Author name code: narukage
ADS astronomy entries on 2022-09-14
author:"Narukage, Noriyuki"
------------------------------------------------------------------------
Title: Quiet Sun Center to Limb Variation of the Linear Polarization
Observed by CLASP2 Across the Mg II h and k Lines
Authors: Rachmeler, L. A.; Bueno, J. Trujillo; McKenzie, D. E.;
Ishikawa, R.; Auchère, F.; Kobayashi, K.; Kano, R.; Okamoto,
T. J.; Bethge, C. W.; Song, D.; Ballester, E. Alsina; Belluzzi,
L.; Pino Alemán, T. del; Ramos, A. Asensio; Yoshida, M.; Shimizu,
T.; Winebarger, A.; Kobelski, A. R.; Vigil, G. D.; Pontieu, B. De;
Narukage, N.; Kubo, M.; Sakao, T.; Hara, H.; Suematsu, Y.; Štěpán,
J.; Carlsson, M.; Leenaarts, J.
Bibcode: 2022ApJ...936...67R
Altcode: 2022arXiv220701788R
The CLASP2 (Chromospheric LAyer Spectro-Polarimeter 2) sounding rocket
mission was launched on 2019 April 11. CLASP2 measured the four Stokes
parameters of the Mg II h and k spectral region around 2800 Å along a
200″ slit at three locations on the solar disk, achieving the first
spatially and spectrally resolved observations of the solar polarization
in this near-ultraviolet region. The focus of the work presented here
is the center-to-limb variation of the linear polarization across these
resonance lines, which is produced by the scattering of anisotropic
radiation in the solar atmosphere. The linear polarization signals of
the Mg II h and k lines are sensitive to the magnetic field from the
low to the upper chromosphere through the Hanle and magneto-optical
effects. We compare the observations to theoretical predictions
from radiative transfer calculations in unmagnetized semiempirical
models, arguing that magnetic fields and horizontal inhomogeneities
are needed to explain the observed polarization signals and spatial
variations. This comparison is an important step in both validating and
refining our understanding of the physical origin of these polarization
signatures, and also in paving the way toward future space telescopes
for probing the magnetic fields of the solar upper atmosphere via
ultraviolet spectropolarimetry.
Title: Study of Time Evolution of Thermal and Nonthermal Emission
from an M-class Solar Flare
Authors: Nagasawa, Shunsaku; Kawate, Tomoko; Narukage, Noriyuki;
Takahashi, Tadayuki; Caspi, Amir; Woods, Thomas N.
Bibcode: 2022ApJ...933..173N
Altcode: 2022arXiv220514369N
We conduct a wide-band X-ray spectral analysis in the energy range
of 1.5-100 keV to study the time evolution of the M7.6-class flare
of 2016 July 23, with the Miniature X-ray Solar Spectrometer (MinXSS)
CubeSat and the Reuven Ramaty High Energy Solar Spectroscopic Imager
(RHESSI) spacecraft. With the combination of MinXSS for soft X-rays and
RHESSI for hard X-rays, a nonthermal component and three-temperature
multithermal component-"cool" (T ≍ 3 MK), "hot" (T ≍ 15 MK), and
"superhot" (T ≍ 30 MK)-were measured simultaneously. In addition,
we successfully obtained the spectral evolution of the multithermal
and nonthermal components with a 10 s cadence, which corresponds to
the Alfvén timescale in the solar corona. We find that the emission
measures of the cool and hot thermal components are drastically
increasing more than hundreds of times and the superhot thermal
component is gradually appearing after the peak of the nonthermal
emission. We also study the microwave spectra obtained by the Nobeyama
Radio Polarimeters, and we find that there is continuous gyrosynchrotron
emission from mildly relativistic nonthermal electrons. In addition,
we conducted a differential emission measure (DEM) analysis by using
Atmospheric Imaging Assembly on board the Solar Dynamics Observatory
and determined that the DEM of cool plasma increases within the flaring
loop. We find that the cool and hot plasma components are associated
with chromospheric evaporation. The superhot plasma component could
be explained by the thermalization of the nonthermal electrons trapped
in the flaring loop.
Title: On the faintest solar coronal hard X-rays observed with FOXSI
Authors: Buitrago-Casas, Juan Camilo; Glesener, Lindsay; Christe,
Steven; Krucker, Säm; Vievering, Juliana; Athiray, P. S.; Musset,
Sophie; Davis, Lance; Courtade, Sasha; Dalton, Gregory; Turin,
Paul; Turin, Zoe; Ramsey, Brian; Bongiorno, Stephen; Ryan, Daniel;
Takahashi, Tadayuki; Furukawa, Kento; Watanabe, Shin; Narukage,
Noriyuki; Ishikawa, Shin-nosuke; Mitsuishi, Ikuyuki; Hagino, Kouichi;
Shourt, Van; Duncan, Jessie; Zhang, Yixian; Bale, Stuart D.
Bibcode: 2022arXiv220504291B
Altcode:
Solar nanoflares are small eruptive events releasing magnetic energy in
the quiet corona. If nanoflares follow the same physics as their larger
counterparts, they should emit hard X-rays (HXRs) but with a rather
faint intensity. A copious and continuous presence of nanoflares would
deliver enormous amounts of energy into the solar corona, possibly
accounting for its high temperatures. To date, there has not been
any direct observation of such sustained and persistent HXRs from the
quiescent Sun. However, Hannah et al. in 2010 constrained the quiet
Sun HXR emission using almost 12 days of quiescent solar-off-pointing
observations by RHESSI. These observations set upper limits at
$3.4\times 10^{-2}$ photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$
and $9.5\times 10^{-4}$ photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$
for the 3-6 keV and 6-12 keV energy ranges, respectively. Observing
feeble HXRs is challenging because it demands high sensitivity
and dynamic range instruments in HXRs. The Focusing Optics X-ray
Solar Imager (FOXSI) sounding rocket experiment excels in these
two attributes. Particularly, FOXSI completed its third successful
flight (FOXSI-3) on September 7th, 2018. During FOXSI-3's flight,
the Sun exhibited a fairly quiet configuration, displaying only one
aged non-flaring active region. Using the entire $\sim$6.5 minutes of
FOXSI-3 data, we constrained the quiet Sun emission in HXRs. We found
$2\sigma$ upper limits in the order of $\sim 10^{-3}$ photons$^{-1}$
s$^{-1}$ cm$^{-2}$ keV$^{-1}$ for the 5-10 keV energy range. FOXSI-3's
upper limit is consistent with what was reported by Hannah et al.,
2010, but FOXSI-3 achieved this result using $\sim$1/2640 less time
than RHESSI. A possible future spacecraft using FOXSI's concept would
allow enough observation time to constrain the current HXR quiet Sun
limits further or perhaps even make direct detections.
Title: Empirical relations between the intensities of Lyman lines
of H and He+
Authors: Gordino, M.; Auchère, F.; Vial, J. -C.; Bocchialini, K.;
Hassler, D. M.; Bando, T.; Ishikawa, R.; Kano, R.; Kobayashi, K.;
Narukage, N.; Trujillo Bueno, J.; Winebarger, A.
Bibcode: 2022A&A...657A..86G
Altcode: 2022arXiv220101519G
Context. Empirical relations between major UV and extreme UV spectral
lines are one of the inputs for models of chromospheric and coronal
spectral radiances and irradiances. They are also needed for the
interpretation of some of the observations of the Solar Orbiter
mission.
Aims: We aim to determine an empirical relation between
the intensities of the H I 121.6 nm and He II 30.4 nm Ly-α lines.
Methods: Images at 121.6 nm from the Chromospheric Lyman-Alpha
Spectro Polarimeter (CLASP) and Multiple XUV Imager (MXUVI) sounding
rockets were co-registered with simultaneous images at 30.4 nm from the
EIT and AIA orbital telescopes in order to derive a spatially resolved
relationship between the intensities.
Results: We have obtained
a relationship between the H I 121.6 nm and He II 30.4 nm intensities
that is valid for a wide range of solar features, intensities, and
activity levels. Additional SUMER data have allowed the derivation of
another relation between the H I 102.5 nm (Ly-β) and He II 30.4 nm
lines for quiet-Sun regions. We combined these two relationships to
obtain a Ly-α/Ly-β intensity ratio that is comparable to the few
previously published results.
Conclusions: The relationship
between the H I 121.6 nm and He II 30.4 nm lines is consistent with the
one previously obtained using irradiance data. We have also observed
that this relation is stable in time but that its accuracy depends on
the spatial resolution of the observations. The derived Ly-α/Ly-β
intensity ratio is also compatible with previous results.
Title: Hard X-ray upper limits of the quiet Sun with new FOXSI
observations
Authors: Buitrago-Casas, Juan Camilo; Glesener, Lindsay; Christe,
Steven; Krucker, Sam; Vievering, Juliana; Athiray, P. S.; Musset,
Sophie; Davis, Lance; Courtade, Sasha; Dalton, Gregory; Turin,
Paul; Turin, Zoe; Ramsey, Brian; Bongiorno, Stephen; Ryan, Daniel;
Takahashi, Tadayuki; Furukawa, Kento; Watanabe, Shin; Narukage,
Noriyuki; Ishikawa, Shin-nosuke; Mitsuishi, Ikuyuki; Hagino, Kouichi
Bibcode: 2021AGUFMSH51A..04B
Altcode:
Solar nanoflares are small eruptive events releasing magnetic energy
in the quiet corona. If nanoflares follow the same physics as their
larger counterparts, they should emit hard X-rays (HXRs) but with a
rather faint intensity. A copious and continuous presence of nanoflares
would result in a sustained and persistent emission in HXRs, which in
turn would deliver enormous amounts of energy into the solar corona,
possibly accounting for its high temperatures. To date, there has not
been any direct observation of such sustained and persistent HXRs from
the quiescent Sun. However, Hannah et al. in 2010 constrained the quiet
Sun HXR emission using almost 12 days of quiescent solar-off-pointing
observations by RHESSI. These observations set $2\sigma$ upper limits
at $3.4\times 10^{-2}$ photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$
and $9.5\times 10^{-4}$ photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$
for the 3-6 keV and 6-12 keV energy ranges, respectively. Observing
feeble HXRs is challenging because it demands high sensitivity and
dynamic range instruments in the HXR energy band. The Focusing Optics
X-ray Solar Imager (FOXSI) sounding rocket experiment excels in these
two attributes when compared with RHESSI. Particularly, FOXSI completed
its third successful flight (FOXSI-3) on September 7th, 2018. During
FOXSI-3s flight, the Sun exhibited a fairly quiet configuration,
displaying only one aged non-flaring active region. Using the entire
$\sim$6.5 minutes of FOXSI-3 data, we constrained the quiet Sun emission
in HXRs. We found $2\sigma$ upper limits in the order of $\sim 10^{-3}$
photons$^{-1}$ s$^{-1}$ cm$^{-2}$ keV$^{-1}$ for the 5-10 keV energy
range. FOXSI-3's upper limit is consistent with what was reported by
Hannah et al., 2010, but FOXSI-3 achieved this result using $\sim$1/2640
less time than RHESSI. A possible future spacecraft using FOXSI's
concept would allow enough observation time to constrain the current
HXR quiet Sun limits further or perhaps even make direct detections.
Title: The FOXSI-4 Sounding Rocket: High Resolution Focused X-ray
Observations of the Sun
Authors: Glesener, Lindsay; Buitrago-Casas, Juan Camilo; Vievering,
Juliana; Pantazides, Athanasios; Musset, Sophie; Panchapakesan,
Subramania Athiray; Baumgartner, Wayne; Bongiorno, Stephen; Champey,
Patrick; Christe, Steven; Courtade, Sasha; Duncan, Jessie; Ishikawa,
Shin-nosuke; Krucker, Sam; Martinez Oliveros, Juan Carlos; Perez-Piel,
Savannah; Mitsuishi, Ikuyuki; Narukage, Noriyuki; Ryan, Daniel;
Takahashi, Tadayuki; Watanabe, Shin
Bibcode: 2021AGUFMSH55B1831G
Altcode:
It has been firmly demonstrated that direct-focusing instruments
can transform the way high-energy X-rays from astronomical objects,
including the Sun, are measured. The NuSTAR spacecraft has increased the
sensitivity to faint astrophysical sources by 100 times as compared with
previous, indirect, imagers. The first three flights of the Focusing
Optics X-ray Solar Imager (FOXSI) sounding rocket established the
usefulness and feasibility of a similar method optimized for the Sun,
and showed that in addition to greater sensitivity, a vastly improved
dynamic range can be obtained in this way. This technology stands
ready to revolutionize understanding of solar flares by elucidating
particle acceleration sites in the corona, studying how electrons
propagate and deposit their energies, and how accelerated particles
escape into interplanetary space. While the fundamental building
blocks of solar hard X-ray (HXR) focusing are in place and ready for a
spacecraft mission, concurrent development is required to prepare for
the next generation of high-energy solar explorers, which will require
higher rate capability and higher angular resolution to investigate
finer-scale structure and to better complement instruments at other
wavelengths. FOXSI-4 features technological advances that enable
high angular resolution as well as measurement of bright sources. In
the first category, we will develop high-precision mirror production
methods and finely pixelated Si CMOS sensors, and will demonstrate
substrip/subpixel resolution in fine-pitch CdTe sensors. Secondly,
we will demonstrate rate capability of these sensors sufficient
for flare measurement, and will develop novel pixelated attenuators
that optimize energy coverage even at high rates. The experiment will
demonstrate these technologies in NASAs first-ever solar flare campaign,
flying in tandem with the Hi-C FLARE rocket and in a campaign with the
SNIFS rocket. The campaign will position multiple rocket experiments
awaiting an opportunistic signal and will launch the experiments for
near-simultaneous observation of the flare.This campaign will allow
for direct collaboration with the Parker Solar Probe (PSP) during one
of its perihelia.
Title: FOXSI-4: the high resolution focusing X-ray rocket payload
to observe a solar flare
Authors: Buitrago-Casas, Juan Camilo; Vievering, Juliana; Musset,
Sophie; Glesener, Lindsay; Athiray, P. S.; Baumgartner, Wayne;
Bongiorno, Stephen; Champey, Patrick; Christe, Steven; Courtade,
Sasha; Dalton, Gregory; Duncan, Jessie; Gilchrist, Kelsey; Ishikawa,
Shin-nosuke; Jhabvala, Christine; Kanniainen, Hunter; Krucker,
Säm.; Gregory, Kyle; Martinez Oliveros, Juan Carlos; McCracken,
Jeff; Mitsuishi, Ikuyuki; Narukage, Noriyuki; Pantazides, Athanasios;
Peretz, Eliad; Perez-Piel, Savannah; Ramanayaka, Aruna; Ramsey, Brian;
Ryan, Danny; Savage, Sabrina; Takahashi, Tadayuki; Watanabe, Shin;
Winebarger, Amy; Zhang, Yixian
Bibcode: 2021SPIE11821E..0LB
Altcode:
The FOXSI-4 sounding rocket will fly a significantly upgraded instrument
in NASA's first solar are campaign. It will deploy direct X-ray focusing
optics which have revolutionized our understanding of astrophysical
phenomena. For example, they have allowed NuSTAR to provide X-ray
imaging and IXPE (scheduled for launch in 2021) to provide X-ray
polarization observations with detectors with higher photon rate
capability and greater sensitivity than their predecessors. The FOXSI
sounding rocket is the first solar dedicated mission using this method
and has demonstrated high sensitivity and improved imaging dynamic range
with its three successful flights. Although the building blocks are
already in place for a FOXSI satellite instrument, further advances are
needed to equip the next generation of solar X-ray explorers. FOXSI-4
will develop and implement higher angular resolution optics/detector
pairs to investigate fine spatial structures (both bright and faint)
in a solar are. FOXSI-4 will use highly polished electroformed Wolter-I
mirrors fabricated at the NASA/Marshall Space Flight Center (MSFC),
together with finely pixelated Si CMOS sensors and fine-pitch CdTe strip
detectors provided by a collaboration with institutes in Japan. FOXSI-4
will also implement a set of novel perforated attenuators that will
enable both the low and high energy spectral components to be observed
simultaneously in each pixel, even at the high rates expected from a
medium (or large) size solar are. The campaign will take place during
one of the Parker Solar Probe (PSP) perihelia, allowing coordination
between this spacecraft and other instruments which observe the Sun
at different wavelengths.
Title: Assessing quiet Sun hard X-rays using observations from the
FOXSI Sounding Rockets
Authors: Buitrago-Casas, J.; Glesener, L.; Christe, S.; Krucker,
S.; Vievering, J.; Athiray, P.; Musset, S.; Ryan, D.; Ishikawa, S.;
Narukage, N.; Bongiorno, S.; Furukawa, K.; Ramsey, B.; Courtade, S.;
Dalton, G.; Turin, P.; Takahashi, T.; Watanabe, S.; Mitsuishi, I.;
Hagino, K.; Duncan, J.
Bibcode: 2021AAS...23810604B
Altcode:
In solar and helio-physics, the coronal heating problem relates to the
question of identifying and explaining the mechanism(s) causing the
corona's temperatures to be a few hundred times hotter than the solar
surface. Among the various plausible hypotheses proposed to explain
this problem, one of the strongest candidates relates to copious low
energy magnetic reconnections (nanoflares) occurring throughout the
solar corona. When examined thoroughly, this mechanism implies heating
that happens impulsively on individual flux tubes (strands). Emission
of hard X-rays (HXRs) should be a consequence of such non-thermal
phenomena, or even of purely thermal transients, if hot enough. In
quiescent solar corona areas, nanoflares should manifest in HXRs via
very faint signatures covering vast regions. Observing feeble HXRs
demands an instrument with high sensitivity and dynamic range for
energies between 4 and 15 keV. FOXSI (which stands for the Focusing
Optics X-ray Solar Imager) is such an instrument. As a payload of
a NASA/LCAS (low-cost access to space program) sounding rocket,
FOXSI has successfully completed three launches. The two most recent
flights (FOXSI-2 and -3) included quiescent areas of the Sun as part
of the targets. For this presentation, we will show a full assessment
of the HXR flux from the quiet Sun observed with FOXSI. We begin by
presenting a thorough characterization of the stray light (ghost rays)
impinging into FOXSI's detectors caused by sources outside of the field
of view. We then identify areas free of ghost rays where the instrument
sensitivity reaches a maximum to quiet Sun HXR detections. Finally,
we implement a Bayesian (known as ON/OFF analysis) to estimate an upper
detectability threshold of quiet Sun HXRs and a probability distribution
for quiet-Sun HXR fluxes when sources are supposed to exist.
Title: Mapping of Solar Magnetic Fields from the Photosphere to the
Top of the Chromosphere with CLASP2
Authors: McKenzie, D.; Ishikawa, R.; Trujillo Bueno, J.; Auchere, F.;
del Pino Aleman, T.; Okamoto, T.; Kano, R.; Song, D.; Yoshida, M.;
Rachmeler, L.; Kobayashi, K.; Narukage, N.; Kubo, M.; Ishikawa, S.;
Hara, H.; Suematsu, Y.; Sakao, T.; Bethge, C.; De Pontieu, B.; Vigil,
G.; Winebarger, A.; Alsina Ballester, E.; Belluzzi, L.; Stepan, J.;
Asensio Ramos, A.; Carlsson, M.; Leenaarts, J.
Bibcode: 2021AAS...23810603M
Altcode:
Coronal heating, chromospheric heating, and the heating &
acceleration of the solar wind, are well-known problems in solar
physics. Additionally, knowledge of the magnetic energy that
powers solar flares and coronal mass ejections, important drivers
of space weather, is handicapped by imperfect determination of the
magnetic field in the sun's atmosphere. Extrapolation of photospheric
magnetic measurements into the corona is fraught with difficulties and
uncertainties, partly due to the vastly different plasma beta between
the photosphere and the corona. Better results in understanding
the coronal magnetic field should be derived from measurements of
the magnetic field in the chromosphere. To that end, we are pursuing
quantitative determination of the magnetic field in the chromosphere,
where plasma beta transitions from greater than unity to less than
unity, via ultraviolet spectropolarimetry. The CLASP2 mission, flown
on a sounding rocket in April 2019, succeeded in measuring all four
Stokes polarization parameters in UV spectral lines formed by singly
ionized Magnesium and neutral Manganese. Because these ions produce
spectral lines under different conditions, CLASP2 thus was able to
quantify the magnetic field properties at multiple heights in the
chromosphere simultaneously, as shown in the recent paper by Ishikawa
et al. In this presentation we will report the findings of CLASP2,
demonstrating the variation of magnetic fields along a track on
the solar surface and as a function of height in the chromosphere;
and we will illustrate what is next for the CLASP missions and the
demonstration of UV spectropolarimetry in the solar chromosphere.
Title: High Resolution FOXSI: The Development Of FOXSI-4
Authors: Glesener, L.; Buitrago-Casas, J.; Duncan, J.; Nagasawa, S.;
Pantazides, A.; Perez-Piel, S.; Zhang, Y.; Vievering, J.; Musset,
S.; Panchapakesan, S.; Baumgartner, W.; Bongiorno, S.; Champey, P.;
Christe, S.; Courtade, S.; Kanniainen, H.; Krucker, S.; Ishikawa,
S.; Martinez Oliveros, J.; Mitsuishi, I.; Narukage, N.; Peretz, E.;
Ryan, D.; Takahashi, T.; Watanabe, S.; Winebarger, A.
Bibcode: 2021AAS...23831301G
Altcode:
It has been firmly demonstrated that direct-focusing instruments
can transform the way high-energy X-rays from astronomical objects,
including the Sun, are measured. The NuSTAR spacecraft has increased the
sensitivity to faint astrophysical sources by 100 times as compared with
previous, indirect, imagers. The first three flights of the Focusing
Optics X-ray Solar Imager (FOXSI) sounding rocket established the
usefulness and feasibility of a similar method optimized for the Sun,
and showed that in addition to greater sensitivity, a vastly improved
dynamic range can be obtained in this way. This technology stands
ready to revolutionize understanding of solar flares by elucidating
particle acceleration sites in the corona, studying how electrons
propagate and deposit their energies, and how accelerated particles
escape into interplanetary space. While the fundamental building
blocks of solar hard X-ray (HXR) focusing are in place and ready for
a spacecraft mission, concurrent development is required to prepare
for a subsequent generation of high-energy solar explorers, which
will require higher rate capability and higher angular resolution to
investigate finer-scale structure and to better complement instruments
at other wavelengths.The fourth flight of FOXSI (FOXSI-4) features
technological advances that enable high angular resolution as well as
measurement of bright sources. In the first category, we are developing
high-precision mirror production methods and finely pixelated Si CMOS
sensors, and will demonstrate substrip/subpixel resolution in fine-pitch
CdTe sensors. Secondly, we will demonstrate a rate capability of these
sensors sufficient for flare measurement, and are developing novel
pixelated attenuators that optimize energy coverage even at high
rates.The experiment will demonstrate these technologies in NASA's
first-ever solar flare campaign, flying in tandem with the Hi-C FLARE
rocket and on the same campaign as the SNIFS rocket. The campaign will
position multiple rocket experiments awaiting an opportunistic signal
and will launch multiple payloads for near-simultaneous observation
of the flare.This campaign will allow for direct collaboration with
the Parker Solar Probe (PSP) during one of its perihelia.
Title: Mapping solar magnetic fields from the photosphere to the
base of the corona
Authors: Ishikawa, Ryohko; Bueno, Javier Trujillo; del Pino Alemán,
Tanausú; Okamoto, Takenori J.; McKenzie, David E.; Auchère,
Frédéric; Kano, Ryouhei; Song, Donguk; Yoshida, Masaki; Rachmeler,
Laurel A.; Kobayashi, Ken; Hara, Hirohisa; Kubo, Masahito; Narukage,
Noriyuki; Sakao, Taro; Shimizu, Toshifumi; Suematsu, Yoshinori; Bethge,
Christian; De Pontieu, Bart; Dalda, Alberto Sainz; Vigil, Genevieve D.;
Winebarger, Amy; Ballester, Ernest Alsina; Belluzzi, Luca; Štěpán,
Jiří; Ramos, Andrés Asensio; Carlsson, Mats; Leenaarts, Jorrit
Bibcode: 2021SciA....7.8406I
Altcode: 2021arXiv210301583I
Routine ultraviolet imaging of the Sun's upper atmosphere shows the
spectacular manifestation of solar activity; yet we remain blind to
its main driver, the magnetic field. Here we report unprecedented
spectropolarimetric observations of an active region plage and
its surrounding enhanced network, showing circular polarization in
ultraviolet (Mg II $h$ & $k$ and Mn I) and visible (Fe I) lines. We
infer the longitudinal magnetic field from the photosphere to the
very upper chromosphere. At the top of the plage chromosphere the
field strengths reach more than 300 gauss, strongly correlated with
the Mg II $k$ line core intensity and the electron pressure. This
unique mapping shows how the magnetic field couples the different
atmospheric layers and reveals the magnetic origin of the heating in
the plage chromosphere.
Title: Optical design of the Chromospheric LAyer Spectro-Polarimeter
(CLASP2)
Authors: Tsuzuki, Toshihiro; Ishikawa, Ryohko; Kano, Ryouhei; Narukage,
Noriyuki; Song, Donguk; Yoshida, Masaki; Uraguchi, Fumihiro; Okamoto,
Takenori J.; McKenzie, David; Kobayashi, Ken; Rachmeler, Laurel;
Auchere, Frederic; Trujillo Bueno, Javier
Bibcode: 2020SPIE11444E..6WT
Altcode:
Chromospheric LAyer Spectro-Polarimeter (CLASP2) was a sounding
rocket experiment, which is a follow-up mission to the Chromospheric
Lyman-Alpha Spectro-Polarimeter (CLASP1) in 2015. To measure the
magnetic fields in the upper solar atmosphere in a highly quantitative
manner, CLASP2 changes the target wavelengths from the hydrogen Ly-α
line (121.567 nm) to Mg II lines near 280 nm. We reused the main
structure and most of the optical components in the CLASP1 instrument,
which reduced the turnaround time and cost. We added a magnifying
optical system to maintain the wavelength resolution, even at the
longer wavelength of CLASP2. Here, we describe the optical design and
performance of the CLASP2 instrument.
Title: The FOXSI-4 Sounding Rocket: High Resolution Focused X-ray
Observations of the Sun
Authors: Glesener, L.; Buitrago-Casas, J. C.; Musset, S.; Vievering,
J. T.; Athiray, P. S.; Baumgartner, W.; Bongiorno, S.; Champey, P. R.;
Christe, S.; Courtade, S.; Duncan, J. M.; Ishikawa, S. N.; Krucker,
S.; Martinez Oliveros, J. C.; Mitsuishi, I.; Narukage, N.; Ryan, D.;
Takahashi, T.; Watanabe, S.; Winebarger, A. R.
Bibcode: 2020AGUFMSH0480011G
Altcode:
It has been firmly demonstrated that direct-focusing instruments
can transform the way high-energy X-rays from astronomical objects,
including the Sun, are measured. The NuSTAR spacecraft has increased the
sensitivity to faint astrophysical sources by 100 times as compared with
previous, indirect, imagers. The first three flights of the Focusing
Optics X-ray Solar Imager (FOXSI) sounding rocket established the
usefulness and feasibility of a similar method optimized for the Sun,
and showed that in addition to greater sensitivity, a vastly improved
dynamic range can be obtained in this way. This technology stands
ready to revolutionize understanding of solar flares by elucidating
particle acceleration sites in the corona, studying how electrons
propagate and deposit their energies, and how accelerated particles
escape into interplanetary space. While the fundamental building
blocks of solar hard X-ray (HXR) focusing are in place and ready for a
spacecraft mission, concurrent development is required to prepare for
the next generation of high-energy solar explorers, which will require
higher rate capability and higher angular resolution to investigate
finer-scale structure and to better complement instruments at other
wavelengths.
FOXSI-4 features technological advances that enable
high angular resolution as well as measurement of bright sources. In
the first category, we will develop high-precision mirror production
methods and finely pixelated Si CMOS sensors, and will demonstrate
substrip/subpixel resolution in fine-pitch CdTe sensors. Secondly,
we will demonstrate rate capability of these sensors sufficient for
flare measurement, and will develop novel pixelated attenuators that
optimize energy coverage even at high rates. The experiment
will demonstrate these technologies in NASA's first-ever solar flare
campaign, flying in tandem with the Hi-C FLARE rocket. The campaign will
position multiple rocket experiments awaiting an opportunistic signal
and will launch the experiments for near-simultaneous observation of
the flare.This campaign will allow for direct collaboration with the
Parker Solar Probe (PSP) during one of its perihelia.
Title: Limits on the X-ray emission of the quiet Sun from the FOXSI
sounding rockets
Authors: Buitrago-Casas, J. C.; Glesener, L.; Christe, S.; Krucker,
S.; Vievering, J. T.; Athiray, P. S.; Musset, S.; Ryan, D.; Ishikawa,
S. N.; Narukage, N.; Bongiorno, S.; Furukawa, K.; Ramsey, B.; Davis,
L.; Courtade, S.; Dalton, G.; Turin, P.; Turin, Z.; Takahashi, T.;
Watanabe, S.; Mitsuishi, I.; Hagino, K.; Duncan, J. M.
Bibcode: 2020AGUFMSH0430002B
Altcode:
Nanoflares are a potential solution for the coronal heating problem. In
the quiet Sun, nanoflares should exhibit hard X-ray (HXR) signatures
manifested to an observer via either i) a single HXR kernel or
ii) HXRs from many flares spread all over the Sun. In both cases,
detecting nanoflare HXRs requires an instrument with superior dynamic
range and sensitivity in the ~4 to 15 keV energy range over previous
solar dedicated HXR telescopes, like RHESSI. The Focusing Optics
X-ray Solar Imager (FOXSI) fulfills these requirements. FOXSI has
successfully flown on three sounding rocket campaigns; the last two
(FOXSI-2 and -3) included the observation of quiet areas of the solar
disk. For FOXSI-3, several techniques were tested and developed to
minimize a background effect unique to hard X-ray focusing optics,
frequently referred to as ghost rays. In this presentation, we
provide, for the first time, a FOXSI sounding rocket assessment of the
HXR flux from the quiet Sun. To fully characterize the sensitivity
of FOXSI, we assessed ghost rays generated by sources outside of
the field of view via a ray-tracing algorithm. This is particularly
important for observations from FOXSI-2 when techniques to minimize
ghost rays were not implemented yet. Using the ray tracing tool, we
identify areas free of ghost rays that contribute to the background
and therefore have maximum sensitivity to quiet Sun HXR emission. We
use a bayesian approach to provide upper thresholds of quiet Sun HXR
emission and probability distributions for the expected flux when a
quiet-Sun HXR source is assumed to exist. We compare this result with
prior constraints such as that made by RHESSI (Hannah et al. 2010).
Title: Use of a ray-tracing simulation to characterize ghost rays
in the FOXSI rocket experiment
Authors: Buitrago-Casas, J. C.; Christe, S.; Glesener, L.; Krucker,
S.; Ramsey, B.; Bongiorno, S.; Kilaru, K.; Athiray, P. S.; Narukage,
N.; Ishikawa, S.; Dalton, G.; Courtade, S.; Musset, S.; Vievering,
J.; Ryan, D.; Bale, S.
Bibcode: 2020JInst..15P1032B
Altcode: 2020arXiv201007049B
Imaging X-rays by direct focusing offers greater sensitivity and
a higher dynamic range compared to techniques based on indirect
imaging. The Focusing Optics X-ray Solar Imager (FOXSI) is a
sounding rocket payload that uses seven sets of nested Wolter-I
figured mirrors to observe the Sun in hard X-rays through direct
focusing. Characterizing the performance of these optics is critical
to optimize their performance and to understand their resulting
data. In this paper, we present a ray-tracing simulation we created and
developed to study Wolter-I X-ray mirrors. We validated the accuracy
of the ray-tracing simulation by modeling the FOXSI rocket optics. We
found satisfactory agreements between the simulation predictions
and laboratory data measured on the optics. We used the ray-tracing
simulation to characterize a background pattern of singly reflected
rays (i.e., ghost rays) generated by photons at certain incident
angles reflecting on only one of a two-segment Wolter-I figure and
still reaching the focal plane. We used the results of the ray-tracing
simulation to understand, and to formulate a set of strategies that
can be used to mitigate, the impact of ghost rays on the FOXSI optical
modules. These strategies include the optimization of aperture plates
placed at the entrance and exit of the smallest Wolter-I mirror used
in FOXSI, a honeycomb type collimator, and a wedge absorber placed
at the telescope aperture. The ray-tracing simulation proved to be
a reliable set of tools to study Wolter-I X-ray optics. It can be
used in many applications, including astrophysics, material sciences,
and medical imaging.
Title: Inverse First Ionization Potential Effects in Giant Solar
Flares Found from Earth X-Ray Albedo with Suzaku/XIS
Authors: Katsuda, Satoru; Ohno, Masanori; Mori, Koji; Beppu, Tatsuhiko;
Kanemaru, Yoshiaki; Tashiro, Makoto S.; Terada, Yukikatsu; Sato,
Kosuke; Morita, Kae; Sagara, Hikari; Ogawa, Futa; Takahashi, Haruya;
Murakami, Hiroshi; Nobukawa, Masayoshi; Tsunemi, Hiroshi; Hayashida,
Kiyoshi; Matsumoto, Hironori; Noda, Hirofumi; Nakajima, Hiroshi;
Ezoe, Yuichiro; Tsuboi, Yohko; Maeda, Yoshitomo; Yokoyama, Takaaki;
Narukage, Noriyuki
Bibcode: 2020ApJ...891..126K
Altcode: 2020arXiv200110643K
We report X-ray spectroscopic results for four giant solar flares
that occurred on 2005 September 7 (X17.0), 2005 September 8 (X5.4),
2005 September 9 (X6.2), and 2006 December 5 (X9.0), obtained from
Earth albedo data with the X-ray Imaging Spectrometer (XIS) on board
Suzaku. The good energy resolution of the XIS (FWHM ∼ 100 eV) enables
us to separate a number of line-like features and detect the underlying
continuum emission. These features include Si Heα, Si Lyα, S Heα,
S Lyα, Ar Heα, and Ca Heα originating from solar flares as well as
fluorescent Ar Kα and Ar Kβ from the Earth's atmosphere. Absolute
elemental abundances (X/H) averaged over the four flares are obtained
to be ∼2.0 (Ca), ∼0.7 (Si), ∼0.3 (S), and ∼0.9 (Ar) at around
flare peaks. This abundance pattern is similar to those of active
stars' coronae showing inverse first ionization potential (I-FIP)
effects, I.e., elemental abundances decrease with decreasing FIP
with a turnover at the low end of the FIP. The abundances are almost
constant during the flares, with the exception of Si which increases by
a factor of ∼2 in the decay phase. The evolution of the Si abundance
is consistent with the finding that the I-FIP plasma originates from
chromospheric evaporation and then mixes with the surrounding low-FIP
biased materials. Flare-to-flare abundance varied by a factor of two,
agreeing with past observations of solar flares. Finally, we emphasize
that Earth albedo data acquired by X-ray astronomy satellites like
Suzaku and the X-Ray Imaging Spectroscopy Mission can significantly
contribute to studies of solar physics.
Title: FOXSI-2 Solar Microflares. I. Multi-instrument Differential
Emission Measure Analysis and Thermal Energies
Authors: Athiray, P. S.; Vievering, Juliana; Glesener, Lindsay;
Ishikawa, Shin-nosuke; Narukage, Noriyuki; Buitrago-Casas, Juan
Camilo; Musset, Sophie; Inglis, Andrew; Christe, Steven; Krucker,
Säm; Ryan, Daniel
Bibcode: 2020ApJ...891...78A
Altcode: 2020arXiv200204200A
In this paper we present the differential emission measures
(DEMs) of two sub-A class microflares observed in hard X-rays
(HXRs) by the FOXSI-2 sounding rocket experiment, on 2014 December
11. The second Focusing Optics X-ray Solar Imager (FOXSI) flight
was coordinated with instruments X-ray Telescope (Hinode/XRT) and
Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA), which
provided observations in soft X-rays and Extreme Ultraviolet. This
unique data set offers an unprecedented temperature coverage,
useful for characterizing the plasma temperature distribution
of microflares. By combining data from FOXSI-2, XRT, and AIA, we
determined a well-constrained DEM for the microflares. The resulting
DEMs peak around 3 MK and extend beyond 10 MK. The emission measures
determined from FOXSI-2 were lower than 1026 cm-5
for temperatures higher than 5 MK; faint emission in this range is best
measured in HXRs. The coordinated FOXSI-2 observations produce one of
the few definitive measurements of the distribution and the amount
of plasma above 5 MK in microflares. We utilize the multi-thermal
DEMs to calculate the amount of thermal energy released during both
the microflares as ∼5.0 × 1028 erg for Microflare 1
and ∼1.6 × 1028 erg for Microflare 2. We also show the
multi-thermal DEMs provide more comprehensive thermal energy estimates
than isothermal approximation, which systematically underestimates
the amount of thermal energy released.
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: FOXSI-4: Instrument Upgrades for a Proposed Fourth Focusing
Optics X-Ray Solar Imager Sounding Rocket Experiment
Authors: Vievering, J. T.; Glesener, L.; Buitrago-Casas, J. C.;
Panchapakesan, S. A.; Musset, S.; Duncan, J. M.; Narukage, N.; Ryan,
D.; Inglis, A. R.; Takahashi, T.; Watanabe, S.; Christe, S.; Krucker,
S.; Turin, P.; Ramsey, B.
Bibcode: 2019AGUFMSH31C3315V
Altcode:
Observations of the Sun in hard X-rays can provide insight into many
solar phenomena, including the mechanisms behind energy release and
transport in flares. The indirect imaging methods used by RHESSI ,
the previous state-of-the-art solar hard X-ray instrument, however,
were fundamentally limited in sensitivity and imaging dynamic range . By
instead using the direct imaging technique of focusing hard X-rays, the
structure and evolution of faint coronal sources, including microflares,
active regions, and flare acceleration sites, can be investigated in
greater depth. FOXSI ( Focusing Optics X-ray Solar Imager ), a hard
X-ray instrument flown on three sounding rocket campaigns to date,
seeks to achieve these improved capabilities by using focusing optics
for solar observations in the 4-20 keV range. A fourth FOXSI sounding
rocket experiment, FOXSI-4, has been proposed for launch in 2023,
and the planned instrument upgrades are presented here. One main
focus of FOXSI-4 will be to improve the angular resolution for solar
hard X-ray instruments through the use of high-resolution optics,
with the goal of reaching a half power diameter (HPD) of ∼5". Higher
resolution will allow for individual footpoints and acceleration sites
to be distinguished during a flare, which would benefit studies of the
chromospheric response and provide constraints on flare acceleration
mechanisms. FOXSI-4 will ideally be part of a flare campaign, in which
multiple solar sounding rockets would be launched one after another
to demonstrate the strength of new solar technologies when utilized
in conjunction for flare observations.
Title: Hardware upgrades and science outcomes from the latest flights
of the FOXSI rocket
Authors: Buitrago-Casas, J. C.; Glesener, L.; Courtade, S.; Vievering,
J. T.; Athiray, P. S.; Musset, S.; Ryan, D.; Dalton, G.; Ishikawa,
S. N.; Narukage, N.; Bongiorno, S.; Furukawa, K.; Davis, L.; Turin,
P.; Turin, Z.; Takahashi, T.; Watanabe, S.; Krucker, S.; Christe,
S.; Ramsey, B.
Bibcode: 2019AGUFMSH31C3316B
Altcode:
FOXSI (which stands for the Focusing Optics X-ray Solar Imager)
is a sounding rocket payload that has completed three successful
flights supported by the Low-Cost Access to Space (LCAS) program of
NASA. FOXSI stands out for being the first telescope optimized to use
direct focusing to perform imaging spectroscopy of solar hard X-rays
(HXRs). We present the latest instrument upgrades incorporated into
the rocket payload for its third flight. We highlight the way these
upgrades substantially improved the telescope performance and we
present the observations obtained. Particularly, we describe the
strategies implemented to reduce stray-light (ghost-ray) background
and the inclusion of a soft X-ray CMOS sensor as well as HXR CdTe
strip detectors to widen the spectral range of the telescope. We finalize with an overview of the science results of the FOXSI
flights. We present a differential emission measure (DEM) and thermal
analyses of microflares observed during the second flight. We prove
the relevance of the FOXSI measurements for obtaining unprecedented
constrained microflare DEMs and discuss their implications on the
energetics of these small flaring events. We finish presenting a
discussion on the FOXSI measurements of an aged active region and
quiet-sun areas observed during its latest flight.
Title: Characterization of Charge Sharing in the FOXSI Sounding Rocket
Hard X-ray Detectors Using the Advanced Light Source at Berkeley
Authors: Duncan, J. M.; Panchapakesan, S. A.; Musset, S.; Vievering,
J. T.; MacDowell, A. A.; Glesener, L.; Davis, L.; Buitrago-Casas,
J. C.; O'Brien, C.; Ishikawa, S. N.; Takahashi, T.; Watanabe, S.;
Narukage, N.; Furukawa, K.; Ryan, D.; Hagino, K.; Courtade, S.;
Christe, S.; Krucker, S.
Bibcode: 2019AGUFMSH31C3317D
Altcode:
The FOXSI sounding rocket experiments represent the first ever
solar-dedicated direct-focusing hard X-ray (HXR) instruments. The
most recent flight (FOXSI-3) occurred in September 2018, utilizing
Wolter-1 style concentric-shell optics and both silicon (Si) and
cadmium telluride (CdTe) double-sided strip detectors. The angular
resolution of the optics (5" FWHM, equivalent to 50um at the detector
bench) is finer than the strip pitch of the Si and CdTe detectors
(75um and 60um, respectively), meaning that the resolution of the
instrument at sounding rocket focal lengths is detector-limited
[1]. In order to further improve characterization of the spatial and
spectral properties of the FOXSI-3 detectors, experiments were recently
completed using Beamline 3.3.2. at the Advanced Light Source (ALS)
at Lawrence Berkeley National Laboratory. Using this beamline, a fine
(2um x 2um or 5um x 5um) monoenergetic x-ray beam was scanned across
detector strips and inter-strip regions in steps much smaller than the
strip pitch. Such scans were performed for both Si and CdTe detectors
at a number of x-ray energies between 5.5-12 keV. These experiments were
particularly motivated by the desire to measure the incidence of charge
sharing, which occurs when a single incident photon causes signals
to be registered in multiple adjacent strips. Precise measurement of
charge sharing behavior is important to optimize characterization of
detector efficiency. Additionally, with a strong understanding of
charge sharing behavior in a detector, spatial resolution could be
improved by sub-strip localization of photon impacts. Here, we present
initial analysis of results from these ALS experiments, including
investigation into charge sharing properties in both the Si and CdTe
FOXSI-3 detectors. We also discuss the implications of these results
for the use of these detectors in the future FOXSI-4 mission, which
will utilize yet-higher-resolution HXR optics. [1] Furukawa,K.,et
al. "Development of 60um pitch CdTe Double-sided Strip Detectors for
the FOXSI-3 sounding rocket experiment." NIMPR, Section A: HSTD11, 2017.
Title: High-frequency Wave Propagation Along a Spicule Observed
by CLASP
Authors: Yoshida, Masaki; Suematsu, Yoshinori; Ishikawa, Ryohko;
Okamoto, Takenori J.; Kubo, Masahito; Kano, Ryouhei; Narukage,
Noriyuki; Bando, Takamasa; Winebarger, Amy R.; Kobayashi, Ken;
Trujillo Bueno, Javier; Auchère, Frédéric
Bibcode: 2019ApJ...887....2Y
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) sounding
rocket experiment, launched in 2015 September, observed the hydrogen
Lyα line (121.6 nm) in an unprecedented high temporal cadence of
0.3 s. CLASP performed sit-and-stare observations of the quiet Sun
near the limb for 5 minutes with a slit perpendicular to the limb
and successfully captured an off-limb spicule evolving along the
slit. The Lyα line is well suited for investigating how spicules
affect the corona because it is sensitive to higher temperatures than
other chromospheric lines, owing to its large optical thickness. We
found high-frequency oscillations of the Doppler velocity with periods
of 20-50 s and low-frequency oscillation of periods of ∼240 s on
the spicule. From a wavelet analysis of the time sequence data of
the Doppler velocity, in the early phase of the spicule evolution,
we found that waves with a period of ∼30 s and a velocity amplitude
of 2-3 km s-1 propagated upward along the spicule with a
phase velocity of ∼470 km s-1. In contrast, in the later
phase, possible downward and standing waves with smaller velocity
amplitudes were also observed. The high-frequency waves observed in
the early phase of the spicule evolution would be related with the
dynamics and the formation of the spicules. Our analysis enabled us to
identify the upward, downward, and standing waves along the spicule
and to obtain the velocity amplitude of each wave directly from the
Doppler velocity for the first time. We evaluated the energy flux
by the upward-propagating waves along the spicule, and discussed the
impact to the coronal heating.
Title: Satellite mission: PhoENiX (Physics of Energetic and
Non-thermal plasmas in the X (= magnetic reconnection) region)
Authors: Narukage, N.
Bibcode: 2019AGUFMSH31C3311N
Altcode:
We are planning a new solar satellite mission, "PhoENiX", for
understanding of particle acceleration during magnetic reconnection. The
main observation targets of this mission are solar flares, which are
generated by magnetic reconnection and accelerate plasma particles. The scientific objectives of this mission are (1) to identify
particle acceleration sites, (2) to investigate temporal evolution
of particle acceleration, and (3) to characterize properties of
accelerated particles, during solar flares. In order to achieve these
science objectives, the PhoENiX satellite is planned to be equipped
with three instruments of (1) Photon-counting type focusing-imaging
spectrometer in soft X-rays (up to ~10 keV) to observe the contexts
of particle accelerations (e.g., shocks, plasmoids, flows, etc.),
(2) Photon-counting type focusing-imaging spectrometer in hard
X-rays (up to ~30 keV) to identify the accelerated particles, and (3)
Spectropolarimeter in soft gamma-rays (spectroscopy is available in the
energy range of from > 20 keV to < 600 keV; spectropolarimetry is
available from > 60 keV to < 600 keV) to detect the anisotropy of
accelerated particles. We plan to realize the PhoENiX satellite mission
around next solar maximum (around 2025). The basic developments
of key technologies for these instruments have been completed. The
soft X-ray imaging spectroscopy is planned to be realized with
the combination of high-precision glass-polished X-ray mirrors and
high-speed CMOS cameras. The hard X-ray imaging spectroscopy consists
of high-precision electroforming X-ray mirrors and CdTe cameras. The
soft gamma-ray spectropolarimeter is a redesigned instrument of
Hitomi / Soft Gamma-ray Detector (SGD) that has Compton cameras with
active shields. Some of these technologies have been demonstrated
by FOXSI sounding rocket series launched in 2012, 2014 and 2018. The
4th flight of FOXSI sounding rocket is being proposed for the X-ray
imaging spectroscopic observation of the solar flare with high spatial
resolution. This is a good opportunity to demonstrate the PhoENiX
satellite in the both point of views of science and technology. In this
presentation, we explain the details of science goal and objectives,
and instruments of the PhoENiX mission.
Title: The Solar High-Resolution X-ray imager (SHRX): A Concept for
a Sounding Rocket Experiment
Authors: Champey, P. R.; Savage, S. L.; Winebarger, A. R.; Broadway,
D.; Kobayashi, K.; Davis, J.; Kolodziejczak, J.; Griffith, C.;
Narukage, N.
Bibcode: 2019AGUFMSH31C3318C
Altcode:
The evolution and spatial distribution of small-scale, high-temperature
plasma structures in the solar corona can be used to address multiple
open science questions, including how the corona is dynamically heated,
and how tremendous amounts of energy are released within seconds during
eruptive events. Despite decades of imaging this plasma in X-rays,
the spatial resolution of available grazing incidence mirrors has
constrained our understanding of this important energy regime. High
temperature plasma can be imaged in the extreme ultraviolet (EUV)
using normal incidence telescopes, which can be more-readily fabricated
to meet high resolution requirements. Multi-layers can be implemented
to limit the narrow passband to select for EUV wavelengths containing
high temperature emission lines. The EUV spectrum, however, contains
cooler emission lines that inevitably contaminate high temperature
channels. Here, we present a design concept for a high-resolution,
(< 1 arcsecond) soft X-ray (SXR) imager to fly aboard a sounding
rocket that will enable solar observations of small-scale structures
containing plasma greater than 5 million degrees. The Solar High
Resolution X-ray imager (SHRX) will observe a narrow SXR band centered
at 1.03 keV (12 Angstroms) using cutting-edge multi-layer coatings and
an improved glass substrate grazing incidence mirror developed at NASA
Marshall Space Flight Center (MSFC). The optical design accommodates
a CMOS detector developed by the Japan Aerospace Exploration Agency
(JAXA), and previously flown aboard the FOXSI-3 sounding rocket. The
detector consists of a 2k X 2k chip, 7 micron square pixel size, and
rapid readout time enabling photon-counting capability. The science
objective is to study small-scale, active region plasma flows associated
with dynamic energy release. Within the constraints of a sounding
rocket experiment, this will be accomplished via sub-arcsecond SXR
observations of active region core plasma in a bandpass that overlaps
with the temperature responses of Hinode/XRT and the SDO/AIA 94Å
channel. The effective area curve of the mirror will be tuned via the
mirror prescription and the multi-layer coating, which will shape the
temperature response of the instrument. Here we present our science
objectives and a technical overview of the instrument concept.
Title: Ghost-ray reduction and early results from the third FOXSI
sounding rocket flight
Authors: Musset, Sophie; Buitrago-Casas, Juan Camilo; Glesener,
Lindsay; Bongiorno, Stephen; Courtade, Sasha; Athiray, P. S.;
Vievering, Juliana; Ishikawa, Shin-nosuke; Narukage, Noriyuki;
Furukawa, Kento; Ryan, Daniel; Dalton, Greg; Turin, Zoe; Davis, Lance;
Takahashi, Tadayuki; Watanabe, Shin; Mitsuishi, Ikuyuki; Hagino,
Kouichi; Kawate, Tomoko; Turin, Paul; Christe, Steven; Ramsey, Brian;
Krucker, Säm.
Bibcode: 2019SPIE11118E..12M
Altcode:
The Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket
experiment demonstrates the technique of focusing hard X-ray (HXR)
optics for the study of fundamental questions about the high-energy
Sun. Solar HXRs provide one of the most direct diagnostics of
accelerated electrons and the impulsive heating of the solar
corona. Previous solar missions have been limited in sensitivity
and dynamic range by the use of indirect imaging, but technological
advances now make direct focusing accessible in the HXR regime, and the
FOXSI rocket experiment optimizes HXR focusing telescopes for the unique
scientific requirements of the Sun. FOXSI has completed three successful
flights between 2012 and 2018. This paper gives a brief overview of
the experiment, focusing on the third flight of the instrument on 2018
Sept. 7. We present the telescope upgrades highlighting our work to
understand and reduce the effects of singly reflected X-rays and show
early science results obtained during FOXSI's third flight.
Title: The FOXSI-3 rocket: Overview and early results of its latest
flight
Authors: Buitrago-Casas, Juan Camilo; Glesener, Lindsay; Courtade,
Sasha; Vievering, Juliana; Athiray Panchapakesan, Subramania; Musset,
Sophie; Ryan, Daniel; Dalton, Gregory; Ishikawa, Shin-Nosuke; Narukage,
Noriyuki; Bongiorno, Stephen; Furukawa, Kento; Davis, Lance; Turin,
Paul; Turin, Zoe; Takahashi, Tadayuki; Watanabe, Shin; Krucker, Sam;
Christe, Steven; Ramsey, Brian
Bibcode: 2019AAS...23412602B
Altcode:
Hard X-rays (HXRs) from the solar corona are closely connected to energy
releases and particle transport in solar flares of all sizes. Expressly,
faint solar HXR emissions are of remarkable interest in understanding
solar flare structure and dynamics. This is because of their connection
with, for instance, loop top emission and small flares. Mainly due to
the indirect imaging methods used by past solar-dedicated HXR imagers,
like RHESSI, faint HXRs observations have been limited by the imaging
dynamic range and sensitivity of the instruments. The Focusing
Optics X-ray Solar Imager (FOXSI) sounding rocket payload is the first
solar-dedicated instrument designed for performing imaging spectroscopy
in the 4-20 keV range by using direct focusing optics. FOXSI has
successfully flown three times from the White Sands Missile Range
in New Mexico. For its latest rocket campaign (FOXSI-3), an enhanced
version of the experiment, which includes optics and detector upgrades,
was implemented for the launch which happened on September 7, 2018. In
this talk, we present an overview of the FOXSI-3 campaign, describing
in detail the improved capabilities of the telescope and how they
allow for better investigation of faint coronal HXRs. We also present
a preliminary analysis of the FOXSI-3 observations.
Title: FOXSI-2 Solar Microflares : Multi-Instrument Differential
Emission Measure Analysis
Authors: Athiray, P. S.; Glesener, Lindsay; Vievering, Juliana;
Ishikawa, Shin-Nosuke; Inglis, Andrew; Narukage, Noriyuki; Ryan,
Daniel; Buitrago-Casas, Juan Camilo; Christe, Steven; Musset, Sophie;
Krucker, Sam
Bibcode: 2019AAS...23422502A
Altcode:
The plasma temperature distribution above 5 MK during microflares is
often loosely constrained due to limited high sensitivity hard X-ray
measurements covering the wide range of temperatures observed. The
Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket experiment
performs direct imaging and spectroscopy of the Sun in hard X-rays,
in the energy range 4 to 20 keV. FOXSI offers better sensitivity for
temperatures above 5 MK by using direct focusing grazing incidence X-ray
optics, the first of its kind for dedicated solar observations. The
second FOXSI flight was launched on 2014 December 11 and observed
microflares, quiescent Sun and quiescent active regions. This flight
was coordinated with the X-ray Telescope (XRT) onboard Hinode and
the Atmospheric Imaging Assembly (AIA) onboard SDO which offers
unprecedented temperature coverage for characterizing the plasma
temperature distribution. We present an overview of microflares
observed during the FOXSI-2 flight with concurrent brightening
observed in Extreme Ultraviolet (EUV) and soft X-rays, which indicates
emission beyond 10 MK. By combining data from FOXSI-2, XRT, and AIA, we
determined a well-constrained DEM for the microflares. The coordinated
FOXSI-2 observations produce one of the few definitive measurements
of the distribution and the amount of plasma above 5 MK in microflares.
Title: Satellite mission: PhoENiX (Physics of Energetic and
Non-thermal plasmas in the X (= magnetic reconnection) region)
Authors: Narukage, Noriyuki
Bibcode: 2019AAS...23412603N
Altcode:
We are studying a new solar satellite mission, "PhoENiX", for
understanding of particle acceleration during magnetic reconnection,
which are ubiquitous features exhibited by a wide range of plasmas
in the universe. The main observation targets of this mission are
solar flares that are caused by magnetic reconnection and accelerate
plasma particles. The sun is a unique target in the sense that it
can be investigated in great detail with good spatial, temporal and
energy resolutions. The scientific objectives of this mission are (1)
to identify particle acceleration sites, (2) to investigate temporal
evolution of particle acceleration, and (3) to characterize properties
of accelerated particles, during magnetic reconnection, i.e., during
solar flares. In order to achieve these science objectives, the
PhoENiX satellite is planned to be equipped with three instruments
of (1) Photon-counting type focusing-imaging spectrometer in soft
X-rays (up to 10 keV) demonstrated by FOXSI-3, (2) Photon-counting
type focusing-imaging spectrometer in hard X-rays (up to 30 keV)
like FOXSI series, and (3) Spectropolarimeter in soft gamma-rays
(spectroscopy is available in the energy range of from > 20 keV
to < 600 keV; spectropolarimetry is available from > 60 keV
to < 600 keV) like Hitomi/SGD. We plan to realize this satellite
mission around next solar maximum (around 2025). In this presentation,
we will explain the details of science goal, science objectives and
instruments of PhoENiX mission. Additionally, in order to demonstrate
the unprecedented observations with PhoENiX, we will show the soft
X-ray photon-counting data taken by FOXSI-3 sounding rocket.
Title: Modeling the Scattering Polarization of the Hydrogen Lyα
Line Observed by CLASP in a Filament Channel
Authors: Štěpán, J.; Trujillo Bueno, J.; Gunár, S.; Heinzel, P.;
del Pino Alemán, T.; Kano, R.; Ishikawa, R.; Narukage, N.; Bando,
T.; Winebarger, A.; Kobayashi, K.; Auchère, F.
Bibcode: 2019ASPC..526..165S
Altcode:
The 400 arcsec spectrograph slit of CLASP crossed mainly quiet
regions of the solar chromosphere, from the limb towards the solar
disk center. Interestingly, in the CLASP slit-jaw images and in the
SDO images of the He II line at 304 Å, we can identify a filament
channel (FC) extending over more than 60 arcsec crossing the slit of
the spectrograph. In order to interpret the peculiar spatial variation
of the Q/I and U/I signals observed by CLASP in the hydrogen Lyα line
(1216 Å), we perform multi-dimensional radiative transfer modeling
in given filament models. In this contribution, we show the first
results of the two-dimensional calculations we have carried out, with
the aim of determining the filament thermal and magnetic structure by
comparing the theoretical and the observed polarization signals. Our
results suggest that the temperature gradients in the filament observed
by CLASP are significantly larger than previously thought.
Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: McKenzie, D. E.; Ishikawa, R.; Trujillo Bueno, J.; Auchére,
F.; Rachmeler, L. A.; Kubo, M.; Kobayashi, K.; Winebarger, A. R.;
Bethge, C. W.; Narukage, N.; Kano, R.; Ishikawa, S.; de Pontieu,
B.; Carlsson, M.; Yoshida, M.; Belluzzi, L.; Štěpán, J.; del Pino
Alemán, T.; Alsina Ballester, E.; Asensio Ramos, A.
Bibcode: 2019ASPC..526..361M
Altcode:
The hydrogen Lyman-α line at 121.6 nm and the Mg k line at 279.5
nm are especially relevant for deciphering the magnetic structure
of the chromosphere since their line-center signals are formed in
the chromosphere and transition region, with unique sensitivities to
magnetic fields. We propose the Chromospheric LAyer Spectro-Polarimeter
(CLASP2), to build upon the success of the first CLASP flight, which
measured the linear polarization in H I Lyman-α. The existing CLASP
instrument will be refitted to measure all four Stokes parameters in
the 280 nm range, including variations due to the anisotropic radiation
pumping, the Hanle effect, and the Zeeman effect.
Title: Comparison of Scattering Polarization Signals Observed by
CLASP: Possible Indication of the Hanle Effect
Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.;
Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa,
Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.;
Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.;
Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso
Sainz, R.; De Pomtieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.
Bibcode: 2019ASPC..526..305I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP; Kano et
al. 2012; Kobayashi et al. 2012; Kubo et al. 2014) observed, for the
first time, the linear polarization produced by scattering processes
in the hydrogen Lyman-α (121.57 nm) and Si III (120.56 nm) lines of
the solar disk radiation. The complexity of the observed scattering
polarization (i.e., conspicuous spatial variations in Q/I and U/I
at spatial scales of 10″-20″ and the absence of center-to- limb
variation at the Lyman-α center; see Kano et al. 2017) motivated us
to search for possible hints of the operation of the Hanle effect by
comparing: (a) the Lyman-α line center signal, for which the critical
field strength (BH) for the onset of the Hanle effect is
53 G, (b) the Lyman-α wing, which is insensitive to the Hanle effect,
and (c) the Si III line, whose BH = 290 G. We focus on four
regions with different total unsigned photospheric magnetic fluxes
(estimated from SDO/HMI observations), and compare the corresponding
U/I spatial variations in the Lyman-α wing, Lyman-α center, and Si III
line. The U/I signal in the Lyman-α wing shows an antisymmetric spatial
distribution, which is caused by the presence of a bright structure in
all the selected regions, regardless of the total unsigned photospheric
magnetic flux. In an internetwork region, the Lyman-α center shows an
antisymmetric spatial variation across the selected bright structure,
but it does not show it in other more magnetized regions. In the Si III
line, the spatial variation of U/I deviates from the above-mentioned
antisymmetric shape as the total unsigned photospheric magnetic flux
increases. We argue that a plausible explanation of this differential
behavior is the operation of the Hanle effect. This work, presented
in an oral contribution at this Workshop, has been published on The
Astrophysical Journal (Ishikawa et al. 2017).
Title: High-speed X-ray imaging spectroscopy system with Zynq SoC
for solar observations
Authors: Ishikawa, Shin-nosuke; Takahashi, Tadayuki; Watanabe,
Shin; Narukage, Noriyuki; Miyazaki, Satoshi; Orita, Tadashi; Takeda,
Shin'ichiro; Nomachi, Masaharu; Fujishiro, Iwao; Hodoshima, Fumio
Bibcode: 2018NIMPA.912..191I
Altcode: 2017arXiv171104372I
We have developed a system combining a back-illuminated
Complementary-Metal-Oxide-Semiconductor (CMOS) imaging sensor and
Xilinx Zynq System-on-Chip (SoC) device for a soft X-ray (0.5-10 keV)
imaging spectroscopy observation of the Sun to investigate the dynamics
of the solar corona. Because typical timescales of energy release
phenomena in the corona span a few minutes at most, we aim to obtain
the corresponding energy spectra and derive the physical parameters,
i.e., temperature and emission measure, every few tens of seconds
or less for future solar X-ray observations. An X-ray photon-counting
technique, with a frame rate of a few hundred frames per second or more,
can achieve such results. We used the Zynq SoC device to achieve the
requirements. Zynq contains an ARM processor core, which is also known
as the Processing System (PS) part, and a Programable Logic (PL) part in
a single chip. We use the PL and PS to control the sensor and seamless
recording of data to a storage system, respectively. We aim to use the
system for the third flight of the Focusing Optics Solar X-ray Imager
(FOXSI-3) sounding rocket experiment for the first photon-counting
X-ray imaging and spectroscopy of the Sun.
Title: CLASP Constraints on the Magnetization and Geometrical
Complexity of the Chromosphere-Corona Transition Region
Authors: Trujillo Bueno, J.; Štěpán, J.; Belluzzi, L.; Asensio
Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Ishikawa,
R.; Kano, R.; Winebarger, A.; Auchère, F.; Narukage, N.; Kobayashi,
K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...866L..15T
Altcode: 2018arXiv180908865T
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
suborbital rocket experiment that on 2015 September 3 measured
the linear polarization produced by scattering processes in the
hydrogen Lyα line of the solar disk radiation. The line-center
photons of this spectral line radiation mostly stem from the
chromosphere-corona transition region (TR). These unprecedented
spectropolarimetric observations revealed an interesting surprise,
namely that there is practically no center-to-limb variation (CLV) in
the Q/I line-center signals. Using an analytical model, we first show
that the geometric complexity of the corrugated surface that delineates
the TR has a crucial impact on the CLV of the Q/I and U/I line-center
signals. Second, we introduce a statistical description of the solar
atmosphere based on a 3D model derived from a state-of-the-art radiation
magnetohydrodynamic simulation. Each realization of the statistical
ensemble is a 3D model characterized by a given degree of magnetization
and corrugation of the TR, and for each such realization we solve the
full 3D radiative transfer problem taking into account the impact
of the CLASP instrument degradation on the calculated polarization
signals. Finally, we apply the statistical inference method presented
in a previous paper to show that the TR of the 3D model that produces
the best agreement with the CLASP observations has a relatively weak
magnetic field and a relatively high degree of corrugation. We emphasize
that a suitable way to validate or refute numerical models of the upper
solar chromosphere is by confronting calculations and observations
of the scattering polarization in ultraviolet lines sensitive to the
Hanle effect.
Title: A Statistical Inference Method for Interpreting the CLASP
Observations
Authors: Štěpán, J.; Trujillo Bueno, J.; Belluzzi, L.; Asensio
Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Kano, R.;
Winebarger, A.; Auchère, F.; Ishikawa, R.; Narukage, N.; Kobayashi,
K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...865...48S
Altcode: 2018arXiv180802725S
On 2015 September 3, the Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) successfully measured the linear polarization produced by
scattering processes in the hydrogen Lyα line of the solar disk
radiation, revealing conspicuous spatial variations in the Q/I and U/I
signals. Via the Hanle effect, the line-center Q/I and U/I amplitudes
encode information on the magnetic field of the chromosphere-corona
transition region, but they are also sensitive to the three-dimensional
structure of this corrugated interface region. With the help of a simple
line-formation model, here we propose a statistical inference method
for interpreting the Lyα line-center polarization observed by CLASP.
Title: Current State of UV Spectro-Polarimetry and its Future
Direction
Authors: Ishikawa, Ryohko; Sakao, Taro; Katsukawa, Yukio; Hara,
Hirohisa; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito;
Auchere, Frederic; De Pontieu, Bart; Winebarger, Amy; Kobayashi,
. Ken; Kano, Ryouhei; Narukage, Noriyuki; Trujillo Bueno, Javier;
Song, Dong-uk; Manso Sainz, Rafael; Asensio Ramos, Andres; Leenaarts,
Jorritt; Carlsson, Mats; Bando, Takamasa; Ishikawa, Shin-nosuke;
Tsuneta, Saku; Belluzzi, Luca; Suematsu, Yoshinori; Giono, Gabriel;
Yoshida, Masaki; Goto, Motoshi; Del Pino Aleman, Tanausu; Stepan,
Jiri; Okamoto, Joten; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Champey,
Patrick; Alsina Ballester, Ernest; Casini, Roberto; McKenzie, David;
Rachmeler, Laurel; Bethge, Christian
Bibcode: 2018cosp...42E1564I
Altcode:
To obtain quantitative information on the magnetic field in low beta
regions (i.e., upper chromosphere and above) has been increasingly
important to understand the energetic phenomena of the outer
solar atmosphere such as flare, coronal heating, and the solar wind
acceleration. In the UV range, there are abundant spectral lines that
originate in the upper chromosphere and transition region. However,
the Zeeman effect in these spectral lines does not give rise to easily
measurable polarization signals because of the weak magnetic field
strength and the larger Doppler broadening compared with the Zeeman
effect. Instead, the Hanle effect in UV lines is expected to be a
suitable diagnostic tool of the magnetic field in the upper atmospheric
layers. To investigate the validity of UV spectro-polarimetry and
the Hanle effect, the Chromospheric Lyman-Alpha Spectro-Polarimeter
(CLASP), which is a NASA sounding- rocket experiment, was launched at
White Sands in US on September 3, 2015. During its 5 minutes ballistic
flight, it successfully performed spectro-polarimetric observations
of the hydrogen Lyman-alpha line (121.57 nm) with an unprecedentedly
high polarization sensitivity of 0.1% in this wavelength range. CLASP
observed the linear polarization produced by scattering process in VUV
lines for the first time and detected the polarization signals which
indicate the operation of the Hanle effect. Following the success
of CLASP, we are confident that UV spectro-polarimetry is the way
to proceed, and we are planning the second flight of CLASP (CLASP2:
Chromospheric LAyer SpectroPolarimeter 2). For this second flight we
will carry out spectro-polarimetry in the Mg II h and k lines around
280 nm, with minimum modifications of the CLASP1 instrument. The linear
polarization in the Mg II k line is induced by scattering processes and
the Hanle effect, being sensitive to magnetic field strengths of 5 to 50
G. In addition, the circular polarizations in the Mg II h and k lines
induced by the Zeeman effect can be measurable in at least plage and
active regions. The combination of the Hanle and Zeeman effects could
help us to more reliably infer the magnetic fields of the upper solar
chromosphere. CLASP2 was selected for flight and is being developed for
launch in the spring of 2019.Based on these sounding rocket experiments
(CLASP1 and 2), we aim at establishing the strategy and refining the
instrument concept for future space missions to explore the enigmatic
atmospheric layers via UV spectro-polarimetry.
Title: Wavefront error measurements and alignment of CLASP2 telescope
with a dual-band pass cold mirror coated primary mirror
Authors: Yoshida, Masaki; Song, Donguk; Ishikawa, Ryoko; Kano, Ryouhei;
Katsukawa, Yukio; Suematsu, Yoshinori; Narukage, Noriyuki; Kubo,
Masahito; Shinoda, Kazuya; Okamoto, Takenori J.; McKenzie, David E.;
Rachmeler, Laurel A.; Auchère, Frédéric; Trujillo Bueno, Javier
Bibcode: 2018SPIE10699E..30Y
Altcode:
"Chromospheric LAyer Spectro-Polarimeter (CLASP2)" is the next sounding
rocket experiment of the "Chromospheric Lyman-Alpha Spectro-Polarimeter
(CLASP)" that succeeded in observing for the first time the linear
polarization spectra in the hydrogen Lyman-α line (121.6 nm) and is
scheduled to be launched in 2019. In CLASP2, we will carry out full
Stokes-vector spectropolarimetric observations in the Mg ii h and k
lines near 280 nm with the spectro-polarimeter (SP), while imaging
observations in the Lyman-α line will be conducted with the slitjaw
optics (SJ). For the wavelength selection of CLASP2, the primary
mirror of the telescope uses a new dual-band pass cold mirror coating
targeting both at 121.6 nm and 280 nm. Therefore, we have to perform
again the alignment of the telescope after the installation of the
recoated primary mirror. Before unmounting the primary mirror from
the telescope structure, we measured the wave-front error (WFE) of the
telescope. The measured WFE map was consistent with what we had before
the CLASP flight, clearly indicating that the telescope alignment has
been maintained even after the flight. After the re-coated primary
mirror was installed the WFE was measured, and coma aberration was
found to be larger. Finally, the secondary mirror shim adjustments
were carried out based on the WFE measurements. In CLASP2 telescope,
we improved a fitting method of WFE map (applying 8th terms circular
Zernike polynomial fitting instead of 37th terms circular Zernike
fitting) and the improved method enables to achieve better performance
than CLASP telescope. Indeed, WFE map obtained after the final shim
adjustment indicated that the required specification (< 5.5 μm
RMS spot radius) that is more stringent than CLASP telescope was met.
Title: Detection of nanoflare-heated plasma in the solar corona by
the FOXSI-2 sounding rocket
Authors: Ishikawa, Shin-nosuke; Glesener, Lindsay; Krucker, Säm;
Christe, Steven; Buitrago-Casas, Juan Camilo; Narukage, Noriyuki;
Vievering, Juliana
Bibcode: 2017NatAs...1..771I
Altcode:
The processes that heat the solar and stellar coronae to several million
kelvins, compared with the much cooler photosphere (5,800 K for the
Sun), are still not well known1. One proposed mechanism
is heating via a large number of small, unresolved, impulsive heating
events called nanoflares2. Each event would heat and cool
quickly, and the average effect would be a broad range of temperatures
including a small amount of extremely hot plasma. However, detecting
these faint, hot traces in the presence of brighter, cooler emission
is observationally challenging. Here we present hard X-ray data from
the second flight of the Focusing Optics X-ray Solar Imager (FOXSI-2),
which detected emission above 7 keV from an active region of the Sun
with no obvious individual X-ray flare emission. Through differential
emission measure computations, we ascribe this emission to plasma
heated above 10 MK, providing evidence for the existence of solar
nanoflares. The quantitative evaluation of the hot plasma strongly
constrains the coronal heating models.
Title: Comparison of Solar Fine Structure Observed Simultaneously
in Lyα and Mg II h
Authors: Schmit, D.; Sukhorukov, A. V.; De Pontieu, B.; Leenaarts,
J.; Bethge, C.; Winebarger, A.; Auchère, F.; Bando, T.; Ishikawa,
R.; Kano, R.; Kobayashi, K.; Narukage, N.; Trujillo Bueno, J.
Bibcode: 2017ApJ...847..141S
Altcode: 2017arXiv170900035S
The Chromospheric Lyman Alpha Spectropolarimeter (CLASP) observed the
Sun in H I Lyα during a suborbital rocket flight on 2015 September
3. The Interface Region Imaging Telescope (IRIS) coordinated with the
CLASP observations and recorded nearly simultaneous and co-spatial
observations in the Mg II h and k lines. The Mg II h and Lyα lines
are important transitions, energetically and diagnostically, in the
chromosphere. The canonical solar atmosphere model predicts that these
lines form in close proximity to each other and so we expect that the
line profiles will exhibit similar variability. In this analysis, we
present these coordinated observations and discuss how the two profiles
compare over a region of quiet Sun at viewing angles that approach the
limb. In addition to the observations, we synthesize both line profiles
using a 3D radiation-MHD simulation. In the observations, we find that
the peak width and the peak intensities are well correlated between the
lines. For the simulation, we do not find the same relationship. We
have attempted to mitigate the instrumental differences between IRIS
and CLASP and to reproduce the instrumental factors in the synthetic
profiles. The model indicates that formation heights of the lines
differ in a somewhat regular fashion related to magnetic geometry. This
variation explains to some degree the lack of correlation, observed
and synthesized, between Mg II and Lyα. Our analysis will aid in the
definition of future observatories that aim to link dynamics in the
chromosphere and transition region.
Title: CLASP/SJ Observations of Rapid Time Variations in the Lyα
Emission in a Solar Active Region
Authors: Ishikawa, Shin-nosuke; Kubo, Masahito; Katsukawa, Yukio;
Kano, Ryouhei; Narukage, Noriyuki; Ishikawa, Ryohko; Bando, Takamasa;
Winebarger, Amy; Kobayashi, Ken; Trujillo Bueno, Javier; Auchère,
Frédéric
Bibcode: 2017ApJ...846..127I
Altcode:
The Chromospheric Lyα SpectroPolarimeter (CLASP) is a sounding
rocket experiment launched on 2015 September 3 to investigate the
solar chromosphere and transition region. The slit-jaw (SJ) optical
system captured Lyα images with a high time cadence of 0.6 s. From
the CLASP/SJ observations, many variations in the solar chromosphere
and transition region emission with a timescale of <1 minute
were discovered. In this paper, we focus on the active region within
the SJ field of view and investigate the relationship between short
(<30 s) temporal variations in the Lyα emission and the coronal
structures observed by Solar Dynamics Observatory/Atmospheric Imaging
Assembly (AIA). We compare the Lyα temporal variations at the coronal
loop footpoints observed in the AIA 211 Å (≈2 MK) and AIA 171 Å
(≈0.6 MK) channels with those in the regions with bright Lyα features
without a clear association with the coronal loop footpoints. We find
more short (<30 s) temporal variations in the Lyα intensity in the
footpoint regions. Those variations did not depend on the temperature
of the coronal loops. Therefore, the temporal variations in the Lyα
intensity at this timescale range could be related to the heating of
the coronal structures up to temperatures around the sensitivity peak
of 171 Å. No signature was found to support the scenario that these
Lyα intensity variations were related to the nanoflares. Waves or
jets from the lower layers (lower chromosphere or photosphere) are
possible causes for this phenomenon.
Title: Methods for reducing singly reflected rays on the Wolter-I
focusing mirrors of the FOXSI rocket experiment
Authors: Buitrago-Casas, Juan Camilo; Elsner, Ronald; Glesener,
Lindsay; Christe, Steven; Ramsey, Brian; Courtade, Sasha; Ishikawa,
Shin-nosuke; Narukage, Noriyuki; Turin, Paul; Vievering, Juliana;
Athiray, P. S.; Musset, Sophie; Krucker, Säm.
Bibcode: 2017SPIE10399E..0JB
Altcode:
In high energy solar astrophysics, imaging hard X-rays by direct
focusing offers higher dynamic range and greater sensitivity compared to
past techniques that used indirect imaging. The Focusing Optics X-ray
Solar Imager (FOXSI) is a sounding rocket payload that uses seven sets
of nested Wolter-I figured mirrors together with seven high-sensitivity
semiconductor detectors to observe the Sun in hard X-rays through direct
focusing. The FOXSI rocket has successfully flown twice and is funded
to fly a third time in summer 2018. The Wolter-I geometry consists
of two consecutive mirrors, one paraboloid and one hyperboloid, that
reflect photons at grazing angles. Correctly focused X-rays reflect
once per mirror segment. For extended sources, like the Sun, off-axis
photons at certain incident angles can reflect on only one mirror and
still reach the focal plane, generating a background pattern of singly
reflected rays (i.e., ghost rays) that can limit the sensitivity of the
observation to faint, focused sources. Understanding and mitigating
the impact of the singly reflected rays on the FOXSI optical modules
will maximize the instruments' sensitivity to background-limited
sources. We present an analysis of the FOXSI singly reflected rays
based on ray-tracing simulations and laboratory measurements, as well
as the effectiveness of different physical strategies to reduce them.
Title: Detection of Heating Processes in Coronal Loops by Soft
X-ray Spectroscopy
Authors: Kawate, Tomoko; Narukage, Noriyuki; Ishikawa, Shin-nosuke;
Imada, Shinsuke
Bibcode: 2017SPD....4810615K
Altcode:
Imaging and Spectroscopic observations in the soft X-ray band will open
a new window of the heating/acceleration/transport processes in the
solar corona. The soft X-ray spectrum between 0.5 and 10 keV consists
of the electron thermal free-free continuum and hot coronal lines such
as O VIII, Fe XVII, Mg XI, Si XVII. Intensity of free-free continuum
emission is not affected by the population of ions, whereas line
intensities especially from highly ionized species have a sensitivity of
the timescale of ionization/recombination processes. Thus, spectroscopic
observations of both continuum and line intensities have a capability of
diagnostics of heating/cooling timescales. We perform a 1D hydrodynamic
simulation coupled with the time-dependent ionization, and calculate
continuum and line intensities under different heat input conditions
in a coronal loop. We also examine the differential emission measure
of the coronal loop from the time-integrated soft x-ray spectra. As a
result, line intensity shows a departure from the ionization equilibrium
and shows different responses depending on the frequency of the heat
input. Solar soft X-ray spectroscopic imager will be mounted in the
sounding rocket experiment of the Focusing Optics X-ray Solar Imager
(FOXSI). This observation will deepen our understanding of heating
processes to solve the “coronal heating problem”.
Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: Rachmeler, Laurel; E McKenzie, David; Ishikawa, Ryohko;
Trujillo Bueno, Javier; Auchère, Frédéric; Kobayashi, Ken;
Winebarger, Amy; Bethge, Christian; Kano, Ryouhei; Kubo, Masahito;
Song, Donguk; Narukage, Noriyuki; Ishikawa, Shin-nosuke; De Pontieu,
Bart; Carlsson, Mats; Yoshida, Masaki; Belluzzi, Luca; Stepan, Jiri;
del Pino Alemná, Tanausú; Ballester, Ernest Alsina; Asensio Ramos,
Andres
Bibcode: 2017SPD....4811010R
Altcode:
We present the instrument, science case, and timeline of the CLASP2
sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha
Spectro-Polarimeter) sounding rocket flight in 2015 resulted in
the first-ever linear polarization measurements of solar hydrogen
Lyman-alpha line, which is sensitive to the Hanle effect and can be used
to constrain the magnetic field and geometric complexity of the upper
chromosphere. Ly-alpha is one of several upper chromospheric lines that
contain magnetic information. In the spring of 2019, we will re-fly
the modified CLASP telescope to measure the full Stokes profile of Mg
II h & k near 280 nm. This set of lines is sensitive to the upper
chromospheric magnetic field via both the Hanle and the Zeeman effects.
Title: CLASP2: The Chromospheric LAyer Spectro-Polarimeter
Authors: Rachmeler, Laurel A.; McKenzie, D. E.; Ishikawa, R.;
Trujillo-Bueno, J.; Auchere, F.; Kobayashi, K.; Winebarger, A.;
Bethge, C.; Kano, R.; Kubo, M.; Song, D.; Narukage, N.; Ishikawa, S.;
De Pontieu, B.; Carlsson, M.; Yoshida, M.; Belluzzi, L.; Stepan, J.;
del Pino Alemán, T.; Alsina Ballester, E.; Asensio Ramos, A.
Bibcode: 2017shin.confE..79R
Altcode:
We present the instrument, science case, and timeline of the CLASP2
sounding rocket mission. The successful CLASP (Chromospheric Lyman-Alpha
Spectro-Polarimeter) sounding rocket flight in 2015 resulted in
the first-ever linear polarization measurements of solar hydrogen
Lyman-alpha line, which is sensitive to the Hanle effect and can be used
to constrain the magnetic field and geometric complexity of the upper
chromosphere. Ly-alpha is one of several upper chromospheric lines that
contain magnetic information. In the spring of 2019, we will re-fly
the modified CLASP telescope to measure the full Stokes profile of Mg
II h & k near 280 nm. This set of lines is sensitive to the upper
chromospheric magnetic field via both the Hanle and the Zeeman effects.
Title: White paper of the "soft X-ray imaging spectroscopy"
Authors: Narukage, Noriyuki; Ishikawa, Shin-nosuke; Kawate, Tomoko;
Imada, Shinsuke; Sakao, Taro
Bibcode: 2017arXiv170604536N
Altcode:
The solar corona is full of dynamic phenomena, e.g., solar flares,
micro flares in active regions, jets in coronal holes and in the polar
regions, X-ray bright points in quiet regions, etc. They are accompanied
by interesting physical processes, namely, magnetic reconnection,
particle acceleration, shocks, waves, flows, evaporation, heating,
cooling, and so on. The understandings of these phenomena and processes
have been progressing step-by-step with the evolution of the observation
technology in EUV and X-rays from the space. But, there are fundamental
questions remain unanswered, or haven't even addressed so far. Our
scientific objective is to understand underlying physics of dynamic
phenomena in the solar corona, covering some of the long-standing
questions in solar physics such as particle acceleration in flares
and coronal heating. In order to achieve these science objectives,
we identify the imaging spectroscopy (the observations with spatial,
temporal and energy resolutions) in the soft X-ray range (from ~0.5
keV to ~10 keV) is a powerful approach for the detection and analysis
of energetic events.
Title: Indication of the Hanle Effect by Comparing the Scattering
Polarization Observed by CLASP in the Lyα and Si III 120.65 nm Lines
Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.;
Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa,
Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.;
Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.;
Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso
Sainz, R.; De Pontieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.
Bibcode: 2017ApJ...841...31I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter is a sounding
rocket experiment that has provided the first successful measurement
of the linear polarization produced by scattering processes in
the hydrogen Lyα line (121.57 nm) radiation of the solar disk. In
this paper, we report that the Si III line at 120.65 nm also shows
scattering polarization and we compare the scattering polarization
signals observed in the Lyα and Si III lines in order to search for
observational signatures of the Hanle effect. We focus on four selected
bright structures and investigate how the U/I spatial variations vary
between the Lyα wing, the Lyα core, and the Si III line as a function
of the total unsigned photospheric magnetic flux estimated from Solar
Dynamics Observatory/Helioseismic and Magnetic Imager observations. In
an internetwork region, the Lyα core shows an antisymmetric spatial
variation across the selected bright structure, but it does not show
it in other more magnetized regions. In the Si III line, the spatial
variation of U/I deviates from the above-mentioned antisymmetric
shape as the total unsigned photospheric magnetic flux increases. A
plausible explanation of this difference is the operation of the Hanle
effect. We argue that diagnostic techniques based on the scattering
polarization observed simultaneously in two spectral lines with very
different sensitivities to the Hanle effect, like Lyα and Si III,
are of great potential interest for exploring the magnetism of the
upper solar chromosphere and transition region.
Title: Polarization Calibration of the Chromospheric Lyman-Alpha
SpectroPolarimeter for a 0.1% Polarization Sensitivity in the VUV
Range. Part II: In-Flight Calibration
Authors: Giono, G.; Ishikawa, R.; Narukage, N.; Kano, R.; Katsukawa,
Y.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.;
Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.;
Tsuneta, S.; Shimizu, T.; Sakao, T.; Cirtain, J.; Champey, P.; Asensio
Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu,
B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.
Bibcode: 2017SoPh..292...57G
Altcode:
The Chromospheric Lyman-Alpha SpectroPolarimeter is a sounding
rocket instrument designed to measure for the first time the linear
polarization of the hydrogen Lyman-α line (121.6 nm). The instrument
was successfully launched on 3 September 2015 and observations were
conducted at the solar disc center and close to the limb during the
five-minutes flight. In this article, the disc center observations are
used to provide an in-flight calibration of the instrument spurious
polarization. The derived in-flight spurious polarization is consistent
with the spurious polarization levels determined during the pre-flight
calibration and a statistical analysis of the polarization fluctuations
from solar origin is conducted to ensure a 0.014% precision on the
spurious polarization. The combination of the pre-flight and the
in-flight polarization calibrations provides a complete picture of
the instrument response matrix, and a proper error transfer method
is used to confirm the achieved polarization accuracy. As a result,
the unprecedented 0.1% polarization accuracy of the instrument in the
vacuum ultraviolet is ensured by the polarization calibration.
Title: Discovery of Scattering Polarization in the Hydrogen Lyα
Line of the Solar Disk Radiation
Authors: Kano, R.; Trujillo Bueno, J.; Winebarger, A.; Auchère, F.;
Narukage, N.; Ishikawa, R.; Kobayashi, K.; Bando, T.; Katsukawa, Y.;
Kubo, M.; Ishikawa, S.; Giono, G.; Hara, H.; Suematsu, Y.; Shimizu,
T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.; Goto, M.; Belluzzi, L.;
Štěpán, J.; Asensio Ramos, A.; Manso Sainz, R.; Champey, P.;
Cirtain, J.; De Pontieu, B.; Casini, R.; Carlsson, M.
Bibcode: 2017ApJ...839L..10K
Altcode: 2017arXiv170403228K
There is a thin transition region (TR) in the solar atmosphere where
the temperature rises from 10,000 K in the chromosphere to millions
of degrees in the corona. Little is known about the mechanisms that
dominate this enigmatic region other than the magnetic field plays a
key role. The magnetism of the TR can only be detected by polarimetric
measurements of a few ultraviolet (UV) spectral lines, the Lyα line
of neutral hydrogen at 121.6 nm (the strongest line of the solar UV
spectrum) being of particular interest given its sensitivity to the
Hanle effect (the magnetic-field-induced modification of the scattering
line polarization). We report the discovery of linear polarization
produced by scattering processes in the Lyα line, obtained with
the Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) rocket
experiment. The Stokes profiles observed by CLASP in quiet regions of
the solar disk show that the Q/I and U/I linear polarization signals are
of the order of 0.1% in the line core and up to a few percent in the
nearby wings, and that both have conspicuous spatial variations with
scales of ∼10 arcsec. These observations help constrain theoretical
models of the chromosphere-corona TR and extrapolations of the
magnetic field from photospheric magnetograms. In fact, the observed
spatial variation from disk to limb of polarization at the line core
and wings already challenge the predictions from three-dimensional
magnetohydrodynamical models of the upper solar chromosphere.
Title: High-Reflectivity Coatings for a Vacuum Ultraviolet
Spectropolarimeter
Authors: Narukage, Noriyuki; Kubo, Masahito; Ishikawa, Ryohko;
Ishikawa, Shin-nosuke; Katsukawa, Yukio; Kobiki, Toshihiko; Giono,
Gabriel; Kano, Ryouhei; Bando, Takamasa; Tsuneta, Saku; Auchère,
Frédéric; Kobayashi, Ken; Winebarger, Amy; McCandless, Jim; Chen,
Jianrong; Choi, Joanne
Bibcode: 2017SoPh..292...40N
Altcode:
Precise polarization measurements in the vacuum ultraviolet (VUV)
region are expected to be a new tool for inferring the magnetic fields
in the upper atmosphere of the Sun. High-reflectivity coatings are key
elements to achieving high-throughput optics for precise polarization
measurements. We fabricated three types of high-reflectivity coatings
for a solar spectropolarimeter in the hydrogen Lyman-α (Lyα ; 121.567
nm) region and evaluated their performance. The first high-reflectivity
mirror coating offers a reflectivity of more than 80 % in Lyα
optics. The second is a reflective narrow-band filter coating that has
a peak reflectivity of 57 % in Lyα , whereas its reflectivity in the
visible light range is lower than 1/10 of the peak reflectivity (∼5
% on average). This coating can be used to easily realize a visible
light rejection system, which is indispensable for a solar telescope,
while maintaining high throughput in the Lyα line. The third is a
high-efficiency reflective polarizing coating that almost exclusively
reflects an s-polarized beam at its Brewster angle of 68° with a
reflectivity of 55 %. This coating achieves both high polarizing power
and high throughput. These coatings contributed to the high-throughput
solar VUV spectropolarimeter called the Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP), which was launched on 3 September, 2015.
Title: Polarization Calibration of the Chromospheric Lyman-Alpha
SpectroPolarimeter for a 0.1 % Polarization Sensitivity in the VUV
Range. Part I: Pre-flight Calibration
Authors: Giono, G.; Ishikawa, R.; Narukage, N.; Kano, R.; Katsukawa,
Y.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.;
Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.
Bibcode: 2016SoPh..291.3831G
Altcode: 2016SoPh..tmp..177G
The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP) is a sounding
rocket experiment designed to measure for the first time the linear
polarization of the hydrogen Lyman-α line (121.6 nm) and requires
a 0.1 % polarization sensitivity, which is unprecedented for a
spectropolarimeter in the vacuum UV (VUV) spectral range.
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: Discovery of Ubiquitous Fast-Propagating Intensity Disturbances
by the Chromospheric Lyman Alpha Spectropolarimeter (CLASP)
Authors: Kubo, M.; Katsukawa, Y.; Suematsu, Y.; Kano, R.; Bando,
T.; Narukage, N.; Ishikawa, R.; Hara, H.; Giono, G.; Tsuneta, S.;
Ishikawa, S.; Shimizu, T.; Sakao, T.; Winebarger, A.; Kobayashi, K.;
Cirtain, J.; Champey, P.; Auchère, F.; Trujillo Bueno, J.; Asensio
Ramos, A.; Štěpán, J.; Belluzzi, L.; Manso Sainz, R.; De Pontieu,
B.; Ichimoto, K.; Carlsson, M.; Casini, R.; Goto, M.
Bibcode: 2016ApJ...832..141K
Altcode:
High-cadence observations by the slit-jaw (SJ) optics system of the
sounding rocket experiment known as the Chromospheric Lyman Alpha
Spectropolarimeter (CLASP) reveal ubiquitous intensity disturbances
that recurrently propagate in either the chromosphere or the transition
region or both at a speed much higher than the speed of sound. The
CLASP/SJ instrument provides a time series of two-dimensional images
taken with broadband filters centered on the Lyα line at a 0.6 s
cadence. The multiple fast-propagating intensity disturbances appear in
the quiet Sun and in an active region, and they are clearly detected in
at least 20 areas in a field of view of 527″ × 527″ during the 5
minute observing time. The apparent speeds of the intensity disturbances
range from 150 to 350 km s-1, and they are comparable
to the local Alfvén speed in the transition region. The intensity
disturbances tend to propagate along bright elongated structures away
from areas with strong photospheric magnetic fields. This suggests
that the observed fast-propagating intensity disturbances are related
to the magnetic canopy structures. The maximum distance traveled by
the intensity disturbances is about 10″, and the widths are a few
arcseconds, which are almost determined by a pixel size of 1.″03. The
timescale of each intensity pulse is shorter than 30 s. One possible
explanation for the fast-propagating intensity disturbances observed
by CLASP is magnetohydrodynamic fast-mode waves.
Title: Quiet-sun and non-flaring active region measurements from
the FOXSI-2 sounding rocket
Authors: Buitrago-Casas, J. C.; Glesener, L.; Christe, S.; Ishikawa,
S. N.; Narukage, N.; Krucker, S.; Bale, S. D.
Bibcode: 2016AGUFMSH13A2280B
Altcode:
Solar hard X-ray (HXR) emissions are a cornerstone for understanding
particle acceleration and energy release in the corona. These
phenomena are present at different size scales and intensities, from
large eruptive events down to the smallest flares. The presence of
HXRs in small, unresolved flares would provide direct evidence of
small reconnection events, i.e. nano-flares, that are thought to
be be important for the unsolved coronal heating problem. Currently
operating solar-dedicated instruments that observe HXRs from the Sun
do not have the dynamic range, nor the sensitivity, crucial to observe
the faintest solar HXRs. The Focusing Optics X-ray Solar Imager (FOXSI)
sounding rocket payload is a novel experiment that develops and applies
direct focusing optics coupled with semiconductor detectors to observe
faint HXRs from the Sun. The FOXSI rocket has successfully completed
two flights, observing areas of the quiet-Sun, active regions and
micro-flares. We present recent data analysis to test the presence of
hot plasma in and outside of active regions observed during the two
flights, focusing on the differential emission measure distribution
of the non-flaring corona.
Title: Optical alignment of the Chromospheric Lyman-Alpha
Spectro-Polarimeter using sophisticated methods to minimize activities
under vacuum
Authors: Giono, G.; Katsukawa, Y.; Ishikawa, R.; Narukage, N.;
Kano, R.; Kubo, M.; Ishikawa, S.; Bando, T.; Hara, H.; Suematsu, Y.;
Winebarger, A.; Kobayashi, K.; Auchère, F.; Trujillo Bueno, J.
Bibcode: 2016SPIE.9905E..3DG
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
sounding-rocket instrument developed at the National Astronomical
Observatory of Japan (NAOJ) as a part of an international
collaboration. The instrument main scientific goal is to achieve
polarization measurement of the Lyman-α line at 121.56 nm emitted from
the solar upper-chromosphere and transition region with an unprecedented
0.1% accuracy. The optics are composed of a Cassegrain telescope
coated with a "cold mirror" coating optimized for UV reflection and
a dual-channel spectrograph allowing for simultaneous observation of
the two orthogonal states of polarization. Although the polarization
sensitivity is the most important aspect of the instrument, the spatial
and spectral resolutions of the instrument are also crucial to observe
the chromospheric features and resolve the Ly-α profiles. A precise
alignment of the optics is required to ensure the resolutions, but
experiments under vacuum conditions are needed since Ly-α is absorbed
by air, making the alignment experiments difficult. To bypass this
issue, we developed methods to align the telescope and the spectrograph
separately in visible light. We explain these methods and present
the results for the optical alignment of the CLASP telescope and
spectrograph. We then discuss the combined performances of both parts
to derive the expected resolutions of the instrument, and compare them
with the flight observations performed on September 3rd 2015.
Title: Chromospheric LAyer SpectroPolarimeter (CLASP2)
Authors: Narukage, Noriyuki; McKenzie, David E.; Ishikawa, Ryoko;
Trujillo-Bueno, Javier; De Pontieu, Bart; Kubo, Masahito; Ishikawa,
Shin-nosuke; Kano, Ryouhei; Suematsu, Yoshinori; Yoshida, Masaki;
Rachmeler, Laurel A.; Kobayashi, Ken; Cirtain, Jonathan W.; Winebarger,
Amy R.; Asensio Ramos, Andres; del Pino Aleman, Tanausu; Štępán,
Jiri; Belluzzi, Luca; Larruquert, Juan Ignacio; Auchère, Frédéric;
Leenaarts, Jorrit; Carlsson, Mattias J. L.
Bibcode: 2016SPIE.9905E..08N
Altcode:
The sounding rocket Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) was launched on September 3rd, 2015, and successfully detected
(with a polarization accuracy of 0.1 %) the linear polarization signals
(Stokes Q and U) that scattering processes were predicted to produce
in the hydrogen Lyman-alpha line (Lyα 121.567 nm). Via the Hanle
effect, this unique data set may provide novel information about the
magnetic structure and energetics in the upper solar chromosphere. The
CLASP instrument was safely recovered without any damage and we have
recently proposed to dedicate its second flight to observe the four
Stokes profiles in the spectral region of the Mg II h and k lines
around 280 nm; in these lines the polarization signals result from
scattering processes and the Hanle and Zeeman effects. Here we describe
the modifications needed to develop this new instrument called the
"Chromospheric LAyer SpectroPolarimeter" (CLASP2).
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: Spectro-polarimetric observation in UV with CLASP to probe
the chromosphere and transition region
Authors: Kano, Ryouhei; Ishikawa, Ryohko; Winebarger, Amy R.; Auchère,
Frédéric; Trujillo Bueno, Javier; Narukage, Noriyuki; Kobayashi,
Ken; Bando, Takamasa; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
Shin-Nosuke; Giono, Gabriel; Hara, Hirohisa; Suematsu, Yoshinori;
Shimizu, Toshifumi; Sakao, Taro; Tsuneta, Saku; Ichimoto, Kiyoshi;
Goto, Motoshi; Cirtain, Jonathan W.; De Pontieu, Bart; Casini, Roberto;
Manso Sainz, Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi,
Luca; Carlsson, Mats
Bibcode: 2016SPD....4710107K
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a NASA
sounding-rocket experiment that was performed in White Sands in
the US on September 3, 2015. During its 5-minute ballistic flight,
CLASP successfully made the first spectro-polarimetric observation in
the Lyman-alpha line (121.57 nm) originating in the chromosphere and
transition region. Since the Lyman-alpha polarization is sensitive
to magnetic field of 10-100 G by the Hanle effect, we aim to infer
the magnetic field information in such upper solar atmosphere with
this experiment.The obtained CLASP data showed that the Lyman-alpha
scattering polarization is about a few percent in the wings and
the order of 0.1% in the core near the solar limb, as it had been
theoretically predicted, and that both polarization signals have a
conspicuous spatio-temporal variability. CLASP also observed another
upper-chromospheric line, Si III (120.65 nm), whose critical field
strength for the Hanle effect is 290 G, and showed a measurable
scattering polarization of a few % in this line. The polarization
properties of the Si III line could facilitate the interpretation of
the scattering polarization observed in the Lyman-alpha line.In this
presentation, we would like to show how the upper chromosphere and
transition region are seen in the polarization of these UV lines and
discuss the possible source of these complicated polarization signals.
Title: Development of precision Wolter mirrors for future solar
x-ray observations
Authors: Sakao, Taro; Matsuyama, Satoshi; Kime, Ayumi; Goto, Takumi;
Nishihara, Akihiko; Nakamori, Hiroki; Yamauchi, Kazuto; Kohmura,
Yoshiki; Miyake, Akira; Hashizume, Hirokazu; Maezawa, Tadakazu;
Suematsu, Yoshinori; Narukage, Noriyuki
Bibcode: 2015SPIE.9603E..0US
Altcode:
High resolution imagery of the solar X-ray corona provides a
crucial key to understand dynamics and heating processes of plasma
particles there. However, X-ray imagery of the Sun with sub-arcsecond
resolution has yet to be conducted due to severe technical difficulty in
fabricating precision Wolter mirrors. For future X-ray observations of
the Sun's corona, we are attempting to realize precision Wolter mirrors
with sub-arcsecond resolution by adopting advanced surface polish and
metrology methods based on nano-technology to sector mirrors which
consist of a portion of an entire annulus. Following fabrication
of the first engineering mirror and subsequent evaluation on the
X-ray focusing performance in 2013, the second engineering mirror
was made with improvements in both precision polish and metrology
introduced. Measurement of focusing performance on the second mirror
at SPring-8 synchrotron facility with 8 keV X-rays has demonstrated
that the FWHM size of the PSF core reached down to 0.2" while its HPD
(Half Power Diameter) size remained at ~3" due to the presence of
small-angle scatter just outside of the core. Also, there was notable
difference in the focal length between sagittal and meridional focusing
which could have been caused by an error in the sag in the meridional
direction of <10 nm in the mirror area. Further improvements to
overcome these issues have been planned for the next engineering mirror.
Title: CLASP: A UV Spectropolarimeter on a Sounding Rocket for
Probing theChromosphere-Corona Transition Regio
Authors: Ishikawa, Ryohko; Kano, Ryouhei; Winebarger, Amy; Auchere,
Frederic; Trujillo Bueno, Javier; Bando, Takamasa; Narukage,
Noriyuki; Kobayashi, Ken; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
Shin-nosuke; Giono, Gabriel; Tsuneta, Saku; Hara, Hirohisa; Suematsu,
Yoshinori; Shimizu, Toshifumi; Sakao, Taro; Ichimoto, Kiyoshi;
Cirtain, Jonathan; De Pontieu, Bart; Casini, Roberto; Manso Sainz,
Rafael; Asensio Ramos, Andres; Stepan, Jiri; Belluzzi, Luca
Bibcode: 2015IAUGA..2254536I
Altcode:
The wish to understand the energetic phenomena of the outer solar
atmosphere makes it increasingly important to achieve quantitative
information on the magnetic field in the chromosphere-corona
transition region. To this end, we need to measure and model the
linear polarization produced by scattering processes and the Hanle
effect in strong UV resonance lines, such as the hydrogen Lyman-alpha
line. A team consisting of Japan, USA, Spain, France, and Norway has
been developing a sounding rocket experiment called the Chromospheric
Lyman-alpha Spectro-Polarimeter (CLASP). The aim is to detect the
scattering polarization produced by anisotropic radiation pumping in
the hydrogen Lyman-alpha line (121.6 nm), and via the Hanle effect to
try to constrain the magnetic field vector in the upper chromosphere
and transition region. In this talk, we will present an overview
of our CLASP mission, its scientific objectives, ground tests made,
and the latest information on the launch planned for the Summer of 2015.
Title: Strategy for Realizing High-Precision VUV Spectro-Polarimeter
Authors: Ishikawa, R.; Narukage, N.; Kubo, M.; Ishikawa, S.; Kano,
R.; Tsuneta, S.
Bibcode: 2014SoPh..289.4727I
Altcode: 2014SoPh..tmp..116I
Spectro-polarimetric observations in the vacuum ultraviolet (VUV)
range are currently the only means to measure magnetic fields in the
upper chromosphere and transition region of the solar atmosphere. The
Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) aims to measure
linear polarization at the hydrogen Lyman-α line (121.6 nm). This
measurement requires a polarization sensitivity better than 0.1 %,
which is unprecedented in the VUV range. We here present a strategy with
which to realize such high-precision spectro-polarimetry. This involves
the optimization of instrument design, testing of optical components,
extensive analyses of polarization errors, polarization calibration
of the instrument, and calibration with onboard data. We expect that
this strategy will aid the development of other advanced high-precision
polarimeters in the UV as well as in other wavelength ranges.
Title: Precision VUV Spectro-Polarimetry for Solar Chromospheric
Magnetic Field Measurements
Authors: Ishikawa, R.; Bando, T.; Hara, H.; Ishikawa, S.; Kano, R.;
Kubo, M.; Katsukawa, Y.; Kobiki, T.; Narukage, N.; Suematsu, Y.;
Tsuneta, S.; Aoki, K.; Miyagawa, K.; Ichimoto, K.; Kobayashi, K.;
Auchère, F.; Clasp Team
Bibcode: 2014ASPC..489..319I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV
spectro-polarimeter optimized for measuring the linear polarization
of the Lyman-α line (121.6 nm) to be launched in 2015 with NASA's
sounding rocket (Ishikawa et al. 2011; Narukage et al. 2011; Kano et
al. 2012; Kobayashi et al. 2012). With this experiment, we aim to (1)
observe the scattering polarization in the Lyman-α line, (2) detect
the Hanle effect, and (3) assess the magnetic fields in the upper
chromosphere and transition region for the first time. The polarization
measurement error consists of scale error δ a (error in amplitude
of linear polarization), azimuth error Δφ (error in the direction
of linear polarization), and spurious polarization ɛ (false linear
polarization signals). The error ɛ should be suppressed below 0.1%
in the Lyman-α core (121.567 nm ±0.02 nm), and 0.5% in the Lyman-α
wing (121.567 nm ±0.05 nm), based on our scientific requirements shown
in Table 2 of Kubo et al. (2014). From scientific justification, we
adopt Δ φ<2° and δ a<10% as the instrument requirements. The
spectro-polarimeter features a continuously rotating MgF2
waveplate (Ishikawa et al. 2013), a dual-beam spectrograph with a
spherical grating working also as a beam splitter, and two polarization
analyzers (Bridou et al. 2011), which are mounted at 90 degree from
each other to measure two orthogonal polarization simultaneously. For
the optical layout of the CLASP instrument, see Figure 3 in Kubo et
al. (2014). Considering the continuous rotation of the half-waveplate,
the modulation efficiency is 0.64 both for Stokes Q and U. All the raw
data are returned and demodulation (successive addition or subtraction
of images) is done on the ground. We control the CLASP polarization
performance in the following three steps. First, we evaluate the
throughput and polarization properties of each optical component in
the Lyman-α line, using the Ultraviolet Synchrotron ORbital Radiation
Facility (UVSOR) at the Institute for Molecular Science. The second
step is polarization calibration of the spectro-polarimeter after
alignment. Since the spurious polarization caused by the axisymmetric
telescope is estimated to be negligibly small because of the symmetry
(Ishikawa et al. 2014), we do not perform end-to-end polarization
calibration. As the final step, before the scientific observation near
the limb, we make a short observation at the Sun center and verify
the polarization sensitivity, because the scattering polarization
is expected to be close to zero at the Sun center due to symmetric
geometry. In order to clarify whether we will be able to achieve the
required polarization sensitivity and accuracy via these steps, we
exercise polarization error budget, by investigating all the possible
causes and their magnitudes of polarization errors, all of which are not
necessarily verified by the polarization calibration. Based on these
error budgets, we conclude that a polarization sensitivity of 0.1% in
the line core, δ a<10% and Δ φ<2° can be achieved combined
with the polarization calibration of the spectro-polarimeter and the
onboard calibration at the Sun center(refer to Ishikawa et al. 2014,
for the detail). We are currently conducting verification tests
of the flight components and development of the UV light source for
the polarization calibration. From 2014 spring, we will begin the
integration, alignment, and calibration. We will update the error
budgets throughout the course of these tests.
Title: A Sounding Rocket Experiment for the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP)
Authors: Kubo, M.; Kano, R.; Kobayashi, K.; Bando, T.; Narukage, N.;
Ishikawa, R.; Tsuneta, S.; Katsukawa, Y.; Ishikawa, S.; Suematsu, Y.;
Hara, H.; Shimizu, T.; Sakao, T.; Ichimoto, K.; Goto, M.; Holloway,
T.; Winebarger, A.; Cirtain, J.; De Pontieu, B.; Casini, R.; Auchère,
F.; Trujillo Bueno, J.; Manso Sainz, R.; Belluzzi, L.; Asensio Ramos,
A.; Štěpán, J.; Carlsson, M.
Bibcode: 2014ASPC..489..307K
Altcode:
A sounding-rocket experiment called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is presently under development to measure
the linear polarization profiles in the hydrogen Lyman-alpha (Lyα)
line at 121.567 nm. CLASP is a vacuum-UV (VUV) spectropolarimeter to aim
for first detection of the linear polarizations caused by scattering
processes and the Hanle effect in the Lyα line with high accuracy
(0.1%). This is a fist step for exploration of magnetic fields in
the upper chromosphere and transition region of the Sun. Accurate
measurements of the linear polarization signals caused by scattering
processes and the Hanle effect in strong UV lines like Lyα are
essential to explore with future solar telescopes the strength
and structures of the magnetic field in the upper chromosphere and
transition region of the Sun. The CLASP proposal has been accepted by
NASA in 2012, and the flight is planned in 2015.
Title: Current progress of optical alignment procedure of CLASP's
Lyman-alpha polarimetry instrument
Authors: Giono, G.; Ishikawa, R.; Katsukawa, Y.; Bando, T.; Kano, R.;
Suematsu, Y.; Narukage, N.; Sakao, Taro; Kobayashi, K.; Auchère, F.
Bibcode: 2014SPIE.9144E..3EG
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
sounding-rocket instrument currently under development at the
National Astronomical Observatory of Japan (NAOJ) as a part of an
international collaboration. CLASP's optics are composed of a Cassegrain
telescope and a spectro-polarimeter which are designed to achieve an
unprecedentedly accurate polarization measurement of the Ly-α line
at 121.6nm emitted from the solar upper-chromosphere and transition
region. CLASP's first flight is scheduled for August 2015. Reaching
such accuracy requires a careful alignment of the optical elements
to optimize the image quality at 121.6 nm. However Ly-α is absorbed
by air and therefore the optics alignment has to be done under vacuum
condition which makes any experiment difficult. To bypass this issue,
we proposed to align the telescope and the spectrograph separately
in visible light. Hence we present our alignment procedure for both
telescope and spectro-polarimeter. We will explain details about the
telescope preliminary alignment before mirrors coating, which was done
in April 2014, present the telescope combined optical performance
and compare them to CLASP tolerance. Then we will present details
about an experiment designed to confirm our alignment procedure for
the CLASP spectro-polarimeter. We will discuss the resulting image
quality achieved during this experiment and the lessons learned.
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: 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: Within the International Collaboration CHAIN: a Summary of
Events Observed with Flare Monitoring Telescope (FMT) in Peru
Authors: Ishitsuka, J.; Asai, A.; Morita, S.; Terrazas, R.; Cabezas,
D.; Gutierrez, V.; Martinez, L.; Buleje, Y.; Loayza, R.; Nakamura,
N.; Takasao, S.; Yoshinaga, Y.; Hillier, A.; Otsuji, K.; Shibata, K.;
Ishitsuka, M.; Ueno, S.; Kitai, R.; Ishii, T.; Ichimoto, K.; Nagata,
S.; Narukage, N.
Bibcode: 2014SunGe...9...85I
Altcode:
In 2008 we inaugurated the new Solar Observatory in collaboration with
Faculty of Sciences of San Luis Gonzaga de Ica National University,
300 km south of Lima. In March of 2010 a Flare Monitoring Telescope
of Hida Observatory of Kyoto University arrived to Ica, part of CHAIN
Project (Continuous H-alpha Imaging Network). In October of the same
year we hosted the First FMT Workshop in Ica, then in July of 2011 the
Second FMT Workshop was opened. Since that we are focused on two events
registered by FMT in Peru to publish results. FMT is a good tool to
introduce young people from universities into scientific knowledge;
it is good also for education in Solar Physics and outreach. Details
of this successful collaboration will be explained in this presentation.
Title: Chromospheric Lyman-alpha spectro-polarimeter (CLASP)
Authors: Kano, Ryouhei; Katsukawa, Yukio; Kubo, Masahito; Auchere,
Frederic; Ishikawa, Ryohko; Kobayashi, Ken; Narukage, Noriyuki;
Trujillo Bueno, Javier; Bando, Takamasa; Ishikawa, Shin-nosuke
Bibcode: 2014cosp...40E1383K
Altcode:
In the solar chromosphere, magneto-hydrodynamic waves and super-sonic
jets ubiquitously happen as revealed by the Japanese solar satellite
Hinode. Now, we understand that the solar chromosphere is not a simple
intermediate layer smoothly connecting the photosphere and corona,
but a site where those dynamics may play an important role in the
chromospheric and coronal heating. Such discoveries imply that the
next frontier in solar physics lies in simultaneous observations
between the dynamics and magnetic structures in the chromosphere and
transition region, where the gas-dominant photosphere changes to the
magnetic-dominant corona. Therefore, we promote the Chromospheric
Lyman-Alpha SpectroPolarimeter (CLASP), which is a NASA's sounding
rocket experiment scheduled in 2015 for aiming to infer the magnetic
field information in the solar chromosphere and transition region. CLASP
makes precise measurement (0.1%) of the polarization profile of the
Lyman-alpha line, and aims to make the first ever measurement of the
Hanle effect polarization caused by magnetic fields in the upper solar
atmosphere. It is also a pathfinder to establish a new measurement
tool for chromospheric and transition-region magnetic fields, and to
make progress on chromospheric studies in future missions.
Title: UV spectropolarimeter design for precise polarization
measurement and its application to the CLASP for exploration of
magnetic fields in solar atmosphere
Authors: Narukage, Noriyuki; Katsukawa, Yukio; Hara, Hirohisa; Kubo,
Masahito; Auchere, Frederic; Ishikawa, Ryohko; Kano, Ryouhei; Bando,
Takamasa; Ishikawa, Shin-nosuke; Suematsu, Yoshinori; Tsuneta, Saku
Bibcode: 2014cosp...40E2232N
Altcode:
In order to measure the magnetic field in the region where the
hot plasma from 10 (4) K to 10 (6) K is occupied, e.g., for solar
atmosphere, the polarimetric measurements in ultra violet (UV)
with 0.1% accuracy are required. In this paper, we propose a new
UV spectropolarimeter design with 0.1% sensitivity in polarization
measurement. This spectropolarimeter has two devices for the 0.1%
accuracy. First, all optical components except the waveplate are the
reflective type ones that can be equipped with the high reflectivity
coating for the high throughput. Secondly, it equips the optically
symmetric dual channels to measure the orthogonal linear polarization
state simultaneously, using a concave diffraction grating as both the
spectral dispersion element and the beam splitter. These two devices
make the spurious polarizations caused by the photon noise, by the
intensity variation of the observation target, and, by the instrument
itself, enough small to achieve the 0.1% accuracy in polarization
measurement. The spectropolarimeter thus designed is currently under
fabrication for the sounding rocket project of Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP) that aims at the direct measurement of the
magnetic fields in solar atmosphere with Lyman-alpha line (121.6 nm)
for the first time.
Title: Chromospheric Lyman Alpha SpectroPolarimeter: CLASP
Authors: Kobayashi, Ken; Kano, R.; Trujillo Bueno, J.; Winebarger,
A. R.; Cirtain, J. W.; Bando, T.; De Pontieu, B.; Ishikawa, R.;
Katsukawa, Y.; Kubo, M.; Narukage, N.; Sakao, T.; Tsuneta, S.;
Auchère, F.; Asensio Ramos, A.; Belluzzi, L.; Carlsson, M.; Casini,
R.; Hara, H.; Ichimoto, K.; Manso Sainz, R.; Shimizu, T.; Stepan,
J.; Suematsu, Y.; Holloway, T.
Bibcode: 2013SPD....44..142K
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a VUV
spectropolarimeter optimized for measuring the linear polarization of
the Lyman-alpha line (121.6 nm). The Lyman-alpha line is predicted to
show linear polarization caused by atomic scattering in the chromosphere
and modified by the magnetic field through the Hanle effect. The
Hanle effect is sensitive to weaker magnetic fields than Zeeman
effect, and is not canceled by opposing fields, making it sensitive
to tangled or unresolved magnetic field structures. These factors make
the Hanle effect a valuable tool for probing the magnetic field in the
chromosphere above the quiet sun. To meet this goal, CLASP is designed
to measure linear polarization with 0.1% polarization sensitivity
at 0.01 nm spectral resolution and 10" spatial resolution. CLASP is
scheduled to be launched in 2015.
Title: 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: Chromospheric Lyman-alpha spectro-polarimeter (CLASP)
Authors: Kano, Ryouhei; Bando, Takamasa; Narukage, Noriyuki; Ishikawa,
Ryoko; Tsuneta, Saku; Katsukawa, Yukio; Kubo, Masahito; Ishikawa,
Shin-nosuke; Hara, Hirohisa; Shimizu, Toshifumi; Suematsu, Yoshinori;
Ichimoto, Kiyoshi; Sakao, Taro; Goto, Motoshi; Kato, Yoshiaki; Imada,
Shinsuke; Kobayashi, Ken; Holloway, Todd; Winebarger, Amy; Cirtain,
Jonathan; De Pontieu, Bart; Casini, Roberto; Trujillo Bueno, Javier;
Štepán, Jiří; Manso Sainz, Rafael; Belluzzi, Luca; Asensio Ramos,
Andres; Auchère, Frédéric; Carlsson, Mats
Bibcode: 2012SPIE.8443E..4FK
Altcode:
One of the biggest challenges in heliophysics is to decipher the
magnetic structure of the solar chromosphere. The importance of
measuring the chromospheric magnetic field is due to both the key role
the chromosphere plays in energizing and structuring the outer solar
atmosphere and the inability of extrapolation of photospheric fields to
adequately describe this key boundary region. Over the last few years,
significant progress has been made in the spectral line formation
of UV lines as well as the MHD modeling of the solar atmosphere. It
is found that the Hanle effect in the Lyman-alpha line (121.567 nm)
is a most promising diagnostic tool for weaker magnetic fields in
the chromosphere and transition region. Based on this groundbreaking
research, we propose the Chromospheric Lyman-Alpha Spectro-Polarimeter
(CLASP) to NASA as a sounding rocket experiment, for making the first
measurement of the linear polarization produced by scattering processes
and the Hanle effect in the Lyman-alpha line (121.567 nm), and making
the first exploration of the magnetic field in the upper chromosphere
and transition region of the Sun. The CLASP instrument consists
of a Cassegrain telescope, a rotating 1/2-wave plate, a dual-beam
spectrograph assembly with a grating working as a beam splitter, and
an identical pair of reflective polarization analyzers each equipped
with a CCD camera. We propose to launch CLASP in December 2014.
Title: The x-ray/EUV telescope for the Solar-C mission: science and
development activities
Authors: Sakao, Taro; Narukage, Noriyuki; Imada, Shinsuke; Suematsu,
Yoshinori; Shimojo, Masumi; Tsuneta, Saku; DeLuca, Edward E.; Watanabe,
Kyoko; Ishikawa, Shin-nosuke
Bibcode: 2012SPIE.8443E..0AS
Altcode:
We report science and development activities of the X-ray/EUV telescope
for the Japanese Solar-C mission whose projected launch around 2019. The
telescope consists of a package of (a) a normal-incidence (NI) EUV
telescope and (b) a grazing-incidence (GI) soft X-ray telescope. The NI
telescope chiefly provides images of low corona (whose temperature 1
MK or even lower) with ultra-high angular resolution (0.2-0.3"/pixel)
in 3 wavelength bands (304, 171, and 94 angstroms). On the other
hand, the GI telescope provides images of the corona with a wide
temperature coverage (1 MK to beyond 10 MK) with the highest-ever
angular resolution (~0.5"/pixel) as a soft X-ray coronal imager. The
set of NI and GI telescopes should provide crucial information for
establishing magnetic and gas-dynamic connection between the corona and
the lower atmosphere of the Sun which is essential for understanding
heating of, and plasma activities in, the corona. Moreover, we attempt
to implement photon-counting capability for the GI telescope with
which imaging-spectroscopy of the X-ray corona will be performed for
the first time, in the energy range from ~0.5 keV up to 10 keV. The
imaging-spectroscopic observations will provide totally-new information
on mechanism(s) for the generation of hot coronal plasmas (heated
beyond a few MK), those for magnetic reconnection, and even generation
of supra-thermal electrons associated with flares. An overview of
instrument outline and science for the X-ray photoncounting telescope
are presented, together with ongoing development activities in Japan
towards soft X-ray photoncounting observations, focusing on high-speed
X-ray CMOS detector and sub-arcsecond-resolution GI mirror.
Title: The Chromospheric Lyman-Alpha SpectroPolarimeter: CLASP
Authors: Kobayashi, K.; Kano, R.; Trujillo-Bueno, J.; Asensio Ramos,
A.; Bando, T.; Belluzzi, L.; Carlsson, M.; De Pontieu, R. C. B.; Hara,
H.; Ichimoto, K.; Ishikawa, R.; Katsukawa, Y.; Kubo, M.; Manso Sainz,
R.; Narukage, N.; Sakao, T.; Stepan, J.; Suematsu, Y.; Tsuneta, S.;
Watanabe, H.; Winebarger, A.
Bibcode: 2012ASPC..456..233K
Altcode:
The magnetic field plays a crucial role in the chromosphere and the
transition region, and our poor empirical knowledge of the magnetic
field in the upper chromosphere and transition region is a major
impediment to advancing the understanding of the solar atmosphere. The
Hanle effect promises to be a valuable alternative to Zeeman effect
as a method of measuring the magnetic field in the chromosphere and
transition region; it is sensitive to weaker magnetic fields, and
also sensitive to tangled, unresolved field structures. CLASP
is a sounding rocket experiment that aims to observe the Hanle effect
polarization of the Lyman α (1215.67Å) line in the solar chromosphere
and transition region, and prove the usefulness of this technique in
placing constraints on the magnetic field strength and orientation
in the low plasma-β region of the solar atmosphere. The Ly-α line
has been chosen because it is a chromospheric/transition-region line,
and because the Hanle effect polarization of this line is predicted to
be sensitive to 10-250 Gauss, encompassing the range of interest. The
CLASP instrument is designed to measure linear polarization in the
Ly-α line with a polarization sensitivity of 0.1%. The instrument is
currently funded for development. The optical design of the instrument
has been finalized, and an extensive series of component-level tests
are underway to validate the design.
Title: Ly-alpha polarimeter design for CLASP rocket experiment
Authors: Kubo, M.; Watanabe, H.; Narukage, N.; Ishikawa, R.; Bando,
T.; Kano, R.; Tsuneta, S.; Kobayashi, K.; Ichimoto, K.; Trujillo Bueno,
J.; Song, D.
Bibcode: 2011AGUFM.P11F1627K
Altcode:
A sounding-rocket program called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is proposed to be launched in the Summer
of 2014. CLASP will observe the upper solar chromosphere in Ly-alpha
(121.567 nm), aiming to detect the linear polarization signal produced
by scattering processes and the Hanle effect for the first time. The
CLASP needs a rotating half-waveplate and a polarization analyzer
working at the Ly-alpha wavelength to measure the linear polarization
signal. We select Magnesium Fluoride (MgF2) as a material of the
optical components because of its birefringent property and high
transparency at UV wavelength. We have confirmed that the reflection
at the Brewster's Angle of MgF2 plate is a good polarization analyzer
for the Ly-alpha line by deriving its ordinary refractive index and
extinction coefficient along the ordinary and extraordinary axes. These
optical parameters are calculated with a least-square fitting in such a
way that the reflectance and transmittance satisfy the Kramers-Kronig
relation. The reflectance and transmittance against oblique incident
angles for the s-polarized and the p-polarized light are measured
using the synchrotron beamline at the Ultraviolet Synchrotron Orbital
Radiation Facility (UVSOR). We have also measured a retardation of
a zeroth-order waveplate made of MgF2. The thickness difference of
the waveplate is 14.57 um.This waveplate works as a half-waveplate at
121.74 nm. From this measurement, we estimate that a waveplate with
the thickness difference of 15.71 um will work as a half-waveplate
at the Ly-alpha wavelength. We have developed a rotating waveplate -
polarization analyzer system called a prototype of CLASP polarimeter,
and input the perfect Stokes Q and U signals. The modulation patterns
that are consistent with the theoretical prediction are successfully
obtained in both cases.
Title: The Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP)j
Authors: Kobayashi, K.; Tsuneta, S.; Trujillo Bueno, J.; Bando, T.;
Belluzzi, L.; Casini, R.; Carlsson, M.; Cirtain, J. W.; De Pontieu,
B.; Hara, H.; Ichimoto, K.; Ishikawa, R.; Kano, R.; Katsukawa, Y.;
Kim, T.; Kubo, M.; Manso Sainz, R.; Narukage, N.; Asensio Ramos,
A.; Robinson, B.; Sakao, T.; Shimizu, T.; Stepan, J.; Suematsu, Y.;
Watanabe, H.; West, E.; Winebarger, A. R.
Bibcode: 2011AGUFM.P14C..05K
Altcode:
We present an overview of the Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP) program. CLASP is a proposed sounding rocket
experiment currently under development as collaboration between Japan,
USA and Spain. The aim is to achieve the first measurement of magnetic
field in the upper chromosphere and transition region of the Sun
through the detection and measurement of Hanle effect polarization
of the Lyman alpha line. The Hanle effect (i.e. the magnetic field
induced modification of the linear polarization due to scattering
processes in spectral lines) is believed to be a powerful tool for
measuring the magnetic field in the upper chromosphere, as it is more
sensitive to weaker magnetic fields than the Zeeman effect, and also
sensitive to magnetic fields tangled at spatial scales too small to be
resolved. The Lyman-alpha (121.567 nm) line has been chosen because
it is a chromospheric/transition-region line, and because the Hanle
effect polarization of the Lyman-alpha line is predicted to be sensitive
to 10-250 Gauss, encompassing the range of interest. Hanle effect is
predicted to be observable as linear polarization or depolarization,
depending on the geometry, with a fractional polarization amplitude
varying between 0.1% and 1% depending on the strength and orientation of
the magnetic field. This quantification of the chromospheric magnetic
field requires a highly sensitive polarization measurement. The
CLASP instrument consists of a large aperture (287 mm) Cassegrain
telescope mated to a polarizing beamsplitter and a matched pair
of grating spectrographs. The polarizing beamsplitter consists
of a continuously rotating waveplate and a linear beamsplitter,
allowing simultaneous measurement of orthogonal polarizations and
in-flight self-calibration. Development of the instrument is underway,
and prototypes of all optical components have been tested using a
synchrotron beamline. The experiment is proposed for flight in 2014.
Title: Photon-counting soft x-ray telescope for the Solar-C mission
Authors: Sakao, Taro; Narukage, Noriyuki; Shimojo, Masumi; Tsuneta,
Saku; Suematsu, Yoshinori; Miyazaki, Satoshi; Imada, Shinsuke;
Nishizuka, Naoto; Watanabe, Kyoko; Dotani, Tadayasu; DeLuca, Edward
E.; Ishikawa, Shin-nosuke
Bibcode: 2011SPIE.8148E..0CS
Altcode: 2011SPIE.8148E..11S
We report instrument outline as well as science of the photon-counting
soft X-ray telescope that we have been studying as a possible scientific
payload for the Japanese Solar-C mission whose projected launch around
2019. Soft X-rays (~1- 10 keV) from the solar corona include rich
information on (1) possible mechanism(s) for heating the bright core of
active regions seen in soft X-rays (namely, the hottest portion in the
non-flaring corona), (2) dynamics and magnetohydrodynamic structures
associated with magnetic reconnection processes ongoing in flares,
and even (3) generation of supra-thermal distributions of coronal
plasmas associated with flares. Nevertheless, imaging-spectroscopic
investigation of the soft X-ray corona has so far remained unexplored
due to difficulty in the instrumentation for achieving this aim. With
the advent of recent remarkable progress in CMOS-APS detector
technology, the photon-counting X-ray telescope will be capable
of, in addition to conventional photon-integration type exposures,
performing imaging-spectroscopic investigation on active regions and
flares, thus providing, for example, detailed temperature information
(beyond the sofar- utilized filter-ratio temperature) at each spatial
point of the observing target. The photon-counting X-ray telescope will
emply a Wolter type I optics with a piece of a segmented mirror whose
focal length 4 meters, combined with a focal-plane CMOS-APS detector
(0.4-0.5"/pixel) whose frame read-out rate required to be as high as
1000 fps.
Title: Ly-alpha polarimeter design for CLASP rocket experiment
Authors: Watanabe, H.; Narukage, N.; Kubo, M.; Ishikawa, R.; Bando, T.;
Kano, R.; Tsuneta, S.; Kobayashi, K.; Ichimoto, K.; Trujillo-Bueno, J.
Bibcode: 2011SPIE.8148E..0TW
Altcode: 2011SPIE.8148E..25W; 2014arXiv1407.4577W
A sounding-rocket program called the Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP) is proposed to be launched in the summer of
2014. CLASP will observe the solar chromosphere in Ly-alpha (121.567
nm), aiming to detect the linear polarization signal produced by
scattering processes and the Hanle effect for the first time. The
polarimeter of CLASP consists of a rotating half-waveplate, a beam
splitter, and a polarization analyzer. Magnesium Fluoride (MgF2) is
used for these optical components, because MgF2 exhibits birefringent
property and high transparency at ultraviolet wavelength. The
development and comprehensive testing program of the optical components
of the polarimeter is underway using the synchrotron beamline at the
Ultraviolet Synchrotron Orbital Radiation Facility (UVSOR). The first
objective is deriving the optical constants of MgF2 by the measurement
of the reflectance and transmittance against oblique incident angles
for the s-polarized and the p-polarized light. The ordinary refractive
index and extinction coefficient along the ordinary and extraordinary
axes are derived with a least-square fitting in such a way that the
reflectance and transmittance satisfy the Kramers-Krönig relation. The
reflection at the Brewster's Angle of MgF2 plate is confirmed to become
a good polarization analyzer at Ly-alpha. The second objective is the
retardation measurement of a zeroth-order waveplate made of MgF2. The
retardation of a waveplate is determined by observing the modulation
amplitude that comes out of a waveplate and a polarization analyzer. We
tested a waveplate with the thickness difference of 14.57 um. The 14.57
um waveplate worked as a half-waveplate at 121.74 nm. We derived that
a waveplate with the thickness difference of 15.71 um will work as a
half-waveplate at Ly-alpha wavelength. We developed a prototype of CLASP
polarimeter using the MgF2 half-waveplate and polarization analyzers,
and succeeded in obtaining the modulation patterns that are consistent
with the theoretical prediction. We confirm that the performance of
the prototype is optimized for measuring linear polarization signal
with the least effect of the crosstalk from the circular polarization.
Title: Overview of Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP)
Authors: Narukage, Noriyuki; Tsuneta, Saku; Bando, Takamasa; Kano,
Ryouhei; Kubo, Masahito; Ishikawa, Ryoko; Hara, Hirohisa; Suematsu,
Yoshinori; Katsukawa, Yukio; Watanabe, Hiroko; Ichimoto, Kiyoshi;
Sakao, Taro; Shimizu, Toshifumi; Kobayashi, Ken; Robinson, Brian; Kim,
Tony; Winebarger, Amy; West, Edward; Cirtain, Jonathan; De Pontieu,
Bart; Casini, Roberto; Trujillo Bueno, Javier; Stepan, Jiri; Manso
Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Carlsson, Mats
Bibcode: 2011SPIE.8148E..0HN
Altcode: 2011SPIE.8148E..16N
The solar chromosphere is an important boundary, through which all of
the plasma, magnetic fields and energy in the corona and solar wind
are supplied. Since the Zeeman splitting is typically smaller than
the Doppler line broadening in the chromosphere and transition region,
it is not effective to explore weak magnetic fields. However, this is
not the case for the Hanle effect, when we have an instrument with
high polarization sensitivity (~ 0.1%). "Chromospheric Lyman- Alpha
SpectroPolarimeter (CLASP)" is the sounding rocket experiment to detect
linear polarization produced by the Hanle effect in Lyman-alpha line
(121.567 nm) and to make the first direct measurement of magnetic
fields in the upper chromosphere and lower transition region. To
achieve the high sensitivity of ~ 0.1% within a rocket flight (5
minutes) in Lyman-alpha line, which is easily absorbed by materials,
we design the optical system mainly with reflections. The CLASP
consists of a classical Cassegrain telescope, a polarimeter and a
spectrometer. The polarimeter consists of a rotating 1/2-wave plate
and two reflecting polarization analyzers. One of the analyzer also
works as a polarization beam splitter to give us two orthogonal linear
polarizations simultaneously. The CLASP is planned to be launched in
2014 summer.
Title: Propagation of Moreton Waves
Authors: Zhang, Yuzong; Kitai, Reizaburo; Narukage, Noriyuki;
Matsumoto, Takuma; Ueno, Satoru; Shibata, Kazunari; Wang, Jingxiu
Bibcode: 2011PASJ...63..685Z
Altcode:
With the Flare-Monitoring Telescope (FMT) and Solar Magnetic Activity
Research Telescope (SMART) at Hida observatory of Kyoto University,
13 events of Moreton waves were captured at Hα center, Hα ±0.5 Å,
and Hα ±0.8 Å wavebands since 1997. With such samples, we have
studied the statistical properties of the propagation of Moreton
waves. Moreton waves were all restricted in sectorial zones with a
mean value of 92°. However, their accompanying EIT waves, observed
simultaneously with SOHO/EIT at extreme-ultraviolet wavelength, were
very isotropic with a quite extended scope of 193°. The average
propagation speeds of the Moreton waves and the corresponding
EIT waves were 664 km s-1 and 205 km s-1,
respectively. Moreton waves propagated either under large-scale
close magnetic flux loops, or firstly in the sectorial region where
two sets of magnetic loops separated from each other and diverged,
and then stopped before the open magnetic flux region. The location
swept by Moreton waves had a relatively weak magnetic field as compared
to the magnetic fields at their sidewalls. The ratio of the magnetic
flux density between the sidewall and the path falls in the range of
1.4 to 3.7 at a height of 0.01 solar radii. Additionally, we roughly
estimated the distribution of the fast magnetosonic speed between the
propagating path and sidewalls in an event on 1997 November 3, and
found a relatively low-fast magnetosonic speed in the path. We also
found that the propagating direction of Moreton waves coincided with
the direction of filament eruption in a few well-observed events. This
favors an interpretation of the ``Piston'' model, although further
studies are necessary for any definitive conclusion.
Title: Imaging Observations of Coronal Magnetic Field by Nobeyama
Radioheliograph
Authors: Shibasaki, K.; Narukage, N.; Yoshimura, K.
Bibcode: 2011ASPC..437..433S
Altcode:
Coronal magnetic field in a post flare arcade of loops above the solar
limb is mapped by the Nobeyama Radioheliograph. Post flare loops are
filled with hot and dense plasma threaded by magnetic field. Thermal
free-free microwave emission from these plasma is bright enough to
carefully measure circular polarization degree. As circular polarization
is the result of gyration of electrons around magnetic field, inversion
of circular polarization degree to magnetic field strength is simple. We
successfully measured the circular polarization degree distribution
at 17 GHz and got a magnetic field map in a post flare arcade of loops
above the solar limb.
Title: A Sounding Rocket Experiment for Spectropolarimetric
Observations with the Lyα Line at 121.6 nm (CLASP)
Authors: Ishikawa, R.; Bando, T.; Fujimura, D.; Hara, H.; Kano,
R.; Kobiki, T.; Narukage, N.; Tsuneta, S.; Ueda, K.; Wantanabe,
H.; Kobayashi, K.; Trujillo Bueno, J.; Manso Sainz, R.; Stepan, J.;
de Pontieu, B.; Carlsson, M.; Casini, R.
Bibcode: 2011ASPC..437..287I
Altcode:
A team consisting of Japan, USA, Spain, and Norway is developing a
high-throughput Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP),
which is proposed to fly with a NASA sounding rocket in 2014. CLASP will
explore the magnetism of the upper solar chromosphere and transition
region via the Hanle effect of the Lyα line for the first
time. This experiment requires spectropolarimetric observations with
high polarimetric sensitivity (∼0.1%) and wavelength resolution
(0.1 Å). The final spatial resolution (slit width) is being discussed
taking into account the required high signal-to-noise ratio. We have
demonstrated the performance of the Lyα polarimeter by
extensively using the Ultraviolet Synchrotron ORbital Radiation Facility
(UVSOR) at the Institute for Molecular Sciences. In this contribution,
we report these measurements at UVSOR together with the current status
of the CLASP project.
Title: Coronal-Temperature-Diagnostic Capability of the Hinode/
X-Ray Telescope Based on Self-Consistent Calibration
Authors: Narukage, N.; Sakao, T.; Kano, R.; Hara, H.; Shimojo, M.;
Bando, T.; Urayama, F.; DeLuca, E.; Golub, L.; Weber, M.; Grigis,
P.; Cirtain, J.; Tsuneta, S.
Bibcode: 2011SoPh..269..169N
Altcode: 2010arXiv1011.2867N; 2011SoPh..tmp....1N
The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray
imager that observes the solar corona with unprecedentedly high angular
resolution (consistent with its 1″ pixel size). XRT has nine X-ray
analysis filters with different temperature responses. One of the most
significant scientific features of this telescope is its capability
of diagnosing coronal temperatures from less than 1 MK to more than
10 MK, which has never been accomplished before. To make full use
of this capability, accurate calibration of the coronal temperature
response of XRT is indispensable and is presented in this article. The
effect of on-orbit contamination is also taken into account in the
calibration. On the basis of our calibration results, we review the
coronal-temperature-diagnostic capability of XRT.
Title: 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: Plasma Outflows in the Corona as Observed With Hinode XRT
Authors: Sakao, T.; Kano, R.; Narukage, N.; Deluca, E. E.; Grigis, P.
Bibcode: 2008AGUFMSH41B1624S
Altcode:
We present imaging observations of plasma outflows in the solar corona
made with X-Ray Telescope (XRT) aboard Hinode satellite. The XRT employs
a back-illuminated CCD as the focal-plane imaging device which enables
us, together with an optimized set of analysis filters, to investigate,
for the first time, dynamic behavior of relatively cool (1-2 MK, say)
plasmas in the corona. The XRT revealed a clear pattern of continuous
outflow of plasmas from the edge of an active region NOAA AR 10942 right
adjacent to a coronal hole. Plasmas of temperature ~1 MK flowed out
with a sub-sonic velocity of typically ~140 km/s along magnetic field
lines that are most likely open towards the interplanetary space. These
outflowing plasmas may constitute a fraction of the (slow) solar
wind. In addition to this discovery, the XRT has so far identified
rich patterns of continuous outflows including those from coronal
hole boundaries and along fan-like field lines rooted inside coronal
holes. XRT observations of such plasma outflows in the corona are
presented and their possible implications to the solar wind discussed.
Title: The Thermal Structures of Solar Corona Revealed with Hinode/XRT
Authors: Narukage, N.; Sakao, T.; Kano, R.
Bibcode: 2008AGUFMSH52A..03N
Altcode:
The solar corona has a wide temperature range from less than 1MK
(1,000,000K) to more than 10MK. The X-ray telescope (XRT) on board
the Hinode satellite has 9 X-ray analysis filters with different
temperature responses making it possible to detect both cool and
hot coronal plasmas. Using the data observed with this telescope,
we successfully derived the coronal temperature and emission measure
around the whole sun, i.e., for not only active regions but also quiet
regions and coronal holes. We also found that coronal structures are
nicely classified using the temperature and emission measure. And the
coronal structures were found to depend on the length of structure
and the heating flux. Furthermore, we calculated the coronal potential
magnetic field using the photospheric magnetic field. To compare the
heating flux estimated with coronal temperature and the calculated
coronal magnetic field might be the great clue to solving the big
coronal heating question: why does the hot 1MK corona stably exist
above the cool 6,000K solar surface? In this talk, we will show some
results of our latest studies about the coronal thermal structures.
Title: Observations and analysis of the April 9, 2008 CME using
STEREO, Hinode TRACE and SoHO data
Authors: Reeves, K. K.; Patsourakos, S.; Stenborg, G.; Miralles, M.;
Deluca, E.; Forbes, T.; Golub, L.; Kasper, J.; Landi, E.; McKenzie,
D.; Narukage, N.; Raymond, J.; Savage, S.; Su, Y.; van Ballegooijen,
A.; Vourlidas, A.; Webb, D.
Bibcode: 2008AGUFMSH12A..04R
Altcode:
On April 9, 2008 a CME originating from an active region behind the limb
was well-observed by STEREO, Hinode, TRACE and SoHO. Several interesting
features connected to this eruption were observed. (1) The interaction
of the CME with open field lines from a nearby coronal hole appeared
to cause an abrupt change in the direction of the CME ejecta. (2) The
prominence material was heated, as evidenced by a change from absorption
to emission in the EUV wavelengths. (3) Because the active region was
behind the limb, the X-Ray Telescope on Hinode was able to take long
enough exposure times to observe a faint current- sheet like structure,
and it was able to monitor the dynamics of the plasma surrounding this
structure. This event is also being studied in the context of activity
that occurred during the Whole Heliosphere Interval (WHI).
Title: Strongly Blueshifted Phenomena Observed with Hinode EIS in
the 2006 December 13 Solar Flare
Authors: Asai, Ayumi; Hara, Hirohisa; Watanabe, Tetsuya; Imada,
Shinsuke; Sakao, Taro; Narukage, Noriyuki; Culhane, J. L.; Doschek,
G. A.
Bibcode: 2008ApJ...685..622A
Altcode: 2008arXiv0805.4468A
We present a detailed examination of strongly blueshifted emission
lines observed with the EUV Imaging Spectrometer on board the Hinode
satellite. We found two kinds of blueshifted phenomenon associated
with the X3.4 flare that occurred on 2006 December 13. One was related
to a plasmoid ejection seen in soft X-rays. It was very bright in all
the lines used for the observations. The other was associated with the
faint arc-shaped ejection seen in soft X-rays. The soft X-ray ejection
is thought to be a magnetohydrodynamic (MHD) fast-mode shock wave. This
is therefore the first spectroscopic observation of an MHD fast-mode
shock wave associated with a flare.
Title: Three Successive and Interacting Shock Waves Generated by a
Solar Flare
Authors: Narukage, Noriyuki; Ishii, Takako T.; Nagata, Shin'ichi;
UeNo, Satoru; Kitai, Reizaburo; Kurokawa, Hiroki; Akioka, Maki;
Shibata, Kazunari
Bibcode: 2008ApJ...684L..45N
Altcode:
We discovered three successive Moreton waves generated by a single solar
flare on 2005 August 3. Although this flare was not special in magnitude
or configuration, Moreton waves (shock waves) successively occurred
three times. Multiple shock waves generated during a single flare have
not been reported before. Furthermore, the faster second-generated
Moreton wave caught up and merged with the slower first-generated
one. This is the first report of shock-shock interaction associated with
a solar flare. The shock-plasma interaction was also detected. When
the third-generated Moreton wave passed through an erupting filament,
the filament was accelerated by the Moreton wave. In this event,
filaments also erupted three times. On the basis of this observation,
we consider that filament eruption is indispensable to the generation
of Moreton waves.
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: Molecular Contamination Assessments on
<i>Hinode</i> X-Ray Telescope
Authors: Urayama, Fumitaka; Bando, Takamasa; Kano, Ryouhei; Hara,
Hirohisa; Narukage, Noriyuki; Sakao, Taro
Bibcode: 2008JSASS..56..536U
Altcode:
The <i>Hinode</i> (Solar-B) was launched by M-V rocket on 22
September 2006 UT. The telemetry data of the <i>Hinode</i>
X-ray Telescope (XRT) showed that the X-ray count rate detected with
the XRT had decreased rapidly since the operational heaters on the
XRT telescope tube were turned on. This is attributed to the fact that
molecular contaminants accumulated onto the CCD with the temperature
of -60ºC resulting in the degradation of the XRT sensitivity. We baked
the CCD at the temperature of 35ºC in order to remove the contaminants
from the CCD surface. However many contaminant spots appeared on the
surface. We found that major contaminant source existed in the telescope
tube, and identified the contaminants as diethylhexyl phthalate (DEHP)
or DEHP-like organics. The mechanisms to yield the contaminant spots
were discussed.
Title: Relation between coronal temperature and magnetic field
Authors: Narukage, Noriyuki; Kano, Ryouhei; Shiota, Daiko; Sakao, Taro
Bibcode: 2008cosp...37.2184N
Altcode: 2008cosp.meet.2184N
The solar corona has a wide temperature range from less than 1MK to
more than 10MK. The X-ray telescope (XRT) on board Hinode satellite
has 9 X-ray analysis filters to observe the almost of whole coronal
plasma. Using the data observed with this telescope, we successfully
derived the coronal temperature around the whole sun. We found that
coronal structures are nicely classified using the temperature and
emission measure. The coronal structures were found to depend on the
length of structure and the heating flux. Furthermore, we calculated
the coronal potential magnetic field in high spatial resolution using
the photospheric magnetic field observed with SOHO/MDI. To compare the
heating flux estimated with coronal temperature and the calculated
coronal magnetic field might be the great clue to solving the big
coronal heating question.
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: Slipping Magnetic Reconnection in Coronal Loops
Authors: Aulanier, Guillaume; Golub, Leon; DeLuca, Edward E.; Cirtain,
Jonathan W.; Kano, Ryouhei; Lundquist, Loraine L.; Narukage, Noriyuki;
Sakao, Taro; Weber, Mark A.
Bibcode: 2007Sci...318.1588A
Altcode:
Magnetic reconnection of solar coronal loops is the main process that
causes solar flares and possibly coronal heating. In the standard
model, magnetic field lines break and reconnect instantaneously at
places where the field mapping is discontinuous. However, another mode
may operate where the magnetic field mapping is continuous but shows
steep gradients: The field lines may slip across each other. Soft
x-ray observations of fast bidirectional motions of coronal loops,
observed by the Hinode spacecraft, support the existence of this
slipping magnetic reconnection regime in the Sun’s corona. This
basic process should be considered when interpreting reconnection,
both on the Sun and in laboratory-based plasma experiments.
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: 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: Hinode Observations of the Onset Stage of a Solar Filament
Eruption
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Berger, Thomas
E.; Bobra, Monica; Davis, John M.; Jibben, Patricia; Kano, Ryohei;
Lundquist, Loraine L.; Myers, D.; Narukage, Noriyuki; Sakao, Taro;
Shibasaki, Kiyoto; Shine, Richard A.; Tarbell, Theodore D.; Weber, Mark
Bibcode: 2007PASJ...59S.823S
Altcode:
We used Hinode X-Ray Telescope (XRT) and Solar Optical Telescope (SOT)
filtergraph (FG) Stokes-V magnetogram observations, to study the
early onset of a solar eruption that includes an erupting filament
that we observe in TRACE EUV images. The filament undergoes a slow
rise for at least 20min prior to its fast eruption and strong soft
X-ray (SXR) flaring; such slow rises have been previously reported,
and the new Hinode data elucidate the physical processes occurring
during this period. XRT images show that during the slow-rise phase,
an SXR sigmoid forms from apparent reconnection low in the sheared core
field traced by the filament, and there is a low-level intensity peak
in both EUV and SXRs during the slow rise. MDI and SOT FG Stokes-V
magnetograms show that the pre-eruption filament is along a neutral
line between opposing-polarity enhanced network cells, and the SOT
magnetograms show that these opposing fields are flowing together
and canceling for at least six hours prior to eruption. From the MDI
data we measured the canceling network fields to be ∼ 40G, and we
estimated that ∼ 1019 Mx of flux canceled during the
five hours prior to eruption; this is only ∼ 5% of the total flux
spanned by the eruption and flare, but apparently its tether-cutting
cancellation was enough to destabilize the sigmoid field holding the
filament and resulted in that field's eruption.
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 the Sheared Magnetic Fields of Two X-Class Flares
Observed by Hinode/XRT
Authors: Su, Yingna; Golub, Leon; van Ballegooijen, Adriaan; Deluca,
Edward E.; Reeves, Kathy K.; Sakao, Taro; Kano, Ryouhei; Narukage,
Noriyuki; Shibasaki Kiyoto
Bibcode: 2007PASJ...59S.785S
Altcode:
We present multi-wavelength observations of the evolution of the sheared
magnetic fields in NOAA Active Region 10930, where two X-class flares
occurred on 2006 December 13 and December 14, respectively. Observations
made with the X-ray Telescope (XRT) and the Solar Optical Telescope
(SOT) aboard Hinode suggest that the gradual formation of the sheared
magnetic fields in this active region is caused by the rotation and
west-to-east motion of an emerging sunspot. In the pre-flare phase
of the two flares, XRT shows several highly sheared X-ray loops in
the core field region, corresponding to a filament seen in the TRACE
EUV observations. XRT observations also show that part of the sheared
core field erupted, and another part of the sheared core field stayed
behind during the flares, which may explain why a large part of the
filament is still seen by TRACE after the flare. About 2-3 hours after
the peak of each flare, the core field becomes visible in XRT again,
and shows a highly sheared inner and less-sheared outer structure. We
also find that the post-flare core field is clearly less sheared than
the pre-flare core field, which is consistent with the idea that the
energy released during the flares is stored in the highly sheared
fields prior to the flare.
Title: An On-Orbit Determination of the On-Axis Point Spread Function
of the Hinode X-Ray Telescope
Authors: Weber, Mark; Deluca, Edward E.; Golub, Leon; Cirtain,
Jonathan; Kano, Ryouhei; Sakao, Taro; Shibasaki, Kiyoto; Narukage,
Noriyuki
Bibcode: 2007PASJ...59S.853W
Altcode:
The Hinode X-ray Telescope provides unprecedented observations of
the solar corona in X-rays, due in part to its fine resolution. The
X-ray point spread function (PSF) was measured before launch at the
NASA X-ray Calibration Facility to have a FWHM of 0.8''. This paper
describes the work to verify the PSF measurements using on-orbit
observations of planetary transits and solar eclipses. Analysis of a
Mercury transit gives a PSF FWHM = 1.0" ± 0.12".
Title: Plans to Observe Flare-Associated Waves with Solar-B
Authors: Narukage, N.
Bibcode: 2007ASPC..369..205N
Altcode:
The textit{Solar-B} satellite has three scientific instruments: the
Solar Optical Telescope (SOT), the X-ray Telescope (XRT) and the EUV
Imaging Spectrograph (EIS). We expect SOT, XRT, and EIS to detect
the origin of Moreton waves, coronal X-ray waves, and line-of-sight
velocity of waves, respectively. In preparation for Solar-B, we examine
the detectable possibility of waves with these telescopes and suggest
methods for observation.
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: Hinode Data Calibration For Precise Image Co-alignment:
XRT vs. SOT
Authors: Shimizu, Toshifumi; DeLuca, E. E.; Lundquist, L.; Sakao,
T.; Kubo, M.; Narukage, N.; Kano, R.; Katsukawa, Y.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Tarbell, T.; Shine, D.; Hinode Team
Bibcode: 2007AAS...210.9417S
Altcode: 2007BAAS...39Q.220S
From late October in 2006, Hinode solar optical telescope (SOT) has
started to produce series of 0.2-0.3 arcsec visible-light images,
revealing dynamical behaviors of solar magnetic fields on the
solar surface. Simultaneously, Hinode X-ray telescope (XRT) has been
providing 1 arcsec resolution X-ray images of the solar corona, giving
the location of heating and dynamics occuring in the corona. Precise
image co-alignment of SOT data on XRT data with sub-arcsec accuracy is
required to provide new information regarding connecting the corona to
the photosphere. This presentation will give an introduction of Hinode
between-telescopes' image co-alignment to SPD participants. For active
region observations with sunspots, sunspots can be used as fiducial to
co-align the data from the two telescopes each other. Satellite jitter
in order of 1 arcsec or less is included in the series of XRT data,
whereas image stabilization system (correlation tracker) removes the
satellite jitter from the series of SOT images. Telescope pointings show
orbital variation in order of a few arcsec, which can be well predicted
from Hinode orbit information. Modeling co-alignment is under study
and it is the only precise method for quiet Sun and limb observations.
Title: 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: Structure and Coronal Activity around Filament Channels
Observed with Hinode XRT And TRACE
Authors: Lundquist, Loraine L.; van Ballegooijen, A. A.; Reeves,
K. K.; Sakao, T.; DeLuca, E. E.; Narukage, N.; Kano, R.
Bibcode: 2007AAS...210.9427L
Altcode: 2007BAAS...39..221L
The combination of multi-wavelength, high resolution, high cadence
data from the Hinode X-Ray Telescope (XRT) and the Transition Region
And Coronal Explorer (TRACE) give an unprecedented view of solar
active region dynamics and coronal topology. We focus on examples of
filament structures observed by TRACE and XRT in December 2006 and
February 2007. Co-alignment of observations in these two instruments
yields a striking picture of the coronal structures, with loops lying
both along and above the filament. Overlying loops exhibit remarkable
dynamics while the filament lies dormant, and numerous x-point and
triple-leg structures undergo repeated brightenings. We also employ
magnetic field data from SOT and from SOLIS to compare a non-linear
force-free model of the coronal magnetic field with the observed loops.
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: 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: Statistical Analysis of Reconnection Inflows in Solar Flares
Observed with SOHO EIT
Authors: Narukage, Noriyuki; Shibata, Kazunari
Bibcode: 2006ApJ...637.1122N
Altcode:
We report observations of reconnection inflows in extreme ultraviolet
(EUV) Fe XII λ195 images with the Extreme Ultraviolet Imaging Telescope
(EIT) on board the Solar and Heliospheric Observatory (SOHO). Yokoyama
and colleagues reported the first example observed on 1999 March 18. We
survey the EIT data from 1996 to 2000 and find six new inflow events. We
measure the inflow velocity vinflow for each event and find
that vinflow is about 2.6-38 km s-1. Furthermore,
using the six EIT inflow events observed simultaneously with Yohkoh SXT
(including the Yokoyama event), we calculate the reconnection rate as
MA≡vinflow/vA=0.001-0.07. It is also
found that the plasmoid ejection and/or coronal mass ejection (CME)
are closely related to the inflow. The velocity of the CME exhibits
a correlation with the inflow velocity.
Title: Magnetic Fields and Intensity Changes in Coronal Dimming
Regions
Authors: Attrill, G. D. R.; Narukage, N.; Shibata, K.; Harra, L. K.
Bibcode: 2005ESASP.596E..11A
Altcode: 2005ccmf.confE..11A
No abstract at ADS
Title: Observations of Flare-Associated Waves with SolarB
Authors: Narukage, N.; Shibata, K.
Bibcode: 2004ASPC..325..389N
Altcode:
In Hα, a flare-associated chromospheric wave (called a Moreton
wave) was discovered in 1960, and after that such waves are
sometimes observed. Uchida (1968, 1974) identified the Moreton
wave as the intersection of a coronal MHD fast-mode shock and the
chromosphere. Recently, the Soft X-ray Telescope (SXT) on board Yohkoh
observed coronal wave-like disturbances (X-ray waves). Narukage et
al. (2002, 2004) showed two X-ray waves are MHD fast-mode shock,
i.e. coronal counterparts of the Moreton waves. The SolarB has
Solar Optical Telescope (SOT), X-Ray Telescope (XRT) and EUV Imaging
Spectrometer (EIS) on board and will be launched in 2006. We expect
SOT, XRT and EIS will detect chromospheric Moreton waves, coronal X-ray
waves and line-of-sight velocity of waves, respectively. In preparation
for SolarB, we examine the detectable possibility of waves with these
telescopes and suggest methods for observation.
Title: Filament Oscillations and Moreton Waves Associated with
EIT Waves
Authors: Okamoto, Takenori J.; Nakai, Hidekazu; Keiyama, Atsushi;
Narukage, Noriyuki; UeNo, Satoru; Kitai, Reizaburo; Kurokawa, Hiroki;
Shibata, Kazunari
Bibcode: 2004ApJ...608.1124O
Altcode:
In this paper we compare EUV Imaging Telescope (EIT) waves with
simultaneous phenomena seen in Hα in order to address the question
of what an EIT wave is. We surveyed the events associated with solar
flares larger than GOES M-class in 1999-2002. The Hα data are taken
with the Flare-monitoring Telescope (FMT) at the Hida Observatory
of Kyoto University. Among 14 simultaneous observations of EIT
waves and Hα, 11 were found to have filament eruptions, three were
associated with Moreton waves, and one was found to have only filament
oscillations. This shows that we cannot see clear wave fronts in
Hα even if EIT waves exist, but that it is possible to recognize
invisible waves by means of filament oscillations. The nature of
filament oscillations and Moreton waves associated with EIT waves is
examined in detail, and it is found that the filament oscillations
were caused by EIT waves.
Title: Moreton waves observed at Hida Observatory
Authors: Narukage, Noriyuki; Eto, Shigeru; Kadota, Miwako; Kitai,
Reizaburo; Kurokawa, Hiroki; Shibata, Kazunari
Bibcode: 2004IAUS..223..367N
Altcode: 2005IAUS..223..367N
Moreton waves are flare-associated waves observed to propagate across
the solar disk in Halpha, especially in the wing of Halpha. The Flare
Monitoring Telescope at Hida Observatory of Kyoto University observed
12 events associated with flare waves (i.e., Moreton waves and/or
filament oscillations) in Halpha from 1997 to 2002. We review our
studies of Moreton waves based on these observations; relation between
EIT wave and Moreton wave (Eto et al. 2002),simultaneous observation
with X-ray wave (Narukage et al. 2002),three dimensional structure of
flare-associated wave (Narukage et al. 2004),relation between Moreton
waves and filament eruptions.
Title: Statistical analysis of reconnection inflows in solar flares
Authors: Narukage, N.; Shibata, K.
Bibcode: 2004cosp...35.3696N
Altcode: 2004cosp.meet.3696N
Solar flare is an explosion on the solar surface and releases huge
energy in a short time. It is widely believed that the energy
is stored in magnetic field and the flare is caused by magnetic
reconnection. Yohkoh, a Japanese solar X-ray satellite launched in 1991,
discovered various evidence of the magnetic reconnection, e.g. cusp
shaped loops, plasmoid ejections, and etc. The reconnection model
has been established at least phenomenologically by Yohkoh. However,
the inflow, which is predicted by the reconnection theory, has not been
discovered, and it remains mystery. In 2000, Yokoyama et al. discovered
such reconnection inflow in a solar flare observed with SOHO/EIT,
but no other observation of reconnection inflow has been reported
until now. The generality of inflow remains doubtful. We surveyed
the reconnection inflow in the full Sun movies taken with SOHO/EIT
and discovered 13 inflows. We measured the line-of-sight velocity of
the inflows using SOHO/EIT images, the angle between magnetic neutral
line and line-of-sight direction in the inflows using SOHO/MDI images,
and the energy release rate of the flares associated with the inflows
using Yohkoh/SXT images. Based on this results, we estimated some
physical quantities of the inflows, e.g. the real inflow velocity and
reconnection rate. This result is conclusive evidence of reconnection
and the clue to the solution of flare mechanism.
Title: Relation between a Moreton Wave and an EIT Wave Observed on
1997 November 4
Authors: Eto, Shigeru; Isobe, Hiroaki; Narukage, Noriyuki; Asai, Ayumi;
Morimoto, Taro; Thompson, Barbara; Yashiro, Seiji; Wang, Tongjiang;
Kitai, Reizaburo; Kurokawa, Hiroki; Shibata, Kazunari
Bibcode: 2002PASJ...54..481E
Altcode:
We consider the relationship between two flare-associated waves,
a chromospheric Moreton wave and a coronal EIT wave, based on an
analysis of an X-class flare event in AR 8100 on 1997 November 4. A
Moreton wave was observed in Hα + 0.8 Å, and Hα - 0.8 Å with the
Flare-Monitoring Telescope (FMT) at the Hida Observatory. An EIT wave
was observed in EUV with the Extreme ultraviolet Imaging Telescope
(EIT) on board SOHO. The propagation speeds of the Moreton wave and
the EIT wave were approximately 715 km s-1 and 202 km
s-1, respectively. The times of visibility for the Moreton
wave did not overlap those of the EIT wave, but the continuation of the
former is indicated by a filament oscillation. Data on the speed and
location clearly show that the Moreton wave differed physically from
the EIT wave in this case. The Moreton wave preceded the EIT wave,
which is inconsistent with an identification of the EIT wave with a
fast-mode MHD shock.
Title: Simultaneous Observation of a Moreton Wave on 1997 November
3 in Hα and Soft X-Rays
Authors: Narukage, N.; Hudson, H. S.; Morimoto, T.; Akiyama, S.;
Kitai, R.; Kurokawa, H.; Shibata, K.
Bibcode: 2002ApJ...572L.109N
Altcode:
We report the observation of a Moreton wave in Hα (line center and
+/-0.8 Å) with the Flare Monitoring Telescope at the Hida Observatory
of Kyoto University at 4:36-4:41 UT on 1997 November 3. The same
region (NOAA Active Region 8100) was simultaneously observed in soft
X-rays with the soft X-ray telescope on board Yohkoh, and a wavelike
disturbance (``X-ray wave'') was also found. The position of the wave
front as well as the direction of propagation of the X-ray wave roughly
agree with those of the Moreton wave. The propagation speeds of the
Moreton wave and the X-ray wave are about 490+/-40 and 630+/-100 km
s-1, respectively. Assuming that the X-ray wave is an MHD
fast-mode shock, we can estimate the propagation speed of the shock, on
the basis of MHD shock theory and the observed soft X-ray intensities
ahead of and behind the X-ray wave front. The estimated fast shock
speed is 400-760 km s-1, which is in rough agreement with
the observed propagation speed of the X-ray wave. The fast-mode Mach
number of the X-ray wave is also estimated to be about 1.15-1.25. These
results suggest that the X-ray wave is a weak MHD fast-mode shock
propagating through the corona and hence is the coronal counterpart
of the Moreton wave.
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: Multi-wavelength Observations of a Moreton Wave on 2000 March 3
Authors: Narukage, N.; Morimoto, T.; Kitai, R.; Kurokawa, H.;
Shibata, K.
Bibcode: 2002aprm.conf..449N
Altcode:
Moreton waves are flare-associated waves observed to propagate across
the solar disk in Hα (Moreton, 1960). Such waves have been identified
as the intersections of a coronal fast-mode shock fronts and the
chromosphere (Uchida, 1968). We report the observation of a Moreton
wave in Hα (line center and ± 0.8 Å) with the Flare Monitoring
Telescope (FMT) at the Hida Observatory of Kyoto University on 2000
March 3. The same region (NOAA 8882) was simultaneously observed in
soft X-rays with the soft X-ray Telescope (SXT) on board Yohkoh, and
a coronal wave-like disturbance (``X-ray wave") was also found. The
region (NOAA 8882) is near the solar limb. Hence the chromospheric
Moreton wave propagated on the solar disk at a speed of 1050 km/s,
whereas the coronal X-ray wave propagated towards the outer corona
at 1300 km/s. We identified the X-ray wave as an MHD fast-mode shock,
i.e. a coronal counterpart of the Moreton wave, using MHD shock theory
and the observed soft X-ray intensities (Narukage et al., 2002). On the
basis of this result, the propagation of these two waves indicates the
3-dimensional structure of the flare-associated shock wave. This event
is the first observation of the 3-d structure of the shock. Moreover, a
type II radio burst and a coronal mass ejection (CME) were also observed
simultaneously. The shock speed given by the type II radio burst is 1150
km/s. The CME propagated at a speed of 800 km/s. A basic component of
CME is a density enhancement, and the shock preceding the CME propagates
roughly 1.5 times faster than the CME, in this case at 1200 km/s.
Title: Multi-Wavelength Observation of A Moreton Wave on November
3, 1997
Authors: Narukage, N.; Shibata, K.; Hudson, H. S.; Eto, S.; Isobe,
H.; Asai, A.; Morimoto, T.; Kozu, H.; Ishii, T. T.; Akiyama, S.;
Kitai, R.; Kurokawa, H.
Bibcode: 2002mwoc.conf..295N
Altcode:
No abstract at ADS
Title: Statistical Study of the Reconnection Rate in Solar Flares
Authors: Isobe, H.; Morimoto, T.; Eto, S.; Narukage, N.; Shibata, K.
Bibcode: 2002mwoc.conf..171I
Altcode:
The soft X-ray telescope (SXT) aboard Yohkoh has established that the
driving mechanism of solar flares is magnetic reconnection. However,
the physics of reconnection has not been clarified. One of the
current puzzles is: what determines the reconnection rateNULL The
reconnection rate is defined as reconnected magnetic flux per unit time
or equivalently the ratio of inflow speed into reconnection point to
Alfven velocity in non-dimension, and is one of the most important
physical quantities in reconnection physics. However, observations
have not yet succeeded to statistically determine the reconnection rate
because direct observation of reconnection inflow and coronal magnetic
field is difficult. In this poster we present a method to determine
the reconnection rate from observational data, which use the following
relations: H = frac B2 4pi vinL2
vinB = vfootBfoot. Here H, L,
vfoot and Bfoot are respectively the flare
heating rate, size of the flare arcade, separation velocity of the two
ribbon, and magnetic field strength of the foot points. Since these four
quantities can be obtained from observational data, the relations above
give the inflow velocity vin and coronal magnetic field B,
and thus the reconnection rate can be determined. Appling this method
to many flare observations, we will determine the reconnection rate
in solar flares statistically. A preliminary result is presented.
Title: Simultaneous observations of Moreton waves in Hα and Soft
X-ray
Authors: Narukage, N.; Hudson, H.; Morimoto, T.; Kitai, R.; Kurokawa,
H.; Shibata, K.
Bibcode: 2002cosp...34E1337N
Altcode: 2002cosp.meetE1337N
Moreton waves are flare-associated waves observed to propagate
across the solar disk in H (Moreton, 1960). Such waves have been
identified as the intersections of a coronal fast-mode shock fronts
and the chromosphere (Uchida, 1967). We report the two observations of
Moreton waves in H (line center and +/- 0.8 A) with the Flare Monitoring
Telescope (FMT) at the Hida Observatory of Kyoto University. The both
events were simultaneously observed in soft X-rays with the Soft X-ray
Telescope (SXT) on board Yohkoh, and wave-like disturbances ("X-ray
wave") were also found. One event occurred in solar-disk on November 3,
1997, the other near solar limb on March 3, 2000. Assuming that the
X-ray waves are the MHD fast shocks, we can estimate the propagation
speeds of the shocks, based on the MHD shock theory and the observed
soft X-ray intensities ahead and behind the X-ray wave fronts. It is
found that the estimated fast shock speeds are in rough agreement with
the observed propagation speeds of the X-ray waves. The fast mode Mach
numbers of the X-ray waves are also estimated. These results suggest
that the X-ray waves are MHD fast shocks propagating through the corona
and hence are the coronal counterparts of the Moreton waves.
Title: Observations of Moreton Waves and EIT Waves
Authors: Shibata, K.; Eto, S.; Narukage, N.; Isobe, H.; Morimoto,
T.; Kozu, H.; Asai, A.; Ishii, T.; Akiyama, S.; Ueno, S.; Kitai, R.;
Kurokawa, H.; Yashiro, S.; Thompson, B. J.; Wang, T.; Hudson, H. S.
Bibcode: 2002mwoc.conf..279S
Altcode:
The Moreton wave is a flare-associated wave observed in H alpha, and
is now established to be a fast mode MHD shock emitted from the flare,
but the physical mechanism to create the wave is still puzzling. On
the other hand, the EIT wave is a newly discovered flare-associated
wave observed in EUV with the Extreme ultraviolet Imaging Telescope
(EIT) aboard SOHO, and in this case, not only its origin but also
its physical property are both puzzling. We study the relationship
of these two flare-associated waves, Moreton waves and EIT waves, by
analyzing 4 events observed on Nov. 3 and 4, 1997, Aug. 8, 1998, and
Mar. 3, 2000 (Narukage et al. 2001). The Moreton waves were observed
in Ha, Ha+0.8A and Ha-0.8A with the Flare Monitoring Telescope (FMT)
at the Hida Observatory of Kyoto University, while the EIT waves were
observed with SOHO/EIT. In the typical case associated with an X-class
flare in AR 8100 on 4 November 1997 (Eto et al. 2001) the propagation
speeds of the Moreton wave and the EIT wave were approximately 780
km/s and 200 km/s respectively. The data on speed and location show
clearly that the Moreton wave differs physically from the EIT wave in
this case. The detailed analyses of the other events (Nov. 3, 1997,
Aug. 8, 1998, and Mar. 3, 2000) will also be presented, with Yohkoh/SXT
data in the lucky case.