsuneta, S.
Bibcode: 1993BAAS...25.1179M
Altcode:
No abstract at ADS
Title: The Relationship of X-ray Bright Points to the Photospheric
Magnetic Fields
Authors: Harvey, K. L.; Strong, K.; Nitta, N.; Tsuneta, S.
Bibcode: 1993BAAS...25.1179H
Altcode:
No abstract at ADS
Title: Multitemperature Observations of an Emerging Flux Region
Authors: Bruner, M. E.; Acton, L. W.; Brown, W. A.; Lemen, J. R.;
Shine, R.; Strong, K. T.; Tarbell, T.; Dulk, G.; Tsuneta, S.; Bastian,
T.; Dame, L.
Bibcode: 1993BAAS...25.1179B
Altcode:
No abstract at ADS
Title: Observations of an Emerging Flux Region
Authors: Brown, W. A.; Acton, L. W.; Bruner, M. E.; Lemen, J. R.;
Shine, R.; Strong, K. T.; Tarbell, T.; Dulk, G.; Tsuneta, S.; Bastian,
T.; Dame, L.
Bibcode: 1993BAAS...25Q1214B
Altcode:
No abstract at ADS
Title: The Dynamics of Coronal Holes as Determined From X-ray Synoptic
Maps Derived From SXT Imagery
Authors: Slater, G. L.; Linford, G. A.; Strong, K. T.; Acton, L. W.;
Tsuneta, S.; Hara, H.; Takahashi, T.; Hiei, H.; Kubo, M.; Harvey,
K.; Bornmann, P.; McIntosh, P. S.; Sime, D.; Watari, S.
Bibcode: 1993BAAS...25.1179S
Altcode:
No abstract at ADS
Title: Yohkoh-SXT Observations from the Spartan and Nixt Max91
Campaign
Authors: Morrison, M.; Bruner, M.; Freeland, S.; Lemen, J.; Linford,
G.; Nitta, N.; Slater, G.; Strong, K.; Hara, H.; Kano, R.; Shimizu,
T.; Tsuneta, S.; Hudson, H.; Ogawara, Y.; Kosugi, T.; Sakao, T.;
Watanabe, T.; Takeda, A.; Acton, L.
Bibcode: 1993BAAS...25.1213M
Altcode:
No abstract at ADS
Title: X ray jets in the solar corona: Observations with YOHKOH Soft
X Ray Telescope
Authors: Shibata, Kazunari; Ishido, Y.; Acton, L.; Strong, K.;
Hirayama, T.; Uchida, Yutaka; McAllister, A.; Matsumoto, R.; Tsuneta,
Saku; Shimizu, T.
Bibcode: 1993ppcn.conf..207S
Altcode:
The discovery of x-ray jet like features using the soft x-ray telescope
onboard Yohkoh satellite is reported. The origin of newly discovered
x-ray jets and the relation to known solar jets at other wavelengths
are discussed. The jets are associated with flare like bright points,
flaring emerging flux regions, or flaring active regions. They appear
to recur at the same place. The following characteristics are found:
in some cases, a dark void appears after ejection at the footpoint of
the jet; some jets show structure which suggests a helical magnetic
field configuration along the jet; one of the jets associated with a
flaring bright point was found to be identified as an H alpha surge. In
this case, the x-ray bright point is situated just on H alpha bright
point at the footpoint of the surge. The top of the surge is not bright
in x-rays.
Title: Large-scale structure of the solar plasma corona. An analysis
of Yohkoh SXT images.
Authors: Saito, T.; Minami, Shigeyuki; Kozuka, Y.; Takahashi, T.;
Hudson, H.; Tsuneta, Saku; Watanabe, T.
Bibcode: 1993ppcn.conf..215S
Altcode:
The YOHKOH SXT images are analyzed to find the large-scale structure
of the solar plasma corona. The clarified characteristics are preferred
position of active regions and its possible mechanism, rules governing
the coronal hole channel, a relation between the inner and outer
corona, formation of the 4-sector structure, and the outer corona in
pseudo-aligned phase. These characteristics are in agreement with
both the rotational reversing model and the triple-dipole model on
the structure and dynamics of the heliomagnetosphere.
Title: Highlights of Yohkoh results.
Authors: Tsuneta, Saku
Bibcode: 1993ppcn.conf...75T
Altcode:
The highlights from the solar observation satellite Yohkoh are presented
with emphasis on the results from its Soft X-ray Telescope (SXT). The
highly dynamical and transient nature of the coronal magnetic fields
revealed by SXT is drastically changing our view of the solar corona
and behavior of magnetized plasma in general. Some of the initial
discoveries are presented.
Title: Dynamics of the Solar Corona Observed with the YOHKOH Soft
X-ray Telescope
Authors: Tsuneta, S.; Lemen, J. R.
Bibcode: 1993ASSL..183..113T
Altcode: 1993pssc.symp..113T
No abstract at ADS
Title: Observations of X-ray Jets Using YOHKOH Soft X-Ray Telescope
Authors: Shibata, K.; Ishido, Y.; Acton, L.; Strong, K.; Hirayama,
T.; Uchida, Y.; McAllister, A.; Matsumoto, R.; Tsuneta, S.; Shimizu,
T.; Hara, H.; Sakurai, T.; Ichimoto, K.; Nishino, Y.; Ogawara, Y.
Bibcode: 1993ASPC...46..343S
Altcode: 1993IAUCo.141..343S; 1993mvfs.conf..343S
No abstract at ADS
Title: Application of the Yohkoh Soft X-ray Telescope (SXT) to Solar
Terrestrial Prediction
Authors: Watari, S.; Akioka, M.; Nishikawa, J.; Nitta, N.; Strong,
K.; Tsuneta, S.
Bibcode: 1993stp2.conf..370W
Altcode:
No abstract at ADS
Title: Solar Flare as an Ongoing Magnetic Reconnection Process
(Invited)
Authors: Tsuneta, Saku
Bibcode: 1993ASPC...46..239T
Altcode: 1993mvfs.conf..239T; 1993IAUCo.141..239T
No abstract at ADS
Title: Microflaring at the feet of large active region loops
Authors: Porter, Jason; Moore, Ron; Roumeliotis, George; Shimizu,
Toshifumi; Tsuneta, Saku; Sturrock, Peter; Acton, Loren
Bibcode: 1993STIN...9670891P
Altcode:
By superposing Yohkoh SXT images on an MSFC magnetogram of an active
region, we find that the brightest loops in the bipolar magnetic
envelope spanning the active region are rooted near a compact site
of mixed polarity and microflaring. Apparently, the enhanced coronal
heating in these high loops is a consequence of the microflaring and/or
related magnetic activity at this end site.
Title: Yohkoh/SXT Observations and Models For an Eruptive Flare
Authors: Martens, P. C. H.; Tsuneta, S.
Bibcode: 1992AAS...181.5502M
Altcode: 1992BAAS...24.1211M
On Dec. 2, 1991 Yohkoh/SXT obtained a unique sequence of high quality
X-ray images of what appeared to be a plasmoid ejection and two-ribbon
flare, viewed in cross-section on the Solar limb. We will show a
movie displaying the preflare plasmoid formation, the eruption of the
plasmoid followed by the onset of the flare, and finally what appears
to be the formation of postflare loops in a quadrupole type field
configuration. We have modelled this sequence of events with a simple
Martens-Kuin circuit approach, approximating the plasmoid/filament
as a line current, added to a background field consisting of three
line-dipoles. Overlays of the X-ray movie with the calculated magnetic
field morphology show excellent agreement, and thus lend further
credibility to the two-ribbon flare scenario developed by Carmichael,
Sturrock, Hirayama and many others thereafter.
Title: Comparison between YOHKOH Soft X-ray Images and 3D MHD
Simulations of Solar Emerging Flux Regions
Authors: Matsumoto, R.; Tajima, T.; Kaisig, M.; Shibata, K.; Ishido,
Y.; Tsuneta, S.; Shimizu, T.; Kawai, G.; Kurokawa, H.; Akioka, M.;
Acton, L.; Strong, K.; Nitta, N.
Bibcode: 1992AAS...181.8109M
Altcode: 1992BAAS...24.1253M
The soft X-ray telescope on the Yohkoh mission enabled us to observe
the evolution of emerging flux regions (EFR) in coronal X-rays with
high spatial and temporal resolution. Furthermore, we now have enough
computing capability to perform three-dimensional MHD simulation
of EFRs with sufficient spacial resolution to study details of the
flux emergence process. These new tools provide the opportunity to
investigate the physics involved in the formation of coronal loops
in much more detail. We carried out 3D MHD simulations of emerging
magnetic flux regions under various intial conditions; (1) a horizontal
magnetic flux sheet, (2) a bundle of horizontal flux tubes, and (3)
a flux sheet with sheared magnetic fields. Numerical results show that
coronal magnetic loops are formed due to the enhanced buoyancy resulting
from gas precipitating along magnetic field lines. The interchange modes
help to produce a fine fibrous structure perpendicular to the magnetic
field direction in the linear stage, while the undular modes determine
the overall loop structure. We observe in 3D simulations that during the
ascendance of loops the bundle of flux tubes, or even the flux sheet,
developes into dense filaments pinched between magnetic loops. We
also find that magnetic field lines are twisted by the vortex motion
produced by the horizontal expansion of magnetic loops. Our numerical
results may explain the observed signatures such as (1) the spacial
relation between soft X-ray loops and Hα arch filaments obtained by
coordinated observation between Yohkoh and ground-based observatories
(Kawai et al. 1992), (2) the rate of increase in size of soft X-ray
loops in EFRs (Ishido et al. 1992), (3) emergence of twisted magnetic
loops, and (4) the threshold flux for formation of chromospheric arch
filament systems (AFS).
Title: GINGA Observations of X-Ray Flares on Algol
Authors: Stern, R. A.; Uchida, Y.; Tsuneta, S.; Nagase, F.
Bibcode: 1992ApJ...400..321S
Altcode:
The Ginga X-ray satellite observed Algol (Beta Per) for 2 days in
1989 January, including both the primary optical eclipse and most
of the secondary eclipse. We derive upper limits of about 20 and
10 percent, respectively, for the eclipsed flux fraction during the
two eclipses. A large flare lasting over 12 hr was seen prior to and
during secondary eclipse. High-temperature Fe line emission is clearly
detected in the proportional counter data. The Fe line equivalent
width is variable during the flare, ranging from 0.4-1.0 keV. Except
for two intervals during the flare rise, the observed equivalent width
is lower than predicted using solar abundances and an optically thin
plasma model. Similar behavior has also been observed by Ginga in a
large flare on UX Ari: in both events, opacity effects at line center
may be playing a significant role. Loop model analysis of the large
flare suggests that it involves a substantially longer loop or loops
than a shorter duration Algol flare seen with Exosat.
Title: Flare-Related Relaxation of Magnetic Shear as Observed with
the Soft X-Ray Telescope of YOHKOH and with Vector Magnetographs
Authors: Sakurai, Takashi; Shibata, Kazunari; Ichimoto, Kiyoshi;
Tsuneta, Saku; Acton, Loren W.
Bibcode: 1992PASJ...44L.123S
Altcode:
The soft X-ray Telescope of Yohkoh observed an M-class flare on 1992
February 6. As the flare progressed, an initially sheared coronal loop
structure was seen to evolve toward a relaxed magnetic configuration. In
association with this evolution, the vector magnetograph observations
detected a decrease in the electric currents.
Title: Effective Geometrical Thickness and Electron Density of a
Flare of 1991 December 2 Observed with the Soft X-Ray Telescope of
YOHKOH and Coronagraph
Authors: Ichimoto, Kiyoshi; Hirayama, Tadashi; Yamaguchi, Asami;
Kumagai, Kazuyoshi; Tsuneta, Saku; Hara, Hirohisa; Acton, Loren W.;
Bruner, Marilyn E.
Bibcode: 1992PASJ...44L.117I
Altcode:
A very small geometrical thickness of 1000 km was found for an M3.7
flare of 1991 December 2, which occurred beyond the limb. While
the Yohkoh soft X-ray telescope gives the emission measure, a new
coronagraph which can observe continuum images at 6630- Angstroms gives
the electron column density originating from electron scattering of a
10(7) K flare plasma. The reasoning for the latter is because [Fe XIV]
5303 Angstroms images show a much different shape compared with X-ray
and the 6630- Angstroms continuum, and there was no Hα emission. From
these we obtained an electron density of 4times 10(10) cm(-3) and the
above-mentioned small length in the line of sight. Since the apparent
width of a flaring plasma both in soft X-ray and continuum images
measured parallel to the limb is ~ 4 times 10(4) km at a height of 7
times 10(4) km, the smallness of the effective length of 1000 km is
striking, and may have significant bearing on the energy conversion
of the flare. A brief discussion concerning the origin of the mass
and magnetic morphology is given.
Title: Observations of the Variability of Coronal Bright Points by
the Soft X-Ray Telescope on YOHKOH
Authors: Strong, Keith T.; Harvey, Karen; Hirayama, Tadashi; Nitta,
Nariaki; Shimizu, Toshifumi; Tsuneta, Saku
Bibcode: 1992PASJ...44L.161S
Altcode:
We present the initial results of a study of X-ray bright points (XBPs)
made with data from the Yohkoh Soft X-ray Telescope. High temporal
and spatial resolution observations of several XBPs illustrate their
intensity variability over a wide variety of time scales from a few
minutes to hours as well as rapid changes in their morphology. Several
XBPs produced flares during their lifetime. These XBP flares often
involve magnetic loops, which are considerably larger than the XBP
itself, and which brighten along their lengths at speeds of up to 1100
km s(-1) . We speculate on the origin of the XBP variability and flares.
Title: Observations of X-Ray Jets with the YOHKOH Soft X-Ray Telescope
Authors: Shibata, Kazunari; Ishido, Yoshinori; Acton, Loren W.; Strong,
Keith T.; Hirayama, Tadashi; Uchida, Yutaka; McAllister, Alan H.;
Matsumoto, Ryoji; Tsuneta, Saku; Shimizu, Toshifumi; Hara, Hirohisa;
Sakurai, Takashi; Ichimoto, Kiyoshi; Nishino, Yohei; Ogawara, Yoshiaki
Bibcode: 1992PASJ...44L.173S
Altcode:
Time series of Soft X-ray Telescope images have revealed many X-ray
jets in the solar corona. The typical size of a jet is 5 times 10(3)
--4 times 10(5) km, the translational velocity is 30--300 km s(-1) ,
and the corresponding kinetic energy is estimated to be 10(25) --10(28)
erg. Many of the jets are associated with flares in X-ray bright points,
emerging flux regions, or active regions. They sometimes occur several
times from the same X-ray feature. In some cases, a dark void appears
after ejection at the footpoint of the jet. The void seems to be
the result of a change in the topology of the X-ray emitting plasma,
perhaps due to magnetic reconnection. Some jets show a structure which
suggests a helical magnetic field configuration along the jet. One
of the jets associated with a flaring bright point was identified as
being an Hα surge. In this case, the X-ray bright point is situated
just on the Hα bright point at the footpoint of the surge. The top
of the surge is not bright in X-rays. We briefly discuss the origin
of these newly discovered X-ray jets.
Title: The Morphology of 20times 10(6) K Plasma in Large Non-Impulsive
Solar Flares
Authors: Acton, Loren W.; Feldman, Uri; Bruner, Marilyn E.; Doschek,
George A.; Hirayama, Tadashi; Hudson, Hugh S.; Lemen, James R.;
Ogawara, Yoshiaki; Strong, Keith T.; Tsuneta, Saku
Bibcode: 1992PASJ...44L..71A
Altcode:
We have examined images of 10 flares observed by the Soft X-ray
Telescope on-board the Yohkoh spacecraft. These images show that the
hottest portion of the soft X-ray flare is located in compact regions
that appear to be situated at the tops of loops. These compact regions
form at, or shortly after, flare onset, and persist well into the decay
phase of the flares. In some cases, the compact regions are only a
few thousand kilometers in size and are small compared to the lengths
of flaring loops. This is inconsistent with the smoother intensity
distribution along the loops expected from models of chromospheric
evaporation.
Title: The Structure of the Coronal Soft X-Ray Source Associated
with the Dark Filament Disappearance of 1991 September 28 Using the
YOHKOH Soft X-Ray Telescope
Authors: McAllister, Alan; Uchida, Yutaka; Tsuneta, Saku; Strong,
Keith T.; Acton, Loren W.; Hiei, Eijiro; Bruner, Marilyn E.; Watanabe,
Takashi; Shibata, Kazunari
Bibcode: 1992PASJ...44L.205M
Altcode:
The internal structure of an X-ray emitting elongated object
appearing in association with Hα -dark filament disappearance of 1991
September 28 was analyzed with the help of a fine-structure enhancing
technique. We present a description of the soft X-ray structures and
their evolution, while focusing on the central, brightest part of the
structure, which is also the most difficult to resolve. We start with
the idea of applying the standard ``eruption-reconnection'' models
of Hα double-ribbon flares with filament disappearences in order to
explain this event as the appearence of an arcade of loops across the
initial dark filament position, with a row of hot spots at reconnection
sites along the loop tops. Our study of the Yohkoh Soft X-ray images,
including their fine-structure enhancement, the making of an accurately
aligned movie, and a preliminary comparison with Hα data, however,
has led us to question the applicability of these models to this type
of event. It seems, rather, that much of the bright structure comprises
heated pre-existing loops, which interact where they cross each other
in a complex ``knot'' at the northern end of the disappearing dark
filament. The bright part turns out to comprise highly sheared loops,
perhaps being pushed up by the slowly rising axial field of the dark
filament, which is, however, contained under the arcade, rather than
having broken through it. We conclude that there is a strong possibility
that much of the dark filament mass remains in the heated unwinding
axial field and briefly discuss the theoretical implications.
Title: Thickness Variations along Coronal Loops Observed by the Soft
X-Ray Telescope on YOHKOH
Authors: Klimchuk, James A.; Lemen, James R.; Feldman, Uri; Tsuneta,
Saku; Uchida, Yutaka
Bibcode: 1992PASJ...44L.181K
Altcode:
It has been suggested that observed coronal loops have constant
thicknesses. However, if plasma loops coincide with magnetic loops,
then we might expect many loops to be significantly broader at their
tops than at their footpoints (since, on average, magnetic fields
must diverge with height in the solar corona). It is important to
understand how the thicknesses of loops vary along their lengths, since
such a variation is related to the distribution of electric currents
in the corona and is therefore relevant to solar flares and coronal
heating. We here present preliminary results of our investigation of
thickness variations along coronal loops observed with the Soft X-ray
Telescope (SXT) on board the Yohkoh satellite.
Title: The X Flare of 1991 November 15: Coordinated Mees/Yohkoh
Observations
Authors: Canfield, Richard C.; Hudson, Hugh S.; Leka, K. D.; Mickey,
Donald L.; Metcalf, Thomas R.; Wuelser, Jean-Pierre; Acton, Loren W.;
Strong, Keith T.; Kosugi, Takeo; Sakao, Taro; Tsuneta, Saku; Culhane,
J. Leonard; Phillips, Andrew; Fludra, Andrzej
Bibcode: 1992PASJ...44L.111C
Altcode:
This is a preliminary report on two unique new results from coordinated
observations at Mees Solar Observatory and Yohkoh of the X1.5 flare
of 1991 November 15, using vector magnetograms, Hα imaging spectra,
X-ray images, and X-ray spectra. First, we find a close spatial
relationship between Hα redshifts and X-rays from a flare loop and
its footpoints at a time of large X-ray blueshifts. Second, we find
that impulsive-phase hard X-rays originate in regions that are near,
but not coincident with, the peaks of the vertical electrical current
density distribution in AR 6919.
Title: The Status of YOHKOH in Orbit: an Introduction to the Initial
Scientific Results
Authors: Ogawara, Yoshiaki; Acton, Loren W.; Bentley, Robert D.;
Bruner, Marilyn E.; Culhane, J. Leonard; Hiei, Eijiro; Hirayama,
Tadashi; Hudson, Hugh S.; Kosugi, Takeo; Lemen, James R.; Strong, Keith
T.; Tsuneta, Saku; Uchida, Yutaka; Watanabe, Tetsuya; Yoshimori, Masato
Bibcode: 1992PASJ...44L..41O
Altcode:
In this introductory article accompanying the initial scientific
papers from the Yohkoh mission, we briefly summarize the design
and in-orbit function of the spacecraft and its four scientific
instruments. Although these initial results include mainly studies
based upon individual Yohkoh experiments at this early stage, there
are also analyses of combined data sets provided by several on-board
and ground-based instruments in progress. The results presented here,
and anticipated future results, suggest that the Yohkoh observations
with their comprehensive coverage of solar high-energy phenomena will
come to represent a significant milestone in the progress of solar
physics. This will be true not only regarding flares, but also for
fainter coronal structures and even coronal holes.
Title: Coronal/Interplanetary Disturbances Associated with
Disappearing Solar Filaments
Authors: Watanabe, Takashi; Kozuka, Yukio; Ohyama, Masamitsu; Kojima,
Masayoshi; Yamaguchi, Kisuke; Watari, Shin-Ichi; Tsuneta, Saku;
Joselyn, Jo A.; Harvey, Karen L.; Acton, Loren W.; Klimchuk, James. A.
Bibcode: 1992PASJ...44L.199W
Altcode:
We discuss two examples of coronal/interplanetary disturbances
associated with the disappearance of a 35(deg) long quiescent filament
occurring near the solar disk center on 1991 September 28 (McAllister
et al. 1992, Publ. Astron. Soc. Japan, 44, L205) and with a 25(deg)
long eruptive prominence at the eastern solar limb taking place on
1991 November 7. Bright soft X-ray arcades were observed for both
cases with the Yohkoh SXT, about 2--3 hr after the onset of each
Hα event. For the erupting prominence on November 7, the arcade
did not appear before the prominence reached a height of about 0.3
solar radii above the limb. This suggests that magnetic reconnection
occurred below the relevant Hα structures. A transient coronal hole
was formed in the immediate vicinity of the disappearing filament on
September 28. Formation of the new coronal hole is suggested to be a
cause of the filament disappearance. An interplanetary disturbance was
detected by radio scintillation (IPS) observations immediately after
the filament disappeared.
Title: The YOHKOH mission for high-energy solar physics
Authors: Acton, L.; Tsuneta, S.; Ogawara, Y.; Bentley, R.; Bruner, M.;
Canfield, R.; Culhane, L.; Doschek, G.; Hiei, E.; Hirayama, T. Hudson,
H.; Kosugi, T.; Lang, J.; Lemen, J.; Nishimura, J.; Makishima, K.;
Uchida, Y.; Watanabe, T.
Bibcode: 1992Sci...258..618A
Altcode: 1992Sci...258..591A
Data on solar flare mechanisms and the sun's corona will be generated
by Japan's Yohkoh satellite's X-ray imaging sensors and X-ray and
gamma-ray spectrometers. It is noted that the X-ray corona above active
regions expands, in some cases almost continually, in contradiction of
the widely accepted model of magnetohydrostatic equilibrium in such
regions. Flaring X-ray bright points have been discovered to often
involve ejecta into an adjacent, much larger and fainter magnetic loop,
which brightens along its length at speeds up to 1000 km/sec.
Title: Detailed Comparison between Hα and YOHKOH Soft X-Ray Images
of a Confined Two-Ribbon Flare
Authors: Kurokawa, Hiroki; Kawai, Goro; Kitai, Reizaburo; Funakoshi,
Yasuhiro; Nakai, Yoshihiro; Tsuneta, Saku; Kosugi, Takeo; Enome,
Shinzo; Acton, Loren W.; Ogawara, Yoshiaki
Bibcode: 1992PASJ...44L.129K
Altcode:
The spatial and temporal relationships between soft X-ray loops
and Hα flare Kernels were studied for the 1B (M2.6) flare of 1991
December 5. Most of flare energy was released inside three soft X-ray
loops whose footpoints were bright as Hα Kernels. We suggest that the
interaction among pre-existing or emerging magnetic loops is essential
for the successive energy release in a confined two-ribbon flare.
Title: High-Temperature Plasmas in Active Regions Observed with the
Soft X-Ray Telescope aboard YOHKOH
Authors: Hara, Hirohisa; Tsuneta, Saku; Lemen, James R.; Acton,
Loren W.; McTiernan, James M.
Bibcode: 1992PASJ...44L.135H
Altcode:
High-temperature plasmas reaching 5--6times 10(6) K in solar
active regions have been found with the soft X-ray telescope aboard
Yohkoh. NOAA region 6919 was investigated in detail using five different
X-ray filters: The temperature of a bright loop in the active region
is 5.7times 10(6) K, with an emission measure of 5.0times 10(28)
cm(-5) ; in a fainter part of the region plasma, we find 5.0times
10(6) \ K and 4.0times 10(27) cm(-5) . This indicates that such
high-temperature plasmas exist in the active region, irrespective of
the brightness. Another observation of the quiet corona was conducted in
order to investigate the reliability of a temperature analysis with the
same filter pairs which show such high temperatures in active regions:
The inferred temperature was 2.7times 10(6) K, and the emission measure
1.3times 10(26) cm(-5) , which is consistent with the typical results
of Skylab. Therefore, the high-temperature plasmas in solar active
regions are considered to be real.
Title: Global Restructuring of the Coronal Magnetic Fields Observed
with the YOHKOH Soft X-Ray Telescope
Authors: Tsuneta, Saku; Takahashi, Tetsuo; Acton, Loren W.; Bruner,
Marilyn E.; Harvey, Karen L.; Ogawara, Yoshiaki
Bibcode: 1992PASJ...44L.211T
Altcode:
We present an example of the large-scale ``restructuring" of a polar
coronal magnetic structure taking place over a time period of 20
hr. A large-scale closed-loop arcade appears to be created from an
open field structure formed in association with the disappearance of a
polar crown filament. The loops increase their height with time. The
loop formation propagates westward, and a cusp structure, inside
of which is bright in X-rays, is seen on the west limb. This global
structural change of the coronal magnetic field appears to take place
only through a non-explosive, quasi-steady magnetic reconnection. The
Yohkoh soft X-ray images show that the solar corona is full of such
global restructuring, suggesting that magnetic reconnection is a
primary device for the general coronal magnetic evolution.
Title: Transient Brightenings in Active Regions Observed by the Soft
X-Ray Telescope on YOHKOH
Authors: Shimizu, Toshifumi; Tsuneta, Saku; Acton, Loren W.; Lemen,
James R.; Uchida, Yutaka
Bibcode: 1992PASJ...44L.147S
Altcode:
The Soft X-ray Telescope (SXT) aboard the Yohkoh satellite has revealed
that active regions show many compact loop brightenings which we call
``active-region transient brightenings.'' The released energy by an
``active-region transient brightening'' is considerably less than
10(29) erg, which is the low end of the subflare energy range. Small
soft X-ray enhancements observed by the GOES satellites are identified
to relatively intense ``active-region transient brightenings.'' The
transient brightening occurs on the average of one every ~ 3 min in
``active'' active regions and down to one every ~ 1 hr in ``quieter''
active regions. This suggests that the transient brightening is a
very common phenomenon in active regions and that the magnetic loops
in active regions are far from static.
Title: Observation of a Solar Flare at the Limb with the YOHKOH Soft
X-Ray Telescope
Authors: Tsuneta, Saku; Hara, Hirohisa; Shimizu, Toshifumi; Acton,
Loren W.; Strong, Keith T.; Hudson, Hugh S.; Ogawara, Yoshiaki
Bibcode: 1992PASJ...44L..63T
Altcode:
A long-enduring soft X-ray flare at the solar limb was well observed
by the Soft X-ray Telescope aboard the Yohkoh spacecraft from its
pre-flare stage through the post-flare phase. A ``helmet streamer"
arch appears several hours prior to the flare, in association with a
continuous expansion and restructuring of the active-region magnetic
structure. This arch then starts to flare, and increases its height and
footpoint separation at v = 10--30 km s(-1) . The arch has a complex
temperature structure in the rising phase, whereas the outer arches
have systematically higher temperatures in the decay phase. Magnetic
reconnection in a neutral sheet at the loop top, created by pre-flare
magnetic restructuring, would explain this type of flare.
Title: Comparison between Hα and YOHKOH Soft X-Ray Images of Emerging
Flux Regions
Authors: Kawai, Goro; Kurokawa, Hiroki; Tsuneta, Saku; Shimizu,
Toshifumi; Shibata, Kazunari; Acton, Loren W.; Strong, Keith T.;
Nitta, Nariaki
Bibcode: 1992PASJ...44L.193K
Altcode:
We carried out a detailed comparison between Hα and Yohkoh Soft X-ray
(SXR) images of three emerging flux regions. The main results are:
(1) In general, SXR bright features coincide well in space with Hα
arch filament systems in the emerging flux regions (EFR). (2) Some
young and active parts of EFRs are especially bright in SXR. (3)
The SXR structures related to EFR show fairly rapid changes in both
brightness and shape. These results are consistent with the model that
the emerging cool loops of EFRs evolve into hot coronal loops through
some heating processes.
Title: Arcade Formation and the Non-Eruption of Dissappearing Hα
Filaments as Seen with the YOHKOH Soft X-Ray Telescope
Authors: McAllister, A. H.; Uchida, Y.; Tsuneta, S.; Strong, K.
Bibcode: 1992AAS...180.2303M
Altcode: 1992BAAS...24..760M
Several examples have been found of a type of initial structure made up
of a group of nested arched loops, at a large angle to the vertical,
with long twisted threads emerging from between their foot points,
giving the impression that the filaments dive into the mouth of a
tunnel defined by the arches. These structures are often correllated
with Hα dark filaments that are aligned along the long threads and
extend under the arches. On at least two occassions, on the Sep. 28th
1991, and Feb. 21st 1992, there were brightenings in such structures
associated with untwisting of the twisted threads while the arched
loops were replaced by an arcade, under which a bright axial thread is
seen along the same line as the long twisted threads. During this time
the Hα dark filaments disappear. We examined several of these events
using image analysis techniques to bring out the fine structure, and
show in detail the evolution of the new soft x-ray arcade perpendicular
to the disappearing dark filament and of the bright axial thread that
lies along the arcade. At a glance this thread seems to correspond
to the locus of the reconnecting points in the inverse Y-shaped
reconnection, in helmet-like configuration models (Sturrock, Hirayama,
Kopp-Pneuman). We find, however, that 1) this bright thread seems to
connect to the long untwisting threads, and that 2) it does not rise up
through the overlying arcade. There is likewise no sign of reconnection
in the overlying corona, as expected in those models. Therefore,
it seems that at least the major part of the heated mass as well as
the longitudinal field of the dark filament simply remained inside
the arcade which stays intact, requiring a new way of explaining the
phenomenon. We present a more detailed discription of this type of
event and comment on the implications to existing theoretical models.
Title: November 15, 1991 X Flare -- The Movie: Hα , Soft X-rays,
and Hard X-rays and Magnetic Fields
Authors: Wulser, J. -P.; Acton, L.; Sakao, T.; Canfield, R.; Kosugi,
T.; Slater, G.; Strong, K.; Tsuneta, S.
Bibcode: 1992AAS...180.3003W
Altcode: 1992BAAS...24..775W
The X1.5/3B flare on 1991 November 15, 22:33 UT was well observed
by the Hα Imaging Spectrograph and the Vector Magnetograph
(Stokes Polarimeter) at Mees Solar Observatory, and by the Soft-
and Hard X-ray Telescopes (SXT and HXT) aboard YOHKOH. We have
combined this multispectral dataset into a series of temporally and
spatially co-aligned video movies and analyzed the morphological
and temporal relationships of the various flare emissions. The
earliest manifestations of this flare include unresolved preflare SXR
brightenings very close to the magnetic neutral line and preflare
motions of filaments seen in Hα . In the flare core, SXR and Hα
emission show moving and rotating coronal structures which we interpret
as a successive brightening of adjacent loops during the main phase
of the flare. The HXR source shows much more dramatic variability
than the SXR source, and they are clearly not cospatial. On the other
hand, there is a close spatial relationship between the HXR and Hα
blue wing emission sites. The Hα , HXR, and SXR images all point to
acceleration and heating in a region that starts close to the neutral
line and moves outward during each HXR burst and during the gradual
phase. Spectacular mass ejections are seen in both SXR and Hα , with
clear unwinding of tightly coiled structures, acceleration of X-ray
and Hα material to velocities of order 1000 km/s, and a striking
thermal bifurcation between hot and cold plasma.
Title: Early Results from the YOHKOH Soft X-ray Telescope
Authors: Bruner, M. E.; Acton, L. W.; Lemen, J.; Hirayama, T.;
Tsuneta, S.
Bibcode: 1992AAS...180.2301B
Altcode: 1992BAAS...24..759B
The The Soft X-ray Telescope on the Yohkoh satellite, launched by
Japan on August 30, 1992, has proved to be a resounding success. It
is providing a wealth of new information and many surprises, both on
flares and on the behavior of the solar corona. Performance of the
telescope has met or exceed our most optimistic expectations and
it appears to be in perfect focus. Unlike the Skylab instruments,
the Yohkoh telescope is not limited by a finite supply of film,
permitting long sequences of images to be made with relatively high
time resolution. Repetition rates for a given exposure / filter
combination are typically a few seconds per frame to a few minutes
per frame, depending on the selected field size. Movies assembled from
long exposure sequences have shown the corona to be even more dynamic
than expected. Major re-structuring, involving large fractions of the
visible corona, can take place in an hour or two. Smaller regions are
even more dynamic, changing almost continuously. Movies, created from
long exposure sequences, have demonstrated the fundamental importance of
large-scale coronal loops in connecting widely separated regions such
that activity in one region quickly affects the physical conditions
at remote sites. The images also show that the majority of the loops
have nearly constant cross sections along their lengths, rather than
one that increases with height. Several X-class flares have been
observed; the surprising result is that they do not appear to be very
dynamic in soft X-rays. The flare kernels seem to consist of compact
loop structures that brighten and then fade without changing size or
shape. Bright points are not as prominent as in the Skylab images;
a result of using a CCD (a linear detector) rather than film which has
a logarithmic response. The other instruments on Yohkoh are producing
equally exciting results; it seems clear that the Yohkoh mission will
produce many major advances in our knowledge of the flare mechanism.
Title: Electric Currents and Coronal Structures in Two Flare-
Productive Active Regions, AR 6850 and AR 6952
Authors: Metcalf, T. R.; Canfield, R. C.; Hudson, H. S.; Mickey,
D. L.; Strong, K. T.; Tsuneta, S.
Bibcode: 1992AAS...180.3004M
Altcode: 1992BAAS...24R.775M
In this study, we examine the spatial and temporal relationship between
coronal structures observed with the Soft X-Ray Telescope (SXT) on
board the YOHKOH spacecraft and vertical electric currents derived
from vector magnetograms obtained at the Mees Solar Observatory,
Haleakala, Hawaii. We have focused on two active regions, AR 6850
(October 1991) and AR 6952 (December 1991). In both active regions,
we observed significant current structures which persisted over time
scales of days. The SXR emitting coronal structures, however, changed
on much shorter time scales, indicating that there is no compelling,
direct spatial and temporal relationship between the non-flaring SXR
structures and the long-lived electric current systems. We have seen
at least one case (in AR 6952) where a SXR brightening was associated
spatially with a change in the vertical electric current. In this case,
the the vertical current dissipated between December 8, 00:35 UT and
the next observation at 00:48 UT on December 9, leaving a bright SXR
structure which was observed at 24:27 UT on December 8. Hence, although
more data must be analyzed to make a compelling case, it is possible
that the SXR emission is related more closely to changes in the electric
current systems rather than simply to the presence of these currents.
Title: X-ray Bright Point Flares Observed by YOHKOH
Authors: Harvey, K. L.; Strong, K.; Nitta, N.; Tsuneta, S.; Shimizu, T.
Bibcode: 1992AAS...180.1806H
Altcode: 1992BAAS...24..755H
X-ray images taken by the Soft X-Ray Telescope (SXT) on board the
Japanese Satellite Yohkoh are being used to study the characteristics
and variability of X-ray bright points and their relation to
the underlying photospheric magnetic field and chromospheric
structures. Though during this maximum phase of Cycle 22 there are few
X-ray bright points at any given time, more than a thousand have been
observed since Yohkoh began its observation in September 1991. Many of
these bright points flare; in many cases, these small-scale flares are
associated with with observed effects detected spanning substantial
distances away from the flaring bright point. This paper will report
on an investigation of the dynamics of the flares in these small-scale
coronal structures. Events will be discussed that show their complexity
and their relation to the large-scale coronal magnetic fields as
identified by coronal structures observed in X-rays.
Title: Temperature Structure of Solar Flares Observed by the
YOHKOH SXT
Authors: McTiernan, J. M.; Kane, S. R.; Loran, J. M.; Lemen, J. R.;
Acton, L. W.; Hara, H.; Tsuneta, S.
Bibcode: 1992AAS...180.3002M
Altcode: 1992BAAS...24Q.775M
Hot plasmas from several solar flares have been observed by the Soft
X-ray Telescope (SXT) on board the Yohkoh satellite. For a sample of
flares observed by the SXT with a variety of X-ray filters, we have
calculated temperature and emission measures as functions of space and
time. Initial results from this analysis show the following: (1) The
flare plasmas range in temperarure from several million degrees K up to
greater than 20 million degrees K, depending on the individual event;
(2) The region with the higest temperature does not coincide with
the brightest region. For example, for the flare of 15 November 1991
(2238 UT) the temperature was typically 8-9 million degrees K on the
bright kernels, with temperatures of 15-25 million degrees K on the
edges of the bright regions. The average temperature for the flare was
approximately 10 million degrees K. A preliminary interpretation of
these observational results in terms of the temperature and density
structure inside a magnetic loop will be presented.
Title: The Soft X-ray Telescope for the SOLAR-A mission
Authors: Tsuneta, S.; Acton, L.; Bruner, M.; Lemen, J.; Brown, W.;
Caravalho, R.; Catura, R.; Freeland, S.; Jurcevich, B.; Morrison,
M.; Ogawara, Y.; Hirayama, T.; Owens, J.
Bibcode: 1991SoPh..136...37T
Altcode:
The Soft X-ray Telescope (SXT) of the SOLAR-A mission is designed
to produce X-ray movies of flares with excellent angular and time
resolution as well as full-disk X-ray images for general studies. A
selection of thin metal filters provide a measure of temperature
discrimination and aid in obtaining the wide dynamic range required for
solar observing. The co-aligned SXT aspect telescope will yield optical
images for aspect reference, white-light flare and sunspot studies,
and, possibly, helioseismology. This paper describes the capabilities
and characteristics of the SXT for scientific observing.
Title: SOLAR-A Reformatted Data Files and Observing Log
Authors: Morrison, M. D.; Lemen, J. R.; Acton, L. W.; Bentley, R. D.;
Kosugi, T.; Tsuneta, S.; Ogawara, Y.; Watanabe, T.
Bibcode: 1991SoPh..136..105M
Altcode:
All of the SOLAR-A telemetry data will be reformatted before
distribution to the analysis computers and the various users. This
paper gives an overview of the files which will be created and the
format and organization which the files will use. The organization
has been chosen to be efficient in space, to ease access to the data,
and to allow for the data to be transportable to different machines. An
observing log file will be created automatically using the reformatted
data files as the input. It will be possible to perform searches with
the observing log to list cases where instruments are in certain modes
and/or seeing certain signal levels.
Title: The SOLAR-A Mission - An Overview
Authors: Ogawara, Y.; Takano, T.; Kato, T.; Kosugi, T.; Tsuneta, S.;
Watanabe, T.; Kondo, I.; Uchida, Y.
Bibcode: 1991SoPh..136....1O
Altcode:
The SOLAR-A spacecraft is to be launched by the Institute of Space and
Astronautical Science, Japan (ISAS) in August, 1991. As a successor
of HINOTORI, this mission is dedicated principally to the study of
solar flares, especially of high-energy phenomena observed in the
X- and gamma-ray ranges. The SOLAR-A will be the unique space solar
observatory during the current activity maximum period (1989-1992). With
a coordinated set of instruments including hard X-ray and soft X-ray
imaging telescopes as well as spectrometers with advanced capabilities,
it will reveal many new aspects of flares and help better understand
their physics, supporting international collaborations with ground-based
observatories as well as theoretical investigations. An overview of
this mission, including the satellite, its scientific instruments, and
its operation, is given in this paper. Also the scientific objectives
are briefly discussed.
Title: Soft X-ray Telescope (SXT) (Extended Abstract)
Authors: Tsuneta, Saku; Acton, Loren
Bibcode: 1991LNP...387...18T
Altcode: 1991fpsa.conf...18T
No abstract at ADS
Title: Plasma diagnostic capabilities of the Soft X-Ray Telescope
on Solar-A
Authors: Strong, K. T.; Acton, L. W.; Brown, W. A.; Claflin, E. S.;
Lemen, J. R.; Tsuneta, S.
Bibcode: 1991AdSpR..11e..73S
Altcode: 1991AdSpR..11...73S
We present the predicted response of the Solar-A Soft X-Ray Telescope
(SXT) to various solar targets. From prelaunch calibrations of the
SXT flight mirror, X-ray filters, and CCD detector, we are able to
predict exposure times and image cadence for a representative range of
temperatures and emission measures of the coronal plasma. We find that
the SXT is very sensitive; it should be able to observe active regions
and flares at its nominal cadence (2 s) with exposure times ranging
from 0.0001 to 1 s. The SXT temperature diagnostic capabilities are
presented for various combinations of the X-ray filters. SXT data can
be used to reproduce accurately the temperature and emission measure
of an isothermal plasma. However, if there is a wide distribution
of temperatures in a pixel, reconstructing the original differential
emission measure distribution becomes more uncertain.
Title: GINGA Observations of a Long Duration X-Ray Flare in the
Algol System
Authors: Stern, R. A.; Haisch, B. M.; Nagase, F.; Uchida, Y.;
Tsuneta, S.
Bibcode: 1990ASPC....9..224S
Altcode: 1990csss....6..224S
Algol was observed by the Ginga X-ray satellite for about 2 days in
January 1989, including both the primary and most of the secondary
optical eclipses. No evidence for X-ray eclipses was seen. A large
flare lasting over 12 h was detected prior to and during secondary
eclipse. The flare began with a peak temperature of about 69 MK,
gradually decaying to about 36 MK. Variable Fe line emission at 6.7
keV ws observed. The Fe line equivalent width is in clear disagreement
with theoretical predictions for an optically thin plasma.
Title: Ginga Observations of a Long-Duration X-ray Flare in Algol
Authors: Stern, R. A.; Haisch, B. M.; Nagase, F.; Uchida, Y.;
Tsuneta, S.
Bibcode: 1989BAAS...21.1205S
Altcode:
No abstract at ADS
Title: The soft X-ray telescope for the solar A mission.
Authors: Bruner, M. E.; Acton, L. W.; Brown, W. A.; Stern, R. A.;
Hirayama, T.; Tsuneta, S.; Watanabe, T.; Ogawara, Y.
Bibcode: 1989GMS....54..187B
Altcode: 1989sspp.conf..187B; 1989opss.conf..187B
The Solar A mission, being conducted by the Japanese Institute
for Astronautical and Space Sciences, is a project to study solar
flares using a cluster of instruments on an orbiting satellite. It
is scheduled to be launched in September or October of 1991. The
emphasis of the mission is on imaging and spectroscopy of hard and
soft X-rays. The Soft X-Ray Telescope (SXT), one of two major imaging
instruments on the satellite, is a joint U.S.-Japan project. It is
being prepared at Lockheed under NASA sponsorship. The electronic
control system for the SXT is based on microprocessors and is a joint
effort between Lockheed and the National Astronomical Observatory of
Japan (NAOJ). The SXT uses a glancing incidence telescope of 1.55 m
effective focal length to form images in the 0.25 to 3.0 keV range on
a 1024×1024 virtual phase CCD detector. A selection of thin metallic
filters located near the focal plane provides the capability for
electron temperature diagnostics. Knowledge of the alignment of soft
X-ray images with respect to features observable in visible light
is provided by a coaxially mounted aspect telescope which forms its
image on the CCD sensor when the thin metallic filter is replaced by
an appropriate glass filter. A novel mechanical design has permitted
a very lightweight structure that remains stiff enough to survive the
severe launch environment. Other Solar A instruments include a hard
X-ray telescope, a Bragg crystal spectrometer, a wide band spectrometer,
and a radiation belt monitor.
Title: Particle acceleration.
Authors: Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.;
Alissandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.;
Ellison, D.; Evenson, P.; Forrest, D. J.; Holman, G.; Kane, S. R.;
Kaufmann, P.; Kundu, M. R.; Lin, R. P.; MacKinnon, A.; Nakajima,
H.; Pesses, M.; Pick, M.; Ryan, J.; Schwartz, R. A.; Smith, D. F.;
Trottet, G.; Tsuneta, S.; van Hoven, G.
Bibcode: 1989epos.conf..127V
Altcode:
Contents: 1. Introduction. 2. Phenomena associated with
mildly-relativistic electrons. 3. Phenomena associated with ions and
relativistic electrons in solar flares. 4. Theoretical studies of
particle acceleration. 5. Achievements - outstanding questions.
Title: The SOLAR-A soft X-ray telescope experiment
Authors: Acton, L.; Bruner, M.; Brown, W.; Lemen, J.; Hirayama, T.;
Tsuneta, S.; Watanabe, T.; Ogawara, Y.
Bibcode: 1988AdSpR...8k..93A
Altcode: 1988AdSpR...8...93A
The Japanese SOLAR-A mission for the study of high energy solar physics
is timed to observe the sun during the next activity maximum. This small
spacecraft includes a carefully coordinated complement of instruments
for flare studies. In particular, the soft X-ray telescope (SXT)
will provide X-ray images of flares with higher sensitivity and time
resolution than have been available before. This paper describes the
scientific capabilities of the SXT and illustrates it application to
the study of an impulsive compact flare.
Title: X-ray observations of solar flares.
Authors: Tsuneta, Saku
Bibcode: 1988ASSL..143..325T
Altcode: 1988acse.conf..325T
Major observational highlights of the last solar maximum are
reviewed with emphasis on the results obtained by Japanese Hinotori
satellite. Three different types of flares were observed by Hinotori:
type A flares have purely thermal nature. Type B flares are impulsive
bursts. Type C flares have gradually varying hard X-ray and microwave
sources located high in the corona. SOLAR-A spacecraft is scheduled to
be launched in the next solar maximum (1991) to continue the systematic
study of the X-ray sun begun by Hinotori and SMM. The main instruments
onboard are hard (10 - 70 keV) and soft (0.1 keV - 2 keV) X-ray imaging
telescopes for observing flares and the quiet sun.
Title: Impulsive and hot thermal solar flares
Authors: Tsuneta, Saku
Bibcode: 1987SoPh..113...35T
Altcode: 1982SoPh..113...35T
Some X-class flares (hot thermal flares, HTF) observed with the
Hinotori satellite show unique behavior: slow time variability, a
compact hard X-ray source containing dense (n > 1011
cm−3) and hot (T > 3 × 107 K) plasma, and
unusually weak microwave emission in spite of the intense magnetic field
(B > 330 G) required theoretically to sustain the hot plasma. These
observations show that HTF's have essentially thermal characteristics
throughout the flare evolution, while in impulsive flares, there is
a transition in the energy release mode from particle acceleration
(impulsive phase) to plasma heating (gradual phase). This behavior
can be explained in a unified manner by employing parallel DC electric
field acting over large distances.
Title: Phenomena Associated with Ions and Relativistic Electrons
Authors: Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.;
Allisandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.;
Ellison, D.; Evenson, P.; Forrest, D. J.; Holman, G.; Kane, S. R.;
Kaufmann, P.; Kundu, M. R.; Lin, R. P.; MacKinnon, A.; Nakajima,
H.; Pesses, M.; Pick, M.; Ryan, J.; Schwartz, R. A.; Smith, D. F.;
Trottet, G.; Tsuneta, S.; van Hoven, G.
Bibcode: 1986epos.conf.2.30V
Altcode: 1986epos.confB..30V
No abstract at ADS
Title: Mechanisms for Particle Accleration in Flares
Authors: Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.;
Allisandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.;
Ellison, D.; Evenson, P.; Forrest, D. J.; Holman, G.; Kane, S. R.;
Kaufmann, P.; Kundu, M. R.; Lin, R. P.; MacKinnon, A.; Nakajima,
H.; Pesses, M.; Pick, M.; Ryan, J.; Schwartz, R. A.; Smith, D. F.;
Trottet, G.; Tsuneta, S.; van Hoven, G.
Bibcode: 1986epos.conf.2.42V
Altcode: 1986epos.confB..42V
No abstract at ADS
Title: Phenomena Associated with Mildly Relativistic Electrons
Authors: Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.;
Allisandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.;
Ellison, D.; Evenson, P.; Forrest, D. J.; Holman, G.; Kane, S. R.;
Kaufmann, P.; Kundu, M. R.; Lin, R. P.; MacKinnon, A.; Nakajima,
H.; Pesses, M.; Pick, M.; Ryan, J.; Schwartz, R. A.; Smith, D. F.;
Trottet, G.; Tsuneta, S.; van Hoven, G.
Bibcode: 1986epos.conf..2.2V
Altcode: 1986epos.confB...2V
No abstract at ADS
Title: Particle acceleration.
Authors: Vlahos, L.; Machado, M. E.; Ramaty, R.; Murphy, R. J.;
Allisandrakis, C.; Bai, T.; Batchelor, D.; Benz, A. O.; Chupp, E.;
Ellison, D.; Evenson, P.; Forrest, D. J.; Holman, G.; Kane, S. R.;
Kaufmann, P.; Kundu, M. R.; Lin, R. P.; MacKinnon, A.; Nakajima,
H.; Pesses, M.; Pick, M.; Ryan, J.; Schwartz, R. A.; Smith, D. F.;
Trottet, G.; Tsuneta, S.; van Hoven, G.
Bibcode: 1986NASCP2439....2V
Altcode:
Contents: 1. Introduction. 2. Phenomena associated with
mildly-relativistic electrons: soft and hard X-ray source structure,
location and development, microwave source structure, location and
development, time structures and time delays in radio and hard X-rays,
microwave rich flares, decimetric - metric observations and comparison
with X-ray observations, discussion of models for X-ray and microwave
emission. 3. Phenomena associated with ions and relativistic electrons:
gamma-ray observations, neutron observations, implications of gamma-ray
and neutron observations, interplanetary charged-particle observations,
acceleration mechanisms. 4. Mechanisms for particle acceleration
in flares: particle acceleration in reconnecting magnetic fields,
electron acceleration along the magnetic field with sub-Dreicer electric
fields, lower hybrid waves, Fermi acceleration and MHD turbulence,
shock acceleration, acceleration of electrons by intense radio waves,
preferential acceleration of heavy ions. 5. Achievements - outstanding
questions.
Title: A Extended "superhot" Solar Flare X-Ray Source
Authors: Hudson, H. S.; Ohki, K. I.; Tsuneta, S.
Bibcode: 1985ICRC....4...50H
Altcode: 1985ICRC...19d..50H
A superhot hard X-ray source in a solar flare occulted by the solar limb
was identified. Its hard X-ray image was found to show great horizontal
extent but little vertical extent. An H alpha brightening at the same
limb position about an hour later suggests a multi-component loop
prominence system, so that it appears that a superhot source can evolve
in the same manner as a normal solar soft X-ray source. The assignment
of plausiable values to physical parameters in the source suggests
(from the simplest form of classical thermal-conduction theory) that
either new physics will be required to suppress conduction, or else
that gradual energy release well after the impulsive phase of the
flare must occur. In this respect too, the superhot source appears
to resemble ordinary soft X-ray sources, except of course that its
temperature is higher.
Title: Heating and acceleration processes in hot thermal and impulsive
solar flares
Authors: Tsuneta, S.
Bibcode: 1985ApJ...290..353T
Altcode:
A simple numerical model describing the time-dependent characteristics
of hot thermal impulsive solar flares is presented. The model is
based on observations in the hard X-ray (about 10 keV) region carried
out onboard the Hinotori satellite. It is assumed in the model that a
steady electric field is applied by an external driver during the course
of flare evolution. Preliminary integrations of the model show that
the plasma density and in the energy release site plays an important
role in determining the mode of energy release in the flare. In the
impulsive phase, more than 10 to the 35th electrons per sec can escape
due to the relatively low plasma density of no more than 4 x 10 to the
10th per cubic cm. The estimated number of runaway electrons in the
model is found to be consistent with the observed target flux above
30-40 keV. In the gradual phase, electron runaway was reduced due to an
increase in plasma density. The plasma in the energy release site is in
the classical state throughout the flare, irrespective of the possible
ion-cyclotron turbulence at the onset of the impulsive phase. The model
parameters for the gradual phase of flare activity are given in a table.
Title: Hard X-ray imaging observations of solar hot thermal flares
with the HINOTORI spacecraft
Authors: Tsuneta, S.; Nitta, N.; Takakura, T.; Makishima, K.; Murakami,
T.; Oda, M.; Ogawara, Y.; Ohki, K.; Tanaka, K.
Bibcode: 1984ApJ...284..827T
Altcode:
Two solar hard X-ray bursts of a new type (hot thermal flare) were
observed with hard X-ray imaging telescopes and other instruments on
Japanese spacecraft Hinotori. The flares have no clear impulsive phase
below 40 keV and emit intense hard X-rays (10-50 keV) with extremely
steep spectra from a small region with size (FWHM) of 10-20 arcsec. This
source contains a hot thermal plasma of (3-3.5) x 10 to the 7th K with
an emission measure of the order of 10 to the 49th/cu cm. One of the
flares occurred just on the limb, and the centroid of the hard X-ray
(14-38 keV) source was located at (6 + or - 3) x 10 to the 3rd km
above the photosphere. It is concluded that the energy continuously
released goes into heating rather than acceleration almost throughout
the flare. Typical impulsive flares may usually have a similar nature
in the later phase (gradual phase) of the flare evolution.
Title: Hard X-ray imaging of the solar flare on 1981 May 13 with
the HINOTORI spacecraft
Authors: Tsuneta, S.; Takakura, T.; Nitta, N.; Makishima, K.; Murakami,
T.; Oda, M.; Ogawara, Y.; Kondo, I.; Ohki, K.; Tanaka, K.
Bibcode: 1984ApJ...280..887T
Altcode:
Hard X-ray images and X-ray spectra of an intense solar flare that
occurred at E58N09 on May 13, 1981 are presented and discussed. The
observation was made with Japanese solar X-ray spacecraft Hinotori. An
unusual hard X-ray source, observed at 14-38 keV, had a steady
spatial displacement of approximately 1 arcmin toward the limb from
the two-ribbon H-alpha flare during the 16 minutes of hard X-ray
observation, including the time of maximum flux. This suggests that the
source was located near the top of a coronal loop structure connecting
the two ribbons, at an estimated altitude of approximately 40,000 km
above the photosphere. The soft X-ray (5-10 keV) source nearly coincided
in position and size with the hard X-ray source. Near the peak of hard
X-ray time profile, approximately 40 percent of the total count rate of
the hard X-ray image is estimated to come from a power-law component,
as observed with the hard X-ray spectrometer. The parameters of the
thermal plasma near the loop top were determined to be n = 3 x 10
to the 10th per cu cm, T = 2 x 10 to the 7th K, and beta = 16(pi)
n k T/(B squared) approximately 1.0. Intense heat conduction from the
thermal plasma near the loop top to the transition region appears to
be in equilibrium with the continuous energy release near the loop top.
Title: Image processing software system of the X-ray telescope aboard
the HINOTORI spacecraft.
Authors: Tsuneta, S.
Bibcode: 1984AnTok..20....1T
Altcode: 1984AOTok..20....1T
Hard X-ray imaging of solar flares were successfully made with
the imaging X-ray telescope (SXT) aboard the Japanese solar flare
observation satellite HINOTORI, using the technique of the rotating
modulation collimator. The attitude-determination/image processing
software systems for the SXT are developed and verified. The method of
attitude analysis of the spacecraft, and image synthesis procedure are
described in detail. By the accurate determination of the spacecraft
aspect, the effect of nutation and time variation of the attitude of
the spacecraft on the X-ray data are almost completely corrected. This
makes possible the extremely accurate determination of the flare
location on the solar disk, and the synthesis of the hard X-ray image
with excellent quality.
Title: Part Two - Hard X-Ray Observations of Solar Flares - Recent
Results from HINOTORI Spacecraft
Authors: Tsuneta, S.
Bibcode: 1984apoa.conf..243T
Altcode:
Hard X-ray observations by the Japanese solar flare observation
spacecraft Hinotori are reviewed with emphasis on the results obtained
with the hard X-ray imaging telescopes. At least three types of X-ray
flares with distinctly different characteristics in hard X-ray image,
spectrum and time variability are clearly identified. They are discussed
in detail.
Title: Time variations of hard X-ray bursts observed with the Solar
X-ray Telescope aboard Hinotori (with a movie)
Authors: Kosugi, T.; Tsuneta, S.
Bibcode: 1983SoPh...86..333K
Altcode:
We have developed a new method for synthesizing hard X-ray maps from the
raw data of the Solar X-ray Telescope (SXT) aboard Hinotori. Using this
method we analyzed five typical SXT events and summarized their images
in a movie with a time resolution of about 8 s (half spin period of the
satellite). The movie clearly shows that (1) three different classes
of bursts, i.e., the gradual thermal burst, the multiple impulsive
burst, and the extended outburst, have different structures and show
quite different variations from each other, and that (2) the source
of the extended outburst is located in the corona above 104
km and its shape appears to be a large loop.
Title: Hard X-ray imaging of a solar limb flare with the X-ray
telescope aboard the HINOTORI satellite
Authors: Takakura, T.; Tsuneta, S.; Nitta, N.; Makishima, K.; Murakami,
T.; Ogawara, Y.; Oda, M.; Ohki, K.; Miyamoto, S.
Bibcode: 1983ApJ...270L..83T
Altcode:
X-ray images of the intense solar X-ray burst of Apr. 27, 1981 which
were made aboard the satellite Hinotori are discussed. The hard
X-ray telescope aboard the satellite is described, and the mapping
spectrometric functions are considered. The hard X-ray images are shown
along with time profiles of the flare. The images reveal the height
structure of a strong hard X-ray source located in the corona. The
source contains two sources, a steady main one of about 20 arcsec and
a subordinate one exhibiting variable intensity relative to the main
source. Both sources were located in the corona without any evidence
of an appreciable chromospheric source throughout the observation. The
obtained photon spectra fit better to power laws than to isothermal
spectra.
Title: General aspects of hard X-ray flares observed by Hinotori:
Gradual burst and impulsive burst
Authors: Ohki, K.; Takakura, T.; Tsuneta, S.; Nitta, N.
Bibcode: 1983SoPh...86..301O
Altcode:
We survey here the observational results on five gradual and four
impulsive type events from the hard X-ray imaging (SXT) and spectrometer
(HXM) instruments on the Hinotori satellite. A set of differences are
clearly recognized between the gradual and impulsive type bursts. These
are: (1) Hard X-ray images show the existence of a large coronal
source for each gradual burst and a wide variety of source structures
for impulsive bursts. (2) The source heights of the impulsive bursts
appear to be low. (3) All gradual bursts show power-law spectra while
impulsive bursts show exponential thermal spectra at least before the
maximum phase. (4) Energy-dependent peak delays are observed only in
gradual bursts. From these differences we suggest that two different
acceleration and emission mechanisms are involved with these two kinds
of hard X-ray bursts.
Title: Vertical Structure of Hard X-Ray Flares
Authors: Tsuneta, S.; Takakura, T.; Nitta, N.; Ohki, K.; Makishima,
K.; Murakami, T.; Oda, M.; Ogawara, Y.
Bibcode: 1983SoPh...86..313T
Altcode:
This paper presents studies of the vertical structure of hard X-ray
flares for two contrasting examples. The 1981 May 13 flare contained
a coronal hard X-ray source which was located above 50000 km above
the photosphere. On the other hand, the 1981 July 20 flare had a
chromospheric double source structure in the initial phase. Electrons
in this case were able to stream freely from the corona to the
chromosphere.
Title: Hard X-Ray Images of Impulsive Bursts
Authors: Takakura, T.; Ohki, K.; Tsuneta, S.; Nitta, N.
Bibcode: 1983SoPh...86..323T
Altcode:
A morphological study is made for the hard X-ray images (25-50 keV)
of nine impulsive bursts observed by Hinotori. Most of them revealed
single sources, either extended or compact, during the whole duration
of the bursts. The sources of all of four spike bursts in the present
sample are compact. After the main phase of the impulsive bursts,
generally the source size becomes smaller accompanying a shift of
position. The X-ray source size is much greater than that of the Hα
kernel in two events out of three. Four possible explanations for the
X-ray source to be single are suggested. One of these is the strong
electric field along the magnetic field as demonstrated to be produced
at the decay of force-free current.
Title: Hard X-ray imaging of solar flares with the HINOTORI
spacecraft.
Authors: Tsuneta, S.
Bibcode: 1983AstHe..76..289T
Altcode:
No abstract at ADS
Title: Sub-second Pulsations Simultaneously Observed at Microwaves
and Hard X-rays in a Solar Burst
Authors: Takakura, T.; Kaufmann, P.; Degaonkar, S. S.; Costa, J. E. R.;
Ohki, K.; Nitta, N.; Tsuneta, S.
Bibcode: 1982BAAS...14..879T
Altcode:
No abstract at ADS
Title: Hard X-Ray Imaging by SXT - Compact Sources
Authors: Tsuneta, S.; Ohki, K.; Takakura, T.; Nitta, N.; Makishima,
K.; Murakami, T.; Ogawara, Y.; Oda, M.; Kondo, I.
Bibcode: 1982sofl.symp..130T
Altcode:
No abstract at ADS
Title: Hard X-Ray Imaging by SXT - Extended Sources
Authors: Takakura, T.; Ohki, K.; Tsuneta, S.; Nitta, N.; Makishima,
K.; Murakami, T.; Ogawara, Y.; Oda, M.
Bibcode: 1982sofl.symp..142T
Altcode:
No abstract at ADS
Title: Results from the Hard X-Ray Spectrometer - Hxm
Authors: Ohki, K.; Nitta, N.; Tsuneta, S.; Takakura, T.; Makishima,
K.; Murakami, T.; Ogawara, Y.; Oda, M.
Bibcode: 1982sofl.symp...69O
Altcode:
No abstract at ADS
Title: Hard X-ray imaging of solar flares with HINOTORI SXT
Authors: Takakura, T.; Nitta, N.; Tsuneta, S.; Makishima, K.; Murakami,
T.; Oda, M.; Ogawara, Y.; Ohki, K.; Shibuya, N.; Miyamoto, S.
Bibcode: 1982spte.symp.1597T
Altcode:
Japanese solar X-ray satellite Hinotori was launched on February 21,
1981. The hard X-ray telescope installed in this satellite is designed
to observe the images of hard solar X-ray bursts in a band typically 20
- 40 keV with a high angular resolution, a moderate time resolution and
a wide field of view. More than 100 solar X-ray bursts with sufficient
fluxes for imaging have been detected so far. The instrumentation of
the telescope is presented in this report.
Title: Solar hard X-ray images observed by Astro-A
Authors: Ohki, K.; Tsuneta, S.; Nitta, N.; Takakura, T.; Makishima,
K.; Murakami, T.; Ogawara, Y.; Oda, M.
Bibcode: 1982AIPC...77..395O
Altcode: 1982grtr.work..395O
Observations with the solar X-ray telescope on board the Astro A
satellite are reviewed and analyzed. The instrument has a sensitivity
range in the 17-60 keV interval. A total of 20 large X-ray events were
observed between February and August 1981. Analyses are presented
of one limb and one disk event. The April 27 limb flare in region
3049 produced a count increase to 60,000/sec on the lowest energy
channel. An April 2 event showed a size less than 10 arcsec on the
solar surface. An electron density of 6.2 x 10 to the 46/cu cm was
calculated, with field particles exceeding 20 billion/cu cm. Details
of the satellite scanning capabilities are described.
Title: Fan-Beam Observations of Millimeter Wave Burst Associated
with X-Ray and Gamma-Ray Events Detected from HINOTORI
Authors: Kawabata, K.; Ogawa, H.; Takakura, T.; Tsuneta, S.; Ohki,
K.; Yoshimori, M.; Okudaira, K.; Hirasima, Y.; Kondo, I.
Bibcode: 1982sofl.symp..168K
Altcode:
No abstract at ADS
Title: Hard X-Ray Imaging by SXT - Comparisons with Hα Data
Authors: Ohki, K.; Tsuneta, S.; Takakura, T.; Nitta, N.; Makishima,
K.; Murakami, T.; Ogawara, Y.; Oda, M.; Miyamoto, S.
Bibcode: 1982sofl.symp..102O
Altcode:
No abstract at ADS
Title: Solar Hard X-Ray Images Observed by Astro-A
Authors: Ohki, K.; Tsuneta, S.; Nitta, N.; Takakura, T.; Makishima,
K.; Murakami, T.; Ogawara, Y.; Oda, M.
Bibcode: 1981AIPC...77..395O
Altcode:
The Solar X-ray Telescope (SXT) on board the Astro-A has observed many
events since its launch on February 21, 1981. Several of the largest
events with counting rates <104 c/s, have been analyzed to reveal
very compact sources for the large hard X-ray bursts. Although a few
limb events show some extended features up to about one arcmin, most
events have linear dimensions less than the FWHM of the SXT triangular
response, which is about 30 arcseconds. This compactness of the largest
events may conflict with traditional models of hard X-ray sources,
including thin and thick target models. In this paper, two typical
large events are presented. A disk event on April 2, 1981, shows a
single source with a very small diameter, while a April 27, 1981,
limb event shows a double source structure with unbalanced intensities.