Author name code: shimojo
ADS astronomy entries on 2022-09-14
author:"Shimojo, Masumi"
------------------------------------------------------------------------
Title: Solar Observing with the Atacama Large Millimeter-Submillimeter
Array
Authors: Bastian, Timothy; Shimojo, Masumi; Barta, Miroslav; White,
Stephen; Iwai, Kazumasa
Bibcode: 2022arXiv220901659B
Altcode:
The Atacama Large Millimeter-submillimeter Array (ALMA), sited on the
high desert plains of Chajnantor in Chile, has opened a new window onto
solar physics in 2016 by providing continuum observations at millimeter
and sub-millimeter wavelengths with an angular resolution comparable
to that available at optical (O), ultraviolet (UV), extreme ultraviolet
(EUV), and X-ray wavelengths, and with superior time resolution. In the
intervening years, progress has been made testing and commissioning
new observing modes and capabilities, in developing data calibration
strategies, and in data imaging and restoration techniques. Here we
review ALMA current solar observing capabilities, the process by which
a user may propose to use the instrument, and summarize the observing
process and work flow. We then discuss some of the challenges users
may encounter in imaging and analyzing their data. We conclude with a
discussion of additional solar observing capabilities and modes under
consideration that are intended to further exploit the unique spectral
coverage provided by ALMA.
Title: An ALMA Observation of Time Variations in Chromospheric
Temperature of a Solar Plage Region
Authors: Abe, Masashi; Shimizu, Toshifumi; Shimojo, Masumi
Bibcode: 2022FrASS...9.8249A
Altcode:
Nanoflares and the shock formation of magnetohydrodynamic waves in the
solar chromosphere have been considered as key physical mechanisms
of the heating of the chromosphere and corona. To investigate
candidates of their signature in the mm-wavelength, a tiny active
region located on the solar disk was observed with the Atacama Large
millimeter and sub-millimeter Array (ALMA) at 3 mm, coordinated with
observatories on orbit including Hinode SOT spectro-polarimeter in
the Cycle 4 solar campaign (19 March 2017). ALMA's spatial resolution
was moderate, far from the best performance, but it provided stable
conditions that are suitable to investigate temporal variations in the
mm-wavelength. We determined that the noise level is less than 20 K
(σ) over 1 hour in the 20-s cadence time series of synthesized ALMA
images. The time variations with amplitudes above the noise level
were observed throughout the field of view, but variations exceeding
200 K, corresponding to energy input to the chromosphere on the order
of 1020-22 erg, were localized in two locations. One location was on
the polarity inversion line, where tiny concentrated magnetic patches
exist in weak field and a tiny magnetic flux may be emergent. The
other location was at the outer edge of a bipolar magnetic region,
which was under development with a successive series of magnetic flux
emergence. This observation suggests that nanoflare-class energy inputs
in the chromosphere can occur associated with emerging flux activities.
Title: Over seven decades of solar microwave data obtained with
Toyokawa and Nobeyama Radio Polarimeters
Authors: Shimojo, Masumi; Iwai, Kazumasa
Bibcode: 2022arXiv220507454S
Altcode:
Monitoring observations of solar microwave fluxes and their
polarization began in Japan during the 1950s at Toyokawa and
Mitaka. At present (April 2022), monitoring observations continue
with the Nobeyama Radio Polarimeters (NoRP) at the Nobeyama campus
of the National Astronomical Observatory of Japan (NAOJ). In this
paper, we present a brief history of the solar microwave monitoring
observations preceding those now carried out by NoRP. We then
review the solar microwave obtained at Toyokawa and Nobeyama and
their metadata. The datasets are publicly provided by the Solar
Data Archive System (SDAS) operated by the Astronomy Data Center
of the NAOJ, via http (https://solar.nro.nao.ac.jp/norp/) and FTP
(ftp://solar-pub.nao.ac.jp/pub/nsro/norp/) protocols.
Title: Simultaneous ALMA-Hinode-IRIS Observations on Footpoint
Signatures of a Soft X-Ray Loop-like Microflare
Authors: Shimizu, Toshifumi; Shimojo, Masumi; Abe, Masashi
Bibcode: 2021ApJ...922..113S
Altcode: 2021arXiv210911215S
Microflares have been considered to be among the major energy
input sources to form active solar corona. To investigate the
response of the low atmosphere to events, we conducted an Atacama
Large Millimeter/submillimeter Array (ALMA) observation at 3 mm,
coordinated with Interface Region Imaging Spectrograph (IRIS) and
Hinode observations, on 2017 March 19. During the observations, a soft
X-ray loop-type microflare (active region transient brightening) was
captured using the Hinode X-ray telescope in high temporal cadence. A
brightening loop footpoint is located within narrow fields of view of
ALMA, IRIS slit-jaw imager, and Hinode spectropolarimeter. Counterparts
of the microflare at the footpoint were detected in Si IV and ALMA
images, while the counterparts were less apparent in C II and Mg II
k images. Their impulsive time profiles exhibit the Neupert effect
pertaining to soft X-ray intensity evolution. The magnitude of thermal
energy measured using ALMA was approximately 100 times smaller than
that measured in the corona. These results suggest that impulsive
counterparts can be detected in the transition region and upper
chromosphere, where the plasma is thermally heated via impinging
nonthermal particles. Our energy evaluation indicates a deficit of
accelerated particles that impinge the footpoints for a small class
of soft X-ray microflares. The footpoint counterparts consist of
several brightening kernels, all of which are located in weak (void)
magnetic areas formed in patchy distribution of strong magnetic flux
at the photospheric level. The kernels provide a conceptual image in
which the transient energy release occurs at multiple locations on
the sheaths of magnetic flux bundles in the corona.
Title: Enhancing ALMA's Future Observing Capabilities
Authors: Maud, L.; Villard, E.; Takahashi, S.; Asaki, Y.; Bastian, T.;
Cortes, P.; Crew, G.; Fomalont, E.; Hales, A.; Ishii, S.; Matthews,
L.; Messias, H.; Nagai, H.; Sawada, T.; Schieven, G.; Shimojo, M.;
Vila-Vilaro, B.; Biggs, A.; Petry, D.; Phillips, N.; Paladino, R.
Bibcode: 2021Msngr.183...13M
Altcode:
With each observing cycle at the Atacama Large Millimeter/submillimeter
Array (ALMA) new features and observing modes are offered. Here we
provide some background about how these new capabilities are tested
and then made available to ALMA users. These activities help to drive
the cutting-edge science conducted with ALMA and to maintain ALMA's
position as the foremost interferometric array operating at millimetre
and submillimetre wavelengths. We focus in particular on opening up
high-frequency observing using ALMA's longest baselines, which offers
the highest possible angular resolution.
Title: The ObsMode 2020 Process
Authors: Takahashi, Satoko; Fomalont, Edward B.; Asaki, Yoshiharu;
Crew, Geoff; Matthews, Lynn D.; Cortes, Paulo; Vila-Vilaro, Baltasar;
Bastian, Tim; Shimojo, Masumi; Biggs, Andy; Messias, Hugo; Hales,
Antonio; Villard, Eric; Humphreys, Elizabeth
Bibcode: 2021arXiv210412681T
Altcode:
ObsMode is a yearly process which aims at preparing capabilities
for future ALMA Observing cycles. The process has been running for
a number of years tied to each ALMA observing cycle, with various
leaderships. This document specifically summarizes the ObsMode2020
process (April- October 2020) with a new scheme led by the Joint
ALMA Observatory. In the ObsMode2020 process, seven capabilities are
identified as high priority items, for which it was originally aimed
to be ready for Cycle 9. However, because of the observatory shutdown
due to the covid-19 pandemic, we were forced to delay the test plan by
one year. While no new data sets were obtained during the observatory
shutdown, verifications using the existing data allowed us to offer
the 7m-array polarization capability (in ACA standalone mode, single
field) for Cycle 8 starting from October, 2021. In addition, subsystem
readiness and policy-side preparations for the phased array observing
mode were improved for Cycle 8. Other high priority items were decided
to be carried over to the ObsMode2021 process.
Title: Observations of Solar Spicules at Millimeter and Ultraviolet
Wavelengths
Authors: Bastian, T.; De Pontieu, B.; Shimojo, M.; Iwai, K.;
Alissandrakis, C.; Nindos, A.; Vial, J. C.; White, S. M.
Bibcode: 2020AGUFMSH004..08B
Altcode:
Solar spicules are a ubiquitous chromospheric phenomenon in which
multitudes of dynamic jets with temperatures of order 104
K extend thousands of kilometers into the solar atmosphere. Recent
progress has been made refining the observational characteristics
of spicules using the Hinode Solar Optical Telescope (SOT) and the
Interface Region Imaging Spectrograph (IRIS) observations at optical
and ultraviolet wavelengths, respectively. Two types of spicule
have been identified. Type I spicules, prevalent in solar active
regions, have upward speeds of order 25 km/s and lifetimes of 3-7
min. They may be the limb counterpart to shock-wave-driven fibrils
commonly seen against the solar disk in active regions. In contrast,
type II spicules, more common in quiet regions and coronal holes,
display upward speeds of 50-150 km/s, lifetimes of 30-110 s, and
appear to be partially heated to temperatures of 105 K and
higher. These observations have provoked intense interest in spicules
and have led to proposals that type II spicules play a central role
as a source of hot plasma in the corona. Nevertheless, their role in
mass and energy transport between the lower and upper layers of the
solar atmosphere remains an outstanding problem. Here, we report
imaging observations of solar spicules at millimeter wavelengths using
the Atacama Large Millimeter-submillimeter Array (ALMA) with arcsecond
angular resolution. Continuum millimeter wavelength radiation forms
under conditions of local thermodynamic equilibrium, thereby providing a
complementary tool to UV lines, which form under non-LTE conditions. The
observations were made on 2018 December 24-25 at λ=1.25 mm and λ=3
mm. The ALMA observations pose special challenges, particularly at
1.25 mm, where the limited field of view of the instrument motivated
us to use a novel mosaic imaging technique: multiple pointings were
assembled to form a single map with an angular resolution of 1" x 0.7"
on a cadence of roughly 2 min. In contrast, we were able to image at 3
mm continuously, with a map cadence of 2 s and an angular resolution of
2.3" x 1.3". We compare and contrast the morphology and dynamics
of mm-λ observations of spicules with those obtained by IRIS at UV
wavelengths and place constraints on spicule temperatures and masses
using the joint millimeter-wavelength observations.
Title: Estimating the Temperature and Density of a Spicule from 100
GHz Data Obtained with ALMA
Authors: Shimojo, Masumi; Kawate, Tomoko; Okamoto, Takenori J.;
Yokoyama, Takaaki; Narukage, Noriyuki; Sakao, Taro; Iwai, Kazumasa;
Fleishman, Gregory D.; Shibata, Kazunari
Bibcode: 2020ApJ...888L..28S
Altcode: 2019arXiv191205714S
We succeeded in observing two large spicules simultaneously with the
Atacama Large Millimeter/submillimeter Array (ALMA), the Interface
Region Imaging Spectrograph (IRIS), and the Atmospheric Imaging Assembly
(AIA) on board the Solar Dynamics Observatory. One is a spicule seen
in the IRIS Mg II slit-jaw images and AIA 304 Å images (Mg II/304 Å
spicule). The other one is a spicule seen in the 100 GHz images obtained
with ALMA (100 GHz spicule). Although the 100 GHz spicule overlapped
with the Mg II/304 Å spicule in the early phase, it did not show any
corresponding structures in the IRIS Mg II and AIA 304 Å images after
the early phase. It suggests that the spicules are individual events and
do not have a physical relationship. To obtain the physical parameters
of the 100 GHz spicule, we estimate the optical depths as a function
of temperature and density using two different methods. One is using
the observed brightness temperature by assuming a filling factor,
and the other is using an emission model for the optical depth. As a
result of comparing them, the kinetic temperature of the plasma and
the number density of ionized hydrogen in the 100 GHz spicule are
∼6800 K and 2.2 × 1010 cm-3. The estimated
values can explain the absorbing structure in the 193 Å image, which
appear as a counterpart of the 100 GHz spicule. These results suggest
that the 100 GHz spicule presented in this Letter is classified to a
macrospicule without a hot sheath in former terminology.
Title: Estimating the temperature and density of a spicule from 100
GHz data obtained with ALMA
Authors: Shimojo, M.; Kawate, T.; Okamoto, T. J.; Yokoyama, T.
Bibcode: 2019AGUFMSH41F3336S
Altcode:
We succeeded in observing two large spicules simultaneously with the
Atacama Large Millimeter/submillimeter Array (ALMA), the Interface
Region Imaging Spectrograph explorer (IRIS), and the Atmospheric
Imaging Assembly (AIA) onboard the Solar Dynamics Observatory. One is
a spicule seen in the IRIS Mg II slit-jaw images and AIA 304 Å images
(MgII/304Å spicule). The other one is a spicule seen in the 100 GHz
images obtained with ALMA (100 GHz spicule). Although the 100 GHz
spicule in the early phase overlapped with the MgII/304Å spicule,
we cannot find any remarkable enhancement temporally and spatially
caused by the 100 GHz spicule in the IRIS Mg II and AIA 304 Å
images. Moreover, there is no overlapped region between the 100 GHz
spicule and Mg II/304Å spicule in the late phase. It would suggest
that the spicules are individual events and do not have a physical
relationship. To obtain the physical parameters of the 100 GHz spicule
from the ALMA data, we estimated two optical depths of the 100 GHz
spicule from the observed brightness temperature and an emission model
with assumed temperature and density. As a result of comparing them,
the temperature and density of the 100 GHz spicule are 4000 - 7000 K
and 2.2×1010 cm-3. The estimated values can
explain the absorbing structure that is the counterpart of the 100
GHz spicule in the 193Å image.
Title: Achievements of Hinode in the first eleven years
Authors: Hinode Review Team; Al-Janabi, Khalid; Antolin, Patrick;
Baker, Deborah; Bellot Rubio, Luis R.; Bradley, Louisa; Brooks,
David H.; Centeno, Rebecca; Culhane, J. Leonard; Del Zanna, Giulio;
Doschek, George A.; Fletcher, Lyndsay; Hara, Hirohisa; Harra,
Louise K.; Hillier, Andrew S.; Imada, Shinsuke; Klimchuk, James A.;
Mariska, John T.; Pereira, Tiago M. D.; Reeves, Katharine K.; Sakao,
Taro; Sakurai, Takashi; Shimizu, Toshifumi; Shimojo, Masumi; Shiota,
Daikou; Solanki, Sami K.; Sterling, Alphonse C.; Su, Yingna; Suematsu,
Yoshinori; Tarbell, Theodore D.; Tiwari, Sanjiv K.; Toriumi, Shin;
Ugarte-Urra, Ignacio; Warren, Harry P.; Watanabe, Tetsuya; Young,
Peter R.
Bibcode: 2019PASJ...71R...1H
Altcode:
Hinode is Japan's third solar mission following Hinotori (1981-1982)
and Yohkoh (1991-2001): it was launched on 2006 September 22 and is in
operation currently. Hinode carries three instruments: the Solar Optical
Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These
instruments were built under international collaboration with the
National Aeronautics and Space Administration and the UK Science and
Technology Facilities Council, and its operation has been contributed
to by the European Space Agency and the Norwegian Space Center. After
describing the satellite operations and giving a performance evaluation
of the three instruments, reviews are presented on major scientific
discoveries by Hinode in the first eleven years (one solar cycle long)
of its operation. This review article concludes with future prospects
for solar physics research based on the achievements of Hinode.
Title: The Disappearing Solar Filament of 2013 September 29 and Its
Large Associated Proton Event: Implications for Particle Acceleration
at the Sun
Authors: Cliver, E. W.; Kahler, S. W.; Kazachenko, M.; Shimojo, M.
Bibcode: 2019ApJ...877...11C
Altcode:
We present observations of a notable example of a disappearing solar
filament (DSF) on 2013 September 29 that was associated with a large
solar proton event (SPE) and discuss this event in the context of
four recent studies that compare flare and SPE size parameters. The
DSF-associated flare was characterized by weak radio and soft X-ray
emissions and a low reconnection flux. It was accompanied by a fast
coronal mass ejection (CME) and a decametric-hectometric type II
burst. We assembled a list of eight such events that are outliers
in plots of SPE versus flare size parameters. These events were
characterized by weak magnetic field source regions (predominantly
DSFs but including one case of a transequatorial loop and another
of a decaying active region), fast CMEs, type II bursts with low
starting frequencies, high proton yields (ratio of proton intensity
to 1 MHz radio fluence), and low high-energy Fe/O ratios. The last
of these attributes suggests quasi-parallel shock acceleration. The
relationship between SPE and flare size parameters in large (gradual),
well-connected proton events can be illustrated by a schematic diagram
with three principal regions: (1) a DSF zone of weak flares and large
SPEs, (2) a big flare syndrome main sequence of loosely correlated flare
and SPE parameters, and (3) a zone of moderate to large flares with no
SPEs. The existence of regions 1 and 3 argues against a significant
role for flares in large proton events: region 1 implies that flares
are not necessary for such SPEs, and region 3 indicates that they are
not sufficient.
Title: Observations of photospheric magnetic structure below a dark
filament using the Hinode Spectro-Polarimeter
Authors: Yokoyama, Takaaki; Katsukawa, Yukio; Shimojo, Masumi
Bibcode: 2019PASJ...71...46Y
Altcode: 2019arXiv190110695Y; 2019PASJ..tmp...26Y
The structure of the photospheric vector magnetic field below a
dark filament on the Sun is studied using the observations of the
Spectro-Polarimeter attached to the Solar Optical Telescope onboard
Hinode. Special attention is paid to discriminating between two
suggested models, a flux rope or a bent arcade. "Inverse polarity"
orientation is possible below the filament in a flux rope, whereas
"normal polarity" can appear in both models. We study a filament in the
active region NOAA 10930, which appeared on the solar disk during 2006
December. The transverse field perpendicular to the line of sight has a
direction almost parallel to the filament spine with a shear angle of
30°, the orientation of which includes the 180° ambiguity. To know
whether it is in the normal orientation or in the inverse one, the
center-to-limb variation is used for the solution under the assumption
that the filament does not drastically change its magnetic structure
during the passage. When the filament is near the east limb, we found
that the line-of-site magnetic component below the filament is positive,
while it is negative near the west limb.This change of sign indicates
that the horizontal photospheric field perpendicular to the polarity
inversion line beneath the filament has an "inverse-polarity", which
indicates a flux-rope structure of the filament supporting field.
Title: ALMA Observations of the Solar Chromosphere on the Polar Limb
Authors: Yokoyama, Takaaki; Shimojo, Masumi; Okamoto, Takenori J.;
Iijima, Haruhisa
Bibcode: 2018ApJ...863...96Y
Altcode: 2018arXiv180701411Y
We report the results of the Atacama Large Millimeter/sub-millimeter
Array (ALMA) observations of the solar chromosphere on the southern
polar limb. Coordinated observations with the Interface Region Imaging
Spectrograph (IRIS) are also conducted. ALMA provided unprecedented
high spatial resolution in the millimeter band (≈2.″0) at 100
GHz frequency with a moderate cadence (20 s). The results are as
follows. (1) The ALMA 100 GHz images show saw-tooth patterns on the
limb, and a comparison with Solar Dynamics Observatory/Atmospheric
Imaging Assembly 171 Å images shows a good correspondence of the limbs
with each other. (2) The ALMA animation shows a dynamic thorn-like
structure elongating from the saw-tooth patterns on the limb, with
lengths reaching at least 8″, thus suggesting jet-like activity in
the ALMA microwave range. These ALMA jets are in good correspondence
with the IRIS jet clusters. (3) A blob-ejection event is observed. By
comparing with the IRIS Mg II slit-jaw images, the trajectory of the
blob is located along the spicular patterns.
Title: Erratum: “A First Comparison of Millimeter Continuum and
Mg II Ultraviolet Line Emission from the Solar Chromosphere”
(2017, ApJL,
845, L19)
Authors: Bastian, T. S.; Chintzoglou, G.; De Pontieu, B.; Shimojo,
M.; Schmit, D.; Leenaarts, J.; Loukitcheva, M.
Bibcode: 2018ApJ...860L..16B
Altcode:
No abstract at ADS
Title: First analysis of solar structures in 1.21 mm full-disc ALMA
image of the Sun
Authors: Brajša, R.; Sudar, D.; Benz, A. O.; Skokić, I.; Bárta,
M.; De Pontieu, B.; Kim, S.; Kobelski, A.; Kuhar, M.; Shimojo, M.;
Wedemeyer, S.; White, S.; Yagoubov, P.; Yan, Y.
Bibcode: 2018A&A...613A..17B
Altcode: 2017arXiv171106130B
Context. Various solar features can be seen in emission or absorption
on maps of the Sun in the millimetre and submillimetre wavelength
range. The recently installed Atacama Large Millimetre/submillimetre
Array (ALMA) is capable of observing the Sun in that wavelength range
with an unprecedented spatial, temporal and spectral resolution. To
interpret solar observations with ALMA, the first important step is to
compare solar ALMA maps with simultaneous images of the Sun recorded in
other spectral ranges.
Aims: The first aim of the present work
is to identify different structures in the solar atmosphere seen in the
optical, infrared, and EUV parts of the spectrum (quiet Sun, active
regions, prominences on the disc, magnetic inversion lines, coronal
holes and coronal bright points) in a full-disc solar ALMA image. The
second aim is to measure the intensities (brightness temperatures) of
those structures and to compare them with the corresponding quiet Sun
level.
Methods: A full-disc solar image at 1.21 mm obtained on
December 18, 2015, during a CSV-EOC campaign with ALMA is calibrated and
compared with full-disc solar images from the same day in Hα line, in
He I 1083 nm line core, and with various SDO images (AIA at 170 nm, 30.4
nm, 21.1 nm, 19.3 nm, and 17.1 nm and HMI magnetogram). The brightness
temperatures of various structures are determined by averaging over
corresponding regions of interest in the calibrated ALMA image.
Results: Positions of the quiet Sun, active regions, prominences on
the disc, magnetic inversion lines, coronal holes and coronal bright
points are identified in the ALMA image. At the wavelength of 1.21
mm, active regions appear as bright areas (but sunspots are dark),
while prominences on the disc and coronal holes are not discernible
from the quiet Sun background, despite having slightly less intensity
than surrounding quiet Sun regions. Magnetic inversion lines appear as
large, elongated dark structures and coronal bright points correspond
to ALMA bright points.
Conclusions: These observational results
are in general agreement with sparse earlier measurements at similar
wavelengths. The identification of coronal bright points represents
the most important new result. By comparing ALMA and other maps,
it was found that the ALMA image was oriented properly and that the
procedure of overlaying the ALMA image with other images is accurate
at the 5 arcsec level. The potential of ALMA for physics of the solar
chromosphere is emphasised.
Title: Exploring the Sun with ALMA
Authors: Bastian, T. S.; Bárta, M.; Brajša, R.; Chen, B.; Pontieu,
B. D.; Gary, D. E.; Fleishman, G. D.; Hales, A. S.; Iwai, K.; Hudson,
H.; Kim, S.; Kobelski, A.; Loukitcheva, M.; Shimojo, M.; Skokić,
I.; Wedemeyer, S.; White, S. M.; Yan, Y.
Bibcode: 2018Msngr.171...25B
Altcode:
The Atacama Large Millimeter/submillimeter Array (ALMA) Observatory
opens a new window onto the Universe. The ability to perform continuum
imaging and spectroscopy of astrophysical phenomena at millimetre and
submillimetre wavelengths with unprecedented sensitivity opens up new
avenues for the study of cosmology and the evolution of galaxies, the
formation of stars and planets, and astrochemistry. ALMA also allows
fundamentally new observations to be made of objects much closer
to home, including the Sun. The Sun has long served as a touchstone
for our understanding of astrophysical processes, from the nature of
stellar interiors, to magnetic dynamos, non-radiative heating, stellar
mass loss, and energetic phenomena such as solar flares. ALMA offers
new insights into all of these processes.
Title: A comparison of solar ALMA observations and model based
predictions of the brightness temperature
Authors: Brajša, R.; Kuhar, M.; Benz, A. O.; Skokić, I.; Sudar,
D.; Wedemeyer, S.; Báarta, M.; De Pontieu, B.; Kim, S.; Kobelski,
A.; Shimojo, M.; White, S.; Yagoubov, P.; Yan, Y.; Ludwig, H. G.;
Temmer, M.; Saar, S. H.; Selhorst, C. L.; Beuc, R.
Bibcode: 2018CEAB...42....1B
Altcode:
The new facility Atacama Large Millimeter/submillimeter Array (ALMA) is
capable of observing the Sun in the wavelength range from 0.3 mm to 10
mm with an unprecedented spatial, temporal and spectral resolution. The
first aim of the present work is to identify different structures
in the solar atmosphere (quiet Sun, active regions, filaments on the
disc, and coronal holes) in a full disc solar ALMA image at 1.21 mm
obtained on December 18, 2015 during a CSV-EOC campaign. It is compared
with full disc solar images from the same day in the Hα line (Cerro
Tololo Observatory, NISP), and at three EUV wavelengths (30.4 nm,
21.1 nm, 17.1 nm; a composite SDO image). Positions of the quiet Sun
areas, active regions, filaments on the disc, and coronal holes are
identified in the ALMA image. To interpret solar observations with ALMA
it is important to compare the measured and calculated intensities
of various solar structures. So, the second aim of this work is to
calculate the intensity (brightness temperature) for those structures
(quiet Sun, active regions, filaments on the disc, and coronal holes)
for a broad wavelength range (from 0.3 mm to 10 mm), closely related
to that of the ALMA, and to compare the results with available
ALMA observations. Thermal bremsstrahlung is the dominant radiation
mechanism for explanation of the observed phenomena. A procedure for
calculating the brightness temperature for a given wavelength and
model atmosphere, which integrates the radiative transfer equation
for thermal bremsstrahlung, is used. At the wavelength of 1.21 mm
active regions appear as bright areas, while filaments on the disc and
coronal holes are not discernible from the quiet Sun background. The
models generally agree with the observed results: Active regions are
bright primarily due to higher densities, filaments can appear bright,
dark or not at all and coronal holes cannot be easily identified.
Title: Hinode Science Center at NAOJ
Authors: Shimojo, Masumi
Bibcode: 2018ASSL..449..247S
Altcode:
No abstract at ADS
Title: ALMA Discovery of Solar Umbral Brightness Enhancement at λ =
3 mm
Authors: Iwai, K.; Loukitcheva, M.; Shimojo, M.; Solanki, S. K.;
White, S. M.
Bibcode: 2017AGUFMSH43A2806I
Altcode:
We report the discovery of a brightness enhancement in the center of
a large sunspot umbra at a wavelength of 3 mm using the Atacama Large
Millimeter/sub-millimeter Array (ALMA). Sunspots are among the most
prominent features on the solar surface, but many of their aspects are
surprisingly poorly understood. We analyzed a λ = 3 mm (100 GHz) mosaic
image obtained by ALMA that includes a large sunspot within the active
region AR12470, on 2015 December 16. The 3 mm map has a 300''×300''
field of view and 4.9''×2.2'' spatial resolution, which is the highest
spatial resolution map of an entire sunspot in this frequency range. We
find a gradient of 3 mm brightness from a high value in the outer
penumbra to a low value in the inner penumbra/outer umbra. Within the
inner umbra, there is a marked increase in 3 mm brightness temperature,
which we call an umbral brightness enhancement. This enhanced emission
corresponds to a temperature excess of 800 K relative to the surrounding
inner penumbral region and coincides with excess brightness in the
1330 and 1400 Å slit-jaw images of the Interface Region Imaging
Spectrograph (IRIS), adjacent to a partial lightbridge. This λ = 3 mm
brightness enhancement may be an intrinsic feature of the sunspot umbra
at chromospheric heights, such as a manifestation of umbral flashes, or
it could be related to a coronal plume, since the brightness enhancement
was coincident with the footpoint of a coronal loop observed at 171 Å.
Title: Strong magnetic field generated by the extreme oxygen-rich
red supergiant VY Canis Majoris
Authors: Shinnaga, Hiroko; Claussen, Mark J.; Yamamoto, Satoshi;
Shimojo, Masumi
Bibcode: 2017PASJ...69L..10S
Altcode: 2017PASJ..tmp...11S
Evolved stars experience high mass-loss rates forming thick
circumstellar envelopes (CSEs). The circumstellar material is made of
the result of stellar nucleosynthesis and, as such, plays a crucial role
in the chemical evolution of galaxies and the universe. Since asymmetric
geometries of CSEs are common, and with very complex structures for
some cases, radiative pressure from the stars can explain only a
small portion of the mass-loss processes; thus the essential driving
mechanism is still unknown, particularly for high-mass stars. Here we
report on magnetic field measurements associated with the well-known
extreme red supergiant (RSG) VY Canis Majoris (VY CMa). We measured
the linear polarization and the Zeeman splitting of the SiO v = 0, J =
1-0 transition using a sensitive radio interferometer. The measured
magnetic field strengths are surprisingly high; their upper limits
range between 150 and 650 G within 530 au (∼80 R*) of
the star. The lower limit of the field strength is expected to be at
least ∼10 G based on the high degree of linear polarization. Since
the field strengths are very high, the magnetic field must be a key
element in understanding the stellar evolution of VY CMa, as well
as the dynamical and chemical evolution of the complex CSE of the
star. M-type RSGs, with large stellar surface, were thought to be very
slow rotators. This would seem to make a dynamo in operation difficult,
and would also dilute any fossil magnetic field. At least for VY CMa,
we expect that powerful dynamo processes must still be active to
generate the intense magnetic field.
Title: The First ALMA Observation of a Solar Plasmoid Ejection from
an X-Ray Bright Point
Authors: Shimojo, M.; Hudson, H. S.; White, S. M.; Bastian, T.;
Iwai, K.
Bibcode: 2017AGUFMSH41A2754S
Altcode:
Eruptive phenomena are important features of energy releases events,
such solar flares, and have the potential to improve our understanding
of the dynamics of the solar atmosphere. The 304 A EUV line of helium,
formed at around 10^5 K, is found to be a reliable tracer of such
phenomena, but the determination of physical parameters from such
observations is not straightforward. We have observed a plasmoid
ejection from an X-ray bright point simultaneously with ALMA, SDO/AIA,
and Hinode/XRT. This paper reports the physical parameters of the
plasmoid obtained by combining the radio, EUV, and X-ray data. As
a result, we conclude that the plasmoid can consist either of
(approximately) isothermal ∼10^5 K plasma that is optically thin
at 100 GHz, or a ∼10^4 K core with a hot envelope. The analysis
demonstrates the value of the additional temperature and density
constraints that ALMA provides, and future science observations with
ALMA will be able to match the spatial resolution of space-borne and
other high-resolution telescopes.
Title: Solar ALMA Observations: Constraining the Chromosphere above
Sunspots
Authors: Loukitcheva, Maria A.; Iwai, Kazumasa; Solanki, Sami K.;
White, Stephen M.; Shimojo, Masumi
Bibcode: 2017ApJ...850...35L
Altcode: 2017arXiv171003812L
We present the first high-resolution Atacama Large
Millimeter/Submillimeter Array (ALMA) observations of a sunspot at
wavelengths of 1.3 and 3 mm, obtained during the solar ALMA Science
Verification campaign in 2015, and compare them with the predictions
of semi-empirical sunspot umbral/penumbral atmosphere models. For
the first time, millimeter observations of sunspots have resolved
umbral/penumbral brightness structure at the chromospheric heights,
where the emission at these wavelengths is formed. We find that the
sunspot umbra exhibits a radically different appearance at 1.3 and 3
mm, whereas the penumbral brightness structure is similar at the two
wavelengths. The inner part of the umbra is ∼600 K brighter than the
surrounding quiet Sun (QS) at 3 mm and is ∼700 K cooler than the QS
at 1.3 mm, being the coolest part of sunspot at this wavelength. On
average, the brightness of the penumbra at 3 mm is comparable to
the QS brightness, while at 1.3 mm it is ∼1000 K brighter than
the QS. Penumbral brightness increases toward the outer boundary in
both ALMA bands. Among the tested umbral models, that of Severino et
al. provides the best fit to the observational data, including both
the ALMA data analyzed in this study and data from earlier works. No
penumbral model among those considered here gives a satisfactory fit
to the currently available measurements. ALMA observations at multiple
millimeter wavelengths can be used for testing existing sunspot models,
and serve as an important input to constrain new empirical models.
Title: Variation of the Solar Microwave Spectrum in the Last Half
Century
Authors: Shimojo, Masumi; Iwai, Kazumasa; Asai, Ayumi; Nozawa, Satoshi;
Minamidani, Tetsuhiro; Saito, Masao
Bibcode: 2017ApJ...848...62S
Altcode: 2017arXiv170903695S
The total solar fluxes at 1, 2, 3.75, and 9.4 GHz were observed
continuously from 1957 to 1994 at Toyokawa, Japan, and from 1994 until
now at Nobeyama, Japan, with the current Nobeyama Radio Polarimeters. We
examined the multi-frequency and long-term data sets, and found that not
only the microwave solar flux but also its monthly standard deviation
indicate the long-term variation of solar activity. Furthermore, we
found that the microwave spectra at the solar minima of Cycles 20-24
agree with each other. These results show that the average atmospheric
structure above the upper chromosphere in the quiet-Sun has not varied
for half a century, and suggest that the energy input for atmospheric
heating from the sub-photosphere to the corona have not changed in
the quiet-Sun despite significantly differing strengths of magnetic
activity in the last five solar cycles.
Title: A First Comparison of Millimeter Continuum and Mg II
Ultraviolet Line Emission from the Solar Chromosphere
Authors: Bastian, T. S.; Chintzoglou, G.; De Pontieu, B.; Shimojo,
M.; Schmit, D.; Leenaarts, J.; Loukitcheva, M.
Bibcode: 2017ApJ...845L..19B
Altcode: 2017arXiv170604532B
We present joint observations of the Sun by the Atacama Large
Millimeter/submillimeter Array (ALMA) and the Interface Region Imaging
Spectrograph (IRIS). Both millimeter/submillimeter-λ continuum emission
and ultraviolet (UV) line emission originate from the solar chromosphere
and both have the potential to serve as powerful and complementary
diagnostics of physical conditions in this enigmatic region of the solar
atmosphere. The observations were made of a solar active region on 2015
December 18 as part of the ALMA science verification effort. A map of
the Sun’s continuum emission was obtained by ALMA at a wavelength of
1.25 mm (239 GHz). A contemporaneous map was obtained by IRIS in the
Mg II h doublet line at 2803.5 Å. While a clear correlation between
the 1.25 mm brightness temperature TB and the Mg II h
line radiation temperature Trad is observed, the slope
is <1, perhaps as a result of the fact that these diagnostics
are sensitive to different parts of the chromosphere and that the
Mg II h line source function includes a scattering component. There
is a significant difference (35%) between the mean TB
(1.25 mm) and mean Trad (Mg II). Partitioning the maps
into “sunspot,” “quiet areas,” and “plage regions” we
find the relation between the IRIS Mg II h line Trad and
the ALMA TB region-dependent. We suggest this may be the
result of regional dependences of the formation heights of the IRIS
and ALMA diagnostics and/or the increased degree of coupling between
the UV source function and the local gas temperature in the hotter,
denser gas in plage regions.
Title: Solar Commissioning Observations of the Sun with ALMA
Authors: White, Stephen M.; Shimojo, Masumi; Bastian, Timothy S.;
Iwai, Kazumasa; Hales, Antonio; Brajsa, Roman; Skokic, Ivica; Kim,
Sujin; Hudson, Hugh S.; Loukitcheva, Maria; Wedemeyer, Sven
Bibcode: 2017SPD....4820402W
Altcode:
PI-led science observations have commenced with the Atacama
Large Millimeter-submillimeter Array (ALMA) following an extensive
commissioning effort. This talk will summarize that effort and discuss
some of the scientific results derived from the commissioning data. As
the solar cycle declines, ALMA observations will mainly address
chromospheric science topics. Examples of data obtained during
commissioning, both from the interferometer and from single-dish
observations, will be presented. The temperatures of the layers that
ALMA is most sensitive to have been determined for the two frequency
bands currently used for solar observations. Curious behavior in a
sunspot umbra and an observations of a small chromospheric ejection
will be discussed.
Title: Observing the Sun with the Atacama Large
Millimeter/submillimeter Array (ALMA): High-Resolution Interferometric
Imaging
Authors: Shimojo, M.; Bastian, T. S.; Hales, A. S.; White, S. M.;
Iwai, K.; Hills, R. E.; Hirota, A.; Phillips, N. M.; Sawada, T.;
Yagoubov, P.; Siringo, G.; Asayama, S.; Sugimoto, M.; Brajša, R.;
Skokić, I.; Bárta, M.; Kim, S.; de Gregorio-Monsalvo, I.; Corder,
S. A.; Hudson, H. S.; Wedemeyer, S.; Gary, D. E.; De Pontieu, B.;
Loukitcheva, M.; Fleishman, G. D.; Chen, B.; Kobelski, A.; Yan, Y.
Bibcode: 2017SoPh..292...87S
Altcode: 2017arXiv170403236S
Observations of the Sun at millimeter and submillimeter wavelengths
offer a unique probe into the structure, dynamics, and heating of the
chromosphere; the structure of sunspots; the formation and eruption
of prominences and filaments; and energetic phenomena such as jets
and flares. High-resolution observations of the Sun at millimeter and
submillimeter wavelengths are challenging due to the intense, extended,
low-contrast, and dynamic nature of emission from the quiet Sun,
and the extremely intense and variable nature of emissions associated
with energetic phenomena. The Atacama Large Millimeter/submillimeter
Array (ALMA) was designed with solar observations in mind. The
requirements for solar observations are significantly different from
observations of sidereal sources and special measures are necessary
to successfully carry out this type of observations. We describe the
commissioning efforts that enable the use of two frequency bands,
the 3-mm band (Band 3) and the 1.25-mm band (Band 6), for continuum
interferometric-imaging observations of the Sun with ALMA. Examples of
high-resolution synthesized images obtained using the newly commissioned
modes during the solar-commissioning campaign held in December 2015
are presented. Although only 30 of the eventual 66 ALMA antennas
were used for the campaign, the solar images synthesized from the
ALMA commissioning data reveal new features of the solar atmosphere
that demonstrate the potential power of ALMA solar observations. The
ongoing expansion of ALMA and solar-commissioning efforts will continue
to enable new and unique solar observing capabilities.
Title: Observing the Sun with the Atacama Large
Millimeter/submillimeter Array (ALMA): Fast-Scan Single-Dish Mapping
Authors: White, S. M.; Iwai, K.; Phillips, N. M.; Hills, R. E.; Hirota,
A.; Yagoubov, P.; Siringo, G.; Shimojo, M.; Bastian, T. S.; Hales,
A. S.; Sawada, T.; Asayama, S.; Sugimoto, M.; Marson, R. G.; Kawasaki,
W.; Muller, E.; Nakazato, T.; Sugimoto, K.; Brajša, R.; Skokić, I.;
Bárta, M.; Kim, S.; Remijan, A. J.; de Gregorio, I.; Corder, S. A.;
Hudson, H. S.; Loukitcheva, M.; Chen, B.; De Pontieu, B.; Fleishmann,
G. D.; Gary, D. E.; Kobelski, A.; Wedemeyer, S.; Yan, Y.
Bibcode: 2017SoPh..292...88W
Altcode: 2017arXiv170504766W
The Atacama Large Millimeter/submillimeter Array (ALMA) radio
telescope has commenced science observations of the Sun starting
in late 2016. Since the Sun is much larger than the field of view
of individual ALMA dishes, the ALMA interferometer is unable to
measure the background level of solar emission when observing the
solar disk. The absolute temperature scale is a critical measurement
for much of ALMA solar science, including the understanding of energy
transfer through the solar atmosphere, the properties of prominences,
and the study of shock heating in the chromosphere. In order to provide
an absolute temperature scale, ALMA solar observing will take advantage
of the remarkable fast-scanning capabilities of the ALMA 12 m dishes
to make single-dish maps of the full Sun. This article reports on the
results of an extensive commissioning effort to optimize the mapping
procedure, and it describes the nature of the resulting data. Amplitude
calibration is discussed in detail: a path that uses the two loads in
the ALMA calibration system as well as sky measurements is described
and applied to commissioning data. Inspection of a large number of
single-dish datasets shows significant variation in the resulting
temperatures, and based on the temperature distributions, we derive
quiet-Sun values at disk center of 7300 K at λ =3 mm and 5900 K at
λ =1.3 mm. These values have statistical uncertainties of about 100
K, but systematic uncertainties in the temperature scale that may be
significantly larger. Example images are presented from two periods
with very different levels of solar activity. At a resolution of about
25″, the 1.3 mm wavelength images show temperatures on
the disk that vary over about a 2000 K range. Active regions and plages
are among the hotter features, while a large sunspot umbra shows up as
a depression, and filament channels are relatively cool. Prominences
above the solar limb are a common feature of the single-dish images.
Title: ALMA Discovery of Solar Umbral Brightness Enhancement at λ =
3 mm
Authors: Iwai, Kazumasa; Loukitcheva, Maria; Shimojo, Masumi; Solanki,
Sami K.; White, Stephen M.
Bibcode: 2017ApJ...841L..20I
Altcode: 2017arXiv170503147I
We report the discovery of a brightness enhancement in the center
of a large sunspot umbra at a wavelength of 3 mm using the Atacama
Large Millimeter/sub-millimeter Array (ALMA). Sunspots are among
the most prominent features on the solar surface, but many of their
aspects are surprisingly poorly understood. We analyzed a λ = 3 mm
(100 GHz) mosaic image obtained by ALMA that includes a large sunspot
within the active region AR12470, on 2015 December 16. The 3 mm map
has a 300″ × 300″ field of view and 4.″9 × 2.″2 spatial
resolution, which is the highest spatial resolution map of an entire
sunspot in this frequency range. We find a gradient of 3 mm brightness
from a high value in the outer penumbra to a low value in the inner
penumbra/outer umbra. Within the inner umbra, there is a marked increase
in 3 mm brightness temperature, which we call an umbral brightness
enhancement. This enhanced emission corresponds to a temperature
excess of 800 K relative to the surrounding inner penumbral region
and coincides with excess brightness in the 1330 and 1400 Å slit-jaw
images of the Interface Region Imaging Spectrograph (IRIS), adjacent
to a partial lightbridge. This λ = 3 mm brightness enhancement may be
an intrinsic feature of the sunspot umbra at chromospheric heights,
such as a manifestation of umbral flashes, or it could be related to
a coronal plume, since the brightness enhancement was coincident with
the footpoint of a coronal loop observed at 171 Å.
Title: The First ALMA Observation of a Solar Plasmoid Ejection from
an X-Ray Bright Point
Authors: Shimojo, Masumi; Hudson, Hugh S.; White, Stephen M.; Bastian,
Timothy S.; Iwai, Kazumasa
Bibcode: 2017ApJ...841L...5S
Altcode: 2017arXiv170404881S
Eruptive phenomena such as plasmoid ejections or jets are important
features of solar activity and have the potential to improve our
understanding of the dynamics of the solar atmosphere. Such ejections
are often thought to be signatures of the outflows expected in
regions of fast magnetic reconnection. The 304 Å EUV line of helium,
formed at around 105 K, is found to be a reliable tracer
of such phenomena, but the determination of physical parameters
from such observations is not straightforward. We have observed
a plasmoid ejection from an X-ray bright point simultaneously at
millimeter wavelengths with ALMA, at EUV wavelengths with SDO/AIA,
and in soft X-rays with Hinode/XRT. This paper reports the physical
parameters of the plasmoid obtained by combining the radio, EUV, and
X-ray data. As a result, we conclude that the plasmoid can consist
either of (approximately) isothermal ∼105 K plasma that
is optically thin at 100 GHz, or a ∼104 K core with a
hot envelope. The analysis demonstrates the value of the additional
temperature and density constraints that ALMA provides, and future
science observations with ALMA will be able to match the spatial
resolution of space-borne and other high-resolution telescopes.
Title: The Brightness Temperature of the Quiet Solar Chromosphere
at 2.6 mm
Authors: Iwai, Kazumasa; Shimojo, Masumi; Asayama, Shinichiro;
Minamidani, Tetsuhiro; White, Stephen; Bastian, Timothy; Saito, Masao
Bibcode: 2017SoPh..292...22I
Altcode: 2016arXiv161208241I
The absolute brightness temperature of the Sun at millimeter wavelengths
is an important diagnostic of the solar chromosphere. Because the
Sun is so bright, measurement of this property usually involves
the operation of telescopes under extreme conditions and requires
a rigorous performance assessment of the telescope. In this study,
we establish solar observation and calibration techniques at 2.6
mm wavelength for the Nobeyama 45 m telescope and accurately
derive the absolute solar brightness temperature. We tune the
superconductor-insulator-superconductor (SIS) receiver by inducing
different bias voltages onto the SIS mixer to prevent saturation. Then,
we examine the linearity of the receiver system by comparing outputs
derived from different tuning conditions. Furthermore, we measure
the lunar filled beam efficiency of the telescope using the New Moon,
and then derive the absolute brightness temperature of the Sun. The
derived solar brightness temperature is 7700 ±310 K at 115 GHz. The
telescope beam pattern is modeled as a summation of three Gaussian
functions and derived using the solar limb. The real shape of the Sun
is determined via deconvolution of the beam pattern from the observed
map. Such well-calibrated single-dish observations are important for
high-resolution chromospheric studies because they provide the absolute
temperature scale that is lacking from interferometer observations.
Title: Creation of Super-Hot Plasmas in a Flux Eruption Event as
seen in Soft X-rays with Hinode/XRT
Authors: Sakao, T.; Shimojo, M.; Narukage, N.
Bibcode: 2016AGUFMSH11D..04S
Altcode:
The X-Ray Telescope (XRT) aboard Hinode observes soft X-ray emission
from the solar corona with its energy range 0.06 - 2 keV and is capable
of imaging, and diagnosing, a wide range of coronal temperatures
from below 1 MK to beyond 20 MK, without gaps in the temperature
coverage. In particular, the grazing-incidence nature of the XRT
optics is suited for imaging high-temperature plasmas (>20 MK)
created during the course of flares that are not necessarily well
accessible with coronal imagers utilizing EUV emission lines. We
report XRT observations of an eruptive flare (GOES M1.1) that took
place behind the east limb at 18:30 UT on 14 October 2014. X-ray
images traced a flux eruption which corresponds to the early stage of
a CME observed with SoHO/LASCO, with a flux-rope-like feature ejected
as the flare progressed. Filter-ratio temperatures of the soft X-ray
flaring structure derived from multiple-filter observation of the flare
suggest possible creation of super-hot (reaching as high as 30 MK)
plasmas that distributed from near the apex of the erupting structure
(where the flux rope was present), downwards along the sides of the
structure. The observation may be the first identification in images of
super-hot plasmas in the soft X-ray range, covering up to 2 keV. XRT
observations on the creation of super-hot plasmas during the course
of the flux eruption will be reported and its implication discussed.
Title: Solar Coronal Jets: Observations, Theory, and Modeling
Authors: Raouafi, N. E.; Patsourakos, S.; Pariat, E.; Young, P. R.;
Sterling, A. C.; Savcheva, A.; Shimojo, M.; Moreno-Insertis, F.;
DeVore, C. R.; Archontis, V.; Török, T.; Mason, H.; Curdt, W.;
Meyer, K.; Dalmasse, K.; Matsui, Y.
Bibcode: 2016SSRv..201....1R
Altcode: 2016arXiv160702108R; 2016SSRv..tmp...31R
Coronal jets represent important manifestations of ubiquitous solar
transients, which may be the source of significant mass and energy
input to the upper solar atmosphere and the solar wind. While
the energy involved in a jet-like event is smaller than that of
"nominal" solar flares and coronal mass ejections (CMEs), jets
share many common properties with these phenomena, in particular,
the explosive magnetically driven dynamics. Studies of jets could,
therefore, provide critical insight for understanding the larger,
more complex drivers of the solar activity. On the other side of the
size-spectrum, the study of jets could also supply important clues on
the physics of transients close or at the limit of the current spatial
resolution such as spicules. Furthermore, jet phenomena may hint to
basic process for heating the corona and accelerating the solar wind;
consequently their study gives us the opportunity to attack a broad
range of solar-heliospheric problems.
Title: Solar Observations In Cycle 4 Of ALMA
Authors: Shimojo, Masumi; ALMA Solar Development Team
Bibcode: 2016csss.confE..88S
Altcode:
The Sun is one of scientific targets of the Atacama Large
Millimeter/sub-millimeter Array (ALMA). However, solar observations had
not been offered until Cycle 3, because of a lot of difficulties for
observing the Sun with the radio interferometer for night astronomy. We
have been developing observing schemes for the Sun since 2010, and the
joint ALMA observatory started to offer solar observations from Cycle 4
at last. Since the special treatments are needed for solar observations,
there are some limitations for observing the Sun in comparison with
the observations of other celestial targets. We held the commissioning
campaign in December 2015 for verifying the observing modes, and the
images synthesized from the commissioning data show us new sights of
solar physics. The data obtained with the ALMA will bring about great
scientific achievements.
Title: Evidence of Electron Acceleration around the Reconnection
X-point in a Solar Flare
Authors: Narukage, Noriyuki; Shimojo, Masumi; Sakao, Taro
Bibcode: 2016SPD....4730202N
Altcode:
Particle acceleration is one of the most significant features that
are ubiquitous among space and cosmic plasmas. It is most prominent
during flares in the case of the Sun, with which huge amounts of
electromagnetic radiation and high-energy particles are expelled into
the interplanetary space through acceleration of plasma particles
in the corona. Though it has been well understood that energies of
flares are supplied by the mechanism called magnetic reconnection
based on the observations in X-rays and EUV with space telescopes,
where and how in the flaring magnetic field plasmas are accelerated
has remained unknown due to the low plasma density in the flaring
corona. We here report the first observational identification of the
energetic non-thermal electrons around the point of the ongoing magnetic
reconnection (X-point), with the location of the X-point identified
by soft X-ray imagery and the localized presence of non-thermal
electrons identified from imaging-spectroscopic data at two microwave
frequencies. Considering the existence of the reconnection outflows
that carries both plasma particles and magnetic fields out from
the X-point, our identified non-thermal microwave emissions around
the X-point indicate that the electrons are accelerated around the
reconnection X-point.
Title: Solar Observations with the Atacama Large
Millimeter/submillimeter Array (ALMA)
Authors: Kobelski, A.; Bastian, T. S.; Bárta, M.; Brajša, R.; Chen,
B.; De Pontieu, B.; Fleishman, G.; Gary, D.; Hales, A.; Hills, R.;
Hudson, H.; Hurford, G.; Loukitcheva, M.; Iwai, K.; Krucker, S.;
Shimojo, M.; Skokić, I.; Wedemeyer, S.; White, S.; Yan, Y.; ALMA
Solar Development Team
Bibcode: 2016ASPC..504..327K
Altcode:
The Atacama Large Millimeter/Submillimeter Array (ALMA) is a
joint North American, European, and East Asian project that opens
the mm-sub mm wavelength part of the electromagnetic spectrum for
general astrophysical exploration, providing high-resolution imaging
in frequency bands currently ranging from 84 GHz to 950 GHz (300
microns to 3 mm). It is located in the Atacama desert in northern
Chile at an elevation of 5000 m. Despite being a general purpose
instrument, provisions have been made to enable solar observations
with ALMA. Radiation emitted at ALMA wavelengths originates mostly
from the chromosphere, which plays an important role in the transport
of matter and energy, and the in heating the outer layers of the solar
atmosphere. Despite decades of research, the solar chromosphere remains
a significant challenge: both to observe, owing to the complicated
formation mechanisms of currently available diagnostics; and to
understand, as a result of the complex nature of the structure and
dynamics of the chromosphere. ALMA has the potential to change the
scene substantially as it serves as a nearly linear thermometer at
high spatial and temporal resolution, enabling us to study the complex
interaction of magnetic fields and shock waves and yet-to-be-discovered
dynamical processes. Moreover, ALMA will play an important role in
the study of energetic emissions associated with solar flares at
sub-THz frequencies.
Title: Solar Science with the Atacama Large Millimeter/Submillimeter
Array—A New View of Our Sun
Authors: Wedemeyer, S.; Bastian, T.; Brajša, R.; Hudson, H.;
Fleishman, G.; Loukitcheva, M.; Fleck, B.; Kontar, E. P.; De Pontieu,
B.; Yagoubov, P.; Tiwari, S. K.; Soler, R.; Black, J. H.; Antolin,
P.; Scullion, E.; Gunár, S.; Labrosse, N.; Ludwig, H. -G.; Benz,
A. O.; White, S. M.; Hauschildt, P.; Doyle, J. G.; Nakariakov, V. M.;
Ayres, T.; Heinzel, P.; Karlicky, M.; Van Doorsselaere, T.; Gary,
D.; Alissandrakis, C. E.; Nindos, A.; Solanki, S. K.; Rouppe van
der Voort, L.; Shimojo, M.; Kato, Y.; Zaqarashvili, T.; Perez, E.;
Selhorst, C. L.; Barta, M.
Bibcode: 2016SSRv..200....1W
Altcode: 2015SSRv..tmp..118W; 2015arXiv150406887W
The Atacama Large Millimeter/submillimeter Array (ALMA) is a new
powerful tool for observing the Sun at high spatial, temporal, and
spectral resolution. These capabilities can address a broad range
of fundamental scientific questions in solar physics. The radiation
observed by ALMA originates mostly from the chromosphere—a complex
and dynamic region between the photosphere and corona, which plays a
crucial role in the transport of energy and matter and, ultimately,
the heating of the outer layers of the solar atmosphere. Based on
first solar test observations, strategies for regular solar campaigns
are currently being developed. State-of-the-art numerical simulations
of the solar atmosphere and modeling of instrumental effects can help
constrain and optimize future observing modes for ALMA. Here we present
a short technical description of ALMA and an overview of past efforts
and future possibilities for solar observations at submillimeter and
millimeter wavelengths. In addition, selected numerical simulations
and observations at other wavelengths demonstrate ALMA's scientific
potential for studying the Sun for a large range of science cases.
Title: ALMA Observations of the Sun in Cycle 4 and Beyond
Authors: Wedemeyer, S.; Fleck, B.; Battaglia, M.; Labrosse, N.;
Fleishman, G.; Hudson, H.; Antolin, P.; Alissandrakis, C.; Ayres, T.;
Ballester, J.; Bastian, T.; Black, J.; Benz, A.; Brajsa, R.; Carlsson,
M.; Costa, J.; DePontieu, B.; Doyle, G.; Gimenez de Castro, G.;
Gunár, S.; Harper, G.; Jafarzadeh, S.; Loukitcheva, M.; Nakariakov,
V.; Oliver, R.; Schmieder, B.; Selhorst, C.; Shimojo, M.; Simões,
P.; Soler, R.; Temmer, M.; Tiwari, S.; Van Doorsselaere, T.; Veronig,
A.; White, S.; Yagoubov, P.; Zaqarashvili, T.
Bibcode: 2016arXiv160100587W
Altcode:
This document was created by the Solar Simulations for the Atacama
Large Millimeter Observatory Network (SSALMON) in preparation of
the first regular observations of the Sun with the Atacama Large
Millimeter/submillimeter Array (ALMA), which are anticipated to start
in ALMA Cycle 4 in October 2016. The science cases presented here
demonstrate that a large number of scientifically highly interesting
observations could be made already with the still limited solar
observing modes foreseen for Cycle 4 and that ALMA has the potential
to make important contributions to answering long-standing scientific
questions in solar physics. With the proposal deadline for ALMA Cycle
4 in April 2016 and the Commissioning and Science Verification campaign
in December 2015 in sight, several of the SSALMON Expert Teams composed
strategic documents in which they outlined potential solar observations
that could be feasible given the anticipated technical capabilities
in Cycle 4. These documents have been combined and supplemented
with an analysis, resulting in recommendations for solar observing
with ALMA in Cycle 4. In addition, the detailed science cases also
demonstrate the scientific priorities of the solar physics community
and which capabilities are wanted for the next observing cycles. The
work on this White Paper effort was coordinated in close cooperation
with the two international solar ALMA development studies led by
T. Bastian (NRAO, USA) and R. Brajsa, (ESO). This document will be
further updated until the beginning of Cycle 4 in October 2016. In
particular, we plan to adjust the technical capabilities of the solar
observing modes once finally decided and to further demonstrate the
feasibility and scientific potential of the included science cases by
means of numerical simulations of the solar atmosphere and corresponding
simulated ALMA observations.
Title: Solar Simulations for the Atacama Large Millimeter Observatory
Network
Authors: Wedemeyer, S.; Bastian, T.; Brajša, R.; Barta, M.;
Shimojo, M.
Bibcode: 2015ASPC..499..341W
Altcode: 2015arXiv150206379W
The Atacama Large Millimeter/submillimeter Array (ALMA) will
be a valuable tool for observing the chromosphere of our Sun at
(sub-)millimeter wavelengths at high spatial, temporal and spectral
resolution and as such has great potential to address long-standing
scientific questions in solar physics. In order to make the best use
of this scientific opportunity, the Solar Simulations for the Atacama
Large Millimeter Observatory Network has been initiated. A key goal
of this international collaboration is to support the preparation and
interpretation of future observations of the Sun with ALMA.
Title: A Comparative Study of Confined and Eruptive Solar Flares
using Microwave Observations
Authors: Yashiro, S.; Akiyama, S.; Masuda, S.; Shimojo, M.; Asai,
A.; Imada, S.; Gopalswamy, N.
Bibcode: 2015AGUFMSH43B2447Y
Altcode:
It is well known that about 10% X-class solar flares are not associated
with coronal mass ejections (CMEs). These flares are referred to
as confined flares, which are not associated with mass or energetic
particles leaving the Sun. However, electrons are accelerated to MeV
energies as indicated by the presence of microwave emission with a
turnover frequency of ~15 GHz (Gopalswamy et al. 2009, IAU Symposium
257, p. 283). In this paper, we extend the study of confined flares to
lower soft X-ray flare sizes (M and above) that occurred in the time
window of the Nobeyama Radioheliograph (NoRH). We also make use of the
microwave spectral information from the Nobeyama Radio Polarimeters
(NoRP). During 1996 - 2014, NoRH and NoRP observed 663 flares with
size M1.0 or larger. Using the CME observations made by SOHO/LASCO
and STEREO/SECCHI, we found 215 flares with definite CME association
(eruptive flares) and 202 flares that definitely lacked CMEs (confined
flares). The remaining 146 flares whose CME association is unclear are
excluded from the analysis. We examined the peak brightness temperature
and the spatial size obtained by NoRH. Although there is a large
overlap between the two populations in these properties, we found
that microwave sources with the largest spatial extent and highest
brightness temperature are associated with eruptive flares. Spectral
analysis using NoRP data showed a tendency that more confined flares
had higher turnover frequency (≥17 GHz). We also compare the NoRH
images with the photospheric magnetograms to understand the difference
in the magnetic structure of the two types of flare sources.
Title: Solar ALMA Observations - A New View of Our Host Star
Authors: Wedemeyer, S.; Bastian, T.; Brajša, R.; Barta, M.; Shimojo,
M.; Hales, A.; Yagoubov, P.; Hudson, H.
Bibcode: 2015ASPC..499..345W
Altcode: 2015arXiv150206397W
ALMA provides the necessary spatial, temporal and spectral resolution to
explore central questions in contemporary solar physics with potentially
far-reaching implications for stellar atmospheres and plasma physics. It
can uniquely constraint the thermal and magnetic field structure in
the solar chromosphere with measurements that are highly complementary
to simultaneous observations with other ground-based and space-borne
instruments. Here, we highlight selected science cases.
Title: The Atacama Large Millimeter/Submillimeter Array: a New Asset
for Solar and Heliospheric Physics
Authors: Bastian, Timothy S.; Barta, Miroslav; Brajsa, Roman; Chen,
Bin; De Pontieu, Bart; Fleishman, Gregory; Gary, Dale; Hales, Antonio;
Hills, Richard; Hudson, Hugh; Iwai, Kazamasu; Shimojo, Masumi; White,
Stephen; Wedemeyer, Sven; Yan, Yihua
Bibcode: 2015IAUGA..2257295B
Altcode:
The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint
North American, European, and East Asian interferometric array that
opens the mm-submm wavelength part of the electromagnetic spectrum
for general astrophysical exploration, providing high-resolution
imaging in frequency bands ranging from 86 to 950 GHz. Despite being
a general purpose instrument, provisions have been made to enable
solar observations with ALMA. Radiation emitted at ALMA wavelengths
originates mostly from the chromosphere, which plays an important
role in the transport of energy and matter and the heating of the
outer layers of the solar atmosphere. In this paper we describe
recent efforts to ensure that ALMA can be usefully exploited by
the scientific community to address outstanding questions in solar
physics. We summarize activities under North American and European
ALMA development studies, including instrument testing, calibration
and imaging strategies, a science simulations. With the support of
solar observations, ALMA joins next-generation groundbased instruments
that can be used alone or in combination with other ground-based and
space-based instruments to address outstanding questions in solar
and heliospheric physics. Opportunities for the wider community to
contribute to these efforts will be highlighted.
Title: The 2014 ALMA Long Baseline Campaign: An Overview
Authors: ALMA Partnership; Fomalont, E. B.; Vlahakis, C.; Corder,
S.; Remijan, A.; Barkats, D.; Lucas, R.; Hunter, T. R.; Brogan,
C. L.; Asaki, Y.; Matsushita, S.; Dent, W. R. F.; Hills, R. E.;
Phillips, N.; Richards, A. M. S.; Cox, P.; Amestica, R.; Broguiere,
D.; Cotton, W.; Hales, A. S.; Hiriart, R.; Hirota, A.; Hodge, J. A.;
Impellizzeri, C. M. V.; Kern, J.; Kneissl, R.; Liuzzo, E.; Marcelino,
N.; Marson, R.; Mignano, A.; Nakanishi, K.; Nikolic, B.; Perez,
J. E.; Pérez, L. M.; Toledo, I.; Aladro, R.; Butler, B.; Cortes,
J.; Cortes, P.; Dhawan, V.; Di Francesco, J.; Espada, D.; Galarza,
F.; Garcia-Appadoo, D.; Guzman-Ramirez, L.; Humphreys, E. M.; Jung,
T.; Kameno, S.; Laing, R. A.; Leon, S.; Mangum, J.; Marconi, G.;
Nagai, H.; Nyman, L. -A.; Radiszcz, M.; Rodón, J. A.; Sawada, T.;
Takahashi, S.; Tilanus, R. P. J.; van Kempen, T.; Vila Vilaro, B.;
Watson, L. C.; Wiklind, T.; Gueth, F.; Tatematsu, K.; Wootten, A.;
Castro-Carrizo, A.; Chapillon, E.; Dumas, G.; de Gregorio-Monsalvo, I.;
Francke, H.; Gallardo, J.; Garcia, J.; Gonzalez, S.; Hibbard, J. E.;
Hill, T.; Kaminski, T.; Karim, A.; Krips, M.; Kurono, Y.; Lopez, C.;
Martin, S.; Maud, L.; Morales, F.; Pietu, V.; Plarre, K.; Schieven,
G.; Testi, L.; Videla, L.; Villard, E.; Whyborn, N.; Zwaan, M. A.;
Alves, F.; Andreani, P.; Avison, A.; Barta, M.; Bedosti, F.; Bendo,
G. J.; Bertoldi, F.; Bethermin, M.; Biggs, A.; Boissier, J.; Brand,
J.; Burkutean, S.; Casasola, V.; Conway, J.; Cortese, L.; Dabrowski,
B.; Davis, T. A.; Diaz Trigo, M.; Fontani, F.; Franco-Hernandez, R.;
Fuller, G.; Galvan Madrid, R.; Giannetti, A.; Ginsburg, A.; Graves,
S. F.; Hatziminaoglou, E.; Hogerheijde, M.; Jachym, P.; Jimenez Serra,
I.; Karlicky, M.; Klaasen, P.; Kraus, M.; Kunneriath, D.; Lagos, C.;
Longmore, S.; Leurini, S.; Maercker, M.; Magnelli, B.; Marti Vidal,
I.; Massardi, M.; Maury, A.; Muehle, S.; Muller, S.; Muxlow, T.;
O'Gorman, E.; Paladino, R.; Petry, D.; Pineda, J. E.; Randall, S.;
Richer, J. S.; Rossetti, A.; Rushton, A.; Rygl, K.; Sanchez Monge,
A.; Schaaf, R.; Schilke, P.; Stanke, T.; Schmalzl, M.; Stoehr, F.;
Urban, S.; van Kampen, E.; Vlemmings, W.; Wang, K.; Wild, W.; Yang,
Y.; Iguchi, S.; Hasegawa, T.; Saito, M.; Inatani, J.; Mizuno, N.;
Asayama, S.; Kosugi, G.; Morita, K. -I.; Chiba, K.; Kawashima, S.;
Okumura, S. K.; Ohashi, N.; Ogasawara, R.; Sakamoto, S.; Noguchi, T.;
Huang, Y. -D.; Liu, S. -Y.; Kemper, F.; Koch, P. M.; Chen, M. -T.;
Chikada, Y.; Hiramatsu, M.; Iono, D.; Shimojo, M.; Komugi, S.; Kim,
J.; Lyo, A. -R.; Muller, E.; Herrera, C.; Miura, R. E.; Ueda, J.;
Chibueze, J.; Su, Y. -N.; Trejo-Cruz, A.; Wang, K. -S.; Kiuchi,
H.; Ukita, N.; Sugimoto, M.; Kawabe, R.; Hayashi, M.; Miyama, S.;
Ho, P. T. P.; Kaifu, N.; Ishiguro, M.; Beasley, A. J.; Bhatnagar,
S.; Braatz, J. A., III; Brisbin, D. G.; Brunetti, N.; Carilli, C.;
Crossley, J. H.; D'Addario, L.; Donovan Meyer, J. L.; Emerson, D. T.;
Evans, A. S.; Fisher, P.; Golap, K.; Griffith, D. M.; Hale, A. E.;
Halstead, D.; Hardy, E. J.; Hatz, M. C.; Holdaway, M.; Indebetouw, R.;
Jewell, P. R.; Kepley, A. A.; Kim, D. -C.; Lacy, M. D.; Leroy, A. K.;
Liszt, H. S.; Lonsdale, C. J.; Matthews, B.; McKinnon, M.; Mason,
B. S.; Moellenbrock, G.; Moullet, A.; Myers, S. T.; Ott, J.; Peck,
A. B.; Pisano, J.; Radford, S. J. E.; Randolph, W. T.; Rao Venkata,
U.; Rawlings, M. G.; Rosen, R.; Schnee, S. L.; Scott, K. S.; Sharp,
N. K.; Sheth, K.; Simon, R. S.; Tsutsumi, T.; Wood, S. J.
Bibcode: 2015ApJ...808L...1A
Altcode: 2015arXiv150404877P
A major goal of the Atacama Large Millimeter/submillimeter Array (ALMA)
is to make accurate images with resolutions of tens of milliarcseconds,
which at submillimeter (submm) wavelengths requires baselines up to
∼15 km. To develop and test this capability, a Long Baseline Campaign
(LBC) was carried out from 2014 September to late November, culminating
in end-to-end observations, calibrations, and imaging of selected
Science Verification (SV) targets. This paper presents an overview
of the campaign and its main results, including an investigation of
the short-term coherence properties and systematic phase errors over
the long baselines at the ALMA site, a summary of the SV targets and
observations, and recommendations for science observing strategies at
long baselines. Deep ALMA images of the quasar 3C 138 at 97 and 241 GHz
are also compared to VLA 43 GHz results, demonstrating an agreement at
a level of a few percent. As a result of the extensive program of LBC
testing, the highly successful SV imaging at long baselines achieved
angular resolutions as fine as 19 mas at ∼350 GHz. Observing with
ALMA on baselines of up to 15 km is now possible, and opens up new
parameter space for submm astronomy. .
Title: Observation of the Chromospheric Sunspot at Millimeter Range
with the Nobeyama 45 m Telescope
Authors: Iwai, Kazumasa; Shimojo, Masumi
Bibcode: 2015ApJ...804...48I
Altcode: 2015arXiv150300096I
The brightness temperature of the radio free-free emission at millimeter
range is an effective tool for characterizing the vertical structure
of the solar chromosphere. In this paper, we report on the first
single-dish observation of a sunspot at 85 and 115 GHz with sufficient
spatial resolution for resolving the sunspot umbra using the Nobeyama
45 m telescope. We used radio attenuation material, i.e., a solar
filter, to prevent the saturation of the receivers. Considering the
contamination from the plage by the side lobes, we found that the
brightness temperature of the umbra should be lower than that of
the quiet region. This result is inconsistent with the preexisting
atmospheric models. We also found that the brightness temperature
distribution at millimeter range strongly corresponds to the ultraviolet
continuum emission at 1700 Å, especially at the quiet region.
Title: Hinode, the Sun, and public outreach
Authors: Yaji, K.; Tonooka, H.; Shimojo, M.; Tokimasa, N.; Suzuki,
D.; Nakamichi, A.; Shimoikura, I.
Bibcode: 2015HiA....16..649Y
Altcode:
Extended Abstract Hinode is a solar observation satellite in Japan
and its launch was in September 2006. Its name means ``SUNRISE`` in
Japanese. It has three instruments onboard in visible light, X-ray,
EUV to solve mystery of coronal heating and origins of magnetic
fields. Hinode has been providing us with impressive solar data,
which are very important for not only investigating solar phenomena
but also giving new knowledge about the sun to the public. In order
to efficiently communicate Hinode data to the public, we organized
working group for public use of Hinode data. which are composed of both
researchers and educators in collaboration. As follow, we introduce
our activities in brief. For the public use of Hinode data, at
first, we produced two DVDs introducing Hinode observation results. In
particular, second DVD contains a movie for kids, which are devloped
to picturebook. Now, it is under producing an illustrated book and
a planetarium program. It turn out that the DVDs help the public
understand the sun from questionnaire surveys. Second, we developed
teaching materials from Hinode data and had a science classroom about
the sun, solar observations, practice with PC such as imaging software
at junior high school. As the results, they had much interests in Hinode
data. Third, we have joint observations with high school students and so
on in a few years. The students compare their own data with Hinode data
and have a presentation at science contests. The joint observations make
their motivation higher in their activities. It is important to
record and report our activities in some ways. So, we positively publish
papers and have presentions in domestic/international meetings. Though
we are supported in budget, resources and so on by NAOJ Hinode Team,
we apply research funds for promoting our EPO activities and acquire
some funds such as NAOJ Joint Research Expenses and Grands-Aid for
Scientific Research Funds since the launch. This way, since its
launch, we have continued various and constant EPO activities for the
public use of Hinode data and have been giving intense impacts and
high interest to the public. As the result, our activities contribute
in further extension of Hinode Mission. Those are quite unique and
would be reference of other similar ones. Hinode is now operating
and solar activities might get more higher. As long as SUN RISE,
we would GO FORWARD!!
Title: Observing the Sun with ALMA: A New Window into Solar Physics
Authors: Bastian, Timothy S.; Shimojo, Masumi; Wedemeyer-Bohm, Sven;
ALMA North American Solar Development Team
Bibcode: 2015AAS...22541301B
Altcode:
The Atacama Large Millimeter/Submillimeter Array (ALMA) is a joint
North American, European, and East Asian interferometric array that
opens the mm-submm wavelength part of the electromagnetic spectrum for
general astrophysical exploration, providing high resolution imaging
in frequency bands. Despite being a general purpose instrument,
provisions have been made to enable solar observations with ALMA,
thereby offering a new window into solar physics. Radiation emitted
at ALMA wavelengths originates mostly from the chromosphere, which
plays an important role in the transport of energy and matter and the
heating of the outer layers of the solar atmosphere. Despite decades
of intensive research, an understanding of the chromosphere is still
elusive, and challenging to observe owing to the complicated formation
mechanisms of currently available diagnostics. ALMA will change
the scene substantially as it serves as a nearly linear thermometer
at high spatial, temporal, and spectral resolution, enabling us to
study the complex interaction of magnetic fields and shock waves and
yet-to-be-discovered dynamical processes.Moreover, ALMA will play an
important role in the study of energetic emissions associated with
solar flares at sub-THz frequencies.This presentations introduces
ALMA to the solar physcis community and motivates the science that
can be addressed by ALMA using a number of examples based on 3D MHD
simulations. In addition, the means by which ALMA is used to acquire and
calibrate solar observations will be discussed. Finally, we encourage
potential users to join us in further defining and articulating the
exciting science to be explored with this fundamentally new instrument.
Title: Constraining hot plasma in a non-flaring solar active region
with FOXSI hard X-ray observations
Authors: Ishikawa, Shin-nosuke; Glesener, Lindsay; Christe, Steven;
Ishibashi, Kazunori; Brooks, David H.; Williams, David R.; Shimojo,
Masumi; Sako, Nobuharu; Krucker, Säm
Bibcode: 2014PASJ...66S..15I
Altcode: 2015arXiv150905288I; 2014PASJ..tmp..102I
We present new constraints on the high-temperature emission measure
of a non-flaring solar active region using observations from the
recently flown Focusing Optics X-ray Solar Imager (FOXSI) sounding
rocket payload. FOXSI has performed the first focused hard X-ray
(HXR) observation of the Sun in its first successful flight on 2012
November 2. Focusing optics, combined with small strip detectors,
enable high-sensitivity observations with respect to previous
indirect imagers. This capability, along with the sensitivity of
the HXR regime to high-temperature emission, offers the potential
to better characterize high-temperature plasma in the corona as
predicted by nanoflare heating models. We present a joint analysis of
the differential emission measure (DEM) of active region 11602 using
coordinated observations by FOXSI, Hinode/XRT, and Hinode/EIS. The
Hinode-derived DEM predicts significant emission measure between
1 MK and 3 MK, with a peak in the DEM predicted at 2.0-2.5 MK. The
combined XRT and EIS DEM also shows emission from a smaller population
of plasma above 8 MK. This is contradicted by FOXSI observations that
significantly constrain emission above 8 MK. This suggests that the
Hinode DEM analysis has larger uncertainties at higher temperatures and
that > 8 MK plasma above an emission measure of 3 × 1044
cm-3 is excluded in this active region.
Title: The soft x-ray photon-counting telescope for solar observations
Authors: Sakao, Taro; Narukage, Noriyuki; Suematsu, Yoshinori;
Watanabe, Kyoko; Shimojo, Masumi; Imada, Shinsuke; Ishikawa,
Shin-nosuke; DeLuca, Edward E.
Bibcode: 2014SPIE.9144E..3DS
Altcode:
We present overview and development activities of a soft X-ray
photon-counting spectroscopic imager for the solar corona that
we conceive as a possible scientific payload for future space
solar missions including Japanese Solar-C. The soft X-ray imager
will employ a Wolter I grazing-incidence sector mirror with which
images of the corona (1 MK to beyond 10 MK) will be taken with
the highest-ever angular resolution (0.5"/pixel for a focal length
of 4 m) as a solar Xray telescope. In addition to high-resolution
imagery, we attempt to implement photon-counting capability for the
imager by employing a backside-illuminated CMOS image sensor as the
focal-plane device. 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 with the soft X-ray
imager will provide a noble probe for investigating mechanism(s) of
magnetic reconnection and generation of supra-thermal (non-thermal)
electrons associated with flares. Ongoing development activities in
Japan towards the photon-counting imager is described with emphasis
on that for sub-arcsecond-resolution grazing-incidence mirrors.
Title: Evidence of Electron Acceleration around the Reconnection
X-point in a Solar Flare
Authors: Narukage, Noriyuki; Shimojo, Masumi; Sakao, Taro
Bibcode: 2014ApJ...787..125N
Altcode: 2014arXiv1404.3288N
Particle acceleration is one of the most significant features that
are ubiquitous among space and cosmic plasmas. It is most prominent
during flares in the case of the Sun, with which huge amounts of
electromagnetic radiation and high-energy particles are expelled into
the interplanetary space through acceleration of plasma particles
in the corona. Though it has been well understood that energies of
flares are supplied by the mechanism called magnetic reconnection
based on the observations in X-rays and EUV with space telescopes,
where and how in the flaring magnetic field plasmas are accelerated
has remained unknown due to the low plasma density in the flaring
corona. We here report the first observational identification of the
energetic non-thermal electrons around the point of the ongoing magnetic
reconnection (X-point), with the location of the X-point identified
by soft X-ray imagery and the localized presence of non-thermal
electrons identified from imaging-spectroscopic data at two microwave
frequencies. Considering the existence of the reconnection outflows
that carries both plasma particles and magnetic fields out from
the X-point, our identified non-thermal microwave emissions around
the X-point indicate that the electrons are accelerated around the
reconnection X-point. Additionally, the plasma around the X-point was
also thermally heated up to 10 MK. The estimated reconnection rate of
this event is ~0.017.
Title: The Three-dimensional Analysis of Hinode Polar Jets using
Images from LASCO C2, the Stereo COR2 Coronagraphs, and SMEI
Authors: Yu, H. -S.; Jackson, B. V.; Buffington, A.; Hick, P. P.;
Shimojo, M.; Sako, N.
Bibcode: 2014ApJ...784..166Y
Altcode:
Images recorded by the X-ray Telescope on board the Hinode spacecraft
are used to provide high-cadence observations of solar jetting
activity. A selection of the brightest of these polar jets shows
a positive correlation with high-speed responses traced into the
interplanetary medium. LASCO C2 and STEREO COR2 coronagraph images
measure the coronal response to some of the largest jets, and also the
nearby background solar wind velocity, thereby giving a determination
of their speeds that we compare with Hinode observations. When using
the full Solar Mass Ejection Imager (SMEI) data set, we track these
same high-speed solar jet responses into the inner heliosphere and from
these analyses determine their mass, flow energies, and the extent to
which they retain their identity at large solar distances.
Title: Coronal-Temperature-Diagnostic Capability of the Hinode/ X-Ray
Telescope Based on Self-consistent Calibration. II. Calibration with
On-Orbit Data
Authors: Narukage, N.; Sakao, T.; Kano, R.; Shimojo, M.; Winebarger,
A.; Weber, M.; Reeves, K. K.
Bibcode: 2014SoPh..289.1029N
Altcode: 2013arXiv1307.4489N
The X-Ray Telescope (XRT) onboard the Hinode satellite is an
X-ray imager that observes the solar corona with the capability of
diagnosing coronal temperatures from less than 1 MK to more than
10 MK. To make full use of this capability, Narukage et al. (Solar
Phys.269, 169, 2011) determined the thickness of each of the X-ray
focal-plane analysis filters based on calibration measurements
from the ground-based end-to-end test. However, in their paper,
the calibration of the thicker filters for observations of active
regions and flares, namely the med-Be, med-Al, thick-Al and thick-Be
filters, was insufficient due to the insufficient X-ray flux used in
the measurements. In this work, we recalibrate those thicker filters
using quiescent active region data taken with multiple filters of
XRT. On the basis of our updated calibration results, we present the
revised coronal-temperature-diagnostic capability of XRT.
Title: Unusual migration of the prominence activities in recent
solar cycles
Authors: Shimojo, Masumi
Bibcode: 2014IAUS..300..161S
Altcode:
We investigated the prominence eruptions and disappearances observed
with the Nobeyama Radioheliograph during over 20 years for studying the
anomaly of the recent solar cycle. Although the sunspot number of Cycle
24 is smaller than the previous one dramatically, the occurrence rate,
size and radial velocity of the prominence activities are not changed
significantly. We also found that the occurrence of the prominence
activities in the northern hemisphere is normal from the duration of
the cycle and the migration of the producing region of the prominence
activities. On the other hand, the migration in the southern hemisphere
significantly differs from that in the northern hemisphere and the
previous cycles. Our results suggest that the anomalies of the global
magnetic field distribution started at the solar maximum of Cycle 23.
Title: Extremely Microwave-Rich Solar Flare Observed with Nobeyama
Radioheliograph
Authors: Masuda, Satoshi; Shimojo, Masumi; Kawate, Tomoko; Ishikawa,
Shin-nosuke; Ohno, Masanori
Bibcode: 2013PASJ...65S...1M
Altcode:
A compact flare was observed with Nobeyama Radioheliograph (NoRH)
slightly behind the west limb on 2011 March 10. The microwave
peak flux values at 17 and 34 GHz were about 210 and 133 sfu,
respectively. From the correlation between the 17 GHz peak flux and
the GOES 1-8 Å soft X-ray peak flux, M1.5-class is expected for this
microwave flux. However, only the B1-level enhancement was detected
in the GOES 1-8 Å soft X-ray light curve on the C1-level background
during the flare period. In addition to microwaves, Suzaku detected
hard X-ray emissions, even in the energy range above 100 keV. It is
clear that high-energy electrons were effectively produced in this
flare, while the thermal emission was very weak. Why did this flare
have this unique feature? The following two cases are considered. One
is the case that a magnetic trap for electrons works effectively, and
that each electron continues to emit microwaves in its relatively long
lifetime. The other is that the magnetic field around the looptop region
is intense, and relatively a large number of lower-energy electrons
emit microwaves. Considering the observational facts, such as the short
duration and the small flare loop, the latter case is more plausible.
Title: Unusual Migration of Prominence Activities in the Southern
Hemisphere during Cycles 23-24
Authors: Shimojo, Masumi
Bibcode: 2013PASJ...65S..16S
Altcode: 2013arXiv1308.2780S
The solar activity in Cycles 23-24 shows differences from the
previous cycles that were observed with modern instruments, e.g.,
long cycle duration and a small number of sunspots. To appreciate
the anomalies further, we investigated the prominence eruptions and
disappearances observed with the Nobeyama Radioheliograph for over
20 years. Consequently, we found that the occurrence of prominence
activities in the northern hemisphere is normal because the period of
the number variation is 11 years, and the migration of the producing
region of the prominence activities traces the migration of 11 years
ago. On the other hand, the migration in the southern hemisphere
significantly differs from that in the northern hemisphere and
the previous cycles. The prominence activities occurred over -50°
latitude in spite of the late decay phase of Cycle 23, and the number
of prominence activities in the higher latitude region (over -65°) is
very small, even near the solar maximum of Cycle 24. The results suggest
that the anomalies of the global magnetic field distribution started at
the solar maximum of Cycle 23. A comparison of the butterfly diagram of
the prominence activities with the magnetic butterfly diagram indicates
that the timing of "the rush to the pole" and the polar magnetic field
closely relates to unusual migration. Considering that the rush to
the pole is made of the sunspots, the hemispheric asymmetry of the
sunspots and the strength of the polar magnetic fields are essential
for understanding the anomalies of the prominence activities.
Title: The Science Cases for Building a Band 1 Receiver Suite for ALMA
Authors: Di Francesco, J.; Johnstone, D.; Matthews, B. C.; Bartel, N.;
Bronfman, L.; Casassus, S.; Chitsazzadeh, S.; Chou, H.; Cunningham,
M.; Duchene, G.; Geisbuesch, J.; Hales, A.; Ho, P. T. P.; Houde, M.;
Iono, D.; Kemper, F.; Kepley, A.; Koch, P. M.; Kohno, K.; Kothes, R.;
Lai, S. -P.; Lin, K. Y.; Liu, S. -Y.; Mason, B.; Maccarone, T. J.;
Mizuno, N.; Morata, O.; Schieven, G.; Scaife, A. M. M.; Scott, D.;
Shang, H.; Shimojo, M.; Su, Y. -N.; Takakuwa, S.; Wagg, J.; Wootten,
A.; Yusef-Zadeh, F.
Bibcode: 2013arXiv1310.1604D
Altcode:
We present the various science cases for building Band 1 receivers
as part of ALMA's ongoing Development Program. We describe the new
frequency range for Band 1 of 35-52 GHz, a range chosen to maximize
the receiver suite's scientific impact. We first describe two key
science drivers: 1) the evolution of grains in protoplanetary disks
and debris disks, and 2) molecular gas in galaxies during the era of
re-ionization. Studies of these topics with Band 1 receivers will
significantly expand ALMA's Level 1 Science Goals. In addition, we
describe a host of other exciting continuum and line science cases that
require ALMA's high sensitivity and angular resolution. For example,
ALMA Band 1 continuum data will probe the Sunyaev-Zel'dovich Effect
in galaxy clusters, Very Small Grains and spinning dust, ionized
jets from young stars, spatial and flaring studies of Sgr A*,
the acceleration sites of solar flares, pulsar wind nebulae, radio
supernovae, and X-ray binaries. Furthermore, ALMA Band 1 line data will
probe chemical differentiation in cloud cores, complex carbon chain
molecules, extragalactic radio recombination lines, masers, magnetic
fields through Zeeman effect measurements, molecular outflows from young
stars, the co-evolution of star formation and active galactic nuclei,
and the molecular content of galaxies at z ~ 3. ALMA provides similar
to better sensitivities than the JVLA over 35-50 GHz, with differences
increasing with frequency. ALMA's smaller antennas and shorter
baselines, greater number of baselines, and single-dish capabilities,
however, give it a significant edge for observing extended emission,
making wide-field maps (mosaics), or attaining high image fidelity,
as required by the described science cases.
Title: A Statistical Study of Coronal Active Events in the North
Polar Region
Authors: Sako, Nobuharu; Shimojo, Masumi; Watanabe, Tetsuya; Sekii,
Takashi
Bibcode: 2013ApJ...775...22S
Altcode:
In order to study the relationship between characteristics of polar
coronal active events and the magnetic environment in which such events
take place, we analyze 526 X-ray jets and 1256 transient brightenings
in the polar regions and in regions around the equatorial limbs. We
calculate the occurrence rates of these polar coronal active events
as a function of distance from the boundary of coronal holes, and
find that most events in the polar quiet regions occur adjacent to
and equatorward of the coronal hole boundaries, while events in the
polar coronal holes occur uniformly within them. Based primarily on
the background intensity, we define three categories of regions that
produce activity: polar coronal holes, coronal hole boundary regions,
and polar quiet regions. We then investigate the properties of the
events produced in these regions. We find no significant differences
in their characteristics, for example, length and lifetime, but there
are differences in the occurrence rates. The mean occurrence rate of
X-ray jets around the boundaries of coronal holes is higher than that
in the polar quiet regions, equatorial quiet regions, and polar coronal
holes. Furthermore, the mean occurrence rate of transient brightenings
is also higher in these regions. We make comparison with the occurrence
rates of emerging and canceling magnetic fields in the photosphere
reported in previous studies, and find that they do not agree with
the occurrence rates of transient brightenings found in this study.
Title: Temporal and Spatial Analyses of Spectral Indices of Nonthermal
Emissions Derived from Hard X-Rays and Microwaves
Authors: Asai, Ayumi; Kiyohara, Junko; Takasaki, Hiroyuki; Narukage,
Noriyuki; Yokoyama, Takaaki; Masuda, Satoshi; Shimojo, Masumi;
Nakajima, Hiroshi
Bibcode: 2013ApJ...763...87A
Altcode: 2012arXiv1212.1806A
We studied electron spectral indices of nonthermal emissions seen in
hard X-rays (HXRs) and microwaves. We analyzed 12 flares observed by
the Hard X-Ray Telescope aboard Yohkoh, Nobeyama Radio Polarimeters,
and the Nobeyama Radioheliograph (NoRH), and compared the spectral
indices derived from total fluxes of HXRs and microwaves. Except
for four events, which have very soft HXR spectra suffering from the
thermal component, these flares show a gap Δδ between the electron
spectral indices derived from HXRs δ X and those from
microwaves δμ (Δδ = δ X - δμ)
of about 1.6. Furthermore, from the start to the peak times of the
HXR bursts, the time profiles of the HXR spectral index δ
X evolve synchronously with those of the microwave spectral
index δμ, keeping the constant gap. We also examined the
spatially resolved distribution of the microwave spectral index by
using NoRH data. The microwave spectral index δμ tends
to be larger, which means a softer spectrum, at HXR footpoint sources
with stronger magnetic field than that at the loop tops. These results
suggest that the electron spectra are bent at around several hundreds
of keV, and become harder at the higher energy range that contributes
the microwave gyrosynchrotron emission.
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: Observing the Sun with ALMA
Authors: Benz, A. O.; Brajsa, R.; Shimojo, M.; Karlicky, M.; Testi, L.
Bibcode: 2012IAUSS...6E.205B
Altcode:
The Atacama Large Millimeter Array (ALMA) is in the commissioning
phase for solar observations. A filter reduces the solar radiation
to a level suitable for solar observations. First observations
with one antenna have mapped the Sun by scanning. The results look
promising. The image of the quiet chromosphere shows large spatial
variations in emissivity. Interferometry is much more demanding and
not yet achieved. The current state and problems will be summarized. It
is clear that solar ALMA observations will take more developing time,
but will eventually be possible. The goal is subarcsecond resolution
of the quiet and active submillimeter continuum radiation originating
in the chromosphere and possibly in the flaring corona. A limiting
factor will be the temporal variability of the solar emission.
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: 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: Statistical Study of X-ray Jets in the Polar Region
Authors: Sako, N.; Shimojo, M.; Kitabayashi, T.
Bibcode: 2012ASPC..454..153S
Altcode:
We detected 848 polar X-ray jets occurred in the north polar region,
and investigated the characteristics of the jets statistically. The
470 jets of them occurred in the coronal hole. The occurrence
rate of the jets in the coronal hole and the quiet region are
5.04×10-12 jets/hr/km2 and 7.66×10-12
jets/hr/km2, respectively. We derived five parameters
of the polar X-ray jets. The averaged values of the parameters are
2.91×104 km for the maximum length, 4.42×103
km for the width, 608 sec for the lifetime and 180 km/sec for the
apparent velocity. If we assume that the frequency distribution of
the lifetime and the footpoint flare show the power-law distributions,
and the index is -1.80 ± 0.20 in the coronal hole and -1.84 ± 0.17
in the quiet region. The frequency distribution is steeper than that
of the previous works.
Title: Education and Public Outreach Activities with Hinode Satellite
Data
Authors: Yaji, K.; Tokimasa, N.; Shimojo, M.; Tonooka, H.; Nakamichi,
A.; Suzuki, D.
Bibcode: 2012ASPC..454..457Y
Altcode:
Hinode data are very important for not only investigating solar
phenomena but also giving new knowledge about the sun to the public
and the educational communities, such as public observatories,
planetarium, science museum, and of course, schools. In order to
help the educators to efficiently and actively use Hinode data, we
organized working group for public use of Hinode data. It is a peculiar
point that members of the working group are of both researchers and
educators. That draw an interchange between researchers and educators,
and promoting the various type of activities in collaboration. As
our main activity, we have already produced two kinds of DVDs for
introducing the observational results of Hinode. The DVDs have already
been distributed to the educational communities in Japan. We made
some kinds of surveys for educators to confirm the efficiency of the
DVDs for education and public outreach. In addition, we use Hinode
data to develop educational materials and carried out exhibitions
at some museums. In such way, our activities might be quite unique
in that researchers/educators collaborate each other and a new style
of education and public outreach. In this paper , we introduce these
activities in details and the public impact.
Title: The Event Detection and the Apparent Velocity Estimation
Based on Computer Vision
Authors: Shimojo, M.
Bibcode: 2012ASPC..454..103S
Altcode:
The high spatial and time resolution data obtained by the telescopes
aboard Hinode revealed the new interesting dynamics in solar
atmosphere. In order to detect such events and estimate the velocity
of dynamics automatically, we examined the estimation methods of the
optical flow based on the OpenCV that is the computer vision library. We
applied the methods to the prominence eruption observed by NoRH, and
the polar X-ray jet observed by XRT. As a result, it is clear that the
methods work well for solar images if the images are optimized for the
methods. It indicates that the optical flow estimation methods in the
OpenCV library are very useful to analyze the solar phenomena.
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: A preliminary study of the HOP-187 jet analysis
Authors: Jackson, B.; Yu, H. -S.; Buffington, A.; Clover, J.; Shimojo,
M.; Sako, N.
Bibcode: 2012decs.confE.111J
Altcode:
The Hinode Observing Proposal (HOP)-187, "Tracking X-ray Jets from
the Solar Surface to Interplanetary Space" (Jackson and Shimojo,
2011) was carried out successfully during the summer of 2011. On
two occasions (00-06 UT 17 June, 2011, and 00-08 UT 22 August 2011)
XRT observations were run at a higher cadence over the south polar
region in conjunction with LASCO C2 observations that also provided
an enhanced 5-minute cadence and 100-sec exposures from this
instrument. This campaign effort was joined by the NASA SDO AIA,
the Solar TErrestrial RElations Observatory (STEREO) Coronagraph
(COR II) and Heliospheric Imagers (HI's), ground-based interplanetary
scintillation (IPS) observations from the Solar Terrestrial Environment
Laboratory (STELab) and Ootacamund (Ooty), India, and finally data
from the Solar Mass Ejection Imager (SMEI). In this data analysis,
as in previous campaign-mode operations of the Hinode XRT instrument,
we find a positive correlation between the brightest of the polar jets
and a high-speed response traced into the interplanetary medium. Here,
we report on the preliminary measurements of the jet responses that
were observed during this successful HOP-187 campaign.
Title: Millimeter/sub-millimeter wave observations for chromospheric
science
Authors: Shimojo, Masumi; ALMA Project
Bibcode: 2012decs.confE.103S
Altcode:
Except flares, the mm/sub-mm waves come from the lower chromosphere,
and the emission mechanism of the waves is thermal emission from
optically thick layer. The fact has been known from 1970's. However,
the spatial resolved observation in the wavelength range is very rare,
because most telescopes for mm/sub-mm wave observation do not have the
capability of solar observations and solar interferometric observations
require many antennas for resolving phenomena with short lifetime. The
Atacama Large Millimeter/sub-millimeter Array (ALMA) is the largest
interferometer in the world for astronomical observations in mm/sub-mm
wavelength. ALMA is constructed by 66 antennas and the highest spatial
resolution reaches 0.04 arcsec@100GHz / 0.005 arcsec@900GHz, when ALMA
starts the full operation phase ( 2013). Although the ALMA project
is the huge international astronomical project, it is not known well
that ALMA has the capability to observe the Sun. At the end of 2010,
ALMA project started the scientific verification activity for solar
observation by ALMA and we performed two observing campaigns for
verifying solar observations in May and December 2011. In the paper,
we present the progress of verification activities for ALMA solar
observations and discuss the chromospheric science using ultra-high
spatial resolution data obtained by ALMA.
Title: Solar Radio Type-I Noise Storm Modulated by Coronal Mass
Ejections
Authors: Iwai, K.; Miyoshi, Y.; Masuda, S.; Shimojo, M.; Shiota, D.;
Inoue, S.; Tsuchiya, F.; Morioka, A.; Misawa, H.
Bibcode: 2012ApJ...744..167I
Altcode:
The first coordinated observations of an active region using
ground-based radio telescopes and the Solar Terrestrial Relations
Observatory (STEREO) satellites from different heliocentric longitudes
were performed to study solar radio type-I noise storms. A type-I
noise storm was observed between 100 and 300 MHz during a period from
2010 February 6 to 7. During this period the two STEREO satellites were
located approximately 65° (ahead) and -70° (behind) from the Sun-Earth
line, which is well suited to observe the earthward propagating coronal
mass ejections (CMEs). The radio flux of the type-I noise storm was
enhanced after the preceding CME and began to decrease before the
subsequent CME. This time variation of the type-I noise storm was
directly related to the change of the particle acceleration processes
around its source region. Potential-field source-surface extrapolation
from the Solar and Heliospheric Observatory/Michelson Doppler Imager
(SOHO/MDI) magnetograms suggested that there was a multipolar magnetic
system around the active region from which the CMEs occurred around the
magnetic neutral line of the system. From our observational results,
we suggest that the type-I noise storm was activated at a side-lobe
reconnection region that was formed after eruption of the preceding
CME. This magnetic structure was deformed by a loop expansion that led
to the subsequent CME, which then suppressed the radio burst emission.
Title: An extremely microwave-rich flare observed with Nobeyama
Radio Heliograph
Authors: Masuda, S.; Goto, T.; Shimojo, M.; Kawate, T.
Bibcode: 2011AGUFMSH41A1912M
Altcode:
A compact flare was observed with Nobeyama Radio Heliograph (NoRH)
near the west limb around 2:56 UT on 10 March 2011. Its duration was
only one minute. The peak values of microwave flux at 17GHz and 34GHz
were 210 and 133 SFU, respectively. This level corresponds to the fifth
intense flare observed with NoRH in this solar cycle as of the end
of July, 2011. However, any significant enhance was not found in GOES
X-ray light curve during the flare period. Since the GOES background
level was around C1 at that time, so we can say the upper limit of
this flare was C1. In SDO EUV images, any significant change was not
observed during the flare. From microwave images, this flare might
occur slightly behind the west limb. We check STEREO-A SECCHI EUV
images during the flare period. Again, there was almost no signature
of a flare. Summarizing these observations, any significant enhance
of thermal emissions was not observed in this flare. Only microwave
emissions are detected. Unfortunately RHESSI was in the shadow of the
earth during this flare. What causes the relatively intense microwave
emissions? Considering that the brightness temperature was about 19
MK (the third highest temperature in this cycle as of the end of July
2011), the microwave emissions should be gyro-synchrotron emissions by
high-energy electrons. Fleishman et al. (2011) reported a cold tenuous
flare with acceleration, but without heating. This flare seems to
be similar. However, footpoint regions, i.e., strong magnetic field
regions, were occulted in the case of this flare. Additionally, in
higher-frequency range like 34GHz, intense microwave emissions were
detected. It is more difficult to understand these observational
results. We summarize the characteristics of this unique flare and
discuss what kind of process/situation produced it.
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: Observations of Polar-Region Jets and Their Manifestations
in the Solar Wind
Authors: Jackson, Bernard V.; Clover, John M.; Hick, P. Paul;
Buffington, Andrew; Linford, John C.; Shimojo, Masumi; Sako, Nobuharu
Bibcode: 2011shin.confE.170J
Altcode:
High-cadence images taken by the X-Ray Telescope (XRT) aboard Hinode
(Solar B), have shown that X-ray jets occur at very high frequency over
the polar regions of the Sun. Only the brightest of these explosive
events had been previously observed. It is possible that Alfven waves
generated by jets contribute greatly to the acceleration of the solar
wind; each jet provides a conduit for Alfven waves that add significant
energy to the corona by spreading outward from these localized areas
on the Sun. Here we explore the manifestations of the jet response in
the solar wind using observations from Hinode, the LASCO coronagraph,
and from 3D tomographic observations at greater heights above the
Sun. We attempt to quantify the jet response in the interplanetary
medium from these measurements, and to explore the diminution of this
response with solar radius.
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: Relationship between solar radio type-I noise storm and
Coronal Mass Ejection
Authors: Iwai, K.; Masuda, S.; Miyoshi, Y.; Shimojo, M.; Misawa, H.;
Tsuchiya, F.; Morioka, A.
Bibcode: 2010AGUFMSH54C..06I
Altcode:
Type-I noise storm is one of the solar radio phenomena observed in
a meter wavelength. While type-I is the most frequently observed
solar radio burst, it has little relation to solar flare or other
coronal phenomena. So the generation processes of type-I have not
been understood well. Sharp decreases of type-I noise storms were
observed in some previous studies (Chertok et al., 2001). Decreases
of type-I noise storms appear to be associated with coronal mass
ejections (CMEs) and post-CME phenomena. Therefore, identifying the
ambient magnetic field structure modulated by CME when the type-I noise
storms decrease is important to understand the generation mechanisms of
type-I, thoughobservational results have not been enough to identify
them. In this study, we have investigated an active region which was
located around the solar disk center using ground based radio burst
observation and coronal imaging observations of the STEREO satellites
that located around 65 to 70 degree from the Sun - Earth line. Such
coordinated observations at different angles from the active regions
are essential for studying the type-I noise burst. The observation
of the disc center is best to identify radio bursts because of the
emission directivity, whilethe limb observation can capture easily
the coronal loop structures and their dynamics. A decrease of type-I
noise storm was observed around 100 - 200 MHz on Feb. 7, 2010. In
this event, radio flux of the type-I noise storm decreased for about
1 hour and then finally disappeared after emitted at least for 3
hours. A CME eruption was observed at several hours before the type-I
dissipation. The STEREO observations suggest that the CME moved above
the active region and pre-existing coronal loop structures disappeared
during the type-I dissipation. Another CME was observed 1 hour after
the type-I dissipation. A potential-field source-surface simulation
using SOHO/MDI magnetogram also suggest that there were trans-equatorial
magnetic loops extended from the source region of the CME. We have tried
to explain the observation results using the CME break out model. In
the CME break out model, CMEs emerge inside pre-existing coronal loops
and interact with them. After the eruption of the first CME, a current
sheet is made in the post CME loop, which is usually much less sheared
and their reconnections proceed slowly. Therefore, this current sheet
reconnection region can provide energetic particles weakly for a long
time and it can explain the long duration of the type-I emission. There
is a possibility that flux emergence which lead to this second CME
might cause deformation or destruction of the current sheet of the radio
source region, and suppressed the radio burst emission. This explanation
is consistent with the fact that the type-I dissipation occurred when
the first CME front had reached at a height of several solar radius,
which is so distant from the height of expected radio source region
that the first CME could not modulate the radio source region by itself.
Title: Hard X-ray and microwave sources located around the apex of
a solar flare loop
Authors: Masuda, S.; Shimojo, M.; Watanabe, K.; Minoshima, T.; Yaji, K.
Bibcode: 2010AGUFMSH11B1641M
Altcode:
The apex of a flare loop is one of important regions to understand
particle acceleration in solar flares, under the framework of
the flare model based on magnetic reconnection. At that portion,
nonthermal emissions are observed in hard X-rays and microwave. These
two emissions are originated from electrons accelerated/energized in
different energy ranges. Hard X-rays (~ 50 - 100 keV ) are emitted by
relatively lower-energy (~ 100 keV) accelerated electrons. On the other
hand, microwaves (17 GHz) are emitted by relatively higher-energy (~
1 MeV) electrons. The locations (heights) of these two emitting regions
impose considerable constraints on the acceleration/transport/loss
processes of electrons in solar flares. To compare hard X-ray and
microwave sources, we chose twenty-three events among all events
detected by Nobeyama Radio Heliograph (NoRH) during the almost whole
period of its operation (1992 - 2008). The criteria are (1) limb
event, (2) simultaneous observation with Yohkoh/HXT or RHESSI, (3)
enough number of photons in the energy range of 33 - 53 keV, and (4)
microwave source large enough to resolve the flare loop into footpoint
and looptop sources. However, only seven events among them can be used
for this study. The remaining sixteen events are displaced from the
list due to no hard X-ray looptop source, too complex structure of
multiple loops, and so force. Among the seven events, six events show
that the looptop hard X-ray source is located at a higher altitude than
the looptop microwave source. This result suggests that lower-energy
accelerated electrons (~ 100 keV) are located at a higher altitude than
higher-energy (~ 1 MeV) electrons. What makes this height difference? We
discuss the cause of it from various kinds of viewpoints, e.g. emission
mechanism, trapping effect, transport process, loss process.
Title: The variations of prominence activities during solar cycle
Authors: Shimojo, Masumi
Bibcode: 2010cosp...38.1824S
Altcode: 2010cosp.meet.1824S
The prominence activities (prominence eruption/disappearance) in
the solar atmosphere closely relate with the CMEs that cause great
influences on heliosphere and magnetosphere. Gopal-swarmy et al. (2003)
reported that 72 The Nobeyama Radioheliograph (NoRH) is observing Sun
in microwave (17 GHz) since 1992. At a flare, the main component of
the microwave from Sun is emitted from non-thermal electrons that are
accelerated by flare. On the other hand, the main component of the
microwave is thermal emission when Sun is quiet, and a prominence is
clearly observed in microwave because there is the prominence on the
limb. We developed the automatic prominence activity detection program
based on 17 GHz images observed by NoRH, and investigated the variation
of the properties of the prominence activities that oc-curred from 1992
to the end of 2009. We found the following results. 1. The variation
in the number of prominence activities is similar to that of sunspots
during one solar cycle but there are differences between the peak times
of prominence activities and sunspots. 2. The frequency distribution
as a function of the magnitude of the prominence activities the size of
activated prominences at each phase shows a power-law distribution. The
power-law index of the distribution does not change except around the
solar minimum. 3. The number of promi-nence activities has a dependence
on the latitude On the other hand the average magnitude is independent
of the latitude. In the paper, we will also discuss the relationship
the other properties of prominence eruptions, solar cycle and the
photospheric magnetic field.
Title: Statistical study of the polar X-ray jets
Authors: Sako, Nobuharu; Shimojo, Masumi; Kitabayashi, Teruyuki
Bibcode: 2010cosp...38.2843S
Altcode: 2010cosp.meet.2843S
The X-Ray Telescope(XRT) abroad Hinode had revealed that X-ray jets in
the polar region occur at the high frequency. Savcheva et al. (2007)
studied 104 X-ray jets occurred around the south pole and reported
the parameters of the jets. However, their study included only the
X-ray jets that occurred in the coronal hole. In order to reveal the
properties of the polar X-ray jets in not only the coronal hole but also
the quiet region, we detected 870 polar X-ray jets occurred around the
north pole, and investigated the jets statistically. The 470 jets in
the 848 events occurred in the coronal hole. The occurrence rate of the
jets in the coronal hole and the quiet sun is 5.04×10-12 jets/hr/km2
and 7.66×10-12 jets/hr/km2 , respectively. It shows that the quiet
region is more productive of X-ray jets than the coronal hole. We
derived five parameters of the polar X-ray jets, and the average of
the parameters are 2.91×104 km for the maximum length, 4.42×103 km
for the width, and 180 km/sec for the apparent velocity. The lifetime
and length scale of the jets in this result is smaller than that in
Savcheva et al. (2007). The reason for these differences is that we
could detect smaller jets than the previous work because we used not
only X-ray intensity images but also the running difference images for
detecting the jets. We derived also the frequency distributions of the
parameters and found thatthe frequency distributions of the lifetime
and the X-ray intensity of the footpoint flare show the power-raw
distribution. The power-law index of the lifetime is -4.22±0.36,
and it is smaller than the index(-1.2) derived from the jets that
occurred near the active regions(Shimojo et al. 1996). The difference
indicates that the occurrence rate of the polar X-ray jets with short
lifetime is larger than that of the X-ray jets that occurred near active
regions.On the other hand, the power-raw index of the X-ray intensity
of the footpoint flare is -2.04±0.27. The index is smaller than that
of the X-ray jets near the active regions(Shimojo et al. 1996).
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 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: Imaging Spectroscopy on Preflare Coronal Nonthermal Sources
Associated with the 2002 July 23 Flare
Authors: Asai, Ayumi; Nakajima, Hiroshi; Shimojo, Masumi; Yokoyama,
Takaaki; Masuda, Satoshi; Krucker, Säm
Bibcode: 2009ApJ...695.1623A
Altcode: 2009arXiv0901.3591A
We present a detailed examination on the coronal nonthermal emissions
during the preflare phase of the X4.8 flare that occurred on 2002 July
23. The microwave (17 GHz and 34 GHz) data obtained with Nobeyama
Radioheliograph, at Nobeyama Solar Radio Observatory and the hard
X-ray (HXR) data taken with RHESSI obviously showed nonthermal sources
that are located above the flare loops during the preflare phase. We
performed imaging spectroscopic analyses on the nonthermal emission
sources both in microwaves and in HXRs, and confirmed that electrons
are accelerated from several tens of keV to more than 1 MeV even in this
phase. If we assume the thin-target model for the HXR emission source,
the derived electron spectral indices (~4.7) is the same value as that
from microwaves (~4.7) within the observational uncertainties, which
implies that the distribution of the accelerated electrons follows a
single power law. The number density of the microwave-emitting electrons
is, however, larger than that of the HXR-emitting electrons, unless
we assume low-ambient plasma density of about 1.0 × 109
cm-3 for the HXR-emitting region. If we adopt the
thick-target model for the HXR emission source, on the other hand,
the electron spectral index (~6.7) is much different, while the gap
of the number density of the accelerated electrons is somewhat reduced.
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: 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: The relation between the magnetic fields and the coronal
activities in the solar polar region
Authors: Shimojo, M.
Bibcode: 2008AGUFMSH44A..04S
Altcode:
The telescopes aboard Hinode satellite showed new views in solar
physics. One of new discoveries obtained by Hinode is the activities
in the polar region of the sun. Savcheva et al. (2007) investigated
the coronal hole around the south pole using the high-cadence X-ray
images, and they found that the appearance of X-ray jets in the polar
coronal holes occurs at very high frequency -- about 60 jets/day on
average. The other of new results obtained by Hinode is the magnetic
field measurements of the solar polar region with high accuracy. Tsuneta
et al. (2008) found that many vertically-oriented magnetic flux tube
with field strength as strong as 1--1.2 kG that are scattered in
latitude between 70 -- 90. If the trumpet-like magnetic structures
extend to interplanetary space, there is possibility that they are the
guide field of X-ray jets, coronal plumes and fast-solar wind. Thus,
in order to understand the polar phenomena, it is very important
to investigate the relation between the magnetic field distribution
and the coronal structures. We examined the co-alignment between the
Stokes-V maps of Na, the Stokes-Q maps of Fe, the X-ray images and
the EUV images of the north polar region. At the result, we found
that most of the trumpet-like magnetic structures around the pole
do not associate with the coronal structures. It suggests that the
energy injection for the fast-solar wind is not taking place in the
corona. The other finding from the co-alignment is that X-ray jets are
produced by the emerging/canceling fluxes. It is same as the jets in
the active regions. The existence of the emerging flux near the pole
suggests that the magnetic fields around the pole are provided from
not only the active regions but also the emerging fluxes near the pole.
Title: Hinode/XRT Diagnostics of Loop Thermal Structure
Authors: Reale, F.; Parenti, S.; Reeves, K. K.; Weber, M.; Bobra,
M. G.; Barbera, M.; Kano, R.; Narukage, N.; Shimojo, M.; Sakao, T.;
Peres, G.; Golub, L.
Bibcode: 2008ASPC..397...50R
Altcode:
We investigate possible diagnostics of the thermal structure of coronal
loops from Hinode/XRT observations made with several filters. We
consider the observation of an active region with five filters. We
study various possible combinations of filter data to optimize for
sensitivity to thermal structure and for signal enhancement.
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: 3D Simulations of the Quiet Sun Radio Emission at Millimeter
and Submillimeter Wavelengths
Authors: De La Luz, V.; Lara, A.; Mendoza, E.; Shimojo, M.
Bibcode: 2008GeofI..47..197D
Altcode:
We present 2D projections of 3D simulations of the quiet-sun
radio-emission, at different frequencies on the centimeter-
submillimeter wavelength range (specifically at 1.4, 3.9, 17, 34,
43, 110, 212 and 250 GHz). We have built a 3D, spherically symmetric,
solar model and solved the classical equation of radiative transfer
using quiet-sun temperature and electronic density models. We compare
our results with Nobeyama Radio Heliograph observations at 17 GHz. The
3.9 and 43 GHz images will be useful to calibrate the observations
of the new 5 meter millimeter telescope (RT5) which is going to be
installed at "Sierra Negra" Volcano, in the state of Puebla, México,
at an altitude of 4,600 m. over the sea level. This project is a
collaboration between Instituto Nacional de Astrofísica Óptica y
Electrónica (INAOE) and Universidad Nacional Autónoma de México
(UNAM).
Title: Solar X-ray Jets Observed with the X-ray Telescope aboard
Hinode
Authors: Shimojo, Masumi
Bibcode: 2008AstHe.101..311S
Altcode:
A solar X-ray jet is the jet phenomenon of coronal plasma and it was
discovered by the Soft X-ray Telescope aboard Yohkoh. Since the X-ray
telescope (XRT) aboard Hinode has the high-resolution and the wider
temperature response, the author found that the X-ray jets frequently
occur even in the polar coronal hole. And, XRT also revealed that
the jets generate MHD wave. Based on the XRT results, the author
suggests that the X-ray jets in coronal holes provide the energy for
the acceleration of fast solar wind.
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: Suppression of convection around small magnetic concentrations
Authors: Morinaga, S.; Sakurai, T.; Ichimoto, K.; Yokoyama, T.;
Shimojo, M.; Katsukawa, Y.
Bibcode: 2008A&A...481L..29M
Altcode:
Aims: It is well known that convective motions in the photosphere are
suppressed by magnetic fields. However, it has been difficult to study
the interaction between convection and small magnetic features, such
as G-band bright points (GBPs) or pores with polarimetric measurements,
because of the available spatial resolution (~1´´). This situation is
changed by the advent of the Spectro-Polarimeter (SP) aboard the Hinode
satellite, which has 0.3 arcsec spatial resolution.
Methods:
We analyzed the pore and its surrounding region in NOAA 10940 near the
disk center. We obtained the field strength and filling factor through
the Milne-Eddington inversion of the Stokes profiles. We also derived
the line-of-sight velocity by the shift of the line core. Using these
physical parameters, we investigated the physical conditions needed to
suppress the convection.
Results: We found that the convection
is suppressed, not by the strength of the magnetic field itself,
but by high concentration of magnetic flux tubes. We also found that
GBPs and pores are distinguished in terms of the filling factor (f);
f ≃ 0.6 for GBPs and f=0.8-0.9 for pores.
Title: Coronal Jet Observed by Hinode as the Source of
a3He-rich Solar Energetic Particle Event
Authors: Nitta, Nariaki V.; Mason, Glenn M.; Wiedenbeck, Mark E.;
Cohen, Christina M. S.; Krucker, Säm; Hannah, Iain G.; Shimojo,
Masumi; Shibata, Kazunari
Bibcode: 2008ApJ...675L.125N
Altcode:
We study the solar source of the 3He-rich solar
energetic particle (SEP) event observed on 2006 November 18. The
SEP event showed a clear velocity dispersion at energies below 1 MeV
nucleon-1, indicating its solar origin. We associate the SEP
event with a coronal jet in an active region at heliographic longitude
of W50°, as observed in soft X-rays. This jet was the only noticeable
activity in full-disk X-ray images around the estimated release time of
the ions. It was temporally correlated with a series of type III radio
bursts detected in metric and longer wavelength ranges and was followed
by a nonrelativistic electron event. The jet may be explained in terms
of the model of an expanding loop reconnecting with a large-scale
magnetic field, which is open to interplanetary space for the particles
to be observed at 1 AU. The open field lines appear to be anchored at
the boundary between the umbra and penumbra of the leading sunspot,
where a brightening is observed in both soft and hard X-rays during
the jet activity. Other flares in the same region possibly associated
with 3He-rich SEP events were not accompanied by a jet,
indicative of different origins of this type of SEP event.
Title: The relationship between the magnetic field and the coronal
activities in the polar region
Authors: Shimojo, Masumi
Bibcode: 2008cosp...37.2863S
Altcode: 2008cosp.meet.2863S
The image of the polar region of the sun is changing based on
the observations taken by the three telescopes aboard the Hinode
satellite. Based on the data of Solar Optical Telescope (SOT) aboard
Hinode, Tsuneta et al. (2007) reported that there are many localized
magnetic poles in the polar region, and the magnetic strength of the
magnetic poles is over thousand Gauss. They called the strong magnetic
pole in the polar region "kG-pathce". And, Cirtain, et al. (2007) and
Savcheva, et al. (2007) presented that the occurrence rate of X-ray jets
in the polar region is very high and 10 events/hour. Their result was
obtained by the high resolution observations by X-ray Telescope (XRT)
aboard Hinode. These results are very important for understanding
the fast solar wind that blows from the polar region. On the other
hand, in order to understand the activities in the polar region,
it is very important to investigate the relationship between the
magnetic environments and the coronal structures/activities. In the
paper, for the purpose, we aligned the photospheric images (G-band,
Stoke-IQUV of FeI), the chromospheric images (Ca II H line, Stokes-V
of Na) and coronal images (X-ray) obtained by Hinode, and investigate
the relationship. Basically, the co-alignment process was done based
on the alignment information of the telescopes reported by Shimizu
et al. (2007). And, we aligned the images using the curve of the
solar limb, finally. As the result of the co-alignments, we found the
following things. 1) On most kG-patches in the polar coronal hole,
there is any coronal structure. 2) X-ray jets in the polar coronal hole
are not always associated with the kG-patches. Some X-ray jets are
associated with very weak magnetic field. And, the jets are strongly
associated with the emerging/cancelling magnetic flux. The first one
suggests that the coronal heating is not effective only in the magnetic
field strong, such as the center of the sunspot. The second result
indicates that the producing mechanism of the X-ray jets in the coronal
hole is same as that in the other region. And the result suggests that
the magnetic activities are not weak even in the coronal hole.
Title: Cross calibration of soft X-ray telescopes between Hinode/XRT
and GOES13/SXI
Authors: Narukage, N.; Sakao, T.; Kano, R.; Shimojo, M.; Cirtain,
J.; Deluca, E.; Nitta, N.; Lemen, J.
Bibcode: 2007AGUFMSH53A1050N
Altcode:
The X-Ray Telescope (XRT) aboard Hinode satellite is a grazing
incidence telescope to observe all the coronal features with a wide
temperature range from less than 1MK to more than 10MK. And the XRT
has 9 X-ray analysis filters which are optimized to observed the
almost whole coronal plasma and to derived the coronal temperature
distribution. Meanwhile, the GOES13 satellite carries a Solar X-ray
Imager (SXI) to monitor the solar X-rays. The SXI is also a grazing
incidence telescope and has 7 X-ray filters. The XRT and SXI are
similar telescopes to observe the dynamic solar corona. On 24 Nov 2006,
the XRT and SXI-team performed the simultaneous observation for the
cross calibration between XRT and SXI. In this study, we analyzed
this data set and checked the actual characteristics of each X-ray
analysis filter.
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: Fine Thermal Structure of a Coronal Active Region
Authors: Reale, Fabio; Parenti, Susanna; Reeves, Kathy K.; Weber,
Mark; Bobra, Monica G.; Barbera, Marco; Kano, Ryouhei; Narukage,
Noriyuki; Shimojo, Masumi; Sakao, Taro; Peres, Giovanni; Golub, Leon
Bibcode: 2007Sci...318.1582R
Altcode:
The determination of the fine thermal structure of the solar corona is
fundamental to constraining the coronal heating mechanisms. The Hinode
X-ray Telescope collected images of the solar corona in different
passbands, thus providing temperature diagnostics through energy
ratios. By combining different filters to optimize the signal-to-noise
ratio, we observed a coronal active region in five filters, revealing
a highly thermally structured corona: very fine structures in the
core of the region and on a larger scale further away. We observed
continuous thermal distribution along the coronal loops, as well as
entangled structures, and variations of thermal structuring along the
line of sight.
Title: The Dynamics and Magnteic enviroments of Solar X-ray Jets
observed with Hinode
Authors: Shimojo, M.
Bibcode: 2007AGUFMSH22A0836S
Altcode:
An X-ray jet is a phenomena discovered by SXT/Yohkoh and the observed
properties of the X-ray jets are well explained by the X-ray jet model
based on magnetic reconnection (Shibata et al. 1992). The model proposed
that the X-ray jet is produced by the magnetic reconnection between
pre-exist coronal magnetic field (a part of open field or large loops)
and the emerging flux. The configuration is very simple and we can
easily predict the position of the reconnection site. Hence, we think
that an X-ray jet is a useful phenomenon for investigating the detail
properties of reconnection process in the corona. In the study, we study
the dynamics of fine structures and temperature structures of X-ray
jets using X-ray images observed with the XRT/Hinode and investigate
the detail properties of magnetic reconnection in corona. We also use
the data of magnetic distribution taken by the SOT/Hinode and study
the relationship of magnetic connectivity and reconnection process. At
first, we found that two fine structure dynamics from the X-ray images
observed with the XRT. One of the fine structures observed by XRT is
an expanding loop. The loop appears near the footpoint of the jet when
the footpoint brightening is observed. Additionally, we have found that
the X-ray jets begin 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 the X-ray jet model based on magnetic reconnection, and also
suggest that we must consider the three-dimensional configuration
of magnetic field to understand jet phenomenon."@In the paper, we
also discuss the magnetic environment at X-ray jets sites and the
temperature structure of X-ray jets.
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: 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: 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: 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: Evolution of Hα Kernels and Energy Release in an X-Class Flare
Authors: Asai, A.; Yokoyama, T.; Shimojo, M.; Masuda, S.; Shibata, K.
Bibcode: 2007ASPC..369..461A
Altcode:
The investigation on the evolution of Hα kernels allows us to
derive some key information on the energy release processes and the
particle acceleration mechanisms during a flare. We report a detailed
examination on the relationship between the evolution of the Hα flare
ribbons and the released magnetic energy during an X2.3 solar flare
which occurred on 2001 April 10. In the Hα images, several bright
kernels were observed in the flare ribbons. We identified the conjugated
footpoints, by analyzing the light curve at each Hα kernel, and showed
their connectivities during the flare. Then, based on the magnetic
reconnection model, we calculated quantitatively the released energy
by using the photospheric magnetic field strengths and the separation
speeds of the fronts of the Hα flare ribbons. We confirmed that the
estimated energy release rate corresponds to the nonthermal emission
light curves at the strong emission sources. Finally, we examined the
downward motions at the Hα kernels. The "red-asymmetry" features,
generated by the precipitation of the nonthermal particles and/or
thermal conduction into the chromospheric plasma, were observed for all
the flare ribbons. We also found that the stronger the red-asymmetry
tends to be associated with the brighter Hα kernel.
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: Archiving, Distribution and Analysis of Solar-B Data
Authors: Shimojo, M.
Bibcode: 2007ASPC..369...31S
Altcode:
The Solar-B Mission Operation and Data Analysis (MODA) working
group has been discussing the data analysis system for Solar-B data
since 2001. In the paper, based on the Solar-B MODA document and
the recent work in Japan, we introduce the dataflow from Solar-B to
scientists, the data format and data-level of Solar-B data, and the
data searching/providing system.
Title: Data Archive of the Hinode Mission
Authors: Matsuzaki, K.; Shimojo, M.; Tarbell, T. D.; Harra, L. K.;
Deluca, E. E.
Bibcode: 2007SoPh..243...87M
Altcode:
All of the Hinode telemetry data are to be reformatted and archived
in the DARTS system at ISAS and mirrored to data centers around
the word. The archived data are distributed to users through the
Internet. This paper gives an overview of the files in the archive,
including the file formats. All formats are portable and have
heritage from the previous missions. From the reformatted files, index
information is created for faster data search. Users can perform queries
based on information contained in the index. This allows for searches
to return observations that conform to particular observing conditions.
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: The Dynamics Of Fine Structures In Solar X-ray Jets
Authors: Shimojo, Masumi; Narukage, N.; Kano, R.; Sakao, T.; Tsuneta,
T.; Cirtain, J. W.; Lundquist, L. L.; Deluca, E. E.; Golub, L.
Bibcode: 2007AAS...210.9422S
Altcode: 2007BAAS...39Q.221S
The X-ray telescope(XRT) aboard HINODE satellite has the great
spatial/time resolution in X-ray range. And, the observations using
XRT have revealed the fine structures of solar corona. From the
observations, we found the fine thread structures in the X-ray jets
and the structures move dynamically like wave. We also found that some
X-ray jets start just after small loop expansion in the footpoint
brightening. The observation results suggest that the reconnection
process X-ray jets is very similar to that in large flares.
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: 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: 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: Particle Acceleration in the X3 Event on Dec. 13, 2007
Authors: Shibasaki, Kiyoto; Koshiishi, H.; Shimojo, M.; Minoshima,
T.; Imada, S.; Sakao, T.; Hinode Team
Bibcode: 2007AAS...210.9435S
Altcode: 2007BAAS...39..223S
Even during the solar minimum period, the active region NOAA 10930 had
a complex magnetic configuration especially around the main sunspot
and produced a couple of X-class events. The one on Dec. 13, 2007 was
well observed by Nobeyama Radioheliograph (NoRH) and Polarimeters
(NoRP). Microwave emission associated with this event has several
interesting characteristics: 1. Long lasting non-thermal phase 2. Very large decimetric flux (several thousand times of the quiet
sun flux) and quite different time development of decimetric emission
compared to shorter wavelengths 3. Very high turn-over frequency
(around 35 GHz) This event was also well observed by HINODE
satellite and partially by RHESSI satellite. Optical telescope (SOT) and
Soft X-ray telescope (XRT) onboard HINODE showed that the flare started
around the polarity reversal line which divides the main sunspot and
the closely associated small sunspot with opposite polarity. This line
is the interface of the penumbrae of both sunspots. The flare ribbons
started in the penumbrae and entered into umbrae of both sunspots. Microwave images of the event at 17 and 34 GHz are synthesized
and compared with optical and soft X-ray images taken by SOT and XRT
respectively. Based on these overlays, frequency spectral information
(NoRP) and RHESSI images in the later phase of the event, we try to
locate particle acceleration site and discuss possible mechanisms of
acceleration. 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, development and operation of the mission. NoRH
and NoRP are operated by Nobeyama Solar Radio Observatory, NAOJ. RHESSI
is a NASA project.
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 activity and the solar corona: first results from
the Hinode satellite .
Authors: Reale, Fabio; Parenti, Susanna; Reeves, Kathy K.; Weber,
Mark; Bobra, Monica G.; Barbera, Marco; Kano, Ryohei; Narukage,
Noriyuki; Shimojo, Masumi; Sakao, Taro; Peres, Giovanni; Golub, Leon
Bibcode: 2007MmSAI..78..591R
Altcode:
The structure, dynamics and evolution of the solar corona are governed
by the magnetic field. In spite of significant progresses in our insight
of the physics of the solar corona, several problems are still under
debate, e.g. the role of impulsive events and waves in coronal heating,
and the origin of eruptions, flares and CMEs. The Hinode mission has
started on 22 september 2006 and aims at giving new answers to these
questions. The satellite contains three main instruments, two high
resolution telescopes, one in the optical and one in the X-ray band,
and an EUV imaging spectrometer. On the Italian side, INAF/Osservatorio
Astronomico di Palermo has contributed with the ground-calibration
of the filters of the X-ray telescope. We present some preliminary
mission results, with particular attention to the X-ray telescope data.
Title: Flare Ribbon Expansion and Energy Release
Authors: Asai, Ayumi; Yokoyama, Takaaki; Shimojo, Masumi; Masuda,
Satoshi; Shibata, Kazunari
Bibcode: 2006JApA...27..167A
Altcode:
We report a detailed examination about the relationship between the
evolution of the Hα flare ribbons and the released magnetic energy
during the April 10 2001 flare. In the Hα images, several bright
kernels are observed in the flare ribbons.We identified the conjugated
footpoints, by analyzing the lightcurves at each Hα kernels, and showed
their connectivities during the flare. Then, based on the magnetic
reconnection model, we calculated quantitatively the released energy by
using the photospheric magnetic field strengths and separation speeds
of the Hα flare ribbons. Finally, we examined the downward motions
which are observed at the Hα kernels. We found that the stronger the
red-asymmetry tends to be associated with the brighter the Hα kernel.
Title: Preflare Nonthermal Emission Observed in Microwaves and
Hard X-Rays
Authors: Asai, Ayumi; Nakajima, Hiroshi; Shimojo, Masumi; White,
Stephen M.; Hudson, Hugh S.; Lin, Robert P.
Bibcode: 2006PASJ...58L...1A
Altcode:
We present a detailed examination on nonthermal emissions during
the preflare phase of the X4.8 flare that occurred on 2002 July
23. The microwave (17GHz and 34GHz) data obtained with the Nobeyama
Radioheliograph at Nobeyama Solar Radio Observatory and the hard X-ray
data taken with the Reuven Ramaty High Energy Solar Spectroscopic Imager
obviously showed nonthermal features in the preflare phase. We also
found a faint ejection associated with the flare in the EUV images
taken with the Transition Region and Coronal Explorer. We discuss
the temporal and spatial features of the nonthermal emissions in the
preflare phase, and their relation with the ejection.
Title: One Solar-Cycle Observations of Prominence Activities Using
the Nobeyama Radioheliograph 1992-2004
Authors: Shimojo, Masumi; Yokoyama, Takaaki; Asai, Ayumi; Nakajima,
Hiroshi; Shibasaki, Kiyoto
Bibcode: 2006PASJ...58...85S
Altcode:
We newly developed a method of limb-event detection for the Nobeyama
Radiograph, and show the results over one solar-cycle, 1992 July-2004
December. We detected 785 prominence activities and 31 flares on the
limb by this method. We investigated the relationship between the
distributions of the prominence activities and the solar cycle. As a
result, we found the following facts: 1) The variation in the number of
prominence activities is similar to that of sunspots during one solar
cycle. 2) There are differences between the peak times of prominence
activities and sunspots. 3) The frequency distribution as a function
of the magnitude of the prominence activities (the size of activated
prominences) at each phase shows a power-law distribution. The power-law
index of the distribution does not change, except around the solar
minimum. 4) The number of prominence activities has a dependence on the
latitude. On the other hand, the average magnitude is independent of the
latitude. 5) During the rise phase of the solar cycle, the location of
the high-latitude prominence activities migrates to the pole region. 6)
After a solar polarity reversal, the location of the prominence
activities in the northern hemisphere migrates to the equator. On
the other hand, the prominence activities in the southern hemisphere
occurred in the high-latitude region until the decay phase of Cycle 23.
Title: One solar-cycle observations of prominence activities using
the Nobeyama Radioheliograph 1992--2004
Authors: Shimojo, M.; Yokoyama, T.; Asai, A.; Nakajima, H.;
Shibasaki, K.
Bibcode: 2006cosp...36..417S
Altcode: 2006cosp.meet..417S
We newly developed a method of limb-event detection for the Nobeyama
Radiograph and show the results over one solar-cycle 1992 July --
2004 December We detected 785 prominence activities and 31 flares on
the limb by this method We investigated the relationship between the
distributions of the prominence activities and the solar cycle As a
result we found the following facts 1 The variation in the number of
prominence activities is similar to that of sunspots during one solar
cycle 2 There are differences between the peak times of prominence
activities and sunspots 3 The frequency distribution as a function
of the magnitude of the prominence activities the size of activated
prominences at each phase shows a power-law distribution The power-law
index of the distribution does not change except around the solar
minimum 4 The number of prominence activities has a dependence on the
latitude On the other hand the average magnitude is independent of the
latitude 5 During the rise phase of the solar cycle the location of the
high-latitude prominence activities migrates to the pole region 6 After
a solar polarity reversal the location of the prominence activities
in the northern hemisphere migrates to the equator On the other hand
the prominence activities in the southern hemisphere occurred in the
high-latitude region until the decay phase of Cycle 23
Title: Preflare Nonthermal Emission Observed in Microwaves and
Hard X-Rays
Authors: Asau, A.; Nakajima, H.; Shimojo, M.; White, S. M.; Hudson,
H. S.
Bibcode: 2006apri.meet...46A
Altcode:
No abstract at ADS
Title: Preflare Features in Microwaves and in Hard X-Rays
Authors: Asai, Ayumi; Nakajima, Hiroshi; Shimojo, Masumi; White,
Stephen M.
Bibcode: 2006aogs....2...33A
Altcode:
We present a detailed examination on the nonthermal emissions during
the pre-flare phase of the X4.8 flare which occurred on July 23,
2002. The microwave (17 and 34 GHz) data obtained with Nobeyama
Radioheliograph (NoRH), at Nobeyama Solar Radio Observatory, National
Astronomical Observatory of Japan, and the hard X-ray (HXR) data taken
with Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)
distinctly showed nonthermal features. We examined the temporal,
spatial, and spectroscopic characteristics of the emission sources,
and found loop-top sources during the preflare phase both in HXRs and
in microwaves. Moreover, we found that the electron spectral index
derived from microwave emission closely corresponds to that obtained
from the HXR emission. We also discuss the energy release mechanism
in the preflare phase.
Title: Downflow motions associated with impulsive nonthermal emissions
Authors: Asai, Ayumi; Shimojo, Masumi; Yokoyama, Takaaki; Shibata,
Kazunari
Bibcode: 2005ARAOJ...7....8A
Altcode:
No abstract at ADS
Title: Flare ribbon expansion and energy release rate
Authors: Asai, Ayumi; Shimojo, Masumi; Yokoyama, Takaaki; Masuda,
Satoshi; Kurokawa, Hiroki; Shibata, Kazunari
Bibcode: 2005ARAOJ...7....7A
Altcode:
No abstract at ADS
Title: Derivation of DEM distribution using Yohkoh/SXT
Authors: Shimojo, Masumi
Bibcode: 2005ARAOJ...7...17S
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: Derivation of DEM Distribution Using Yohkoh/SXT
Authors: Shimojo, M.
Bibcode: 2004ASPC..325..313S
Altcode:
We present preliminary results of the DEM analysis for an active
region seen in X-ray images. We apply the Withbroe-Sylwester method to
estimate DEM distributions from X-ray images observed with Yohkoh/SXT,
and obtain the DEM distribution in the temperature range of 2 MK to
10 MK. The DEM distribution of quiet loops in the center of the active
region shows a power-law distribution with an index of 4--5.
Title: Downflow as a Reconnection Outflow
Authors: Asai, A.; Shibata, K.; Yokoyama, T.; Shimojo, M.
Bibcode: 2004ASPC..325..361A
Altcode:
We present a detailed examination about the evolution of TRACE downflow
motions (sunward motions) seen above post-flare loops. We found that
the times when the downflow motions are seen correspond to those of
the bursts of nonthermal emissions in hard X-rays and microwave. These
results mean that the downflows occurred when strong magnetic energy
was released, and that they are, or at least correlated with, the
reconnection outflows. We also propose an observation of downflows as
the reconnection outflows by SolarB.
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: 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: A Quantitative Study of the Homologous Flares on 2000
November 24
Authors: Takasaki, Hiroyuki; Asai, Ayumi; Kiyohara, Junko; Shimojo,
Masumi; Terasawa, Toshio; Takei, Yasuhiro; Shibata, Kazunari
Bibcode: 2004ApJ...613..592T
Altcode:
We present an examination of multiwavelength observations of three
X-class homologous flares that occurred on 2000 November 24. By
investigating the behavior of the two-ribbon flares in Hα and the
ultraviolet (1600 Å), we found that the temporal variation of the
distance between the two ribbons shows a good correlation with the
soft X-ray light curve. From this finding we can derive the relation
dISXR(t)/dt~Vrib(t), where ISXR(t)
is the soft X-ray intensity and Vrib(t) is the separation
velocity of the two ribbons. This relation is similar to the well-known
empirical law, the Neupert effect. We also measured the rise time,
velocity of the plasmoid/filament ejection, and separation velocity of
the two ribbons for each of these homologous flares. Since the magnetic
reconnection model predicts that each of these physical parameters has
a dependence on the coronal magnetic field strength Bc,
we derived the relative Bc between the three flares from
each of the parameters. We compared the relative Bc values,
which are derived from those parameters, and found that they are roughly
equal. Our results successfully support the magnetic reconnection
model. Moreover, the relative hard X-ray maximum intensity in each
flare is consistent with the relative Bc derived above,
if we assume that the hard X-ray intensity is proportional to the
energy release rate as implied by the Neupert effect.
Title: Flare Ribbon Expansion and Energy Release Rate
Authors: Asai, Ayumi; Yokoyama, Takaaki; Shimojo, Masumi; Masuda,
Satoshi; Kurokawa, Hiroki; Shibata, Kazunari
Bibcode: 2004ApJ...611..557A
Altcode:
We have examined the relation between the evolution of the Hα
flare ribbons and the released magnetic energy in a solar flare that
occurred on 2001 April 10. Based on the magnetic reconnection model, the
released energy was quantitatively calculated by using the photospheric
magnetic field strengths and separation speeds of the fronts of the
Hα flare ribbons. We compared the variation of the released energy
with the temporal and spatial fluctuations in the nonthermal radiation
observed in hard X-rays and microwaves. These nonthermal radiation
sources indicate when and where large energy releases occur. We also
estimated the magnetic energy released during the flare. The estimated
energy release rates in the Hα kernels associated with the hard X-ray
sources are locally large enough to explain the difference between the
spatial distributions of the Hα kernels and the hard X-ray sources. We
also reconstructed the peaks in the nonthermal emission by using the
estimated energy release rates.
Title: Downflow Motions Associated with Impulsive Nonthermal Emissions
Observed in the 2002 July 23 Solar Flare
Authors: Asai, Ayumi; Yokoyama, Takaaki; Shimojo, Masumi; Shibata,
Kazunari
Bibcode: 2004ApJ...605L..77A
Altcode:
We present a detailed examination of downflow motions above flare
loops observed in the 2002 July 23 flare. The extreme-ultraviolet
images obtained with the Transition Region and Coronal Explorer show
dark downflow motions (sunward motions) above the postflare loops, not
only in the decay phase but also in the impulsive and main phases. We
also found that the times when the downflow motions start to be
seen correspond to the times when bursts of nonthermal emissions in
hard X-rays and microwaves are emitted. This result implies that the
downflow motions occurred when strong magnetic energy was released
and that they are, or are correlated with, reconnection outflows.
Title: Three-Dimensional Magnetohydrodynamic Numerical Simulations
of Coronal Loop Oscillations Associated with Flares
Authors: Miyagoshi, Takehiro; Yokoyama, Takaaki; Shimojo, Masumi
Bibcode: 2004PASJ...56..207M
Altcode:
We performed three-dimensional MHD numerical simulations for
solar coronal magnetic loop oscillations and found: (1) The loop
oscillation period is determined by its Alfvén time. (2) The
amplitude of oscillation decreases exponentially in time. This is
explained as energy transport by fast-mode MHD waves. The damping
rate, ωdamp, is described as ωdamp ∝
Va/R, where Va is the Alfvén speed around
loops and R is the radius of the loop. Because of computer resources
limitations, the plasma β value is much larger than that of the real
corona. We thus applied a scaling law derived from numerical simulation
results to the real corona parameter ranges and analyzed the results.
Title: The Joint Observations of Prominence Eruptions using Solar-B,
STEREO and NoRH
Authors: Shimojo, M.
Bibcode: 2004cosp...35.1927S
Altcode: 2004cosp.meet.1927S
Prominence/Filament eruption is one of the most spectacular solar
phenomena and causes large disturbances in interplanetary space. Hence,
the trigger mechanism of the eruption will be still a very important
problem for space weather in Solar-B and STEREO era. We analyzed the
simultaneous observation of some prominence eruptions using Nobeyama
Radioheliograph(NoRH) and SOHO/EIT for understanding of the problem. As
a result, we find that a part of the prominence become bright in EUV
and the material of the prominence fall down to solar surface when the
prominence is decelerated. The result suggests that the prominence
is heated by magnetic reconnection between magnetic field of the
prominence and corona. So, the simultaneous observation is very useful
for the understanding of the prominence evolution. After Solar-B and
STEREO are launched, we will be able to know the 3-D configuration
of prominence. In the paper, we discuss the simultaneous observation
of Solar-B, STEREO and NoRH based on our results and proposed the
observation plan for prominence eruption.
Title: Prominence eruptions and coronal mass ejection: a statistical
study using microwave observations
Authors: Gopalswamy, N.; Lu, W.; Yashiro, S.; Shimojo, M.; Shibasaki,
K.
Bibcode: 2004naoj.book...18G
Altcode:
No abstract at ADS
Title: On coronal streamer changes
Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki,
K.; Howard, R. A.
Bibcode: 2004AdSpR..33..676G
Altcode:
Coronal streamer represents one of the pre-eruption configurations
of coronal mass ejections (CMEs), because they overlie prominences
and often possess all the substructures of CMEs. In this paper,
we report on a study of streamer changes associated with prominence
eruptions. The prominence eruptions and streamer changes were observed
by the Nobeyama radioheliograph and Solar and Heliospheric Observatory
(SOHO), respectively. Multiwavelength data showed that at least one of
the streamer events involved heating and small-scale material ejection
that subsequently stalled. After presenting illustrative examples,
we compare the properties of the streamer-related events with those of
general population of prominence events. We find that the properties
of streamer-related prominence events are closer to those of prominence
eruptions with transverse trajectories.
Title: TRACE Downflows and Energy Release
Authors: Asai, A.; Yokoyama, T.; Shimojo, M.; Tandokoro, R.; Fujimoto,
M.; Shibata, K.
Bibcode: 2004ESASP.547..163A
Altcode: 2004soho...13..163A
We have examined in detail the evolution of a big two-ribbon flare which
occurred on 2002 July 23. The extreme ultraviolet images obtained with
TRACE show dark downflow motions (sunward motions) above the post-flare
loop, not only in the decay phase but also in the impulsive and main
phase. We found that the times when the downflow motions are seen
correspond to those of the bursts of nonthermal emissions in hard X-ray
and microwave. This result means that the downflow motions occurred when
strong magnetic energy was released, and that they are, or correlated
with, the reconnection outflows. We also found the ascending motions
of super hot plasma region seen in TRACE and RHESSI associating with
the light curves in hard X-rays and microwaves. This result supports
the Neupert effect.
Title: Flare Ribbon Expansion and Energy Release Rate
Authors: Asai, Ayumi; Yokoyama, Takaaki; Shimojo, Masumi; Masuda,
Satoshi; Shibata, Kazunari
Bibcode: 2004IAUS..223..443A
Altcode: 2005IAUS..223..443A
We report a detailed examination about the relationship between
the evolution of the Halpha flare ribbons and the released magnetic
energy during an X2.3 solar flare which occurred on 2001 April 10. We
successfully evaluated the released energy quantitatively, based on the
magnetic reconnection model. We measured the photospheric magnetic field
strengths and the separation speeds of the fronts of the Halpha flare
ribbon, and estimated the released magnetic energy at the flare by using
those values. Then, we compared the estimated energy release rates with
the nonthermal behaviors observed in hard X-rays and microwaves. We
also estimated the magnetic energy released during the flare. The
estimated energy release rates in the Halpha kernels associated
with the hard X-ray sources are locally large enough to explain the
difference between the spatial distribution of the Halpha kernels and
the hard X-ray sources. Furthermore, we reconstructed the peaks in
the nonthermal emission by using the estimated energy release rates.
Title: Radio and Hard X-Ray Images of High-Energy Electrons in an
X-Class Solar Flare
Authors: White, S. M.; Krucker, S.; Shibasaki, K.; Yokoyama, T.;
Shimojo, M.; Kundu, M. R.
Bibcode: 2003ApJ...595L.111W
Altcode:
We present the first comparison between radio images of high-energy
electrons accelerated by a solar flare and images of hard X-rays
produced by the same electrons at photon energies above 100 keV. The
images indicate that the high-energy X-rays originate at the footpoints
of the loops dominating the radio emission. The radio and hard X-ray
light curves match each other well and are quantitatively consistent
with an origin in a single population of nonthermal electrons with
a power-law index of around 4.5-5. The high-frequency radio spectral
index suggests a flatter energy spectrum, but this is ruled out by the
X-ray spectrum up to 8 MeV. The preflare radio images show a large
hot long-lived loop not visible at other wavelengths. Flare radio
brightness temperatures exceed 109 K, and the peak in the
radio spectrum is as high as 35 GHz: both these two features and the
hard X-ray data require very high densities of nonthermal electrons,
possibly as high as 1010 cm-3 above 20 keV at
the peak of the flare.
Title: Evolution of Flare Ribbons and Energy Release
Authors: Asai, A.; Yokoyama, Takaaki; Shimojo, Masumi; Masuda, Satoshi;
Kurokawa, Hiroki; Shibata, Kazunari
Bibcode: 2003ICRC....6.3367A
Altcode: 2003ICRC...28.3367A
We examined the relation between evolutions of flare ribb ons and
released magnetic energies at a solar flare which occurred on 2001
April 10 in the active region NOAA 9415. We successfully evaluated
the released energy quantitatively, based on the magnetic reconnection
model. We measured the photospheric magnetic field strengths and the
separation speeds of the fronts of the Hα flare ribb on, and estimated
the released magnetic energy at the flare by using those values. Then,
we compared the estimated energy release rates with the nonthermal
behaviors observed in hard X-rays and microwaves. We found that those
at the Hα kernels associated with the HXR sources are locally large
enough to explain the difference between the spatial distribution
the Hα kernels and the hard X-ray sources. Their temporal evolution
of the energy release rates also shows peaks corresponding to hard
X-ray bursts.
Title: Evolution of Conjugate Footpoints inside Flare Ribbons during
a Great Two-Ribbon Flare on 2001 April 10
Authors: Asai, Ayumi; Ishii, Takako T.; Kurokawa, Hiroki; Yokoyama,
Takaaki; Shimojo, Masumi
Bibcode: 2003ApJ...586..624A
Altcode:
We report a detailed examination of the fine structure inside flare
ribbons and the temporal evolution of such structure during an
X2.3 solar flare, which occurred on 2001 April 10. We examined fine
structures, such as systems of conjugate footpoints, inside flare
ribbons by using the Hα images obtained with the Sartorius telescope
at Kwasan Observatory, Kyoto University. We identified the conjugate
footpoints of each Hα kernel in both flare ribbons by a new method
that uses cross-correlation functions of the light curves. We also
compared the sites of the Hα kernels with the spatial configurations
of flare loops seen in the extreme-ultraviolet images obtained with
the Transition Region and Coronal Explorer. We found that the highly
correlated pairs of Hα kernels were connected by flare loops seen
in the 171 Å images. Investigating such fine structures inside the
flare ribbons, we can follow the history of energy release and perhaps
acquire key information about particle acceleration.
Title: Prominence Eruptions and Coronal Mass Ejection: A Statistical
Study Using Microwave Observations
Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki,
K.; Howard, R. A.
Bibcode: 2003ApJ...586..562G
Altcode:
We present the results of a statistical study of a large
number of solar prominence events (PEs) observed by the Nobeyama
Radioheliograph. We studied the association rate, relative timing,
and spatial correspondence between PEs and coronal mass ejections
(CMEs). We classified the PEs as radial and transverse, depending on
whether the prominence moved predominantly in the radial or horizontal
direction. The radial events were faster and attained a larger height
above the solar surface than the transverse events. Out of the 186
events studied, 152 (82%) were radial events, while only 34 (18%)
were transverse events. Comparison with white-light CME data revealed
that 134 (72%) PEs were clearly associated with CMEs. We compare our
results with those of other studies involving PEs and white-light CMEs
in order to address the controversy in the rate of association between
CMEs and prominence eruptions. We also studied the temporal and spatial
relationship between prominence and CME events. The CMEs and PEs seem
to start roughly at the same time. There was no solar cycle dependence
of the temporal relationship. The spatial relationship was, however,
solar cycle dependent. During the solar minimum, the central position
angle of the CMEs had a tendency to be offset closer to the equator
as compared to that of the PE, while no such effect was seen during
solar maximum.
Title: Close Correlation among Hα Surges, Magnetic Flux
Cancellations, and UV Brightenings Found at the Edge of an Emerging
Flux Region
Authors: Yoshimura, Keiji; Kurokawa, Hiroki; Shimojo, Masumi; Shine,
Richard
Bibcode: 2003PASJ...55..313Y
Altcode:
Surge activities were observed at the edge of an emerging flux
region. We studied the relations between the features around the surges
in various data sets: magnetogram, Hα, G-band, UV, EUV, and soft
X-rays. We showed that the surge activities in Hα and the brightenings
in TRACE 1600Å images correlate well in both time and space with the
cancellation of magnetic fluxes around an emerging flux region. In
particular, at the onset of surge activity, a close correlation among
them was clearly found. These facts are consistent with the magnetic
reconnection model. The released energy through magnetic reconnection,
which is estimated to be 1028 erg, is sufficiently large
to produce surge activities. No prominent brightenings were observed
in soft X-ray and EUV images during the surge activities. This may
suggest that the energy releases occurred at a layer of high densities.
Title: Evolution of flare ribbons and energy release
Authors: Asai, A.; Masuda, S.; Yokoyama, T.; Shimojo, M.; Kurokawa,
H.; Ishii, T. T.; Shibatal, K.
Bibcode: 2003AdSpR..32.2561A
Altcode:
We examined the relation between the evolutions of the H α flare
ribbons and the released magnetic energiesat a solar flare which
occurred on 2001 April 10. This is the first study to evaluate the
released energy quantitatively, based on the magnetic reconnection
model, and by using the data obtained with the multi wavelength
observation. We measured the, photospheric magnetic field strengths
and the separation speeds of the fronts of the H α flare ribbon,
and compared them the nonthermal behaviors observed in HXRs and
microwaves. Those nonthermal radiation sources tell us when and
where large energy releases occur. Then, by using the photospheric
and chromospheric features, we estimated the released magnetic energy
at the flare. The estimated energy release rates at the H α kernels
associated with the HXR sources are locally large enough to explain
the difference between the spatial distribution the H α kernels and
the HXR sources. Their temporal evolution of the energy release rates
also shows peaks corresponding to HXR bursts.
Title: Hard X-ray and Microwave Imaging Observations of the
18-July-2002 Flare
Authors: Masuda, S.; Yamamoto, T.; Yoshida, K.; Tanuma, S.; Yokoyama,
T.; Shimojo, M.
Bibcode: 2002AGUFMSH52A0473M
Altcode:
On 18 July 2002, an M-class flare were observed with RHESSI and the
Nobeyama Radio Heliograph (NoRH). We compared the hard X-ray (HXR)
images in the energy range above 30 keV and 17 GHz radio maps taken
during the impulsive phase. Two HXR sources were observed and they
were located at the two ends of a long (~ 20000 km) loop structure,
which was observed with TRACE in the later phase. The stronger HXR
source was located at the northern end of the loop and the weaker
one was at the southern end. On the other hand, a single radio source
was observed in 17 Hz and it was located at the site of the southern
(or weaker) HXR source. In EUV images, a few small ( < 5000 km)
loops were observed near the northern (stronger) HXR source. These
observations suggest that the electron acceleration occurred at the
interaction site between the long loop and the small loops, and then
they precipitated along the two loops. Such flares have been often
observed with Yohkoh/HXT and NoRH in these ten years. Usually two
radio emission sources and one HXR source have been observed. The main
radio source is located at the same location as the HXR source and
the remote radio source are located at the other end of the long loop
where there is no HXR source. It is believed the main radio source
and the HXR source include the emission from two footpoints of the
small loop and a footpoint of the long loop due to the poor spatial
resolutions of HXT and NoRH. In the case of the 18-July-2002 flare,
most of observational facts are consistent to this scenario. However,
the lack of radio emission at the northern region is much different
from the characteristics of the same type of events which have been
observed with HXT and NoRH. We focus our attention on this difference
and confirm whether this flare can be explained by the simple loop-loop
interaction model or not.
Title: Difference between Spatial Distributions of the Hα Kernels
and Hard X-Ray Sources in a Solar Flare
Authors: Asai, Ayumi; Masuda, Satoshi; Yokoyama, Takaaki; Shimojo,
Masumi; Isobe, Hiroaki; Kurokawa, Hiroki; Shibata, Kazunari
Bibcode: 2002ApJ...578L..91A
Altcode: 2002astro.ph..9106A
We present the relation of the spatial distribution of Hα kernels
with the distribution of hard X-ray (HXR) sources seen during the 2001
April 10 solar flare. This flare was observed in Hα with the Sartorius
telescope at Kwasan Observatory, Kyoto University, and in HXRs with
the hard X-ray telescope (HXT) on board Yohkoh. We compared the spatial
distribution of the HXR sources with that of the Hα kernels. While many
Hα kernels are found to brighten successively during the evolution
of the flare ribbons, only a few radiation sources are seen in the
HXR images. We measured the photospheric magnetic field strengths
at each radiation source in the Hα images and found that the Hα
kernels accompanied by HXR radiation have magnetic strengths about 3
times larger than those without HXR radiation. We also estimated the
energy release rates based on the magnetic reconnection model. The
release rates at the Hα kernels with accompanying HXR sources are
16-27 times larger than those without HXR sources. These values are
sufficiently larger than the dynamic range of HXT, which is about 10,
so that the difference between the spatial distributions of the Hα
kernels and the HXR sources can be explained.
Title: Prominence Eruptions and CMEs: A Statistical Study
Authors: Gopalswamy, N.; Shimojo, M.; Yashiro, S.; Shibasaki, K.
Bibcode: 2002AAS...200.3705G
Altcode: 2002BAAS...34..695G
Prominence eruptions are thought to be an integral part of coronal mass
ejections. However, recent statistical studies obtained conflicting
conclusions regarding this relationship: a nearly one-to-one
correspondence to a poor association. We revisited this problem using
all the eruptive prominences detected automatically from the daily
images obtained by the Nobeyama Radioheliograph. The images were
made with a 10 min cadence so only slower eruptions could be detected
from these images. During January 1996 to December 2001, there were
226 prominence eruptions detected this way and 182 of them had white
light observations from the Solar and Heliospheric Observatory (SOHO)
mission. When we compared the radio and white light data, we found
that 76 CMEs, while only 16 remaining 8 suggesting partial eruption. We
conclude that there is good association between CMEs when the prominence
eruptions have a radial component of the velocity is dominant.
Title: Dynamical Features and Evolutional Characteristics of
Brightening Coronal Loops
Authors: Shimojo, Masumi; Kurokawa, Hiroki; Yoshimura, Keiji
Bibcode: 2002SoPh..206..133S
Altcode:
We present a detailed study of coronal loop brightenings observed
in an active region on the solar limb. These brightening loops show
expanding and shrinking motions in EUV coronal line images and also
show downflow along the loops in Lα and Hα images. By means of
time-slice analysis of the images, we found that both the expanding
and shrinking motions of the loops are not real motions of plasma but
apparent motions like post-flare loops, where the loops at the different
height are successively heated and cooled. From a temperature analysis,
the time delay between the brightenings of hot 195 Å and cool Lα
loops is found to be nearly equal to the time-scale of the conduction
cooling. We conclude that these loop brightenings are sources of so
called Hα coronal rains.
Title: Reconnection Rate in the Decay Phase of a Long Duration Event
Flare on 1997 May 12
Authors: Isobe, Hiroaki; Yokoyama, Takaaki; Shimojo, Masumi; Morimoto,
Taro; Kozu, Hiromichi; Eto, Shigeru; Narukage, Noriyuki; Shibata,
Kazunari
Bibcode: 2002ApJ...566..528I
Altcode:
Recent analyses of long duration event (LDE) flares indicate successive
occurrences of magnetic reconnection and resultant energy release
in the decay phase. However, quantitative studies of the energy
release rate and the reconnection rate have not yet been made. In
this paper we focus on the decay phase of an LDE flare on 1997 May
12 and derive the energy release rate H and the reconnection rate
MA=vin/vA, where vin is
the inflow velocity and vA is the Alfvén velocity. For this
purpose, we utilize a method to determine vin and the coronal
magnetic field Bcorona indirectly, using the following
relations:H=2B2corona/4πvinAr,Bcoronavin=Bfootvfoot,where
Ar, Bfoot, and vfoot are the area of
the reconnection region, the magnetic field strength at the footpoints,
and the separation velocity of the footpoints, respectively. Since H,
Ar, vfoot, and Bfoot are obtained from
the Yohkoh Soft X-Ray Telescope data and a photospheric magnetogram,
vin and Bcorona can be determined from these
equations. The results are as follows: H is ~1027 ergs
s-1 in the decay phase. This is greater than 1/10th of
the value found in the rise phase. MA is 0.001-0.01,
which is about 1 order of magnitude smaller than found in previous
studies. However, it can be made consistent with the previous
studies under the reasonable assumption of a nonunity filling
factor. Bcorona is found to be in the range of 5-9 G, which
is consistent with both the potential extrapolation and microwave
polarization observed with the Nobeyama Radioheliograph.
Title: Evolution of Flare Ribbons and Energy Release
Authors: Asai, A.; Masuda, S.; Yokoyama, T.; Shimojo, M.; Ishii,
T. T.; Isobe, H.; Shibata, K.; Kurokawa, H.
Bibcode: 2002aprm.conf..415A
Altcode:
We estimated the released magnetic energy via magnetic reconnection
in the corona by using photospheric and chromospheric features. We
observed an X2.3 flare, which occurred in active region NOAA9415 on 2001
April 10, in Hα with the Sartorius Telescope at Kwasan Observatory,
Kyoto University. Comparing the Hα images with the hard X-ray (HXR)
images obtained with Yohkoh/HXT, we see only two HXR sources which
are accompanied by Hα kernels. At these Hα kernels the large energy
release is thought to be larger than at other Hα kernels. We estimated
the energy release rates at each Hα kernel by using the photospheric
magnetic field strength and the separation speed of the Hα flare
ribbons at the same location. The estimated energy release rates at
the Hα kernels associated with the HXR sources are locally large
enough to explain the different appearance. Their temporal evolution
also shows peaks corresponding to HXR bursts.
Title: The Temperature Analysis of Yohkoh/SXT Data using the CHIANTI
Spectral Database
Authors: Shimojo, M.; Hara, H.; Kano, R.
Bibcode: 2002mwoc.conf..419S
Altcode:
Since the CHIANTI database for astrophysical emission line spectroscopy
was extended to X-ray wavelengths below 50Å recently (Dere et
al. 2000), a temperature response of YOHKOH/SXT has been able to
calculate using the database. The functions of temperature responses of
SXT are very important for plasma diagnostic since we usually derive
the electron temperature of coronal plasma using the observed signal
counts and the ratio of the temperature responses. In this paper,
we present the properties of the SXT temperature responses which are
calculated from the CHIANTI database and also compare them with the
SXT temperature responses which are calculated using Mewe spectral
databases (Mewe, et al., 1985, 1986). We calculated the filter ratios
using CHIANTI database and compared them with the filter ratios which
are calculated from Mewe database. At the result, it is found that
the difference between temperatures which are derived using CHIANTI
and Mewe database is about 2 MK around 5 MK, if we use Al and Al12
filters for the plasma diagnostic. The result is the same as Schmelz
et al.(1999). In the paper, we also discuss the effect of the CHIANTI
spectral databases for previous works which used the filter ratios
based on Mewe database.
Title: Fine Structure inside Flare Ribbons and Temporal Evolution
Authors: Asai, A.; Masuda, S.; Yokoyama, T.; Shimojo, M.; Kurokawa,
H.; Shibata, K.; Ishii, T. T.; Kitai, R.; Isobe, H.; Yaji, K.
Bibcode: 2002mwoc.conf..221A
Altcode:
Non-thermal particles generated in the impulsive phase of
solar flares are observed mainly in microwave, hard X-rays, and
gamma-rays. Observations in Hα can also give important informations
about non-thermal particles precipitating into the chromosphere with
a higher spatial resolution than in other wavelengths. We observed an
X2.3 flare which occurred in the active region NOAA 9415 on 10 April
2001, in Hα with Sartorius Telescope at Kwasan Observatory, Kyoto
University. Thanks to the short exposure time given for the flare, the
Hα images show fine structures inside the flare ribbons. In addition
to Hα, we analyze microwave, hard X-ray, and EUV data obtained with
Nobeyama Radioheliograph, Yohkoh/HXT, and TRACE, respectively. In Hα,
several bright kernels are observed in the flare ribbons. On the other
hand, the hard X-ray images show only a single pair of bright sources
which correspond to one of several pairs of Hα kernels. Examining
the difference in the magnetic field strength and in the time profiles
of Hα emission for these kernels, we discuss the reason why only one
pair kernels are bright in the hard X-ray among the other bright Hα
kernels. Comparing the Hα images with EUV images, we also examine
the three-dimensional structure of solar flares. While broad and
network-like ribbons are observed in Hα, the width of EUV ribbons is
relatively narrow, and EUV ribbons are located at the outer edges of
the corresponding Hα ribbon.
Title: Evolution of flare ribbons and energy release
Authors: Asai, A.; Masuda, S.; Yokoyama, T.; Shimojo, M.; Kurokawa,
H.; Ishii, T.; Shibata, K.
Bibcode: 2002cosp...34E1179A
Altcode: 2002cosp.meetE1179A
Non-thermal particles generated in the impulsive phase of
solar flares are observed mainly in microwave, hard X-rays, and g
amma-rays. Observations in Halpha can also give important informations
about non-thermal particles precipitating into the chromosphere with a
higher spatial resolution than in other wavelengths. We observed an X2.3
flare which occurred in the active region NOAA 9415 on 10 April 2001,
in Halpha with the Sartorius Telescope at Kwasan Observatory, Kyoto
University. Thanks to the short exposure time given for the flare, the
Halpha images show fine structures inside the flare ribbons. In Halpha,
several bright kernels are observed in the flare ribbons. On the other
hand, the hard X-ray images show only a single pair of bright sources
which correspond to one of several pairs of Halpha kernels. In this
paper, we examined the magnetic field strength at each H kernel and
the separation speed of the H flare ribbons, and estimated the energy
release rate with the method based on the magnetic reconnection model
(Isobe et al. 2002). We found that the energy release rate is well
correlated with the time profiles of hard X-ray and microwave.
Title: Origin of coronal streamer distention
Authors: Gopalswamy, N.; Shimojo, M.; Lu, W.; Yashiro, S.; Shibasaki,
K.; Howard, R.
Bibcode: 2002cosp...34E1257G
Altcode: 2002cosp.meetE1257G
Distention of coronal streamers is considered to be one of the
pre-eruption evolution of coronal mass ejections (CMEs), although how
mass is added to the streamers is poorly understood. During our study
of eruptive prominences and their relation to CMEs, we observed a large
number of prominences associated with significant changes in the helmet
streamers overlying the prominences. We used the white light images of
the corona obtained by the Solar and Heliospheric Mission's Large Angle
and Spectrometric Coronagraph images and the microwave images from the
Nobeyama radioheliograph in Japan. We found that the streamer distention
is associated with prominence eruption with mostly horizontal motion
(parallel to the solar limb) or with eruptive prominences with most of
the mass falling back to the solar surface. We suggest that the physical
process which activates the prominences also add mass to the streamers.
Title: Surges, Magnetic Flux Cancellations, and UV Brightenings
around an Emerging Flux Region
Authors: Yoshimura, K.; Kurokawa, H.; Shimojo, M.; Shine, R.
Bibcode: 2002mwoc.conf...99Y
Altcode:
Surge activities, which are observed in Hα images, have been
studying for a long time. Many authors noticed that cancellations
of magnetic flux was an important factor for surge activities and
proposed the models based on magnetic reconnection. But there are not
many observations which have enough cadence for comparison changes
of magnetic field with surge activities. So the correlation between
surges and magnetic flux cancellations is not clear yet. (ex. Zhang
et al. 2001) We studied the temporal and spatial relations between
surge activities and other phenomena which may be accompanied by surge
activities. The data we used here are from coordinated observation with
Swedish Vacuum Solar Telescope on La Palma, TRACE and SOHO/MDI. So
high cadence images for the same target are available in various
wavelengths. MDI, for example, took magnetogram data every one minutes
with high resolution mode at that time. The main results from this study
are as follows: (1) We can not find any large time lag between the onset
of the surge and of the magnetic fields cancellation. This is a conflict
result against the one in Zhang et al. (2) There were UV brightenings
which correlated well with rapid cancellation of magnetic fields. (3)
The UV brightenings located just on neutral lines with some displacement
from the region where rapid magnetic cancellation occurred. These
observational fact can be explained by magnetic reconnection model.
Title: Hard X-Radiation from a Fast Coronal Ejection
Authors: Hudson, H. S.; Kosugi, T.; Nitta, N. V.; Shimojo, M.
Bibcode: 2001ApJ...561L.211H
Altcode:
We have observed a high-speed coronal ejection in hard X-rays,
detectable to an altitude of some 2×105 km in the Yohkoh
23-53 keV energy bands. Simultaneous imaging at 17 and 34 GHz from the
Nobeyama radioheliograph shows complex moving features simultaneous with
the ejection, including a compact source that we identify with the rapid
X-ray source motion. The hard X-ray and microwave observations agree on
ejection velocities in the vicinity of 1000 km s-1. The hard
X-ray sources also corresponded in position angle to a bright coronal
mass ejection (CME) detected about 15 minutes later and temporally to
both fast-drift and slow-drift radio bursts in the decimeter-meter
bands. Other components of coronal hard X-ray emission were also
detected, including an extended long-duration event with a nonthermal
spectrum. We suggest that a major eruptive flare occurred in NOAA Active
Region 9415, approximately 26° beyond the west limb at the time of the
event. Estimating a source density of 4×109 cm-3
from the compact source observed at 17 GHz, we find a total electron
number (>20 keV) of approximately N20~1.3×1036
for the compact part of the source. We infer that these electrons
were trapped in expanding loops forming a part of the CME and may have
contributed substantial pressure within these loops.
Title: Periodic Acceleration of Electrons in the 1998 November 10
Solar Flare
Authors: Asai, A.; Shimojo, M.; Isobe, H.; Morimoto, T.; Yokoyama,
T.; Shibasaki, K.; Nakajima, H.
Bibcode: 2001ApJ...562L.103A
Altcode: 2001astro.ph.11018A
We present an examination of the multiwavelength observation of
a C7.9 flare that occurred on 1998 November 10. This is the first
imaging observation of the quasi-periodic pulsations (QPPs). Four
bursts were observed with the hard X-ray telescope aboard Yohkoh
and the Nobeyama Radioheliograph during the impulsive phase of the
flare. In the second burst, the hard X-ray and microwave time profiles
clearly showed a QPP. We estimated the Alfvén transit time along
the flare loop using the images of the soft X-ray telescope aboard
Yohkoh and the photospheric magnetograms and found that the transit
time was almost equal to the period of the QPP. We therefore suggest,
based on a shock acceleration model, that variations of macroscopic
magnetic structures, such as oscillations of coronal loops, affect
the efficiency of particle injection/acceleration.
Title: One-dimensional and Pseudo-Two-dimensional Hydrodynamic
Simulations of Solar X-Ray Jets
Authors: Shimojo, Masumi; Shibata, Kazunari; Yokoyama, Takaaki;
Hori, Kuniko
Bibcode: 2001ApJ...550.1051S
Altcode:
We present results of one-dimensional hydrodynamic simulations
of the chromospheric evaporation produced by a microflare in a
large-scale loop as a model of X-ray jets. The initial conditions
of the simulations are based on the observations of X-ray jets. We
deposit thermal energy (~1×1028 ergs) in the corona. The
deposited energy is rapidly transported to the chromosphere by
conduction, which heats the dense plasma in the upper chromosphere. As
a result, the gas pressure is increased and drives a strong upflow of
dense, hot plasma along the magnetic loop. We found the following
features of evaporation in the results of our simulations: (1)
the maximum temperature of the evaporating plasma is determined by
the balance between the conductive flux and the heating flux; (2)
the total mass of evaporating plasma is controlled by the balance
between the conductive flux and enthalpy flux; (3) the relationship
between the density neva, height of energy deposition
sflare, and heating rate Fh is described as
neva~F4/7h/s3/7flare
(4) the X-ray intensity along the evaporation-flow plasma decreases
exponentially with distance from the footpoint, and that exponential
intensity distribution holds from the early phase to the decay phase;
(5) in the single-loop model, the temperature decreases with distance
from the energy deposition site (on the other hand, a hot region is
present in front of the evaporation front in the multiple-loop model);
(6) we compare the physical parameters of the evaporation flow with the
observations of the X-ray jet that occurred on 1992 September 3 and
find that the physical parameters of evaporating plasma are similar
to those of the Yohkoh-observed X-ray jet. Since these properties of
the evaporation flow are similar to the observed properties of X-ray
jets, we suggest that an X-ray jet is the evaporation flow produced
by a flare near the footpoint of a large-scale loop. Furthermore,
according to the X-ray intensity distribution along the evaporation
flow, we suggest that a multiple-loop model based on the magnetic
reconnection mechanism can reproduce the properties of an X-ray jet
better than the single-loop model.
Title: Physical Parameters of Solar X-Ray Jets
Authors: Shimojo, Masumi; Shibata, Kazunari
Bibcode: 2000ApJ...542.1100S
Altcode:
We derived the physical parameters of X-ray jets and associated flares
using the high-resolution data taken with the soft X-ray telescope
aboard Yohkoh. We analyzed 16 X-ray jets and found the following
properties of the jets and the footpoint flares: (1) the temperatures
and density of the jets, respectively, are 3-8 MK (average: 5.6 MK) and
0.7-4.0×109 cm-3 (average: 1.7×109
cm-3), (2) the temperatures of the jets are similar to
those of the footpoint flares, (3) the thermal energies of the jets are
1027-1029 ergs, which is 1/4 to 1/7 of those of
the footpoint flares, (4) the apparent velocity of the jets is usually
slower than the sound speed, and (5) there is a correlation between
the temperatures of the jets and the sizes (square root of area)
of the footpoint flares. On the basis of these results, we find that
the temperatures of a jet and a footpoint flare are determined by the
balance between heating flux and conductive flux and that the mass
of a jet is comparable to the theoretical value based on the balance
between conductive flux and enthalpy flux carried by the evaporation
flow. These results suggest that X-ray jets are evaporation flows
produced by the reconnection heating.
Title: Soft X-ray flares and magnetic configuration in a solar active
region in February 1992
Authors: Zhang, H. Q.; Sakurai, T.; Shibata, K.; Shimojo, M.;
Kurokawa, H.
Bibcode: 2000A&A...357..725Z
Altcode:
In this paper, we examine the observational soft X-ray flares and
the relationship with photospheric vector magnetograms in the active
region (NOAA 7070). We analyze the soft X-ray flare on Feb. 24-25,
1992, especially the pre-flare and the relationship with the highly
sheared photospheric vector magnetic field near the photospheric
magnetic neutral line. We find that the initial reconnection of the
magnetic field in the flare on Feb. 24-25, 1992 probably occurs near
the magnetic neutral line in the lower atmosphere of the active region,
where the highly sheared magnetic flux erupts up and triggers the
reconnection of the large-scale magnetic field. The possible process
of the magnetic reconnection of the limb flare on Feb. 20-21, 1992
in this active region is proposed also based on the analogy with the
flare on Feb. 24-25 near the center of the solar disk.
Title: Observational Evidence of Magnetic Reconnection in Solar
X-Ray Jets
Authors: Shimojo, M.; Shibata, K.
Bibcode: 2000AdSpR..26..449S
Altcode:
The solar X-ray jets are one of the most interesting findings of
Soft X-Ray Telescope(SXT) aboard Yohkoh. They are transitory X-ray
enhancements with an apparent collimated motion. In this paper,
we present the observational evidence of magnetic reconnection of
solar X-ray jets.From the morphological study of solar X-ray jets
using SXT, we found the following properties of solar X-ray jets. 1)
Most X-ray jets are associated with flares (microflares - flares)
at their footpoints. 2) When the active regions at the footpoint
of jets can be resolved well, it is found that morphology changes
significantly during jets. 3) 27% of the jets show a gap ( >
104 km) between the exact footpoint of the jet and the
brightest part of the associated flare. Furthermore, as a result of
the co-alignment between magnetograms and SXT images, we found that
the jet-producing region are the mixed polarity region and the region
of evolving magnetic flux (increasing or decreasing). Canfield et
al. (1996) investigated some Hα surges which were associated with
X-ray jets and found some new Ha phenomena (moving-blueshift feature,
converging footpoint motion). They suggested that these phenomena are
the results of magnetic reconnection. As the results, we propose that
the solar X-ray jets are produced by energy input from the (micro)flares
which are generated by magnetic reconnection
Title: Thermal Evolution of Coronal Active Regions Observed with
the Yohkoh Soft X-Ray Telescope
Authors: Yashiro, S.; Shibata, K.; Shimojo, M.
Bibcode: 2000AdSpR..25.1773Y
Altcode:
We study the thermal evolution of active regions in the corona by
analyzing 51 emerging flux regions (EFRs) observed with the soft
X-ray telescope aboard Yohkoh. We derive the mean temperature and
pressure of active regions as a function time using filter ratio
technique, and found that the mean temperature increases with its
expansion. We also studied the relationship between the region
size and the temperature, and found that the temperature (T) and
the pressure (P) of EFRs increase with increasing region size (L);
TαL00.42PαL00.25
Title: Theory and Observations of X-ray Jets
Authors: Shimojo, M.; Shibata, K.
Bibcode: 2000IAUJD...7E...7S
Altcode:
X-ray jets were discovered by soft X-ray telescope aboard Yohkoh
in 1991 as transitory X-ray enhancements with apparent collimated
motion. They are ejected from small flares or microflares, and could
be related to coronal heating mechanism and acceleration of high speed
solar wind. Since their discovery, both theory (especially magnetic
reconnection model) and observations of X-ray jets have been greatly
advanced. We review the current status of the understanding of X-ray
jets from both theoretical and observational points of view, and discuss
the relation to other jet-like phenomena on the Sun, coronal heating,
and acceleration of high speed solar wind.
Title: Thermal Evolution of Coronal Active Regions
Authors: Yashiro, S.; Shibata, K.; Shimojo, M.
Bibcode: 1999spro.proc...99Y
Altcode:
We study the thermal evolution of active regions in the corona by
analyzing 51 emerging flux regions (EFRs) observed with the soft
X-ray telescope aboard Yohkoh. We derive the mean temperature and
pressure of active regions as a function of time using the filter
ratio technique, and found that the mean temperature increases with
its expansion. We also studied the relationship between the region
size and the temperature, and found that the temperature (T) and the
pressure (P) of EFRs increase with increasing region size (L); T ∝
L0.42, P ∝ L0.25. The relation between pressure
and region size, however, is strongly influenced by the assumption of
the region's thickness along the line of sight.
Title: A Microwave Study of Coronal and Chromospheric Ejecta
Authors: Nindos, A.; Kundu, M. R.; Raulin, J. -P.; Shibasaki, K.;
White, S. M.; Nitta, N.; Shibata, K.; Shimojo, M.
Bibcode: 1999spro.proc..135N
Altcode:
We have studied the radio properties of 18 X-ray coronal jets (observed
by the Yohkoh SXT) using Nobeyama 17 GHz data. We also searched for
chromospheric ejecta (Hα surges) during the time intervals that the
X-ray images were available. Microwave emission was associated with the
majority of the X-ray jets. The radio emission came from the base or
the lower part of the jets. We detected radio emission from almost all
jets which showed flare-like activity at their footpoints. The 17 GHz
time profiles were gradual and unpolarized, implying that the emission
was thermal. When possible, we computed the physical properties of the
X-ray-emitting ejected plasma. In one two-sided-loop type jet and one
anemone-type jet, the observed microwave fluxes from the lower part of
the jets were well above the fluxes predicted from the computed electron
temperatures and emission measures of the soft X-ray-emitting material
on the basis of thermal free-free emission. We interpreted the large
discrepancies in terms of the presence of lower temperature material
which cannot be detected by the SXT but produces strong microwave
free-free emission. This is the first time that such material is
observed in two-sided-loop type jets. Thus our observations confirm the
theoretical prediction by Yokoyama and Shibata (1996). We detected no
cool material at the base of the jets. We also observed an Hα surge
which was not associated with an X-ray jet and showed no signatures on
the SXT images but was detected with the Nobeyama Radioheliograph. The
emission of the microwave surge-associated source was free-free from the
chromospheric plasma. Constraints for the surge density were derived.
Title: A Microwave Study of Coronal Ejecta
Authors: Kundu, M. R.; Nindos, A.; Raulin, J. -P.; Shibasaki, K.;
White, S. M.; Nitta, N.; Shibata, K.; Shimojo, M.
Bibcode: 1999ApJ...520..391K
Altcode:
Using Nobeyama 17 GHz data, we have studied the radio properties of
19 coronal jets identified in Yohkoh soft X-ray imaging telescope
(SXT) X-ray observations. The radio data provide information on the
physical conditions in the jets, which complements the data from the
X-ray surveys. Microwave emission was associated with the majority of
the X-ray jets in our sample. The radio emission typically came from
the base or the base and lower part of the jets. We detected radio
emission from almost all jets that showed flarelike activity at their
bases. The jets that were not associated with radio emission did not
show any significant increase in X-ray emission at their bases. The
strongest radio emission came from two of the largest jets in our
sample. Our data show a general correlation between the X-ray jet
fluxes and the associated radio fluxes. The 17 GHz time profiles were
gradual and unpolarized, implying that the emission was thermal. In a
two-sided-loop jet (1992 July 22 event) and one anemone-type jet (1993
February 9 event), the observed microwave fluxes from the lower part
of the jets were well above the fluxes calculated from the computed
physical parameters of the soft X-ray-emitting material on the basis
of thermal free-free emission. We interpret the large discrepancies
in terms of the presence of lower temperature material, which cannot
be detected by the SXT (the SXT is most sensitive to hot plasma above
2×106 K), but which produces strong microwave free-free
emission. This is the first time that such material has been observed
in two-sided-loop-type jets. We also observed motion of a jet-associated
microwave source with a velocity of 55 km s-1. The microwave
motion occurred after the appearance of the X-ray jet. There is clear
evidence that the microwave emission of that source was associated
with the jet and not with the associated small flare.
Title: A Microwave Study of Coronal Ejecta
Authors: Kundu, M. R.; Nindos, A.; Raulin, J. -P.; Shibasaki, K.;
White, S. M.; Nitta, N.; Shibata, K.; Shimojo, M.
Bibcode: 1999AAS...194.1704K
Altcode: 1999BAAS...31..853K
Using Nobeyama 17 GHz data, we have studied the radio properties
of 19 coronal jets identified in Yohkoh SXT X-ray observations. The
radio data provide information on the physical conditions in the jets
which complements the data from the X-ray surveys. Microwave emission
was associated with the majority of the X-ray jets in our sample. The
radio emission typically came from the base or the base and lower part
of the jets. We detected radio emission from almost all jets which
showed flare-like activity at their bases. The jets which were not
associated with radio emission did not show any significant increase
in X-ray emission at their bases. The strongest radio emission came
from two of the largest jets in our sample. Our data show a general
correlation between the X-ray jet fluxes and the associated radio
fluxes. The 17 GHz time profiles were gradual and unpolarized, implying
that the emission was thermal. In a two-sided-loop jet (July 22, 1992
event) and one anemone-type jet (February 9, 1993 event), the observed
microwave fluxes from the lower part of the jets were well above the
fluxes calculated from the computed physical parameters of the soft
X-ray-emitting material on the basis of thermal free-free emission. We
interpret the large discrepancies in terms of the presence of lower
temperature material which cannot be detected by the SXT (the SXT is
most sensitive to hot plasma above 2 x 10(6) K) but which produces
strong microwave free-free emission. This is the first time that
such material has been observed in two-sided-loop type jets. We also
observed motion of a jet-associated microwave source with a velocity
of 55 km/sec. The microwave motion occurred after the appearance of
the X-ray jet. There is clear evidence that the microwave emission of
that source was associated with the jet and not with the associated
small flare.
Title: Occurrence Rate of Microflares in an X-Ray-bright Point within
an Active Region
Authors: Shimojo, Masumi; Shibata, Kazunari
Bibcode: 1999ApJ...516..934S
Altcode:
We examine the occurrence rate of microflares (transient brightenings)
in an X-ray bright point (XBP) during the lifetime of the XBP observed
with the Yohkoh soft X-ray telescope (SXT). The XBP with a size of
~30'' appeared near a preceding spot of NOAA 7270 on 1992
September 1 and disappeared on 1992 September 4. The XBP produced
92 microflares during the observation time of the SXT. We found that
the occurrence rate (number of events per hour) did not change much
during the lifetime of the XBP, although the magnetic flux of the XBP
changed. We also found that the frequency distribution of microflares
as a function of the soft X-ray peak intensity shows a power law with
index 1.7+/-0.4, which is consistent with the previously known index for
flares and microflares based on the data for the whole Sun or a whole
active region. This result suggests that the power-law distribution
of flares holds not only for larger areas but also for smaller areas.
Title: Studies of solar coronal X-ray jets
Authors: Shimojo, Masumi
Bibcode: 1999PhDT.......499S
Altcode:
No abstract at ADS
Title: Magnetic Field Properties of Solar X-Ray Jets
Authors: Shimojo, Masumi; Shibata, Kazunari; Harvey, Karen L.
Bibcode: 1998SoPh..178..379S
Altcode:
From a list of X-ray jets made by Shimojo et al. (1996), we selected
events for which there were magnetic field data from NSO/Kitt
Peak. Using co-aligned SXT and magnetograms, we examined the magnetic
field properties of X-ray jets. We found that 8% of the jets studied
occurred at a single pole (SP), 12% at a bipole (BP), 24% in a mixed
polarity (MP) and 48% in a satellite polarity (ST). If the satellite
polarity region is the same as the mixed polarity region, 72% of the
jets occurred at the (general) mixed polarity region.
Title: Two-Sided-Loop Type X-ray Jets and Metric Radio Bursts
Authors: Kundu, M. R.; Raulin, J. -P.; Nitta, N.; Shibata, K.;
Shimojo, M.
Bibcode: 1998SoPh..178..173K
Altcode: 1998SoPh..178..611K
We have searched for nonthermal radio signatures in the form of metric
type III bursts in conjunction with two-sided-loop-type X-ray jets
observed by the Yohkoh/SXT experiment. We have found no evidence of
type III bursts in association with this particular type of X-ray jets
in contrast to the positive evidence of type III's in association
with anemone-type X-ray jets. This result is consistent with the
simulation results of Yokoyama and Shibata (1995), which show that
anemone-type jets are produced by vertical/oblique plasma flow whereas
the two-sided-loop-type jets are produced by horizontal plasma flow.
Title: Early Evolution of Coronal Active Regions Observed with the
YOHKOH Soft X-Ray Telescope. I. Expansion Velocity
Authors: Yashiro, Seiji; Shibata, Kazunari; Shimojo, Masumi
Bibcode: 1998ApJ...493..970Y
Altcode:
We study the early evolution of active regions in the corona by
analyzing 33 emerging flux regions (EFRs) observed with the soft X-ray
telescope (SXT) aboard Yohkoh during the period from 1992 February to
1996 May. We examine the time variation of the size (projected area)
and the total soft X-ray intensity of the EFRs, and find that the
time-averaged apparent velocity of the expansion of most of the EFRs
is less than 2 km s-1 during the very early phase (t <
6-14 hr after the birth of the EFRs). The average expansion velocity
of 33 EFRs is 1.5 km s-1. This expansion velocity is much
lower than the rise velocity of emerging magnetic loop in the upper
chromosphere, inferred from Hα observations of arch filament systems
as well as MHD simulation and theory. Some possibilities to account
for this discrepancy are discussed.
Title: Physical parameters of solar X-ray jets
Authors: Shimojo, M.; Shibata, K.; Yokoyama, T.; Hori, K.
Bibcode: 1998ESASP.421..163S
Altcode: 1998sjcp.conf..163S
No abstract at ADS
Title: Evolution of Coronal Active Regions Observed with the YOHKOH
Soft X-Ray Telescope
Authors: Yashiro, S.; Shibata, K.; Shimojo, M.
Bibcode: 1998ASSL..229..379Y
Altcode: 1998opaf.conf..379Y
No abstract at ADS
Title: Study of Solar X-Ray Jets Observed by YOHKOH Soft X-Ray
Telescope
Authors: Shimojo, M.; Shibata, K.
Bibcode: 1998ASSL..229..357S
Altcode: 1998opaf.conf..357S
No abstract at ADS
Title: Magnetic Reconnection in the Active Region Inferred by
Homologous Soft X-ray Flares in February 1992
Authors: Zhang, H. Q.; Sakurai, T.; Shibata, K.; Shimojo, M.; Kurokawa,
H.; Morita, S.; Uchida, Y.
Bibcode: 1998ASSL..229..391Z
Altcode: 1998opaf.conf..391Z
No abstract at ADS
Title: X-Ray Plasma Ejections and Jets from Solar Compact Flares
Observed with the YOHKOH Soft X-Ray Telescope
Authors: Ohyama, M.; Shibata, K.; Shimojo, M.; Yokoyama, T.
Bibcode: 1998ASSL..229..333O
Altcode: 1998opaf.conf..333O
No abstract at ADS
Title: Statistical Properties of Microflares in an X-Ray Bright
Point within an Active Region
Authors: Shimojo, M.; Shibata, K.
Bibcode: 1997IAUJD..19E..45S
Altcode:
An X-ray Bright Point (XBP) is a relatively small scale (< 1^{'})
and small lifetime (about 2 days) emission feature. XBPs can be found
at practically all solar latitudes and they are associated with small
magnetic bipoles whose average total magnetic flux is 2 -- 3 times
1019 Mx. Harvey (1985) concluded that about one-third of
XBPs are associated with emerging magnetic flux (ephemeral regions)
while the other two-thirds are associated with canceling magnetic
feature. In this paper we examine the evolution of an XBP in an active
region observed with Yohkoh Soft X-ray Telescope (SXT). An XBP appeared
to be related to a new small emerging flux region near a preceding
spot of NOAA 7270 on September 1, 1992. We studied this "active region"
XBP using high resolution data of SXT. The XBP produced 92 microflares
(transient brightenings) during observation time of SXT, whose frequency
distribution as a function of the soft X-ray peak intensity shows a
single power-law. This result suggests that the power-law distribution
of microflares (Shimizu 1995) is universal and holds even in a small
emerging flux region.
Title: X-ray plasma ejections and jets from solar compact flares
observed with the YOHKOH soft X-ray telescope
Authors: Ohyama, Masamitsu; Shibata, Kazunari; Yokoyama, Takaaki;
Shimojo, Masumi
Bibcode: 1997AdSpR..19.1849O
Altcode:
Yohkoh soft X-ray observations have revealed coronal X-ray plasma
ejections and jets associated with solar flares. We have studied an
X-ray plasma ejection on 1993 November 11 in detail, as a typical
example of X-ray plasma ejections (possibly plasmoids expected from
the reconnection model). The results are as follows: (1) The shape
of the ejected material is a loop before it begins to rise. (2) The
ejecta are already heated to 5 - 16 MK before rising. (3) The kinetic
energy of the ejecta is smaller than the thermal energy content of the
ejecta. (4) The thermal energy of the ejecta is smaller than that of
the flare regions. (5) The acceleration occurs during the impulsive
phase. These results are compared with the characteristics of X-ray
jets, and a possible interpretation (for both plasmoids and jets)
based on the magnetic reconnection model is briefly discussed.
Title: Evolution of Coronal Active Regions Observed with the YOHKOH
Soft X-ray Telescope
Authors: Yashiro, S.; Shibata, K.; Shimojo, M.
Bibcode: 1997IAUJD..19E..58Y
Altcode:
We study the early evolution of active regions in the corona by
analyzing 56 emerging flux regions (EFRs) observed with the soft X-ray
telescope (SXT) aboard Yohkoh during the period from 1992 January to
1996 March. We examine the time variation of the size (projected area)
and the total soft X-ray intensity of the EFRs, and find that the
initial apparent velocity of the expansion of the EFRs is 0.4 - 3.6
km/s, which is much lower than that inferred from H alpha observations
of arch filament systems or from theory. We also find that there are
two types of evolution of EFRs. In one type (which we call the single
expansion type), the size and the total X-ray intensity of the EFR
monotonically increase for a few days after birth, and then slows or
stops. In the other type (multiple expansion type), the size and the
total X-ray intensity of an EFR show a non-monotonic or a multi-step
increase. We also study the thermal evolution of active regions in the
corona, and found that the temperature of EFRs increase with increasing
the region size.
Title: H alpha Surges and X-Ray Jets in AR 7260
Authors: Canfield, Richard C.; Reardon, Kevin P.; Leka, K. D.; Shibata,
K.; Yokoyama, T.; Shimojo, M.
Bibcode: 1996ApJ...464.1016C
Altcode:
We discuss nine events, observed simultaneously as jets in X-rays and
surges in Hα, which are associated with moving magnetic bipoles. The
X-ray jets share many features with those discovered by Yohkoh in active
regions, emerging flux regions, and X-ray bright points (see paper by
Shibata et al.); in particular, they originate near one end of a pair of
small flaring loops. The Hα surges are adjacent to the X-ray jets. At
the bases of these surges we observe both blueshifts (initially) and
redshifts (1-2 minutes later). All the observed surges spin in a sense
consistent with the relaxation of the twist stored in the magnetic
fields of the moving magnetic bipoles. Newly discovered phenomena
include footpoint convergence and moving-blueshift features. We develop a model of the role of magnetic reconnection in these
events. This model explains the temporal and spatial relationship
between the jets and surges, the role of the moving bipoles, the
flaring X-ray loops and their converging Hα footpoints, the Hα
moving-blueshift features, the direction and amount of spin of the
surges, and the relative temporal development of the Hα redshifts
and blueshifts.
Title: Coronal X-ray jets observed with Yohkoh/SXT
Authors: Shibata, K.; Yokoyama, T.; Shimojo, M.
Bibcode: 1996AdSpR..17d.197S
Altcode: 1996AdSpR..17..197S
The soft X-ray telescope (SXT) aboard Yohkoh has discovered coronal
X-ray jets associated with small flares in X-ray bright points
(XBPs), emerging flux regions (EFRs), or active regions (ARs). The
common observed characteristics of these jets are discussed mainly from
morphological points of view. It is suggested that magnetic reconnection
between emerging magnetic flux and the overlying coronal/chromospheric
magnetic field is a key physical process for producing these jets.
Title: Statistical Study of Solar X-Ray Jets Observed with the YOHKOH
Soft X-Ray Telescope
Authors: Shimojo, Masumi; Hashimoto, Shizuyo; Shibata, Kazunari;
Hirayama, Tadashi; Hudson, Hugh S.; Acton, Loren W.
Bibcode: 1996PASJ...48..123S
Altcode:
We have found 100 X-ray jets in the database of full Sun images taken
with the Soft X-ray Telescope (SXT) aboard Yohkoh during the period
from 1991 November through 1992 April. A statistical study for these
jets results in the following characteristics: 1)\ Most are associated
with small flares (microflares--subflares) at their footpoints. 2)\ The
lengths lie in the range of a few times 10(4) --4 times 10(5) km. 3)\
The widths are 5 times 10(3) --10(5) km. 4)\ The apparent velocities are
10--1000 km s(-1) with an average velocity of about 200 km s(-1) . 5)\
The lifetime of the jet extends to ~ 10 hours and the distribution
of the observed lifetime is a power law with an index of ~ 1.2. 6)\
76% of the jets show constant or converging shapes; the width of the
jet is constant or decreases with distance from the footpoint. The
converging type tends to be generated with an energetic footpoint
event and the constant type by a wide energy range of the footpoint
event. 7)\ Many jets ( ~ 68%) appear in or near to active regions
(AR). Among the jets ejected from bright-point like features in ARs,
most ( ~ 86%) are observed to the west of the active region. 8)\ 27%
of the jets show a gap ( > 10(4) km) between the exact footpoint of
the jet and the brightest part of the associated flare. 9)\ The X-ray
intensity distribution along an X-ray jet often shows an exponential
decrease with distance from the footpoint. This exponential intensity
distribution holds from the early phase to the decay phase.
Title: Detection of Nonthermal Radio Emission from Coronal X-ray Jets
Authors: Kundu, M. R.; Raulin, J. P.; Nitta, N.; Hudson, H. S.;
Raoult, A.; Shibata, K.; Shimojo, M.
Bibcode: 1996mpsa.conf..445K
Altcode: 1996IAUCo.153..445K
No abstract at ADS
Title: H alpha Surges and X-ray Jets in AR7260
Authors: Canfield, R. C.; Reardon, K. P.; Leka, K. D.; Shibata, K.;
Yokoyama, T.; Shimojo, M.
Bibcode: 1996mpsa.conf...49C
Altcode: 1996IAUCo.153...49C
No abstract at ADS
Title: Theory and Observations of X-Ray Jets (Invited)
Authors: Shibata, K.; Shimojo, M.; Yokoyama, T.; Ohyama, M.
Bibcode: 1996ASPC..111...29S
Altcode: 1997ASPC..111...29S
The soft X-ray telescope (SXT) aboard Yohkoh has discovered coronal
X-ray jets associated with small flares (microflares - subflares). The
recent development of observations and theoretical modeling of
X-ray jets are reviewed with emphasis upon the role of magnetic
reconnection. The relation to X-ray plasma ejections (plasmoids)
from large flares is also discussed.
Title: X-ray and Magnetic Features of H alpha Surges
Authors: Okubo, A.; Matsumoto, R.; Miyaji, S.; Akioka, M.; Zhang,
H.; Shimojo, M.; Nishino, Y.; Ichimoto, K.; Shibata, K.; Sakurai, T.
Bibcode: 1996mpsa.conf..437O
Altcode: 1996IAUCo.153..437O
No abstract at ADS
Title: Statistical Study of Solar X-ray Jets Observed with the YOHKOH
Soft X-ray Telescope
Authors: Shimojo, M.; Hashimoto, T.; Shibata, K.; Hirayama, T.;
Harvey, K. L.
Bibcode: 1996mpsa.conf..449S
Altcode: 1996IAUCo.153..449S
No abstract at ADS
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: Detection of Nonthermal Radio Emission from Coronal X-Ray Jets
Authors: Kundu, M. R.; Raulin, J. P.; Nitta, N.; Hudson, H. S.;
Shimojo, M.; Shibata, K.; Raoult, A.
Bibcode: 1995ApJ...447L.135K
Altcode:
We report the detection of a type III burst in association with a
dynamic X-ray coronal jet observed by Yohkoh/SXT. The type III burst
observed with the Nancay (France) multifrequency radioheliograph is
spatially and temporally coincident with the X-ray jet. The radio
locations at different frequencies (236.6 and 164 MHz) are aligned
along the length of the jet. The observation of the type III burst in
association with the X-ray jet implies the acceleration of electrons
to several tens of keV, along with the heating responsible for the
production of soft X-rays. This association implies the existence of
open field lines in dense coronal structures identified on the Sun's
disk. This is the first observation of dense coronal structures on the
disk, along which type III emitting nonthermal electrons propagate. We
find that this structure begins to form before the type III emission. At
the time of the type III burst we estimate a density of 6--10 x 108
cm-3 for a temperature of ~5--6 MK at an altitude of 20,000 km.
Title: Coronal X-ray Jets
Authors: Shibata, K.; Yokoyama, T.; Shimojo, M.
Bibcode: 1994kofu.symp...75S
Altcode:
The soft X-ray telescope (SXT) aboard Yohkoh has discovered coronal
X-ray jets associated with small flares in XBPs, EFRs, or ARs. The
common observed characteristics of these jets are discussed mainly from
morphological points of view. It is suggested that magnetic reconnection
between emerging magnetic flux and the overlying coronal/chromospheric
magnetic field is a key physical process for producing these jets.