Author name code: suematsu
ADS astronomy entries on 2022-09-14
author:"Suematsu, Yoshinori"
------------------------------------------------------------------------
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: 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: Instrumental design of the Solar Observing Satellite:
solar-C_EUVST
Authors: Suematsu, Yoshinori; Shimizu, Toshifumi; Hara, Hirohisa;
Kawate, Tomoko; Katsukawa, Yukio; Ichimoto, Kiyoshi; Imada, Shinsuke
Bibcode: 2021SPIE11852E..3KS
Altcode:
The EUV High-Throughput Spectroscopic Telescope (EUVST) of Solar-C
mission is a revolutionary spectrometer that is designed to provide
high-quality and high cadence spectroscopic data covering a wide
temperature range of the chromosphere to flaring corona to investigate
the energetics and dynamics of the solar atmosphere. The EUVST consists
of only two imaging optical components; a 28-cm clear aperture off-axis
parabolic primary mirror and a two-split ellipsoidal grating without a
blocking filter for visible light before the primary mirror to achieve
unprecedented high spatial and temporal resolution in EUV-UV imaging
spectroscopic observations. For this reason, about 53 W of sunlight
is absorbed by the multilayer coating on the mirror. We present an
instrumental design of the telescope, particularly, primary mirror
assembly which enables slit-scan observations for imaging spectroscopy,
an image stabilizing tip-tilt control, and a focus adjustment on
orbit, together with an optomechanical design of the primary mirror
and its supporting system which gives optically tolerant wavefront
error against a large temperature increase due to an absorption of
visible and IR lights.
Title: Critical Science Plan for the Daniel K. Inouye Solar Telescope
(DKIST)
Authors: Rast, Mark P.; Bello González, Nazaret; Bellot Rubio,
Luis; Cao, Wenda; Cauzzi, Gianna; Deluca, Edward; de Pontieu, Bart;
Fletcher, Lyndsay; Gibson, Sarah E.; Judge, Philip G.; Katsukawa,
Yukio; Kazachenko, Maria D.; Khomenko, Elena; Landi, Enrico; Martínez
Pillet, Valentín; Petrie, Gordon J. D.; Qiu, Jiong; Rachmeler,
Laurel A.; Rempel, Matthias; Schmidt, Wolfgang; Scullion, Eamon; Sun,
Xudong; Welsch, Brian T.; Andretta, Vincenzo; Antolin, Patrick; Ayres,
Thomas R.; Balasubramaniam, K. S.; Ballai, Istvan; Berger, Thomas E.;
Bradshaw, Stephen J.; Campbell, Ryan J.; Carlsson, Mats; Casini,
Roberto; Centeno, Rebecca; Cranmer, Steven R.; Criscuoli, Serena;
Deforest, Craig; Deng, Yuanyong; Erdélyi, Robertus; Fedun, Viktor;
Fischer, Catherine E.; González Manrique, Sergio J.; Hahn, Michael;
Harra, Louise; Henriques, Vasco M. J.; Hurlburt, Neal E.; Jaeggli,
Sarah; Jafarzadeh, Shahin; Jain, Rekha; Jefferies, Stuart M.; Keys,
Peter H.; Kowalski, Adam F.; Kuckein, Christoph; Kuhn, Jeffrey R.;
Kuridze, David; Liu, Jiajia; Liu, Wei; Longcope, Dana; Mathioudakis,
Mihalis; McAteer, R. T. James; McIntosh, Scott W.; McKenzie, David
E.; Miralles, Mari Paz; Morton, Richard J.; Muglach, Karin; Nelson,
Chris J.; Panesar, Navdeep K.; Parenti, Susanna; Parnell, Clare E.;
Poduval, Bala; Reardon, Kevin P.; Reep, Jeffrey W.; Schad, Thomas A.;
Schmit, Donald; Sharma, Rahul; Socas-Navarro, Hector; Srivastava,
Abhishek K.; Sterling, Alphonse C.; Suematsu, Yoshinori; Tarr, Lucas
A.; Tiwari, Sanjiv; Tritschler, Alexandra; Verth, Gary; Vourlidas,
Angelos; Wang, Haimin; Wang, Yi-Ming; NSO and DKIST Project; DKIST
Instrument Scientists; DKIST Science Working Group; DKIST Critical
Science Plan Community
Bibcode: 2021SoPh..296...70R
Altcode: 2020arXiv200808203R
The National Science Foundation's Daniel K. Inouye Solar Telescope
(DKIST) will revolutionize our ability to measure, understand,
and model the basic physical processes that control the structure
and dynamics of the Sun and its atmosphere. The first-light DKIST
images, released publicly on 29 January 2020, only hint at the
extraordinary capabilities that will accompany full commissioning of
the five facility instruments. With this Critical Science Plan (CSP)
we attempt to anticipate some of what those capabilities will enable,
providing a snapshot of some of the scientific pursuits that the DKIST
hopes to engage as start-of-operations nears. The work builds on the
combined contributions of the DKIST Science Working Group (SWG) and
CSP Community members, who generously shared their experiences, plans,
knowledge, and dreams. Discussion is primarily focused on those issues
to which DKIST will uniquely contribute.
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: Chromospheric Heating Associated with Strong Photospheric
Downflow Events in Photospheric Flux Tubes
Authors: Suematsu, Yoshinori
Bibcode: 2021cosp...43E1800S
Altcode:
The formation of small-scale strong magnetic features in the quiet
Sun was studied for a long time. It is likely that magnetic field
on the solar surface is collected in the intergranular lanes by
the horizontal flows in granules, and then a convective instability
(collapse), which leads to downflow in the flux tube and a reduction
of the internal gas pressure, intensifies them to kG levels. However,
a static equilibrium with such a strong field would not be realized
and open question remained is the evolution including the possible
rebounding upflow and the associated chromospheric responses, which
may show up as shocks and subsequent heating. Using high resolution
time series of Hinode/SOT filter images in Na D1 line, G-band and Ca
II H band at the quiet Sun disk center, we were able to identify many
point-like downflow (convective collapse) events in the photosphere
and corresponding chromospheric bright points. For each events,
we investigated temporal variations of, photospheric vertical flow
velocities, magnetic flux, G-band intensity (proxy of kG field) and
Ca II H intensity (chromospheric brightening) to see the implications
of convective collapse on the photospheric and chromospheric dynamical
processes.In 500 point-like downflow events studied, most cases indicate
a signature of convective collapse (G-band brightening). Typical
lifetime of downflow is about a few minutes Irrespective of strength
of magnetic flux, strong downflows are always associated with Ca II
H bright points which appear about a minute later, implying a rebound
shock heating of the low chromosphere.
Title: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
for SUNRISE III: optical design and performance
Authors: Tsuzuki, Toshihiro; Katsukawa, Yukio; Uraguchi, Fumihiro;
Hara, Hirohisa; Kubo, Masahito; Nodomi, Yoshifumi; Suematsu, Yoshinori;
Kawabata, Yusuke; Shimizu, Toshifumi; Gandorfer, Achim; Feller, Alex;
Grauf, Bianca; Solanki, Sami; Carlos del Toro Iniesta, Jose
Bibcode: 2020SPIE11447E..AJT
Altcode:
The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) is a
near-IR spectro-polarimeter instrument newly designed for Sunrise III,
which is a balloon-borne solar observatory equipped with a 1 m optical
telescope. To acquire high-quality 3D magnetic and velocity fields,
SCIP selects the two wavelength bands centered at 850 nm and 770 nm,
which contain many spectrum lines that are highly sensitive to magnetic
fields permeating the photosphere and chromosphere. To achieve high
spatial and spectral resolution (0.21 arcsec and 2 × 105),
SCIP optics adopt a quasi-Littrow configuration based on an echelle
grating and two high-order aspheric mirrors. Using different diffraction
orders of the echelle grating, dichroic beam splitter, and polarizing
beam-splitters, SCIP can obtain s- and p-polarization signals in the
two wavelength bands simultaneously within a relatively small space. We
established the wavefront error budget based on tolerance analysis,
surface figure errors, alignment errors, and environmental changes. In
addition, we performed stray light analysis, and designed light traps
and baffles needed to suppress unwanted reflections and diffraction
by the grating. In this paper, we present the details of this optical
system and its performance.
Title: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
for SUNRISE III: opto-mechanical analysis and design
Authors: Uraguchi, Fumihiro; Tsuzuki, Toshihiro; Katsukawa, Yukio;
Hara, Hirohisa; Iwamura, Satoru; Kubo, Masahito; Nodomi, Yoshifumi;
Suematsu, Yoshinori; Kawabata, Yusuke; Shimizu, Toshifumi; Gandorfer,
Achim; del Toro Iniesta, Jose Carlos
Bibcode: 2020SPIE11447E..ABU
Altcode:
The Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) is a
near-IR spectro-polarimeter instrument newly designed for Sunrise III,
a balloon-borne solar observatory with a 1-m diameter telescope. In
order to achieve the strict requirements the SCIP wavefront error, it is
necessary to quantify the errors due to environmen- tal effects such as
gravity and temperature variation under the observation conditions. We
therefore conducted an integrated opto-mechanical analysis incorporating
mechanical and thermal disturbances into a finite element model of
the entire SCIP structure to acquire the nodal displacements of each
optical element, then fed them back to the optical analysis software
in the form of rigid body motion and surface deformation fitted by
polynomials. This method allowed us to determine the error factors
having a significant influence on optical performance. For example,
no significant wavefront degradation was associated with the structural
mountings because the optical element mounts were well designed based
on quasi-kinematic constraints. In contrast, we found that the main
factor affecting wavefront degradation was the rigid body motions of
the optical elements, which must be mini- mized within the allowable
level. Based on these results, we constructed the optical bench using a
sandwich panel as the optical bench consisting of an aluminum-honeycomb
core and carbon fiber reinforced plastic skins with a high stiffness
and low coefficient of thermal expansion. We then confirmed that the
new opto-mechanical model achieved the wavefront error requirement. In
this paper, we report the details of this integrated opto-mechanical
analysis, including the wavefront error budgeting and the design of
the opto-mechanics.
Title: The Solar-C (EUVST) mission: the latest status
Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko; Suematsu,
Yoshinori; Hara, Hirohisa; Tsuzuki, Toshihiro; Katsukawa, Yukio; Kubo,
Masahito; Ishikawa, Ryoko; Watanabe, Tetsuya; Toriumi, Shin; Ichimoto,
Kiyoshi; Nagata, Shin'ichi; Hasegawa, Takahiro; Yokoyama, Takaaki;
Watanabe, Kyoko; Tsuno, Katsuhiko; Korendyke, Clarence M.; Warren,
Harry; De Pontieu, Bart; Boerner, Paul; Solanki, Sami K.; Teriaca,
Luca; Schuehle, Udo; Matthews, Sarah; Long, David; Thomas, William;
Hancock, Barry; Reid, Hamish; Fludra, Andrzej; Auchère, Frederic;
Andretta, Vincenzo; Naletto, Giampiero; Poletto, Luca; Harra, Louise
Bibcode: 2020SPIE11444E..0NS
Altcode:
Solar-C (EUVST) is the next Japanese solar physics mission to
be developed with significant contributions from US and European
countries. The mission carries an EUV imaging spectrometer with
slit-jaw imaging system called EUVST (EUV High-Throughput Spectroscopic
Telescope) as the mission payload, to take a fundamental step towards
answering how the plasma universe is created and evolves and how the
Sun influences the Earth and other planets in our solar system. In
April 2020, ISAS (Institute of Space and Astronautical Science) of JAXA
(Japan Aerospace Exploration Agency) has made the final down-selection
for this mission as the 4th in the series of competitively chosen
M-class mission to be launched with an Epsilon launch vehicle in mid
2020s. NASA (National Aeronautics and Space Administration) has selected
this mission concept for Phase A concept study in September 2019 and
is in the process leading to final selection. For European countries,
the team has (or is in the process of confirming) confirmed endorsement
for hardware contributions to the EUVST from the national agencies. A
recent update to the mission instrumentation is to add a UV spectral
irradiance monitor capability for EUVST calibration and scientific
purpose. This presentation provides the latest status of the mission
with an overall description of the mission concept emphasizing on key
roles of the mission in heliophysics research from mid 2020s.
Title: Sunrise Chromospheric Infrared SpectroPolarimeter (SCIP)
for sunrise III: system design and capability
Authors: Katsukawa, Y.; del Toro Iniesta, J. C.; Solanki, S. K.;
Kubo, M.; Hara, H.; Shimizu, T.; Oba, T.; Kawabata, Y.; Tsuzuki,
T.; Uraguchi, F.; Nodomi, Y.; Shinoda, K.; Tamura, T.; Suematsu,
Y.; Ishikawa, R.; Kano, R.; Matsumoto, T.; Ichimoto, K.; Nagata, S.;
Quintero Noda, C.; Anan, T.; Orozco Suárez, D.; Balaguer Jiménez,
M.; López Jiménez, A. C.; Cobos Carrascosa, J. P.; Feller, A.;
Riethmueller, T.; Gandorfer, A.; Lagg, A.
Bibcode: 2020SPIE11447E..0YK
Altcode:
The Sunrise balloon-borne solar observatory carries a 1 m aperture
optical telescope and provides us a unique platform to conduct
continuous seeing-free observations at UV-visible-IR wavelengths from
an altitude of higher than 35 km. For the next flight planned for
2022, the post-focus instrumentation is upgraded with new spectro-
polarimeters for the near UV (SUSI) and the near-IR (SCIP), whereas
the imaging spectro-polarimeter Tunable Magnetograph (TuMag) is capable
of observing multiple spectral lines within the visible wavelength. A
new spectro-polarimeter called the Sunrise Chromospheric Infrared
spectroPolarimeter (SCIP) is under development for observing near-IR
wavelength ranges of around 770 nm and 850 nm. These wavelength ranges
contain many spectral lines sensitive to solar magnetic fields and
SCIP will be able to obtain magnetic and velocity structures in the
solar atmosphere with a sufficient height resolution by combining
spectro-polarimetric data of these lines. Polarimetric measurements are
conducted using a rotating waveplate as a modulator and polarizing beam
splitters in front of the cameras. The spatial and spectral resolutions
are 0.2" and 2 105, respectively, and a polarimetric sensitivity of
0.03 % (1σ) is achieved within a 10 s integration time. To detect
minute polarization signals with good precision, we carefully designed
the opto-mechanical system, polarization optics and modulation, and
onboard data processing.
Title: Current Status of the Solar-C_EUVST Mission
Authors: Imada, S.; Shimizu, T.; Kawate, T.; Toriumi, S.; Katsukawa,
Y.; Kubo, M.; Hara, H.; Suematsu, Y.; Ichimoto, K.; Watanabe, T.;
Watanabe, K.; Yokoyama, T.; Warren, H.; Long, D.; Harra, L. K.;
Teriaca, L.
Bibcode: 2020AGUFMSH056..05I
Altcode:
Solar-C_EUVST (EUV High-Throughput Spectroscopic Telescope) is designed
to comprehensively understand the energy and mass transfer from the
solar surface to the solar corona and interplanetary space, and to
investigate the elementary processes that take place universally
in cosmic plasmas. As a fundamental step towards answering how the
plasma universe is created and evolves, and how the Sun influences
the Earth and other planets in our solar system, the proposed mission
is designed to comprehensively understand how mass and energy are
transferred throughout the solar atmosphere. Understanding the solar
atmosphere, which connects to the heliosphere via radiation, the solar
wind and coronal mass ejections, and energetic particles is pivotal
for establishing the conditions for life and habitability in the solar
system. The two primary science objectives for Solar-C_EUVST are :
I) Understand how fundamental processes lead to the formation of the
solar atmosphere and the solar wind, II) Understand how the solar
atmosphere becomes unstable, releasing the energy that drives solar
flares and eruptions. Solar-C_EUVST will, A) seamlessly observe all
the temperature regimes of the solar atmosphere from the chromosphere
to the corona at the same time, B) resolve elemental structures of the
solar atmosphere with high spatial resolution and cadence to track their
evolution, and C) obtain spectroscopic information on the dynamics of
elementary processes taking place in the solar atmosphere. In this
talk, we will first discuss the science target of the Solar-C_EUVST,
and then discuss the current status of the Solar-C_EUVST mission.
Title: Thermal design of the Solar-C (EUVST) telescope
Authors: Suematsu, Yoshinori; Shimizu, Toshifumi; Hara, Hirohisa;
Kawate, Tomoko; Katsukawa, Yukio; Ichimoto, Kiyoshi; Imada, Shinsuke;
Nagae, Kazuhiro; Yamazaki, Atsumu; Hattori, Tomoya
Bibcode: 2020SPIE11444E..3KS
Altcode:
The EUV High-Throughput Spectroscopic Telescope (EUVST) of Solar-C
mission consists of only two imaging optical components; a 28-cm clear
aperture off-axis parabolic primary mirror and a two-split ellipsoidal
grating without a blocking filter for visible light before the primary
mirror to achieve unprecedented high spatial and temporal resolution in
EUV-UV imaging spectroscopic observations. For this reason, about 60
W of sunlight is absorbed by the multilayer coating on the mirror. We
report a thermal design of telescope in which the temperature of the
primary mirror bonding part and underlying tip-tilt and slit-scanning
mechanisms is well lower than a glass transition temperature of adhesive
(about 60°C) and thermal deformation of the primary mirror is small,
although it is non-negligibly small.
Title: A sensitivity analysis of the updated optical design for
EUVST on the Solar-C mission
Authors: Kawate, Tomoko; Tsuzuki, Toshihiro; Shimizu, Toshifumi;
Imada, Shinsuke; Katsukawa, Yukio; Hara, Hirohisa; Suematsu, Yoshinori;
Ichimoto, Kiyoshi; Hattori, Tomoya; Narasaki, Shota; Warren, Harry P.;
Teriaca, Luca; Korendyke, Clarence M.; Brown, Charles M.; Auchere,
Frederic
Bibcode: 2020SPIE11444E..3JK
Altcode:
The EUV high-throughput spectroscopic telescope (EUVST) onboard the
Solar-C mission has the high spatial (0.4'') resolution over a wide
wavelength range in the vacuum ultraviolet. To achieve high spatial
resolution under a design constraint given by the JAXA Epsilon launch
vehicle, we further update the optical design to secure margins
needed to realize 0.4'' spatial resolution over a field of view of
100''×100''. To estimate the error budgets of spatial and spectral
resolutions due to installation and fabrication errors, we perform a
sensitivity analysis for the position and orientation of each optical
element and for the grating parameters by ray tracing with the Zemax
software. We obtain point spread functions (PSF) for rays from 9
fields and at 9 wavelengths on each detector by changing each parameter
slightly. A full width at half maximum (FWHM) of the PSF is derived at
each field and wavelength position as a function of the perturbation
of each optical parameter. Assuming a mount system of each optical
element and an error of each optical parameter, we estimate spatial
and spectral resolutions by taking installation and fabrication errors
into account. The results of the sensitivity analysis suggest that
budgets of the total of optical design and the assembly errors account
for 15% and 5.8% of our budgets of the spatial resolution in the long
wavelength and short wavelength bands, respectively. On the other hand,
the grating fabrication errors give a large degradation of spatial and
spectral resolutions, and investigations of compensators are needed
to relax the fabrication tolerance of the grating surface parameters.
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: Relationship between Point-like Photospheric Downflows and
Convective Collapse Events Seen in Hinode/SOT
Authors: Suematsu, Y.
Bibcode: 2019AGUFMSH43E3384S
Altcode:
The formation of small-scale strong magnetic features in the quiet Sun
was studied for a long time. It is likely that magnetic field on the
solar surface is collected in the intergranular lanes by the horizontal
flows in granules, and then a convective instability (collapse), which
leads to downflow in the flux tube and a reduction of the internal gas
pressure, intensifies them to kG levels. However, a static equilibrium
with such a strong field would not be realized and the open question
remained is the evolution including the possible rebounding upflow
and the associated chromospheric responses, which may show up as
shocks and subsequent heating. Using high-resolution time series of
Hinode/SOT filter images in Na D1 line and Ca II H band at the quiet
Sun disk center, we were able to identify many point-like downflows in
the photosphere and corresponding chromospheric bright points, which
are not always associated with magnetic field intensifications. For
each event, we determined the duration, photospheric vertical flow
velocities, line-of-sight field strength increase and the signature of
chromospheric brightening. We present the implications of point-like
downflows on the photospheric and chromospheric dynamical processes.
Title: Achievements of Hinode in the first eleven years
Authors: Hinode Review Team; Al-Janabi, Khalid; Antolin, Patrick;
Baker, Deborah; Bellot Rubio, Luis R.; Bradley, Louisa; Brooks,
David H.; Centeno, Rebecca; Culhane, J. Leonard; Del Zanna, Giulio;
Doschek, George A.; Fletcher, Lyndsay; Hara, Hirohisa; Harra,
Louise K.; Hillier, Andrew S.; Imada, Shinsuke; Klimchuk, James A.;
Mariska, John T.; Pereira, Tiago M. D.; Reeves, Katharine K.; Sakao,
Taro; Sakurai, Takashi; Shimizu, Toshifumi; Shimojo, Masumi; Shiota,
Daikou; Solanki, Sami K.; Sterling, Alphonse C.; Su, Yingna; Suematsu,
Yoshinori; Tarbell, Theodore D.; Tiwari, Sanjiv K.; Toriumi, Shin;
Ugarte-Urra, Ignacio; Warren, Harry P.; Watanabe, Tetsuya; Young,
Peter R.
Bibcode: 2019PASJ...71R...1H
Altcode:
Hinode is Japan's third solar mission following Hinotori (1981-1982)
and Yohkoh (1991-2001): it was launched on 2006 September 22 and is in
operation currently. Hinode carries three instruments: the Solar Optical
Telescope, the X-Ray Telescope, and the EUV Imaging Spectrometer. These
instruments were built under international collaboration with the
National Aeronautics and Space Administration and the UK Science and
Technology Facilities Council, and its operation has been contributed
to by the European Space Agency and the Norwegian Space Center. After
describing the satellite operations and giving a performance evaluation
of the three instruments, reviews are presented on major scientific
discoveries by Hinode in the first eleven years (one solar cycle long)
of its operation. This review article concludes with future prospects
for solar physics research based on the achievements of Hinode.
Title: ngGONG: The Next Generation GONG - A New Solar Synoptic
Observational Network
Authors: Hill, Frank; Hammel, Heidi; Martinez-Pillet, Valentin; de
Wijn, A.; Gosain, S.; Burkepile, J.; Henney, C. J.; McAteer, J.; Bain,
H. M.; Manchester, W.; Lin, H.; Roth, M.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2019BAAS...51g..74H
Altcode: 2019astro2020U..74H
The white paper describes a next-generation GONG, a ground-based
geographically distributed network of instrumentation to continually
observe the Sun. This would provide data for solar magnetic field
research and space weather forecasting, and would extend the time
coverage of helioseismology.
Title: Development of Solar-C_EUVST structural design
Authors: Suematsu, Yoshinori; Shimizu, Toshifumi; Hara, Hirohisa;
Katsukawa, Yukio; Kawate, Tomoko; Ichimoto, Kiyoshi; Imada, Shinsuke
Bibcode: 2019SPIE11118E..1OS
Altcode:
The Solar-C_EUVST is a mission designed to provide high-quality solar
spectroscopic data covering a wide temperature range of the chromosphere
to flaring corona. To fulfill a high throughput requirement, the
instrument consists of only two optical components; a 28-cm primary
mirror and a segmented toroidal grating which have high reflective
coatings in EUV-UV range. We present a mission payload structural
design which accommodates long focal length optical components and
a launcher condition/launch environment (JAXA Epsilon). We also
present a mechanical design of primary mirror assembly which enables
slit-scan observations, an image stabilizing tip-tilt control, and a
focus adjustment on orbit, together with an optomechanical design of
the primary mirror and its supporting system which gives optically
tolerant wavefront error against a large temperature increase due to
an absorption of visible and IR lights.
Title: Concept study of Solar-C_EUVST optical design
Authors: Kawate, Tomoko; Shimizu, Toshifumi; Imada, Shinsuke; Tsuzuki,
Toshihiro; Katsukawa, Yukio; Hara, Hirohisa; Suematsu, Yoshinori;
Ichimoto, Kiyoshi; Warren, Harry; Teriaca, Luca; Korendyke, Clarence
M.; Brown, Charles
Bibcode: 2019SPIE11118E..1NK
Altcode:
The main characteristics of Solar-C_EUVST are the high temporal and
high spatial resolutions over a wide temperature coverage. In order
to realize the instrument for meeting these scientific requirements
under size constraints given by the JAXA Epsilon vehicle, we examined
four-dimensional optical parameter space of possible solutions of
geometrical optical parameters such as mirror diameter, focal length,
grating magnification, and so on. As a result, we have identified
the solution space that meets the EUVST science objectives and rocket
envelope requirements. A single solution was selected and used to define
the initial optical parameters for the concept study of the baseline
architecture for defining the mission concept. For this solution, we
optimized the grating and geometrical parameters by ray tracing of the
Zemax software. Consequently, we found an optics system that fulfills
the requirement for a 0.4" angular resolution over a field of view of
100" (including margins) covering spectral ranges of 170-215, 463-542,
557-637, 690-850, 925-1085, and 1115-1275 A. This design achieves an
effective area 10 times larger than the Extreme-ultraviolet Imaging
Spectrometer onboard the Hinode satellite, and will provide seamless
observations of 4.2-7.2 log(K) plasmas for the first time. Tolerance
analyses were performed based on the optical design, and the moving
range and step resolution of focus mechanisms were identified. In
the presentation, we describe the derivation of the solution space,
optimization of the optical parameters, and show the results of ray
tracing and tolerance analyses.
Title: The Solar-C_EUVST mission
Authors: Shimizu, Toshifumi; Imada, Shinsuke; Kawate, Tomoko;
Ichimoto, Kiyoshi; Suematsu, Yoshinori; Hara, Hirohisa; Katsukawa,
Yukio; Kubo, Masahito; Toriumi, Shin; Watanabe, Tetsuya; Yokoyama,
Takaaki; Korendyke, Clarence M.; Warren, Harry P.; Tarbell, Ted; De
Pontieu, Bart; Teriaca, Luca; Schühle, Udo H.; Solanki, Sami; Harra,
Louise K.; Matthews, Sarah; Fludra, A.; Auchère, F.; Andretta, V.;
Naletto, G.; Zhukov, A.
Bibcode: 2019SPIE11118E..07S
Altcode:
Solar-C EUVST (EUV High-Throughput Spectroscopic Telescope) is a
solar physics mission concept that was selected as a candidate for
JAXA competitive M-class missions in July 2018. The onboard science
instrument, EUVST, is an EUV spectrometer with slit-jaw imaging
system that will simultaneously observe the solar atmosphere from the
photosphere/chromosphere up to the corona with seamless temperature
coverage, high spatial resolution, and high throughput for the first
time. The mission is designed to provide a conclusive answer to the
most fundamental questions in solar physics: how fundamental processes
lead to the formation of the solar atmosphere and the solar wind, and
how the solar atmosphere becomes unstable, releasing the energy that
drives solar flares and eruptions. The entire instrument structure
and the primary mirror assembly with scanning and tip-tilt fine
pointing capability for the EUVST are being developed in Japan, with
spectrograph and slit-jaw imaging hardware and science contributions
from US and European countries. The mission will be launched and
installed in a sun-synchronous polar orbit by a JAXA Epsilon vehicle in
2025. ISAS/JAXA coordinates the conceptual study activities during the
current mission definition phase in collaboration with NAOJ and other
universities. The team is currently working towards the JAXA final
down-selection expected at the end of 2019, with strong support from
US and European colleagues. The paper provides an overall description
of the mission concept, key technologies, and the latest status.
Title: Design of all-reflective space-borne 1-m aperture solar
optical telescope
Authors: Suematsu, Y.; Hara, H.; Katsukawa, Y.; Kano, R.; Shimizu,
T.; Ichimoto, K.
Bibcode: 2019SPIE11180E..0RS
Altcode:
A 1-m aperture optical telescope is planned for a future Japanese solar
mission. The telescope is designed to provide high spatial resolution
data of solar lower atmosphere from the photosphere to the uppermost
chromosphere with enhanced spectroscopic and spectro-polarimetric
capabilities covering a wide wavelength region from UV to near IR where
many useful spectral lines and continua exist for physical diagnosis of
the solar magnetized atmosphere. We designed an allreflective telescope
to fulfill the scientific and engineering requirements. From a thermal
view point, a Gregorian telescope is the most suitable. To avoid
chromatic aberration, a tri-aspheric-mirror collimator coupling to
the Gregorian was designed to give a diffraction-limited performance
over the FOV by allowing a field curvature. The field curvature can
be compensated by an off-axis Ritchey Chretien reimaging optics at an
entrance of focal plane instrument, which has an opposite sign in the
field curvature to the Gregorian. We also briefly studied structural
design of all-reflective 1-m aperture solar optical telescope for the
space solar mission.
Title: Chromospheric polarimetry through multiline observations of
the 850 nm spectral region III: Chromospheric jets driven by twisted
magnetic fields
Authors: Quintero Noda, C.; Iijima, H.; Katsukawa, Y.; Shimizu,
T.; Carlsson, M.; de la Cruz Rodríguez, J.; Ruiz Cobo, B.; Orozco
Suárez, D.; Oba, T.; Anan, T.; Kubo, M.; Kawabata, Y.; Ichimoto,
K.; Suematsu, Y.
Bibcode: 2019MNRAS.486.4203Q
Altcode: 2019MNRAS.tmp.1081N; 2019arXiv190409151Q
We investigate the diagnostic potential of the spectral lines at 850
nm for understanding the magnetism of the lower atmosphere. For that
purpose, we use a newly developed 3D simulation of a chromospheric
jet to check the sensitivity of the spectral lines to this phenomenon
as well as our ability to infer the atmospheric information through
spectropolarimetric inversions of noisy synthetic data. We start
comparing the benefits of inverting the entire spectrum at 850 nm versus
only the Ca II 8542 Å spectral line. We found a better match of the
input atmosphere for the former case, mainly at lower heights. However,
the results at higher layers were not accurate. After several tests,
we determined that we need to weight more the chromospheric lines
than the photospheric ones in the computation of the goodness of the
fit. The new inversion configuration allows us to obtain better fits and
consequently more accurate physical parameters. Therefore, to extract
the most from multiline inversions, a proper set of weights needs to
be estimated. Besides that, we conclude again that the lines at 850
nm, or a similar arrangement with Ca II 8542 Å plus Zeeman-sensitive
photospheric lines, pose the best-observing configuration for examining
the thermal and magnetic properties of the lower solar atmosphere.
Title: Synoptic Studies of the Sun as a Key to Understanding Stellar
Astrospheres
Authors: Martinez Pillet, Valentin; Hill, Frank; Hammel, Heidi B.;
de Wijn, Alfred G.; Gosain, Sanjay; Burkepile, Joan; Henney, Carl;
McAteer, R. T. James; Bain, Hazel; Manchester, Ward; Lin, Haosheng;
Roth, Markus; Ichimoto, Kiyoshi; Suematsu, Yoshinori
Bibcode: 2019BAAS...51c.110M
Altcode: 2019astro2020T.110M; 2019arXiv190306944M
Ground-based solar observations provide key contextual data (i.e., the
"big picture") to produce a complete description of the only astrosphere
we can study in situ: our Sun's heliosphere. This white paper outlines
the current paradigm for ground-based solar synoptic observations,
and indicates those areas that will benefit from focused attention.
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: Study of the polarization produced by the Zeeman effect in
the solar Mg I b lines
Authors: Quintero Noda, C.; Uitenbroek, H.; Carlsson, M.; Orozco
Suárez, D.; Katsukawa, Y.; Shimizu, T.; Ruiz Cobo, B.; Kubo, M.; Oba,
T.; Kawabata, Y.; Hasegawa, T.; Ichimoto, K.; Anan, T.; Suematsu, Y.
Bibcode: 2018MNRAS.481.5675Q
Altcode: 2018arXiv181001067Q; 2018MNRAS.tmp.2566Q
The next generation of solar observatories aim to understand the
magnetism of the solar chromosphere. Therefore, it is crucial to
understand the polarimetric signatures of chromospheric spectral
lines. For this purpose, we here examine the suitability of the three
Fraunhofer Mg I b1, b2, and b4 lines
at 5183.6, 5172.7, and 5167.3 Å, respectively. We start by describing
a simplified atomic model of only six levels and three line transitions
for computing the atomic populations of the 3p-4s (multiplet number
2) levels involved in the Mg I b line transitions assuming non-local
thermodynamic conditions and considering only the Zeeman effect using
the field-free approximation. We test this simplified atom against
more complex ones finding that, although there are differences in the
computed profiles, they are small compared with the advantages provided
by the simple atom in terms of speed and robustness. After comparing
the three Mg I lines, we conclude that the most capable one is the
b2 line as b1 forms at similar heights and always
shows weaker polarization signals, while b4 is severely
blended with photospheric lines. We also compare Mg I b2
with the K I D1 and Ca II 8542 Å lines finding that the
former is sensitive to the atmospheric parameters at heights that
are in between those covered by the latter two lines. This makes Mg I
b2 an excellent candidate for future multiline observations
that aim to seamlessly infer the thermal and magnetic properties of
different features in the lower solar atmosphere.
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: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
for the SUNRISE balloon-borne solar observatory
Authors: Suematsu, Yoshinori; Katsukawa, Yukio; Hara, Hirohisa;
Ichimoto, Kiyoshi; Shimizu, Toshifumi; Kubo, Masahito; Barthol,
Peter; Riethmueller, Tino; Gandorfer, Achim; Feller, Alex; Orozco
Suárez, David; Del Toro Iniesta, Jose Carlos; Kano, Ryouhei; Ishikawa,
Shin-nosuke; Ishikawa, Ryohko; Tsuzuki, Toshihiro; Uraguchi, Fumihiro;
Quintero Noda, Carlos; Tamura, Tomonori; Oba, Takayoshi; Kawabata,
Yusuke; Nagata, Shinichi; Anan, Tetsu; Cobos Carrascosa, Juan Pedro;
Lopez Jimenez, Antonio Carlos; Balaguer Jimenez, Maria; Solanki, Sami
Bibcode: 2018cosp...42E3285S
Altcode:
The SUNRISE balloon-borne solar observatory carries a 1 m aperture
optical telescope, and allows us to perform seeing-free continuous
observations at visible-IR wavelengths from an altitude higher than
35 km. In the past two flights, in 2009 and 2013, observations mainly
focused on fine structures of photospheric magnetic fields. For the
third flight planned for 2021, we are developing a new instrument
for conducting spectro-polarimetry of spectral lines formed over a
larger height range in the solar atmosphere from the photosphere to
the chromosphere. Targets of the spectro-polarimetric observation
are (1) to determine 3D magnetic structure from the photosphere to
the chromosphere, (2) to trace MHD waves from the photosphere to the
chromosphere, and (3) to reveal the mechanism driving chromospheric
jets, by measuring height- and time-dependent velocities and magnetic
fields. To achieve these goals, a spectro-polarimeter called SCIP
(Sunrise Chromospheric Infrared spectroPolarimeter) is designed to
observe near-infrared spectrum lines sensitive to solar magnetic
fields. The spatial and spectral resolutions are 0.2 arcsec and
200,000, respectively, while 0.03% polarimetric sensitivity is
achieved within a 10 sec integration time. The optical system employs
an Echelle grating and off-axis aspheric mirrors to observe the two
wavelength ranges centered at 850 nm and 770 nm simultaneously by
two cameras. Polarimetric measurements are performed using a rotating
waveplate and polarization beam-splitters in front of the cameras. For
detecting minute polarization signals with good precision, we carefully
assess the temperature dependence of polarization optics, and make
the opto-structural design that minimizes the thermal deformation
of the spectrograph optics. Another key technique is to attain good
(better than 30 msec) synchronization among the rotating phase of
the waveplate, read-out timing of cameras, and step timing of a
slit-scanning mirror. On-board accumulation and data processing are
also critical because we cannot store all the raw data read-out from the
cameras. We demonstrate that we can reduce the data down to almost 10%
with loss-less image compression and without sacrificing polarimetric
information in the data. The SCIP instrument is developed by internal
collaboration among Japanese institutes including Japan Aerospace
Exploration Agency (JAXA), the Spanish Sunrise consortium, and the
German Max Planck Institute for Solar System Research (MPS) with a
leadership of the National Astronomical Observatory of Japan (NAOJ).
Title: Solar Flare Observations with Integral Field Spectroscopy in
H-alpha Spectra and SDO/AIA
Authors: Suematsu, Yoshinori
Bibcode: 2018cosp...42E3284S
Altcode:
Integral field spectroscopy is a two dimensional spectroscopic
technique, providing spectra simultaneously for each spatial direction
of an extended two-dimensional field. Using the field integral
spectroscopy made of microlenslet-array (30x30 lenslets) in H-alpha
spectrum, GOES C- and M-class flares on 3 Nov 2011 were successfully
observed with the 60 cm aperture Domeless Solar Telescope at Hida
Observatory, Kyoto University. The data spatially sampled with 0.5
arcsec over 10x10 arcsec FOV and 1 nm wavelength band centered H-alpha
line demonstrated that simultaneous 2D spectroscopic observations
over extended solar structures, at a high spatial resolution and
temporal cadence, are important to track and understand the physics of
transient phenomena happening in impulsive flare bright kernels. We
made monochromatic images at given wavelengths in the H-alpha line
and nearby continuum to co-align the data with X-ray, UV images and
magnetograms from SDO/AIA and HMI. To reveal dynamical properties of
the flare kernels, we carried out line profile analysis and derived
2-D distribution of parameters such as line-of-sight velocity and line
width. The results clearly show the rapid development of red asymmetry
at the flare kernels, giving a large downward Doppler shifts of up to
50 km/sec. The accompanied formation of coronal dynamic flaring loop
structures seen in SDO X-ray images are consistent with a scenario
of downward motion of compressed chromospheric flare kernels due do
impulsive heat flow from the corona to the chromosphere and simultaneous
evaporation of the chromospheric material into the corona.
Title: Science Objectives of the Solar-C_EUVST
Authors: Imada, Shinsuke; Suematsu, Yoshinori
Bibcode: 2018cosp...42E1542I
Altcode:
Solar-C EUVST (EUV High-Throughput Spectroscopic Telescope) is
designed to comprehensively understand the energy and mass transfer
from the solar surface to the solar corona and interplanetary
space, and to investigate the elementary processes that take place
universally in cosmic plasmas. The proposed mission is a fundamental
step for answering how the plasma universe is created and evolves,
and how the Sun influences the Earth and other planets in our solar
system. The two primary science objectives for Solar-C EUVST are : I)
Understand how fundamental processes lead to the formation of the solar
atmosphere and the solar wind, II) Understand how the solar atmosphere
becomes unstable, releasing the energy that drives solar flares and
eruptions. Solar-C EUVST will, A) seamlessly observe all the temperature
regimes of the solar atmosphere from the chromosphere to the corona at
the same time, B) resolve elemental structures of the solar atmosphere
with high spatial resolution and cadence to track their evolution,
and C) obtain spectroscopic information on the dynamics of elementary
processes taking place in the solar atmosphere. In this talk, we will
first discuss the science target of the Solar-C EUVST, and discuss the
science topic associated flare in detail. Photospheric motions lead to
the accumulation of free magnetic energy in the corona. This system
eventually becomes unstable, releasing the energy through magnetic
reconnection. This process of energy conversion heats the plasma to
high temperatures and drives coronal mass ejections (CMEs). By measuring
the properties of multi-temperature flaring plasma, Solar-C EUVST will
investigate why the reconnection is fast despite the high magnetic
Reynolds number. It will also monitor the temporal evolution of solar
active regions and identify the triggering mechanism for the flare
and eruption. Therefore two important science objectives are defined
for the flare physics. The first objective is "Understand the Fast
Magnetic Reconnection Process". Magnetic reconnection is one of the
fundamental processes for converting magnetic energy into the thermal
and kinetic energy of the plasma. This process occurs much faster
than is predicted by classical theory. Solar-C EUVST will observe the
dynamics of magnetic structures to understand the mechanisms that lead
to fast magnetic reconnection in partially or fully ionized plasmas. The
second objective is "Identify the Signatures of Global Energy Buildup
and the Local Triggering of the Flare and Eruption". Understanding the
accumulation and release of free magnetic energy in the corona is a
fundamental problem. Solar-C EUVST will perform long-term monitoring
of active regions to identify the signatures of energy buildup and
high-resolution observations to understand the triggers of energy
release.
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: Solar polarimetry in the K I D2 line : A novel
possibility for a stratospheric balloon
Authors: Quintero Noda, C.; Villanueva, G. L.; Katsukawa, Y.; Solanki,
S. K.; Orozco Suárez, D.; Ruiz Cobo, B.; Shimizu, T.; Oba, T.; Kubo,
M.; Anan, T.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2018A&A...610A..79Q
Altcode: 2018arXiv180101655Q
Of the two solar lines, K I D1 and D2, almost
all attention so far has been devoted to the D1 line, as
D2 is severely affected by an O2 atmospheric
band. This, however, makes the latter appealing for balloon and space
observations from above (most of) the Earth's atmosphere. We estimate
the residual effect of the O2 band on the K I D2
line at altitudes typical for stratospheric balloons. Our aim is to
study the feasibility of observing the 770 nm window. Specifically,
this paper serves as a preparation for the third flight of the Sunrise
balloon-borne observatory. The results indicate that the absorption
by O2 is still present, albeit much weaker, at the expected
balloon altitude. We applied the obtained O2 transmittance
to K I D2 synthetic polarimetric spectra and found that in
the absence of line-of-sight motions, the residual O2 has
a negligible effect on the K I D2 line. On the other hand,
for Doppler-shifted K I D2 data, the residual O2
might alter the shape of the Stokes profiles. However, the residual
O2 absorption is sufficiently weak at stratospheric levels
that it can be divided out if appropriate measurements are made,
something that is impossible at ground level. Therefore, for the
first time with Sunrise III, we will be able to perform polarimetric
observations of the K I D2 line and, consequently, we will
have improved access to the thermodynamics and magnetic properties of
the upper photosphere from observations of the K I lines.
Title: Ten-Year Results of Solar Optical Telescope (SOT) Onboard
Hinode
Authors: Suematsu, Yoshinori
Bibcode: 2018ASSL..449...27S
Altcode:
No abstract at ADS
Title: Development of compact integral field unit for spaceborne
solar spectro-polarimeter
Authors: Suematsu, Y.; Koyama, M.; Sukegawa, T.; Enokida, Y.; Saito,
K.; Okura, Y.; Nakayasu, T.; Ozaki, S.; Tsuneta, S.
Bibcode: 2017SPIE10563E..4MS
Altcode:
A 1.5-m class aperture Solar Ultra-violet Visible and IR telescope
(SUVIT) and its instruments for the Japanese next space solar mission
SOLAR-C [1] are under study to obtain critical physical parameters in
the lower solar atmosphere. For the precise magnetic field measurements
covering field-of-view of 3 arcmin x3 acmin, a full stokes polarimetry
at three magnetic sensitive lines in wavelength range of 525 nm
to 1083 nm with a four-slit spectrograph of two dinesional image
scanning mechanism is proposed: one is a true slit and the other
three are pseudo-slits from integral field unit (IFU). To suit this
configuration, besides a fiber bundle IFU, a compact mirror slicer IFU
is designed and being developed. Integral field spectroscopy (IFS),
which is realized with IFU, is a two dimensional spectroscopy, providing
spectra simultaneously for each spatial direction of an extended
two-dimensional field. The scientific advantages of the IFS for studies
of localized and transient solar surface phenomena are obvious. There
are in general three methods [2][3] to realize the IFS depending on
image slicing devices such as a micro-lenslet array, an optical fiber
bundle and a narrow rectangular image slicer array. So far, there exist
many applications of the IFS for ground-based astronomical observations
[4]. Regarding solar instrumentations, the IFS of micro-lenslet array
was done by Suematsu et al. [5], the IFS of densely packed rectangular
fiber bundle with thin clads was realized [6] and being developed for
4-m aperture solar telescope DKIST by Lin [7] and being considered for
space solar telescope SOLAR-C by Katsukawa et al. [8], and the IFS with
mirror slicer array was presented by Ren et al. [9] and under study
for up-coming large-aperture solar telescope in Europe by Calcines
et al. [10] From the view point of a high efficiency spectroscopy,
a wide wavelength coverage, a precision spectropolarimetry and space
application, the image slicer consisting of all reflective optics is the
best option among the three. However, the image slicers are presently
limited either by their risk in the case of classical glass polishing
techniques (see Vivès et al. [11] for recent development) or by their
optical performances when constituted by metallic mirrors. For space
instruments, small sized units are much advantageous and demands that
width of each slicer mirror is as narrow as an optimal slit width (<
100 micron) of spectrograph which is usually hard to manufacture with
glass polishing techniques. On the other hand, Canon is developing
a novel technique for such as high performance gratings which can be
applicable for manufacturing high optical performance metallic mirrors
of small dimensions. For the space-borne spectrograph of SUVIT to be
aboard SOLAR-C, we designed the IFS made of a micro image slicer of 45
arrayed 30-micron-thick metal mirrors and a pseudo-pupil metal mirror
array re-formatting three pseudo-slits; the design is feasible for
optical configuration sharing a spectrograph with a conventional real
slit. According to the optical deign, Canon manufactured a prototype
IFU for evaluation, demonstrating high performances of micro image
slicer and pupil mirrors; enough small micro roughness for visible light
spectrographs, sharp edges for efficient image slices, surface figure
for high image quality, etc. In the following, we describe the optical
design of IFU feasible for space-borne spectrograph, manufacturing
method to attain high optical performance of metal mirrors developed
by Canon, and resulted performance of prototype IFU in detail.
Title: Instrument design and on-orbit performance of the solar
optical telescope aboard hinode (Solar-B)
Authors: Suematsu, Yoshinori; Ichimoto, Kiyoshi; Katsukawa, Yukio;
Tsuneta, Saku; Shimizu, Toshifumi
Bibcode: 2017SPIE10566E..2ZS
Altcode:
The Solar Optical Telescope (SOT) aboard Solar-B satellite (Hinode)
is designed to perform high-precision photometric and polarimetric
observations of the solar lower atmosphere in visible light spectra
(388-668 nm) with a spatial resolution of 0.2 to 0.3 arcsec. The
SOT consists of two components; the optical telescope assembly (OTA)
consisting of a 50-cm aperture Gregorian telescope with a collimating
lens unit and an active tip-tilt mirror for an image-stabilization and
an accompanying focal plane package (FPP) housing two filtergraphs and a
spectro-polarimeter. Since its first-light observation on 25 Oct. 2006,
the image-stabilization system has been working with performance
better than 0.01 arcsec rms and the SOT has been continuously
providing unprecedented solar data of high spatial resolution. Since
the opto-mechanical and -thermal performance of the OTA is crucial
to attain unprecedented high-quality solar observations, we here
describe in detail the instrument design and on-orbit diffraction-limit
performance of the OTA, the largest state-of-the-art solar telescope
yet flown in space.
Title: Instrument design of 1.5-m aperture solar optical telescope
for the Solar-C Mission
Authors: Suematsu, Yoshinori; Katsukawa, Yukio; Shimizu, Toshifumi;
Ichimoto, Kiyoshi
Bibcode: 2017SPIE10564E..0TS
Altcode:
A 1.5 m aperture optical telescope is planned for the next Japanese
solar mission SOLAR-C as one of major three observing instruments. The
optical telescope is designed to provide high-angular-resolution
investigation of lower atmosphere from the photosphere to the uppermost
chromosphere with enhanced spectroscopic and spectropolarimetric
capability covering a wide wavelength region from 280 nm to 1100
nm. The opto-mechanical and -thermal performance of the telescope is
crucial to attain high-quality solar observations and we present a
study of optical and structural design of the large aperture space
solar telescope, together with conceptual design of its accompanying
focal plane instruments: wide-band and narrow-band filtergraphs and
a spectro-polarimeter for high spatial and temporal observations in
the solar photospheric and chromospheric lines useful for sounding
physical condition of dynamical phenomena.
Title: Chromospheric polarimetry through multiline observations of
the 850-nm spectral region - II. A magnetic flux tube scenario
Authors: Quintero Noda, C.; Kato, Y.; Katsukawa, Y.; Oba, T.; de la
Cruz Rodríguez, J.; Carlsson, M.; Shimizu, T.; Orozco Suárez, D.;
Ruiz Cobo, B.; Kubo, M.; Anan, T.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2017MNRAS.472..727Q
Altcode: 2017arXiv170801333Q
In this publication, we continue the work started in Quintero Noda et
al., examining this time a numerical simulation of a magnetic flux
tube concentration. Our goal is to study if the physical phenomena
that take place in it, in particular, the magnetic pumping, leaves
a specific imprint on the examined spectral lines. We find that the
profiles from the interior of the flux tube are periodically doppler
shifted following an oscillation pattern that is also reflected in
the amplitude of the circular polarization signals. In addition, we
analyse the properties of the Stokes profiles at the edges of the flux
tube discovering the presence of linear polarization signals for the Ca
II lines, although they are weak with an amplitude around 0.5 per cent
of the continuum intensity. Finally, we compute the response functions
to perturbations in the longitudinal field, and we estimate the field
strength using the weak-field approximation. Our results indicate
that the height of formation of the spectral lines changes during the
magnetic pumping process, which makes the interpretation of the inferred
magnetic field strength and its evolution more difficult. These results
complement those from previous works, demonstrating the capabilities and
limitations of the 850-nm spectrum for chromospheric Zeeman polarimetry
in a very dynamic and complex atmosphere.
Title: Optical and thermal design of 1.5-m aperture solar UV visible
and IR observing telescope for Solar-C mission
Authors: Suematsu, Y.; Katsukawa, Y.; Shimizu, T.; Ichimoto, K.;
Horiuchi, T.; Matsumoto, Y.; Takeyama, N.
Bibcode: 2017SPIE10565E..0RS
Altcode:
The next Japanese solar mission, SOLAR-C, which has been envisaged
after successful science operation of Hinode (SOLAR-B) mission, is
perusing two plans: plan-A and plan-B, and under extensive study from
science objectives as well as engineering point of view. The plan-A
aims at performing out-of-ecliptic observations for investigating, with
helioseismic approach, internal structure and dynamo mechanisms of the
Sun. It also explores polar regions where fast solar wind is believed
to originate. A baseline orbit for plan-A is a circular orbit of 1 AU
distance from the Sun with its inclination at around or greater than
40 degrees. The plan-B aims to study small-scale plasma processes and
structures in the solar atmosphere which attract researchers' growing
interest, followed by many Hinode discoveries [1], for understanding
fully dynamism and magnetic nature of the atmosphere. With plan-B,
high-angular-resolution investigation of the entire solar atmosphere
(from the photosphere to the corona, including their interface layers,
i.e., chromosphere and transition region) is to be performed with
enhanced spectroscopic and spectro-polarimetric capability as compared
with Hinode, together with enhanced sensitivity towards ultra-violet
wavelengths. The orbit of plan-B is either a solar synchronous polar
orbit of altitude around 600 km or a geosynchronous orbit to ensure
continuous solar observations. After the decision of any one of the
two plans, the SOLAR-C will be proposed for launch in mid-2010s. In
this paper, we will present a basic design of one of major planned
instrumental payload for the plan-B: the Solar Ultra-violet Visible
and near IR observing Telescope (hereafter referred to as SUVIT). The
basic concept in designing the SUVIT is to utilize as much as possible
a heritage of successful telescope of the Solar Optical Telescope
(SOT) aboard Hinode [2]. Major differences of SUVIT from SOT are
the three times larger aperture of 1.5 m, which enables to collect
one order of magnitude more photons than SOT, relatively shorter
telescope length of 2.8 m to accommodate a launcher's nosecone size
for possible dual-satellite-launch configuration, and much wider
observing wavelength from UV (down to 250 nm) through near IR (up
to 1100 nm). The large aperture is essentially important to attain
scientific goals of the plan-B, especially for accurate diagnostics of
the dynamic solar chromosphere as revealed by Hinode, although this
make it difficult to design the telescope because of ten times more
solar heat load introduced into the telescope. The SUVIT consists of
two optically separable components; the telescope assembly (TA) and
an accompanying focal plane package equipped with filtergraphs and
spectrographs. Opto-mechanical and -thermal performance of the TA is
crucial to attain high-quality solar observations and here we present
a status of feasible study in its optical and thermal designing for
diffraction-limited performance at visible wavelength in a reasonably
wide field of view.
Title: Solar polarimetry through the K I lines at 770 nm
Authors: Quintero Noda, C.; Uitenbroek, H.; Katsukawa, Y.; Shimizu,
T.; Oba, T.; Carlsson, M.; Orozco Suárez, D.; Ruiz Cobo, B.; Kubo,
M.; Anan, T.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2017MNRAS.470.1453Q
Altcode: 2017arXiv170510002Q
We characterize the K I D1 & D2 lines in
order to determine whether they could complement the 850 nm window,
containing the Ca II infrared triplet lines and several Zeeman sensitive
photospheric lines, that was studied previously. We investigate the
effect of partial redistribution on the intensity profiles, their
sensitivity to changes in different atmospheric parameters, and
the spatial distribution of Zeeman polarization signals employing a
realistic magnetohydrodynamic simulation. The results show that these
lines form in the upper photosphere at around 500 km, and that they
are sensitive to the line-of-sight velocity and magnetic field strength
at heights where neither the photospheric lines nor the Ca II infrared
lines are. However, at the same time, we found that their sensitivity
to the temperature essentially comes from the photosphere. Then, we
conclude that the K I lines provide a complement to the lines in the
850 nm window for the determination of atmospheric parameters in the
upper photosphere, especially for the line-of-sight velocity and the
magnetic field.
Title: Compact integral field unit for optical telescope of the
Solar-C mission
Authors: Suematsu, Y.; Saito, K.; Koyama, M.; Koyama, M.; Enokida,
Y.; Okura, Y.; Nakayasu, T.; Sukegawa, T.
Bibcode: 2017SPIE10562E..0SS
Altcode:
A Japan-led international solar mission "SOLAR-C" is being proposed
for mid-2020s launch.
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: Chromospheric polarimetry through multiline observations of
the 850-nm spectral region
Authors: Quintero Noda, C.; Shimizu, T.; Katsukawa, Y.; de la Cruz
Rodríguez, J.; Carlsson, M.; Anan, T.; Oba, T.; Ichimoto, K.;
Suematsu, Y.
Bibcode: 2017MNRAS.464.4534Q
Altcode: 2016arXiv161006651Q
Future solar missions and ground-based telescopes aim to understand the
magnetism of the solar chromosphere. We performed a supporting study in
Quintero Noda et al. focused on the infrared Ca II 8542 Å line and we
concluded that it is one of the best candidates because it is sensitive
to a large range of atmospheric heights, from the photosphere to the
middle chromosphere. However, we believe that it is worth trying to
improve the results produced by this line observing additional spectral
lines. In that regard, we examined the neighbourhood solar spectrum
looking for spectral lines which could increase the sensitivity to
the atmospheric parameters. Interestingly, we discovered several
photospheric lines which greatly improve the photospheric sensitivity
to the magnetic field vector. Moreover, they are located close to a
second chromospheric line which also belongs to the Ca II infrared
triplet, I.e. the Ca II 8498 Å line, and enhances the sensitivity to
the atmospheric parameters at chromospheric layers. We conclude that the
lines in the vicinity of the Ca II 8542 Å line not only increase its
sensitivity to the atmospheric parameters at all layers, but also they
constitute an excellent spectral window for chromospheric polarimetry.
Title: Pre-eruption Oscillations in Thin and Long Features in a
Quiescent Filament
Authors: Joshi, Anand D.; Hanaoka, Yoichiro; Suematsu, Yoshinori;
Morita, Satoshi; Yurchyshyn, Vasyl; Cho, Kyung-Suk
Bibcode: 2016ApJ...833..243J
Altcode: 2016arXiv161204917J
We investigate the eruption of a quiescent filament located close to
an active region. Large-scale activation was observed in only half of
the filament in the form of pre-eruption oscillations. Consequently
only this half erupted nearly 30 hr after the oscillations
commenced. Time-slice diagrams of 171 Å images from the Atmospheric
Imaging Assembly were used to study the oscillations. These were
observed in several thin and long features connecting the filament
spine to the chromosphere below. This study traces the origin of
such features and proposes their possible interpretation. Small-scale
magnetic flux cancellation accompanied by a brightening was observed
at the footpoint of the features shortly before their appearance, in
images recorded by the Helioseismic and Magnetic Imager. A slow rise of
the filament was detected in addition to the oscillations, indicating
a gradual loss of equilibrium. Our analysis indicates that a change in
magnetic field connectivity between two neighbouring active regions
and the quiescent filament resulted in a weakening of the overlying
arcade of the filament, leading to its eruption. It is also suggested
that the oscillating features are filament barbs, and the oscillations
are a manifestation during the pre-eruption phase of the filaments.
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: 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: Analysis of a spatially deconvolved solar pore
Authors: Quintero Noda, C.; Shimizu, T.; Ruiz Cobo, B.; Suematsu,
Y.; Katsukawa, Y.; Ichimoto, K.
Bibcode: 2016MNRAS.460.1476Q
Altcode: 2016arXiv160501796Q; 2016MNRAS.tmp..847Q
Solar pores are active regions with large magnetic field strengths
and apparent simple magnetic configurations. Their properties
resemble the ones found for the sunspot umbra although pores do
not show penumbra. Therefore, solar pores present themselves as an
intriguing phenomenon that is not completely understood. We examine
in this work a solar pore observed with Hinode/SP using two state
of the art techniques. The first one is the spatial deconvolution
of the spectropolarimetric data that allows removing the stray
light contamination induced by the spatial point spread function
of the telescope. The second one is the inversion of the Stokes
profiles assuming local thermodynamic equilibrium that let us to
infer the atmospheric physical parameters. After applying these
techniques, we found that the spatial deconvolution method does not
introduce artefacts, even at the edges of the magnetic structure,
where large horizontal gradients are detected on the atmospheric
parameters. Moreover, we also describe the physical properties of
the magnetic structure at different heights finding that, in the
inner part of the solar pore, the temperature is lower than outside,
the magnetic field strength is larger than 2 kG and unipolar, and
the line-of-sight velocity is almost null. At neighbouring pixels,
we found low magnetic field strengths of same polarity and strong
downward motions that only occur at the low photosphere, below the
continuum optical depth log τ = -1. Finally, we studied the spatial
relation between different atmospheric parameters at different heights
corroborating the physical properties described before.
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: Development of a near-infrared detector and a fiber-optic
integral field unit for a space solar observatory SOLAR-C
Authors: Katsukawa, Yukio; Kamata, Yukiko; Anan, Tetsu; Hara,
Hirohisa; Suematsu, Yoshinori; Bando, Takamasa; Ichimoto, Kiyoshi;
Shimizu, Toshifumi
Bibcode: 2016SPIE.9904E..5IK
Altcode:
We are developing a high sensitivity and fast readout near-infrared
(NIR) detector and an integral field unit (IFU) for making
spectro-polarimetric observations of rapidly varying chromospheric
spectrum lines, such as He I 1083 nm and Ca II 854 nm, in the
next space-based solar mission SOLAR-C. We made tests of a 1.7 μm
cutoff H2RG detector with the SIDECAR ASIC for the application in
SOLAR-C. It's important to verify its perfor- mance in the temperature
condition around -100 °C, which is hotter than the typical temperature
environment used for a NIR detector. We built a system for testing the
detector between -70 °C and -140 °C. We verified linearity, read-out
noise, and dark current in both the slow and fast readout modes. We
found the detector has to be cooled down lower than -100 °C because
of significant increase of the number of hot pixels in the hotter
environment. The compact and polarization maintenance IFU was designed
using fiber-optic ribbons consisting of rectangular cores which exhibit
good polarization maintenance. A Silicone adhesive DC-SE9187L was used
to hold the fragile fiber-optic ribbons in a metal housing. Polarization
maintenance property was confirmed though polarization calibration
as well as temperature control are required to suppress polarization
crosstalk and to achieve the polarization accuracy in SOLAR-C.
Title: Analysis of spatially deconvolved polar faculae
Authors: Quintero Noda, C.; Suematsu, Y.; Ruiz Cobo, B.; Shimizu,
T.; Asensio Ramos, A.
Bibcode: 2016MNRAS.460..956Q
Altcode: 2016MNRAS.tmp..838Q; 2016arXiv160500330Q
Polar faculae are bright features that can be detected in
solar limb observations and they are related to magnetic field
concentrations. Although there are a large number of works studying
them, some questions about their nature as their magnetic properties
at different heights are still open. Thus, we aim to improve the
understanding of solar polar faculae. In that sense, we infer
the vertical stratification of the temperature, gas pressure,
line-of-sight velocity and magnetic field vector of polar faculae
regions. We performed inversions of the Stokes profiles observed
with Hinode/Spectropolarimeter after removing the stray light
contamination produced by the spatial point spread function of the
telescope. Moreover, after solving the azimuth ambiguity, we transform
the magnetic field vector to local solar coordinates. The obtained
results reveal that the polar faculae are constituted by hot plasma with
low line-of-sight velocities and single polarity magnetic fields in the
kilogauss range that are nearly perpendicular to the solar surface. We
also found that the spatial location of these magnetic fields is
slightly shifted respect to the continuum observations towards the
disc centre. We believe that this is due to the hot wall effect that
allows detecting photons that come from deeper layers located closer
to the solar limb.
Title: Development of compact metal-mirror image slicer unit for
optical telescope of the SOLAR-C mission
Authors: Suematsu, Y.; Saito, K.; Koyama, M.; Enokida, Y.; Okura,
Y.; Nakayasu, T.; Sukegawa, T.
Bibcode: 2016SPIE.9904E..11S
Altcode:
To realize an integral field unit (IFU) for a one-meter class optical
telescope (SUVIT) on board Japanese next solar mission (SOLAR-C),
we studied an optical design and manufacturing method to attain high
optical performances for IFU, using a novel manufacturing technique
developed by Canon. The IFU consists of micro-image slicer of 45 arrayed
30-micron-thick metal mirrors and a pseudo-pupil mirror array for
making three pseudo-slits, providing possible optical configuration
for a coexistence with a usual slit spectrograph without movable
mechanism. The IFU mirrors were deposited by a protected silver coating
for high reflectivity in visible and near IR wavelength region. We
present the optical design, performance of prototype IFU and space
qualification tests of the silver coating.
Title: Spectropolarimetric capabilities of Ca II 8542 Å line
Authors: Quintero Noda, C.; Shimizu, T.; de la Cruz Rodríguez, J.;
Katsukawa, Y.; Ichimoto, K.; Anan, T.; Suematsu, Y.
Bibcode: 2016MNRAS.459.3363Q
Altcode: 2016MNRAS.tmp..667Q; 2016arXiv160404957Q
The next generation of space- and ground-based solar missions aim
to study the magnetic properties of the solar chromosphere using the
infrared Ca II lines and the He I 10830 Å line. The former seem to be
the best candidates to study the stratification of magnetic fields in
the solar chromosphere and their relation to the other thermodynamical
properties underlying the chromospheric plasma. The purpose of this
work is to provide a detailed analysis of the diagnostic capabilities
of the Ca II 8542 Å line, anticipating forthcoming observational
facilities. We study the sensitivity of the Ca II 8542 Å line
to perturbations applied to the physical parameters of reference
semi-empirical 1D model atmospheres using response functions and we
make use of 3D magnetohydrodynamics simulations to examine the expected
polarization signals for moderate magnetic field strengths. Our results
indicate that the Ca II 8542 Å line is mostly sensitive to the layers
enclosed in the range log τ = [0, -5.5], under the physical conditions
that are present in our model atmospheres. In addition, the simulated
magnetic flux tube generates strong longitudinal signals in its centre
and moderate transversal signals, due to the vertical expansion of
magnetic field lines, in its edge. Thus, observing the Ca II 8542 Å
line we will be able to infer the 3D geometry of moderate magnetic
field regions.
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 the Universal Tunable Filter and High-resolution
Imaging Observation with the Fuxian Solar Observatory
Authors: Hagino, M.; Ichimoto, K.; Ueno, S.; Kimura, G.; Otsuji, K.;
Kitai, R.; Zhong, L.; Xu, Z.; Shinoda, K.; Hara, H.; Suematsu, Y.;
Shimizu, T.
Bibcode: 2016ASPC..504..103H
Altcode:
We have developed a new narrow-band universal tunable filter to perform
imaging spectroscopy of the solar chromosphere. The development stage
of the filter has been almost finished and we shifted to the scientific
observation phase by using large grand-based telescopes. Using the
filter, a series of high-resolution images were obtained with the 1m
vacuum solar telescope at the Fuxian Solar Observatory. We succeeded in
observing several flares and fine structures of the chromospheric layer.
Title: The SOLAR-C Mission: Science Objectives and Current Status
Authors: Suematsu, Y.; Solar-C Working Group
Bibcode: 2016ASPC..504..299S
Altcode:
The SOLAR-C is a Japan-led international solar mission for mid-2020s
designed to investigate the magnetic activities of the Sun, focusing on
the study in heating and dynamical phenomena of the chromosphere and
corona, and to advance algorithms for predicting short and long term
solar magnetic activities. For these purposes, SOLAR-C will carry three
dedicated instruments; the Solar UV-Vis-IR Telescope (SUVIT), the EUV
Spectroscopic Telescope (EUVST) and the High Resolution Coronal Imager
(HCI), to jointly observe the entire visible solar atmosphere with
essentially the same high spatial resolution (0.1"-0.3"), performing
high resolution spectroscopic measurements over all atmospheric regions
and spectro-polarimetric measurements from the photosphere through
the upper chromosphere. SOLAR-C will also contribute to understand
the solar influence on the Sun-Earth environments with synergetic
wide-field observations from ground-based and other space missions.
Title: Analysis of horizontal flows in the solar granulation
Authors: Quintero Noda, C.; Shimizu, T.; Suematsu, Y.
Bibcode: 2016MNRAS.457.1703Q
Altcode: 2016arXiv160103814Q
Solar limb observations sometimes reveal the presence of a satellite
lobe in the blue wing of the Stokes I profile from pixels belonging to
granules. The presence of this satellite lobe has been associated in
the past to strong line-of-sight gradients and, as the line-of-sight
component is almost parallel to the solar surface, to horizontal
granular flows. We aim to increase the knowledge about these horizontal
flows studying a spectropolarimetric observation of the north solar
pole. We will make use of two state of the art techniques, the spatial
deconvolution procedure that increases the quality of the data removing
the stray light contamination, and spectropolarimetric inversions that
will provide the vertical stratification of the atmospheric physical
parameters where the observed spectral lines form. We inverted the
Stokes profiles using a two component configuration, obtaining that
one component is strongly blueshifted and displays a temperature
enhancement at upper photospheric layers while the second component has
low redshifted velocities and it is cool at upper layers. In addition,
we examined a large number of cases located at different heliocentric
angles, finding smaller velocities as we move from the centre to the
edge of the granule. Moreover, the height location of the enhancement
on the temperature stratification of the blueshifted component also
evolves with the spatial location on the granule being positioned on
lower heights as we move to the periphery of the granular structure.
Title: The SOLAR-C Mission
Authors: Suematsu, Y.
Bibcode: 2015AGUFMSH21C..03S
Altcode:
The Solar-C is a Japan-led international solar mission planned to
be launched in mid2020. It is designed to investigate the magnetic
activities of the Sun, focusing on the study in heating and dynamical
phenomena of the chromosphere and corona, and also to develop an
algorithm for predicting short and long term solar evolution. Since
it has been revealed that the different parts of the magnetized
solar atmosphere are essentially coupled, the SOLAR-C should tackle
the spatial scales and temperature regimes that need to be observed
in order to achieve a comprehensive physical understanding of this
coupling. The science of Solar-C will greatly advance our understanding
of the Sun, of basic physical processes operating throughout the
universe. To dramatically improve the situation, SOLAR-C will carry
three dedicated instruments; the Solar UV-Vis-IR Telescope (SUVIT),
the EUV Spectroscopic Telescope (EUVST) and the High Resolution
Coronal Imager (HCI), to jointly observe the entire visible solar
atmosphere with essentially the same high spatial resolution (0.1-0.3
arcsec), performing high resolution spectroscopic measurements over
all atmospheric regions and spectro-polarimetric measurements from
the photosphere through the upper chromosphere. In addition, Solar-C
will contribute to our understanding on the influence of the Sun-Earth
environments with synergetic wide-field observations from ground-based
and other space missions. Some leading science objectives and the
mission concept, including designs of the three instruments aboard
SOLAR-C will be presented.
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: Photon Mean Free Paths, Scattering, and Ever-Increasing
Telescope Resolution
Authors: Judge, P. G.; Kleint, L.; Uitenbroek, H.; Rempel, M.;
Suematsu, Y.; Tsuneta, S.
Bibcode: 2015SoPh..290..979J
Altcode: 2014arXiv1409.7866J; 2015SoPh..tmp....3J
We revisit an old question: what are the effects of observing stratified
atmospheres on scales below a photon mean free path λ? The mean free
path of photons emerging from the solar photosphere and chromosphere
is ≈ 102 km. Using current 1 m-class telescopes, λ is
on the order of the angular resolution. But the Daniel K. Inoue Solar
Telescope will have a diffraction limit of 0.020″ near the atmospheric
cutoff at 310 nm, corresponding to 14 km at the solar surface. Even
a small amount of scattering in the source function leads to physical
smearing due to this solar "fog", with effects similar to a degradation
of the telescope point spread function. We discuss a unified picture
that depends simply on the nature and amount of scattering in the
source function. Scalings are derived from which the scattering in the
solar atmosphere can be transcribed into an effective Strehl ratio,
a quantity useful to observers. Observations in both permitted (e.g.,
Fe I 630.2 nm) and forbidden (Fe I 525.0 nm) lines will shed light on
both instrumental performance as well as on small-scale structures in
the solar atmosphere.
Title: Photospheric Flow Field Related to the Evolution of the Sun's
Polar Magnetic Patches Observed by Hinode Solar Optical Telescope
Authors: Kaithakkal, Anjali John; Suematsu, Y.; Kubo, M.; Iida, Y.;
Shiota, D.; Tsuneta, S.
Bibcode: 2015ApJ...799..139K
Altcode: 2014arXiv1412.8023K
We investigated the role of photospheric plasma motions in the formation
and evolution of polar magnetic patches using time-sequence observations
with high spatial resolution. The observations were obtained with
the spectropolarimeter on board the Hinode satellite. From the
statistical analysis using 75 magnetic patches, we found that they are
surrounded by strong converging, supergranulation associated flows
during their apparent lifetime and that the converging flow around
the patch boundary is better observed in the Doppler velocity profile
in the deeper photosphere. Based on our analysis, we suggest that the
like-polarity magnetic fragments in the polar region are advected and
clustered by photospheric converging flows, thereby resulting in the
formation of polar magnetic patches. Our observations show that, in
addition to direct cancellation, magnetic patches decay by fragmentation
followed by unipolar disappearance or unipolar disappearance without
fragmentation. It is possible that the magnetic patches of existing
polarity fragment or diffuse away into smaller elements and eventually
cancel out with opposite polarity fragments that reach the polar region
around the solar cycle maximum. This could be one of the possible
mechanisms by which the existing polarity decays during the reversal
of the polar magnetic field.
Title: Fine-Scale Structure of Solar Polar Faculae and their relation
to Magnetic Patches
Authors: Suematsu, Y.; Kaithakkal, A. J.
Bibcode: 2014AGUFMSH31C..07S
Altcode:
The fine-scale structure and dynamics of solar polar faculae were
studied using Hinode/SOT spectro-polarimetric and filtergraphic
observations at polar regions. It is revealed that polar magnetic
patches of large flux have substructures, with a few small faculae
in the much larger patches. It was also found that faculae tend to
have higher intrinsic magnetic field strengths compared with the
non-facular regions inside the associated magnetic patches. G-band
images reveal much thinner facular structures of close to 0.1 arcsec and
the faculae appear as a cluster of thin tapered tube-like structures;
individual size is about 0.2 x 0.5 arcsec, reaching the maximum closer
mid-way to the limb, are likely projected on the limb-side neighboring
granules with center-ward dark lanes. Typical lifetime of each facular
elements is about five minutes, showing side-way motion during the
life. Corresponding bright fine elongated structures are seen in Ca
II H, although such structures are more numerous and therefore there
does not always exist one-to-one correspondence of Ca II H bright
structures with the G-band facular elements. In H-alpha and Na I D line
wing, fibril structure emanating limb-ward from the faulae and Ca II H
bright regions. Those facts imply that the polar faculae appear in the
root of intense vertically-oriented thin magnetic flux tubes which are
consistent with the result from the magnetic properties reduced from
the spectro-polarimetry. Those results suggest that the Spruit's hot
wall effect explains the appearance of faculae in intense vertically
oriented flux tube whose formation is dynamically changing.
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: Large aperture solar optical telescope and instruments for
the SOLAR-C mission
Authors: Suematsu, Y.; Katsukawa, Y.; Hara, H.; Kano, R.; Shimizu,
T.; Ichimoto, K.
Bibcode: 2014SPIE.9143E..1PS
Altcode:
A large aperture solar optical telescope and its instruments
for the SOLAR-C mission are under study to provide the critical
physical parameters in the lower solar atmosphere and to resolve the
mechanism of magnetic dynamic events happening there and in the upper
atmosphere as well. For the precise magnetic field measurements and
high angular resolution in wide wavelength region, covering FOV of 3
arcmin x3 arcmin, an entrance aperture of 1.4 m Gregorian telescope is
proposed. Filtergraphs are designed to realize high resolution imaging
and pseudo 2D spectro-polarimetry in several magnetic sensitive lines of
both photosphere and chromosphere. A full stokes polarimetry is carried
out at three magnetic sensitive lines with a four-slit spectrograph
of 2D image scanning mechanism. We present a progress in optical and
structural design of SOLAR-C large aperture optical telescope and its
observing instruments which fulfill science requirements.
Title: Development of micro image slicer of integral field unit for
spaceborne solar spectrograph
Authors: Suematsu, Y.; Sukegawa, T.; Okura, Y.; Nakayasu, T.; Enokida,
Y.; Koyama, M.; Saito, K.; Ozaki, S.; Tsuneta, S.
Bibcode: 2014SPIE.9151E..1SS
Altcode:
We present an innovative optical design for image slicer integral field
unit (IFU) and manufacturing method which overcome optical limitation of
metallic mirrors. Our IFU consists of micro image slicer of 45 arrayed
highly-narrow flat metallic mirrors and a pseudo pupil mirror array
of off-axis conic aspheres forming three pseudo slits of re-arranged
slicer images. A prototype IFU demonstrates their optical quality high
enough for a visible light spectrograph. The each slicer mirror is 1.58
mm in length and 30μm in width with surface roughness < 1 nm rms,
edge sharpness < 0.1μm, etc. This IFU is small-sized and can be
implemented in a multi-slit spectrograph without any moving mechanism
and fore optics in which one slit is real and the others are of pseudo
slits from the IFU. Those properties are well suitable for space-borne
spectrograph to be aboard such as a next Japanese solar mission SOLAR-C.
Title: 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: Development of a universal tunable filter for future solar
observations
Authors: Hagino, M.; Ichimoto, K.; Kimura, G.; Nakatani, Y.; Kawate,
T.; Shinoda, K.; Suematsu, Y.; Hara, H.; Shimizu, T.
Bibcode: 2014SPIE.9151E..5VH
Altcode:
We have developed a new narrowband tunable filter to perform imaging
spectroscopy of the solar chromosphere. Using Liquid Crystal Variable
Retarders (LCVRs) as the tuning elements for wavelength, wide-band
polarizers and super achromatic half-wave plates, it is possible to make
high speed tuning (about 0.1Sec), to exclude mechanical drives (and oil
tank), and to cover a wide wavelength range (510-100nm). This filter
builds up with seven stages each consisting of a pair of calcites,
LCVR, half-wave plates and linear polarizer. The full width at half
maximum (FWHM) of the filter transmission is about 0.025nm at 656.3nm.We
demonstrate that the concept of the universal tunable filter using the
LCVR's as tuning elements is highly promising for future application
to space mission and ground based observations.
Title: UV spectropolarimeter design for precise polarization
measurement and its application to the CLASP for exploration of
magnetic fields in solar atmosphere
Authors: Narukage, Noriyuki; Katsukawa, Yukio; Hara, Hirohisa; Kubo,
Masahito; Auchere, Frederic; Ishikawa, Ryohko; Kano, Ryouhei; Bando,
Takamasa; Ishikawa, Shin-nosuke; Suematsu, Yoshinori; Tsuneta, Saku
Bibcode: 2014cosp...40E2232N
Altcode:
In order to measure the magnetic field in the region where the
hot plasma from 10 (4) K to 10 (6) K is occupied, e.g., for solar
atmosphere, the polarimetric measurements in ultra violet (UV)
with 0.1% accuracy are required. In this paper, we propose a new
UV spectropolarimeter design with 0.1% sensitivity in polarization
measurement. This spectropolarimeter has two devices for the 0.1%
accuracy. First, all optical components except the waveplate are the
reflective type ones that can be equipped with the high reflectivity
coating for the high throughput. Secondly, it equips the optically
symmetric dual channels to measure the orthogonal linear polarization
state simultaneously, using a concave diffraction grating as both the
spectral dispersion element and the beam splitter. These two devices
make the spurious polarizations caused by the photon noise, by the
intensity variation of the observation target, and, by the instrument
itself, enough small to achieve the 0.1% accuracy in polarization
measurement. The spectropolarimeter thus designed is currently under
fabrication for the sounding rocket project of Chromospheric Lyman-Alpha
SpectroPolarimeter (CLASP) that aims at the direct measurement of the
magnetic fields in solar atmosphere with Lyman-alpha line (121.6 nm)
for the first time.
Title: The Association of Polar Faculae with Polar Magnetic Patches
Examined with Hinode Observations
Authors: Kaithakkal, Anjali John; Suematsu, Y.; Kubo, M.; Shiota,
D.; Tsuneta, S.
Bibcode: 2013ApJ...776..122K
Altcode: 2013arXiv1311.0980K
The magnetic properties of the Sun's polar faculae are investigated with
spectropolarimetric observations of the north polar region obtained by
the Hinode satellite in 2007 September. Polar faculae are embedded in
nearly all magnetic patches with fluxes greater than 1018
Mx, while magnetic patches without polar faculae dominate in the flux
range below 1018 Mx. The faculae are considerably smaller
than their parent patches, and single magnetic patches contain single
or multiple faculae. The faculae in general have higher intrinsic
magnetic field strengths than the surrounding regions within their
parent patches. Less than 20% of the total magnetic flux contributed
by the large (>=1018 Mx) concentrations, which are known
to be modulated by the solar cycle, is accounted for by the associated
polar faculae.
Title: 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: Next space solar observatory SOLAR-C: mission instruments
and science objectives
Authors: Katsukawa, Y.; Watanabe, T.; Hara, H.; Ichimoto, K.; Kubo,
M.; Kusano, K.; Sakao, T.; Shimizu, T.; Suematsu, Y.; Tsuneta, S.
Bibcode: 2012IAUSS...6E.207K
Altcode:
SOLAR-C, the fourth space solar mission in Japan, is under study with a
launch target of fiscal year 2018. A key concept of the mission is to
view the photosphere, chromosphere, and corona as one system coupled
by magnetic fields along with resolving the size scale of fundamental
physical processes connecting these atmospheric layers. It is especially
important to study magnetic structure in the chromosphere as an
interface layer between the photosphere and the corona. The SOLAR-C
satellite is equipped with three telescopes, the Solar UV-Visible-IR
Telescope (SUVIT), the EUV/FUV High Throughput Spectroscopic Telescope
(EUVS/LEMUR), and the X-ray Imaging Telescope (XIT). Observations
with SUVIT of photospheric and chromospheric magnetic fields make it
possible to infer three dimensional magnetic structure extending from
the photosphere to the chromosphere and corona.This helps to identify
magnetic structures causing magnetic reconnection, and clarify how
waves are propagated, reflected, and dissipated. Phenomena indicative
of or byproducts of magnetic reconnection, such as flows and shocks,
are to be captured by SUVIT and by spectroscopic observations using
EUVS/LEMUR, while XIT observes rapid changes in temperature distribution
of plasma heated by shock waves.
Title: Instrument Design of the Large Aperture Solar UV Visible and
IR Observing Telescope (SUVIT) for the SOLAR-C Mission
Authors: Suematsu, Y.; Katsukawa, Y.; Shimizu, T.; Ichimoto, K.;
Takeyama, N.
Bibcode: 2012ASPC..463..439S
Altcode:
We present an instrumental design of one major solar observation payload
planned for the SOLAR-C mission: the Solar Ultra-violet Visible and
near IR observing Telescope (SUVIT). The SUVIT is designed to provide
high-angular-resolution investigation of the lower solar atmosphere,
from the photosphere to the uppermost chromosphere, with enhanced
spectroscopic and spectro-polarimetric capability in wide wavelength
regions from 280 nm (Mg II h&k lines) to 1100 nm (He I 1083 nm
line) with 1.5 m class aperture and filtergraphic and spectrographic
instruments.
Title: Association of Polar Faculae with the Polar Magnetic Patches
as Revealed by Hinode
Authors: Kaithakkal, A. J.; Tsuneta, S.; Suematsu, Y.; Kubo, M.;
Shiota, D.; Shimojo, M.
Bibcode: 2012AGUFMSH13C2273K
Altcode:
Polar faculae are small bright features in the polar region of the
Sun. They are observed with concentrations of magnetic fields. Previous
studies have shown that the number of polar faculae at latitudes greater
than 50 degrees has 11-year periodicity like the sunspot cycle, but
becomes a maximum in the solar minimum period. The aim of this study is
to understand the magnetic properties of faculae, which are believed
to be associated with the polar magnetic patches. We analysed data of
the north polar region taken by the Hinode/SOT spectropolarimeter (SP)
in September 2007. Accurate measurements of vector magnetic fields
at high spatial resolution by Hinode/SP for the first time allow us
to compare polar faculae with polar magnetic fields in detail. The
continuum intensity map is corrected for limb darkening. There are many
patchy magnetic field structures in the polar region and thresholds on
both size and intensity for the patches are applied to automatically
choose faculae. The definition of magnetic patch is same as in Shiota et
al. (2012 ApJ). We find that magnetic patches are not uniformly bright
but contain smaller faculae inside. The following results describe
the properties of faculae associated with the majority polarity
patches. Our results show that a positive correlation exists between
total flux and average intensity contrast of faculae. On average the
contribution of polar faculae to the total flux of the patch is less
than 30% and the area occupied by polar faculae with in a patch is
roughly 20-25%. We find that there are patches without faculae and
their number is much larger than those with faculae. We also find
that faculae are present in all the patches with total flux ≥ 10^19
Mx. Our result show that faculae are polarity independent and hence are
associated with minority polarity patches as well. But the flux of these
minority polarity faculae is <10^18 Mx in most of the cases. These
results suggest that the magnetic patches and polar faculae do not
have a one-to-one spatial correspondence and have fine structure, and
may raise a fundamental question on our current understanding on the
formation of the faculae. Shiota et al. (2012 ApJ) report that there
are two classes of magnetic patches: small (< 10^18 Mx) and large
(≥10^18 Mx) of which the large patches contribute to the cyclic
variation of the polar magnetic flux. This is consistent with the
concept of faculae as a proxy of the majority polarity magnetic flux.
Title: Science and Instrument Design of 1.5-m Aperture Solar Optical
Telescope for the SOLAR-C Mission
Authors: Suematsu, Y.; Katsukawa, Y.; Ichimoto, K.; Shimizu, T.
Bibcode: 2012IAUSS...6E.208S
Altcode:
We present science cases and a design of one of major instruments for
SOLAR-C mission; 1.5-m-class aperture solar ultra-violet visible and
near IR observing Telescope (SUVIT). The SOLAR-C mission aims at fully
understanding dynamism and magnetic nature of the solar atmosphere by
observing small-scale plasma processes and structures. The SUVIT is
designed to provide high-angular-resolution investigation of lower
atmosphere from the photosphere to the uppermost chromosphere with
enhanced spectroscopic and spectro-polarimetric capability covering
a wide wavelength region from 280 nm (Mg II h&k) to 1100 nm (He
I 1083 nm), using focal plane instruments: wide-band and narrow-band
filtergraphs and a spectrograph for high-precision spectro-polarimetry
in the solar photospheric and chromospheric lines. We will discuss
about instrument design to realize the science cases.
Title: Solar Fine-Scale Structures. I. Spicules and Other Small-Scale,
Jet-Like Events at the Chromospheric Level: Observations and Physical
Parameters
Authors: Tsiropoula, G.; Tziotziou, K.; Kontogiannis, I.; Madjarska,
M. S.; Doyle, J. G.; Suematsu, Y.
Bibcode: 2012SSRv..169..181T
Altcode: 2012SSRv..tmp...65T; 2012arXiv1207.3956T
Over the last two decades the uninterrupted, high resolution
observations of the Sun, from the excellent range of telescopes aboard
many spacecraft complemented with observations from sophisticated
ground-based telescopes have opened up a new world producing
significantly more complete information on the physical conditions of
the solar atmosphere than before. The interface between the lower solar
atmosphere where energy is generated by subsurface convection and the
corona comprises the chromosphere, which is dominated by jet-like,
dynamic structures, called mottles when found in quiet regions,
fibrils when found in active regions and spicules when observed at
the solar limb. Recently, space observations with Hinode have led to
the suggestion that there should exist two different types of spicules
called Type I and Type II which have different properties. Ground-based
observations in the Ca ii H and K filtergrams reveal the existence of
long, thin emission features called straws in observations close to
the limb, and a class of short-lived events called rapid blue-shifted
excursions characterized by large Doppler shifts that appear only
in the blue wing of the Ca ii infrared line. It has been suggested
that the key to understanding how the solar plasma is accelerated
and heated may well be found in the studies of these jet-like,
dynamic events. However, while these structures are observed and
studied for more than 130 years in the visible, but also in the UV
and EUV emission lines and continua, there are still many questions
to be answered. Thus, despite their importance and a multitude of
observations performed and theoretical models proposed, questions
regarding their origin, how they are formed, their physical parameters,
their association with the underlying photospheric magnetic field, how
they appear in the different spectral lines, and the interrelationship
between structures observed in quiet and active regions on the disk
and at the limb, as well as their role in global processes has not
yet received definitive answers. In addition, how they affect the
coronal heating and solar wind need to be further explored. In this
review we present observations and physical properties of small-scale
jet-like chromospheric events observed in active and quiet regions,
on the disk and at the limb and discuss their interrelationship.
Title: Design of large aperture solar optical telescope for the
SOLAR-C mission
Authors: Suematsu, Y.; Katsukawa, Y.; Hara, H.; Shimizu, T.;
Ichimoto, K.
Bibcode: 2012SPIE.8442E..25S
Altcode:
A large aperture optical telescope is planned for the next Japanese
solar mission SOLAR-C as one of major three observing instruments. The
optical telescope is designed to provide high-angular-resolution
investigation of lower atmosphere from the photosphere to the uppermost
chromosphere with enhanced spectroscopic and spectro-polarimetric
capability covering a wide wavelength region from 280 nm to 1100
nm. The opto-mechanical and -thermal performance of the telescope is
crucial to attain high-quality solar observations and we present a
study of optical and structural design of the large aperture space
solar telescope, together with conceptual design of its accompanying
focal plane instruments: wide-band and narrow-band filtergraphs and
a spectro-polarimeter for high spatial and temporal observations in
the solar photospheric and chromospheric lines useful for sounding
physical condition of dynamical phenomena.
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: Excitation of Slow-Modes in Network Magnetic Elements
Authors: Kato, Y.; Steiner, O.; Steffen, M.; Suematsu, Y.
Bibcode: 2012ASPC..455..237K
Altcode:
From radiation magnetohydrodynamic (RMHD) simulations of the solar
atmosphere we have found a new mechanism for the excitation of
longitudinal slow modes within magnetic flux concentrations. It is
found that the convective downdrafts in the immediate surroundings of
magnetic elements are responsible for the excitation of slow modes. The
coupling between the external downdraft and the plasma motion internal
to the flux concentration is mediated by the inertial forces of the
downdraft that act on the magnetic flux concentration. These forces
pump the internal atmosphere in the downward direction, which entails
a fast downflow in the photospheric and chromospheric layers of the
magnetic element. Subsequent to the transient pumping phase, the
atmosphere rebounds, causing a slow mode traveling along the magnetic
flux concentration in the upward direction and developing into a shock
wave in chromospheric heights, possibly capable of producing some kind
of dynamic fibril. This event occurs recurrently. We compare the power
spectra of the temperature and velocity of the flux-sheet atmosphere
to the corresponding spectra of the unmagnetized atmosphere.
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: Precursor of Sunspot Penumbral Formation Discovered with
Hinode SOT Observation
Authors: Shimizu, T.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2012ASPC..456...43S
Altcode:
We newly found a precursory signature of sunspot penumbral formation
in Ca II H images. The precursor is a dark annular zone (width 3"-5")
around the umbra (pore), which was formed soon after the pore formation
and existed until the penumbral formation. The penumbra was developed
as if to fill the annular zone. Pre-existing ambient magnetic field
islands were moved to be distributed at the outer edge of the annular
zone and did not come into the zone. The observations indicate that
the annular zone is different from sunspot moat flow region and that
the zone is visible only in chromospheric Ca II H images, not in
photospheric G-band images. We conclude that the annular zone reflects
the formation of a magnetic canopy overlying the region surrounding
the umbra at the chromospheric level, much before the formation of the
penumbra at the photospheric level. We can predict the region and size
of the penumbra, by looking at the appearance of dark zone around pores.
Title: Precursor of Sunspot Penumbral Formation Discovered with
Hinode Solar Optical Telescope Observations
Authors: Shimizu, Toshifumi; Ichimoto, Kiyoshi; Suematsu, Yoshinori
Bibcode: 2012ApJ...747L..18S
Altcode: 2012arXiv1202.1025S
We present observations of a precursory signature that would be helpful
for understanding the formation process of sunspot penumbrae. The Hinode
Solar Optical Telescope successfully captured the entire evolution of a
sunspot from the pore to a large well-developed sunspot with penumbra
in an emerging flux region appearing in NOAA Active Region 11039. We
found an annular zone (width 3''-5'') surrounding the umbra (pore)
in Ca II H images before the penumbra formed around the umbra. The
penumbra developed as if to fill the annular zone. The annular zone
shows weak magnetogram signals, meaning less magnetic flux or highly
inclined fields there. Pre-existing ambient magnetic field islands were
distributed at the outer edge of the annular zone and did not come into
the zone. There are no strong systematic flow patterns in the zone,
but we occasionally observed small magnetic flux patches streaming
out. The observations indicate that the annular zone is different from
the sunspot moat flow region and that it represents the structure in the
chromosphere. We conclude that the annular zone reflects the formation
of a magnetic canopy overlying the region surrounding the umbra at the
chromospheric level, long before the formation of the penumbra at the
photospheric level. The magnetic field structure in the chromosphere
needs to be considered in the formation process of the penumbrae.
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: Integral Field Spectroscopy of the Sun with Microlens Array
and Liquid Crystal Retarders
Authors: Suematsu, Y.; Shinoda, K.; Sano, I.; Kobiki, T.
Bibcode: 2011AGUFMSH13B1947S
Altcode:
Simultaneous spectrographic observations over extended solar structures,
at a high spatial resolution and temporal cadence, are important
to track and understand the physics of transient phenomena such as
Ellerman bombs, flare kernels, prominences/filaments and spicules. With
two-dimensional (2-D) field spectral data, we can make monochromatic
images at a given wavelength in a designed passband and line profile
analysis to derive 2-D distribution of atmospheric parameters. One
technique to produce a spectrum of each spatial elements in an extended
two-dimensional field is to use a micro-lens array. Replacing a slit
of a conventional spectrograph with a micro-lens array then helps to
capture two-dimensionally distributed short spectra from 2-D field
using additional optics inserted, a bandpass filter and a large format
detector. For observations of magnetic field, we can add polarization
modulator made of liquid crystal retarders which give a sequence of
alternative orthogonal polarization states with time. We describe a
design concept and limitations for observations with the micro-lens
array spectrograph and an initial result applied for a few existing
solar telescopes at NAOJ and Hida Observatory, Kyoto University.
Title: Focal plane instrument for the Solar UV-Vis-IR Telescope
aboard SOLAR-C
Authors: Katsukawa, Yukio; Suematsu, Yoshinori; Shimizu, Toshifumi;
Ichimoto, Kiyoshi; Takeyama, Norihide
Bibcode: 2011SPIE.8148E..0EK
Altcode: 2011SPIE.8148E..13K
It is presented the conceptual design of a focal plane instrument for
the Solar UV-Vis-IR Telescope (SUVIT) aboard the next Japanese solar
mission SOLAR-C. A primary purpose of the telescope is to achieve
precise as well as high resolution spectroscopic and polarimetric
measurements of the solar chromosphere with a big aperture of 1.5 m,
which is expected to make a significant progress in understanding basic
MHD processes in the solar atmosphere. The focal plane instrument
consists of two packages: A filtergraph package is to get not only
monochromatic images but also Dopplergrams and magnetograms using a
tunable narrow-band filter and interference filters. A spectrograph
package is to perform accurate spectro-polarimetric observations for
measuring chromospheric magnetic fields, and is employing a Littrow-type
spectrograph. The most challenging aspect in the instrument design is
wide wavelength coverage from 280 nm to 1.1 μm to observe multiple
chromospheric lines, which is to be realized with a lens unit including
fluoride glasses. A high-speed camera for correlation tracking of
granular motion is also implemented in one of the packages for an
image stabilization system, which is essential to achieve high spatial
resolution and high polarimetric accuracy.
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: Overview of Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP)
Authors: Narukage, Noriyuki; Tsuneta, Saku; Bando, Takamasa; Kano,
Ryouhei; Kubo, Masahito; Ishikawa, Ryoko; Hara, Hirohisa; Suematsu,
Yoshinori; Katsukawa, Yukio; Watanabe, Hiroko; Ichimoto, Kiyoshi;
Sakao, Taro; Shimizu, Toshifumi; Kobayashi, Ken; Robinson, Brian; Kim,
Tony; Winebarger, Amy; West, Edward; Cirtain, Jonathan; De Pontieu,
Bart; Casini, Roberto; Trujillo Bueno, Javier; Stepan, Jiri; Manso
Sainz, Rafael; Belluzzi, Luca; Asensio Ramos, Andres; Carlsson, Mats
Bibcode: 2011SPIE.8148E..0HN
Altcode: 2011SPIE.8148E..16N
The solar chromosphere is an important boundary, through which all of
the plasma, magnetic fields and energy in the corona and solar wind
are supplied. Since the Zeeman splitting is typically smaller than
the Doppler line broadening in the chromosphere and transition region,
it is not effective to explore weak magnetic fields. However, this is
not the case for the Hanle effect, when we have an instrument with
high polarization sensitivity (~ 0.1%). "Chromospheric Lyman- Alpha
SpectroPolarimeter (CLASP)" is the sounding rocket experiment to detect
linear polarization produced by the Hanle effect in Lyman-alpha line
(121.567 nm) and to make the first direct measurement of magnetic
fields in the upper chromosphere and lower transition region. To
achieve the high sensitivity of ~ 0.1% within a rocket flight (5
minutes) in Lyman-alpha line, which is easily absorbed by materials,
we design the optical system mainly with reflections. The CLASP
consists of a classical Cassegrain telescope, a polarimeter and a
spectrometer. The polarimeter consists of a rotating 1/2-wave plate
and two reflecting polarization analyzers. One of the analyzer also
works as a polarization beam splitter to give us two orthogonal linear
polarizations simultaneously. The CLASP is planned to be launched in
2014 summer.
Title: The SOLAR-C mission: current status
Authors: Shimizu, Toshifumi; Tsuneta, Saku; Hara, Hirohisa; Ichimoto,
Kiyoshi; Kusano, Kanya; Sakao, Taro; Sekii, Takashi; Suematsu,
Yoshinori; Watanabe, Tetsuya
Bibcode: 2011SPIE.8148E..0BS
Altcode: 2011SPIE.8148E..10S
Two mission concepts (plan A: out-of-ecliptic mission and plan B:
high resolution spectroscopic mission) have been studied for the next
Japanese-led solar mission Solar-C, which will follow the scientific
success of the Hinode mission. The both mission concepts are concluded
as equally important and attractive for the promotion of space solar
physics. In the meantime we also had to make efforts for prioritizing
the two options, in order to proceed to next stage of requesting the
launch of Solar-C mission at the earliest opportunity. This paper
briefly describes the two mission concepts and the current status
on our efforts for prioritizing the two options. More details are
also described for the plan B option as the first-priority Solar-C
mission. The latest report from the Solar-C mission concept studies
was documented as "Interim Report on the Solar-C Mission Concept."
Title: Short telescope design of 1.5-m aperture solar UV visible
and IR telescope aboard Solar-C
Authors: Suematsu, Y.; Katsukawa, Y.; Shimizu, T.; Ichimoto, K.;
Horiuchi, T.; Matsumoto, Y.; Takeyama, N.
Bibcode: 2011SPIE.8148E..0DS
Altcode: 2011SPIE.8148E..12S
We present an optical and thermal design of one of major instrumental
payload planned for SOLAR-C mission/Plan-B (high resolution
spectroscopic option): the telescope assembly of Solar Ultra-violet
Visible and near IR observing Telescope (SUVIT). To accommodate a
launcher's nosecone size, a wide observing wavelength coverage from UV
(down to 280 nm) through near IR (up to 1100 nm), and an 0.1 arcsec
resolution in the field of 200 arcsec diameter, a short telescope
design was made for a 1.5 m aperture solar Gregorian telescope with
the compact design of three-mirror collimator unit.
Title: Modeling and verification of the diffraction-limited visible
light telescope aboard the solar observing satellite HINODE
Authors: Katsukawa, Y.; Suematsu, Y.; Tsuneta, S.; Ichimoto, K.;
Shimizu, T.
Bibcode: 2011SPIE.8336E..0FK
Altcode: 2011SPIE.8336E..14K
HINODE, Japanese for "sunrise", is a spacecraft dedicated for
observations of the Sun, and was launched in 2006 to study the Sun's
magnetic fields and how their explosive energies propagate through the
different atmospheric layers. The spacecraft carries the Solar Optical
Telescope (SOT), which has a 50 cm diameter clear aperture and provides
a continuous series of diffraction-limited visible light images from
space. The telescope was developed through international collaboration
between Japan and US. In order to achieve the diffraction-limited
performance, thermal and structural modeling of the telescope was
extensively used in its development phase to predict how the optical
performance changes dependent on the thermal condition in orbit. Not
only the modeling, we devoted many efforts to verify the optical
performance in ground tests before the launch. The verification in
the ground tests helped us to find many issues, such as temperature
dependent focus shifts, which were not identified only through the
thermal-structural modeling. Another critical issue was micro-vibrations
induced by internal disturbances of mechanical gyroscopes and momentum
wheels for attitude control of the spacecraft. Because the structural
modeling was not accurate enough to predict how much the image quality
was degraded by the micro-vibrations, we measured their transmission
in a spacecraft-level test.
Title: Excitation of magneto-acoustic waves in network magnetic
elements
Authors: Kato, Yoshiaki; Steiner, Oskar; Steffen, Matthias; Suematsu,
Yoshinori
Bibcode: 2011IAUS..273..442K
Altcode:
From radiation magnetohydrodynamic (RMHD) simulations we track the
temporal evolution of a vertical magnetic flux sheet embedded in a
two-dimensional non-stationary atmosphere that reaches all the way
from the upper convection zone to the low chromosphere. Examining its
temporal behavior near the interface between the convection zone and
the photosphere, we describe the excitation of propagating longitudinal
waves within the magnetic element as a result of convective motion in
its surroundings.
Title: Excitation of Slow Modes in Network Magnetic Elements Through
Magnetic Pumping
Authors: Kato, Yoshiaki; Steiner, Oskar; Steffen, Matthias; Suematsu,
Yoshinori
Bibcode: 2011ApJ...730L..24K
Altcode: 2011arXiv1102.5164K
From radiation magnetohydrodynamic simulations of the solar atmosphere,
we find a new mechanism for the excitation of longitudinal slow modes
within magnetic flux concentrations. We find that the convective
downdrafts in the immediate surroundings of magnetic elements are
responsible for the excitation of slow modes. The coupling between
the external downdraft and the plasma motion internal to the flux
concentration is mediated by the inertial forces of the downdraft that
act on the magnetic flux concentration. These forces, in conjunction
with the downward movement, pump the internal atmosphere in the
downward direction, which entails a fast downdraft in the photospheric
and chromospheric layers of the magnetic element. Subsequent to the
transient pumping phase, the atmosphere rebounds, causing a slow
mode traveling along the magnetic flux concentration in the upward
direction. It develops into a shock wave in chromospheric heights,
possibly capable of producing some kind of dynamic fibril. We propose
an observational detection of this process.
Title: Sunspot Proper Motion and Flare Onset Prediction
Authors: Suematsu, Y.; Yatini, C. Y.
Bibcode: 2010AGUFMSH43B1819S
Altcode:
Proper motion of sunspots in several active regions was studied to
detect their indicator on flare onset, using data from the Solar Flare
Telescope at Mitaka, TRACE and Hinode. The proper motion of individual
sunspots was derived using a local correlation tracking method. As
a result, we found that the sunspots that are located under or close
to H-alpha flaring patches showed a change in their moving direction
prior to the flare onset. The change in their movements took place a
half to two hours before the flare onset. On the other hand, sunspots
in non-flaring areas or non-flaring active regions did not show this
kind of change. It is likely, therefore, that if a sunspot shows
the particular movement, a H-alpha flare is to occur in its nearby
region. In two of the active regions, the flare ribbons were located
on a emerging bipolar pair of sunspots. The disturbance in the usual
motion of the bipolar sunspots and in other sunspots as well can be
interpreted as a sign of magnetic shear development leading to final
magnetic energy buildup before its sudden release. We suggest that
the change in sunspot motion in a short time scale prior to the flare
onset can be regarded as a good indicator in predicting the onset
timing and location of H-alpha flare.
Title: Quiescent Prominence Dynamics Observed with the Hinode Solar
Optical Telescope. I. Turbulent Upflow Plumes
Authors: Berger, Thomas E.; Slater, Gregory; Hurlburt, Neal; Shine,
Richard; Tarbell, Theodore; Title, Alan; Lites, Bruce W.; Okamoto,
Takenori J.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Magara, Tetsuya;
Suematsu, Yoshinori; Shimizu, Toshifumi
Bibcode: 2010ApJ...716.1288B
Altcode:
Hinode/Solar Optical Telescope (SOT) observations reveal two new
dynamic modes in quiescent solar prominences: large-scale (20-50 Mm)
"arches" or "bubbles" that "inflate" from below into prominences, and
smaller-scale (2-6 Mm) dark turbulent upflows. These novel dynamics are
related in that they are always dark in visible-light spectral bands,
they rise through the bright prominence emission with approximately
constant speeds, and the small-scale upflows are sometimes observed to
emanate from the top of the larger bubbles. Here we present detailed
kinematic measurements of the small-scale turbulent upflows seen in
several prominences in the SOT database. The dark upflows typically
initiate vertically from 5 to 10 Mm wide dark cavities between the
bottom of the prominence and the top of the chromospheric spicule
layer. Small perturbations on the order of 1 Mm or less in size
grow on the upper boundaries of cavities to generate plumes up to
4-6 Mm across at their largest widths. All plumes develop highly
turbulent profiles, including occasional Kelvin-Helmholtz vortex
"roll-up" of the leading edge. The flows typically rise 10-15 Mm before
decelerating to equilibrium. We measure the flowfield characteristics
with a manual tracing method and with the Nonlinear Affine Velocity
Estimator (NAVE) "optical flow" code to derive velocity, acceleration,
lifetime, and height data for several representative plumes. Maximum
initial speeds are in the range of 20-30 km s-1, which
is supersonic for a ~10,000 K plasma. The plumes decelerate in the
final few Mm of their trajectories resulting in mean ascent speeds
of 13-17 km s-1. Typical lifetimes range from 300 to 1000
s (~5-15 minutes). The area growth rate of the plumes (observed as
two-dimensional objects in the plane of the sky) is initially linear
and ranges from 20,000 to 30,000 km2 s-1 reaching
maximum projected areas from 2 to 15 Mm2. Maximum contrast of
the dark flows relative to the bright prominence plasma in SOT images
is negative and ranges from -10% for smaller flows to -50% for larger
flows. Passive scalar "cork movies" derived from NAVE measurements show
that prominence plasma is entrained by the upflows, helping to counter
the ubiquitous downflow streams in the prominence. Plume formation
shows no clear temporal periodicity. However, it is common to find
"active cavities" beneath prominences that can spawn many upflows in
succession before going dormant. The mean flow recurrence time in these
active locations is roughly 300-500 s (5-8 minutes). Locations remain
active on timescales of tens of minutes up to several hours. Using a
column density ratio measurement and reasonable assumptions on plume
and prominence geometries, we estimate that the mass density in the
dark cavities is at most 20% of the visible prominence density, implying
that a single large plume could supply up to 1% of the mass of a typical
quiescent prominence. We hypothesize that the plumes are generated from
a Rayleigh-Taylor instability taking place on the boundary between
the buoyant cavities and the overlying prominence. Characteristics,
such as plume size and frequency, may be modulated by the strength
and direction of the cavity magnetic field relative to the prominence
magnetic field. We conclude that buoyant plumes are a source of
quiescent prominence mass as well as a mechanism by which prominence
plasma is advected upward, countering constant gravitational drainage.
Title: Review of Hinode results
Authors: Suematsu, Y.
Bibcode: 2010AN....331..605S
Altcode:
Hinode is an observatory-style satellite, carrying three advanced
instruments being designed and built to work together to explore
the physical coupling between the photosphere and the upper layers
for understanding the mechanism of dynamics and heating. The three
instruments aboard are the Solar Optical Telescope (SOT), which
can provide high-precision photometric and polarimetric data of the
lower atmosphere in the visible light (388-668 nm) with a spatial
resolution of 0.2-0.3 arcseconds, the X-Ray Telescope (XRT) which
takes a wide field of full sun coverage X-ray images being capable
of diagnosing the physical condition of coronal plasmas, and the EUV
Imaging Spectrometer (EIS) which observes the upper transition region
and coronal emission lines in the wavelength ranges of 17-21 nm and
25-29 nm. Since first-light observations in the end of October 2006,
Hinode has been continuously providing unprecedented high-quality
solar data. We will present some new findings of the sun with Hinode,
focusing on those from SOT.
Title: On the evaluation of image quality of Hinode Solar Optical
Telescope
Authors: Suematsu, Y.
Bibcode: 2009AGUFMSH51A1254S
Altcode:
The phase diversity method is a useful tool to estimate a
wavefront error of a whole optical system from an object through a
detector. Generally, in this method, both on-focus and out of focus
images are taken simultaneously by splitting a beam just before the
final focal plane. From a pair of these two images and known de-focus
value, a wavefront error at a pupil which is assumed to be represented
a series of the circle polynomials are derived so as to minimize the
difference of observed images from the disturbed by the wavefront. In
case of the Solar Optical Telescope (SOT), on-focus and out of focus
images are taken sequentially by moving a focusing lens. Therefore, the
sequence of images may have other aberration than the defocus because of
an introduced wavefront error of the moving focusing lens. We describe
a modified phase diversity method which can be applied to the SOT. The
obtained results, which are useful to improve the image quality,
are discussed by comparing the case of standard phase diversity method.
Title: A New View of Fine Scale Dynamics and Magnetism of Sunspots
Revealed by Hinode/SOT
Authors: Ichimoto, K.; Suematsu, Y.; Katsukawa, Y.; Tsuneta, S.;
Shimojo, M.; Shimizu, T.; Shine, R. A.; Tarbell, T. D.; Berger, T.;
Title, A. M.; Lites, B. W.; Kubo, M.; Yokoyama, T.; Nagata, S.
Bibcode: 2009ASPC..405..167I
Altcode:
The Solar Optical Telescope on-board Hinode is providing a new view of
the fine scale dynamics in sunspots with its high spatial resolution and
unprecedented image stability. We present three features related to the
Evershed flow each of which raises a new puzzle in sunspot dynamics;
i.e., twisting appearance of penumbral filaments, the source and sink
of individual Evershed flow channels, and the net circular polarization
in penumbrae with its spatial relation to the Evershed flow channels.
Title: Local Twist and Current Helicity Distributions of Active
Region NOAA 10930
Authors: Su, J. T.; Sakurai, T.; Suematsu, Y.; Hagino, M.; Liu, Yu
Bibcode: 2009ApJ...697L.103S
Altcode:
Hinode high-quality vector magnetograms and G-band data are utilized
to study the distributions of local twist α z and current
helicity hc on the active region of NOAA 10930. The new
findings are as follows. (1) The patches of positive and negative
helicities were intermixed showing a mesh pattern in the umbra and
a thread pattern in the penumbra. (2) For its main stable sunspot
(MSS), there was a positive-helicity patch accounting for ~43% of the
umbra area surrounding the inner umbra, which had a predominantly
negative helicity. For its minor rotating sunspot (MRS), there
was a negative-helicity patch appearing in the umbra. (3) The fine
distributions of α z and hc on a penumbral
filament indicated that it may be possible for the two opposite
helicities to coexist in a filament and their magnitudes were nearly
equivalent.
Title: Has Hinode Revealed the Missing Turbulent Flux of the
Quiet Sun?
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A. M.; Ichimoto, K.; Katsukawa,
Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2009ASPC..405..173L
Altcode:
The Hinode Spectro-Polarimeter has revealed the presence of surprisingly
strong horizontal magnetic fields nearly everywhere in the quiet
solar atmosphere. These horizontal fields, along with measures of the
vertical fields, may be the signature of the ``hidden turbulent flux''
of the quiet Sun. The measured horizontal fields average at least to
55 Gauss: nearly 5 times that of the measured longitudinal apparent
flux density. The nature of these fields are reviewed, and discussed
in the light of recent magneto-convection numerical simulations of
the quiet Sun.
Title: Hinode Observation of the Magnetic Fields in a Sunspot Light
Bridge Accompanied by Long-Lasting Chromospheric Plasma Ejections
Authors: Shimizu, Toshifumi; Katsukawa, Yukio; Kubo, Masahito; Lites,
Bruce W.; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Tsuneta, Saku;
Nagata, Shin'ichi; Shine, Richard A.; Tarbell, Theodore D.
Bibcode: 2009ApJ...696L..66S
Altcode:
We present high-resolution magnetic field measurements of a sunspot
light bridge (LB) that produced chromospheric plasma ejections
intermittently and recurrently for more than 1 day. The observations
were carried out with the Hinode Solar Optical Telescope on 2007
April 29 and 30. The spectro-polarimeter reveals obliquely oriented
magnetic fields with vertical electric current density higher than
100 mA m-2 along the LB. The observations suggest that
current-carrying highly twisted magnetic flux tubes are trapped below
a cusp-shaped magnetic structure along the LB. The presence of trapped
current-carrying flux tubes is essential for causing long-lasting
chromospheric plasma ejections at the interface with pre-existing
vertically oriented umbral fields. A bidirectional jet was clearly
detected, suggesting magnetic reconnections occurring at very low
altitudes, slightly above the height where the vector magnetic fields
are measured. Moreover, we found another strong vertical electric
current on the interface between the current-carrying flux tube
and pre-existing umbral field, which might be a direct detection
of the currents flowing in the current sheet formed at the magnetic
reconnection sites.
Title: Prominence Formation Associated with an Emerging Helical
Flux Rope
Authors: Okamoto, Takenori J.; Tsuneta, Saku; Lites, Bruce W.; Kubo,
Masahito; Yokoyama, Takaaki; Berger, Thomas E.; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shibata, Kazunari; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
Bibcode: 2009ApJ...697..913O
Altcode: 2009arXiv0904.0007O
The formation and evolution process and magnetic configuration of
solar prominences remain unclear. In order to study the formation
process of prominences, we examine continuous observations of a
prominence in NOAA AR 10953 with the Solar Optical Telescope on
the Hinode satellite. As reported in our previous Letter, we find
a signature suggesting that a helical flux rope emerges from below
the photosphere under a pre-existing prominence. Here we investigate
more detailed properties and photospheric indications of the emerging
helical flux rope, and discuss their relationship to the formation of
the prominence. Our main conclusions are: (1) a dark region with absence
of strong vertical magnetic fields broadens and then narrows in Ca II
H-line filtergrams. This phenomenon is consistent with the emergence
of the helical flux rope as photospheric counterparts. The size of the
flux rope is roughly 30,000 km long and 10,000 km wide. The width is
larger than that of the prominence. (2) No shear motion or converging
flows are detected, but we find diverging flows such as mesogranules
along the polarity inversion line. The presence of mesogranules may
be related to the emergence of the helical flux rope. (3) The emerging
helical flux rope reconnects with magnetic fields of the pre-existing
prominence to stabilize the prominence for the next several days. We
thus conjecture that prominence coronal magnetic fields emerge in
the form of helical flux ropes that contribute to the formation and
maintenance of the prominence.
Title: The Magnetic Landscape of the Sun's Polar Region
Authors: Tsuneta, S.; Ichimoto, K.; Katsukawa, Y.; Lites, B. W.;
Matsuzaki, K.; Nagata, S.; Orozco Suárez, D.; Shimizu, T.; Shimojo,
M.; Shine, R. A.; Suematsu, Y.; Suzuki, T. K.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2008ApJ...688.1374T
Altcode: 2008arXiv0807.4631T
We present observations of the magnetic landscape of the polar region
of the Sun that are unprecedented in terms of spatial resolution,
field of view, and polarimetric precision. They were carried out with
the Solar Optical Telescope aboard Hinode. Using a Milne-Eddington
inversion, we find many vertically oriented magnetic flux tubes
with field strengths as strong as 1 kG scattered in latitude between
70° and 90°. They all have the same polarity, consistent with the
global polarity of the polar region. The field vectors are observed to
diverge from the centers of the flux elements, consistent with a view
of magnetic fields that are expanding and fanning out with height. The
polar region is also found to have ubiquitous horizontal fields. The
polar regions are the source of the fast solar wind, which is channeled
along unipolar coronal magnetic fields whose photospheric source is
evidently rooted in the strong-field, vertical patches of flux. We
conjecture that vertical flux tubes with large expansion around the
photospheric-coronal boundary serve as efficient chimneys for Alfvén
waves that accelerate the solar wind.
Title: Estimation of Spicule Magnetic Field Using Observed MHD Waves
by the Hinode SOT
Authors: Kim, Yeon-Han; Bong, Su-Chan; Park, Young-Deuk; Cho,
Kyung-Suk; Moon, Yong-Jae; Suematsu, Yoshinori
Bibcode: 2008JKAS...41..173K
Altcode:
No abstract at ADS
Title: Nature of Small-Scale Jets On the Solar Chromosphere Revealed
with Hinode
Authors: Suematsu, Y.
Bibcode: 2008AGUFMSH41B1623S
Altcode:
The Solar Optical Telescope aboard Hinode has revealed the nature of
small-scale jets of the solar chromosphere. Jet-like structures are
ubiquitous there not only in the quiet Sun but also in active region
and even in sunspot penumbra. They are likely to play an important role
in maintaining the energy balance of the local atomsphere and the mass
balance of the corona. High time and spatial resolution observations
for the first time have revealed that the small-scale jets consist of
highly dynamic multi-threads of as thin as a few tenths of arcsecond
and shows prominent lateral movement or oscillation with rotation
on its axis during its life. The fine structure and lateral motion
indicate that the small-scale can be ejected by magnetic reconnection
at footpoints. Since the most small-scale jets emanate from seemingly
uni-polar magnetic region and the relevant magnetic reconnection should
take place in unresolved spatial scale contrary to the larger-scale jets
in which bipole magnetic structures are found at their footpoints. We
discuss multi-scale structures of the chromospheric jets.
Title: Magnetic Fields of the Quiet Sun: A New Quantitative
Perspective From Hinode
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa, Y.;
Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ASPC..397...17L
Altcode:
This article summarizes results of studies presented in two papers
already published: Lites et al. (2007a); Lites et al. (2007b). Please
see these for further details.
Title: On-orbit Performance of the Solar Optical Telescope aboard
Hinode
Authors: Ichimoto, K.; Katsukawa, Y.; Tarbell, T.; Shine, R. A.;
Hoffmann, C.; Berger, T.; Cruz, T.; Suematsu, Y.; Tsuneta, S.; Shimizu,
T.; Lites, B. W.
Bibcode: 2008ASPC..397....5I
Altcode: 2008arXiv0804.3248I
On-orbit performance of the Solar Optical Telescope (SOT) aboard Hinode
is described with some attention to its unpredicted aspects. In general,
SOT reveals an excellent performance and has been providing outstanding
data. Some unexpected features exist, however, in behaviours of the
focus position, throughput and structural stability. Most of them are
recovered by the daily operation i.e., frequent focus adjustment,
careful heater setting and corrections in data analysis. The
tunable filter contains air bubbles which degrade the data quality
significantly. Schemes for tuning the filter without disturbing the
bubbles have been developed and tested, and some useful procedures
to obtain Dopplergrams and magnetograms are now available. October
and March, when the orbit of satellite becomes nearly perpendicular
to the direction towards the Sun, provide a favourable condition for
continuous runs of the narrow-band filter imager.
Title: High Resolution Observations of Spicules with Hinode/SOT
Authors: Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Shimizu, T.;
Okamoto, T.; Tsuneta, S.; Tarbell, T.; Shine, R. A.
Bibcode: 2008ASPC..397...27S
Altcode:
High time cadence unprecedented images at the limb with Ca II H line
filtergraph from the Solar Optical Telescope (SOT) aboard Hinode
have revealed that a spicule consists of highly dynamic multi-threads
(typically twin) as thin as a few tenths of an arcsecond, and shows
prominent lateral movement or oscillation with rotation on its axis
during its life. This multi-thread structure and lateral motion indicate
that the spicules can be driven by magnetic reconnection at unresolved
spatial scales at their footpoints.
Title: Evolution of Magnetic Fields at the Boundary of the Penumbra
Authors: Kubo, M.; Ichimoto, K.; Shimizu, T.; Lites, B. W.; Tsuneta,
S.; Suematsu, Y.; Katsukawa, Y.; Nagata, S.; Tarbell, T.; Shine,
R. A.; Title, A. M.
Bibcode: 2008ASPC..397...79K
Altcode:
The formation of moving magnetic features (MMFs) separating from the
penumbra were successfully observed with the Solar Optical Telescope
(SOT) aboard the Hinode satellite. We find that bright features in
the outer penumbra are located at the penumbral spines, which have
magnetic fields more vertical than the surroundings, or located at the
MMFs separating from the spines. This suggests that convection in the
outer penumbra is related to the disintegration of the sunspot.
Title: Erratum: The Analysis of Penumbral Fine Structure Using an
Advanced Inversion Technique
Authors: Jurcák, Jan; Bellot Rubio, Luis; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi;
Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.; Tsuneta,
Saku
Bibcode: 2008PASJ...60..933J
Altcode:
In the article [PASJ 59, S601-S606 (2007)], the word ''CSIC'' was
omitted from the affiliation of Dr. Luis Bellot Rubio. The correct
affiliation is : 2Instituto de Astrofísica de Andalucía
(CSIC), Apdo. de Correos 3004, 18080 Granada, Spain
Title: Disintegration of Magnetic Flux in Decaying Sunspots as
Observed with the Hinode SOT
Authors: Kubo, M.; Lites, B. W.; Ichimoto, K.; Shimizu, T.; Suematsu,
Y.; Katsukawa, Y.; Tarbell, T. D.; Shine, R. A.; Title, A. M.; Nagata,
S.; Tsuneta, S.
Bibcode: 2008ApJ...681.1677K
Altcode: 2008arXiv0806.0415K
Continuous observations of sunspot penumbrae with the Solar Optical
Telescope aboard Hinode clearly show that the outer boundary of the
penumbra fluctuates around its averaged position. The penumbral outer
boundary moves inward when granules appear in the outer penumbra. We
discover that such granules appear one after another while moving
magnetic features (MMFs) are separating from the penumbral "spines"
(penumbral features that have fields that are stronger and more vertical
than those of their surroundings). These granules that appear in the
outer penumbra often merge with bright features inside the penumbra
that move with the spines as they elongate toward the moat region. This
suggests that convective motions around the penumbral outer boundary are
related to the disintegration of magnetic flux in the sunspot. We also
find that dark penumbral filaments frequently elongate into the moat
region in the vicinity of MMFs that detach from penumbral spines. Such
elongating dark penumbral filaments correspond to nearly horizontal
fields extending from the penumbra. Pairs of MMFs with positive and
negative polarities are sometimes observed along the elongating dark
penumbral filaments. This strongly supports the notion that such
elongating dark penumbral filaments have magnetic fields with a "sea
serpent"-like structure. Evershed flows, which are associated with the
penumbral horizontal fields, may be related to the detachment of the
MMFs from the penumbral spines, as well as to the formation of the MMFs
along the dark penumbral filaments that elongate into the moat region.
Title: Polarization Calibration of the Solar Optical Telescope
onboard Hinode
Authors: Ichimoto, K.; Lites, B.; Elmore, D.; Suematsu, Y.; Tsuneta,
S.; Katsukawa, Y.; Shimizu, T.; Shine, R.; Tarbell, T.; Title, A.;
Kiyohara, J.; Shinoda, K.; Card, G.; Lecinski, A.; Streander, K.;
Nakagiri, M.; Miyashita, M.; Noguchi, M.; Hoffmann, C.; Cruz, T.
Bibcode: 2008SoPh..249..233I
Altcode: 2008SoPh..tmp...69I
The Solar Optical Telescope (SOT) onboard Hinode aims to obtain vector
magnetic fields on the Sun through precise spectropolarimetry of
solar spectral lines with a spatial resolution of 0.2 - 0.3 arcsec. A
photometric accuracy of 10−3 is achieved and, after the
polarization calibration, any artificial polarization from crosstalk
among Stokes parameters is required to be suppressed below the level
of the statistical noise over the SOT's field of view. This goal was
achieved by the highly optimized design of the SOT as a polarimeter,
extensive analyses and testing of optical elements, and an end-to-end
calibration test of the entire system. In this paper we review both
the approach adopted to realize the high-precision polarimeter of the
SOT and its final polarization characteristics.
Title: Image Stabilization System for Hinode (Solar-B) Solar Optical
Telescope
Authors: Shimizu, T.; Nagata, S.; Tsuneta, S.; Tarbell, T.; Edwards,
C.; Shine, R.; Hoffmann, C.; Thomas, E.; Sour, S.; Rehse, R.; Ito,
O.; Kashiwagi, Y.; Tabata, M.; Kodeki, K.; Nagase, M.; Matsuzaki,
K.; Kobayashi, K.; Ichimoto, K.; Suematsu, Y.
Bibcode: 2008SoPh..249..221S
Altcode:
The Hinode Solar Optical Telescope (SOT) is the first space-borne
visible-light telescope that enables us to observe magnetic-field
dynamics in the solar lower atmosphere with 0.2 - 0.3 arcsec spatial
resolution under extremely stable (seeing-free) conditions. To achieve
precise measurements of the polarization with diffraction-limited
images, stable pointing of the telescope (<0.09 arcsec, 3σ) is
required for solar images exposed on the focal plane CCD detectors. SOT
has an image stabilization system that uses image displacements
calculated from correlation tracking of solar granules to control
a piezo-driven tip-tilt mirror. The system minimizes the motions
of images for frequencies lower than 14 Hz while the satellite and
telescope structural design damps microvibration in higher frequency
ranges. It has been confirmed from the data taken on orbit that
the remaining jitter is less than 0.03 arcsec (3σ) on the Sun. This
excellent performance makes a major contribution to successful precise
polarimetric measurements with 0.2 - 0.3 arcsec resolution.
Title: The Solar Optical Telescope for the Hinode Mission: An Overview
Authors: Tsuneta, S.; Ichimoto, K.; Katsukawa, Y.; Nagata, S.; Otsubo,
M.; Shimizu, T.; Suematsu, Y.; Nakagiri, M.; Noguchi, M.; Tarbell,
T.; Title, A.; Shine, R.; Rosenberg, W.; Hoffmann, C.; Jurcevich,
B.; Kushner, G.; Levay, M.; Lites, B.; Elmore, D.; Matsushita, T.;
Kawaguchi, N.; Saito, H.; Mikami, I.; Hill, L. D.; Owens, J. K.
Bibcode: 2008SoPh..249..167T
Altcode: 2008SoPh..tmp...74T; 2007arXiv0711.1715T
The Solar Optical Telescope (SOT) aboard the Hinode satellite
(formerly called Solar-B) consists of the Optical Telescope Assembly
(OTA) and the Focal Plane Package (FPP). The OTA is a 50-cm
diffraction-limited Gregorian telescope, and the FPP includes the
narrowband filtergraph (NFI) and the broadband filtergraph (BFI), plus
the Stokes Spectro-Polarimeter (SP). The SOT provides unprecedented
high-resolution photometric and vector magnetic images of the
photosphere and chromosphere with a very stable point spread function
and is equipped with an image-stabilization system with performance
better than 0.01 arcsec rms. Together with the other two instruments
on Hinode (the X-Ray Telescope (XRT) and the EUV Imaging Spectrometer
(EIS)), the SOT is poised to address many fundamental questions about
solar magnetohydrodynamics. This paper provides an overview; the
details of the instrument are presented in a series of companion papers.
Title: Frequent Occurrence of High-Speed Local Mass Downflows on
the Solar Surface
Authors: Shimizu, T.; Lites, B. W.; Katsukawa, Y.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Nagata, S.; Kubo, M.; Shine, R. A.; Tarbell,
T. D.
Bibcode: 2008ApJ...680.1467S
Altcode: 2008arXiv0804.1167S
We report on new spectropolarimetric measurements with simultaneous
filter imaging observation, revealing the frequent appearance of
polarization signals indicating high-speed, probably supersonic,
downflows that are associated with at least three different
configurations of magnetic fields in the solar photosphere. The
observations were carried out with the Solar Optical Telescope on
board the Hinode satellite. High-speed downflows are excited when a
moving magnetic feature is newly formed near the penumbral boundary of
sunspots. Also, a new type of downflows is identified at the edge of
sunspot umbra that lack accompanying penumbral structures. These may
be triggered by the interaction of magnetic fields swept by convection
with well-concentrated magnetic flux. Another class of high-speed
downflows are observed in quiet Sun and sunspot moat regions. These are
closely related to the formation of small concentrated magnetic flux
patches. High-speed downflows of all types are transient time-dependent
mass motions. These findings suggest that the excitation of supersonic
mass flows are one of the key observational features of the dynamical
evolution occurring in magnetic-field fine structures on the solar
surface.
Title: Cooperative Observation of Ellerman Bombs between the Solar
Optical Telescope aboard Hinode and Hida/Domeless Solar Telescope
Authors: Matsumoto, Takuma; Kitai, Reizaburo; Shibata, Kazunari;
Nagata, Shin'ichi; Otsuji, Kenichi; Nakamura, Tahei; Watanabe, Hiroko;
Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu,
Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.; Lites, Bruce W.;
Shine, Richard A.; Title, Alan M.
Bibcode: 2008PASJ...60..577M
Altcode:
High-resolution CaIIH broad-band filter images of NOAA10933 on 2007
January 5 were obtained by the Solar Optical Telescope aboard the Hinode
satellite. Many small-scale (∼1") bright points were observed outside
the sunspot and inside the emerging flux region. We identified some of
these bright points with Ellerman bombs (EBs) by using Hα images taken
by the Domeless Solar Telescope at Hida observatory. The sub-arcsec
structures of two EBs seen in CaIIH were studied in detail. Our
observation showed the following two aspects: (1) The CaIIH bright
points identified with EBs were associated with the bipolar magnetic
field structures, as reported by previous studies. (2)The structure
of the CaIIH bright points turned out to consist of the following two
parts: a central elongated bright core (0.7" × 0.5") located along
the magnetic neutral line and a diffuse halo (1.2"×1.8").
Title: The Solar Optical Telescope of Solar-B ( Hinode): The Optical
Telescope Assembly
Authors: Suematsu, Y.; Tsuneta, S.; Ichimoto, K.; Shimizu, T.; Otsubo,
M.; Katsukawa, Y.; Nakagiri, M.; Noguchi, M.; Tamura, T.; Kato, Y.;
Hara, H.; Kubo, M.; Mikami, I.; Saito, H.; Matsushita, T.; Kawaguchi,
N.; Nakaoji, T.; Nagae, K.; Shimada, S.; Takeyama, N.; Yamamuro, T.
Bibcode: 2008SoPh..249..197S
Altcode: 2008SoPh..tmp...26S
The Solar Optical Telescope (SOT) aboard the Solar-B satellite (Hinode)
is designed to perform high-precision photometric and polarimetric
observations of the Sun in visible light spectra (388 - 668 nm)
with a spatial resolution of 0.2 - 0.3 arcsec. The SOT consists of
two optically separable components: the Optical Telescope Assembly
(OTA), consisting of a 50-cm aperture Gregorian with a collimating lens
unit and an active tip-tilt mirror, and an accompanying Focal Plane
Package (FPP), housing two filtergraphs and a spectro-polarimeter. The
optomechanical and optothermal performance of the OTA is crucial to
attain unprecedented high-quality solar observations. We describe in
detail the instrument design and expected stable diffraction-limited
on-orbit performance of the OTA, the largest state-of-the-art solar
telescope yet flown in space.
Title: Emergence of a helical flux rope and prominence formation
Authors: Okamoto, T. J.; Tsuneta, S.; Lites, B. W.; Kubo, M.; Yokoyama,
T.; Berger, T. E.; Ichimoto, K.; Katsukawa, Y.; Nagata, S.; Shibata,
K.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2008AGUSMSP43B..06O
Altcode:
We report a discovery about emergence of a helical flux rope. The
episode may be related to the formation and evolution of an active
region prominence. Statistical studies by previous authors indicate that
numerous prominences have the inverse-polarity configuration suggesting
the helical magnetic configurations. There are two theoretical
models about formation of such a coronal helical magnetic field in
association with prominences: flux rope model and sheared-arcade
model. We have so far no clear observational evidence to support
either model. In order to find a clue about the formation of the
prominence, we had continuous observations of NOAA AR 10953 with the
SOT during 2007 April 28 to May 9. A prominence was located over the
polarity inversion line in the south-east of the main sunspot. These
observations provided us with a time series of vector magnetic fields
on the photosphere under the prominence. We found four new features:
(1) The abutting opposite-polarity regions on the two sides along
the polarity inversion line first grew laterally in size and then
narrowed. (2) These abutting regions contained vertically-weak,
but horizontally-strong magnetic fields. (3) The orientations of
the horizontal magnetic fields along the polarity inversion line on
the photosphere gradually changed with time from a normal- polarity
configuration to an inverse-polarity one. (4) The horizontal-magnetic
field region was blueshifted. These indicate that helical flux rope
emerges from below the photosphere into the corona along the polarity
inversion line under the prominence. We suggest that this supply of a
helical magnetic flux possibly into the corona is related to formation
and maintenance of active-region prominences.
Title: Changes of Magnetic Structure in 3-D Associated with the X3.4
Flare of 2006 December 13
Authors: Jing, J.; Wiegelmann, T.; Suematsu, Y.; Kubo, M.; Wang, H.
Bibcode: 2008AGUSMSP51C..02J
Altcode:
Recent observations demonstrated that sunspot structure can change
rapidly and irreversibly after flares. One of the most puzzling results
is the increase in magnetic shear around flaring magnetic polarity
inversion line after flares. However, all these observations were
made at the photosphere level. We study the altitude variation of the
non-potentiality of the magnetic fields associated with the 4B/X3.4
flare of 2006 December 13. The vector magnetograms with unprecedented
quality from Hinode before and after the flare are used as the boundary
conditions to extrapolate the 3-dimensional non-linear force-free
magnetic fields and the potential fields. The former are computed
with the optimization algorithm and the latter with Green's function
method. At the photosphere boundary, magnetic shear increases after the
flare in a local area close to the flaring magnetic polarity inversion
line. Two measures of the magnetic non-potentiality, the weighted mean
shear θw and the total magnetic shear θwB, are calculated in this area
at progressively higher altitude. By comparing their altitude variation
profiles before and after the flare, we find that the non-potentiality
of the local area increases after the flare below ~8 Mm and decreases
from that height to ~70 Mm. Beyond 70 Mm, the magnetic fields approach
potential for both times.
Title: Disintegration of Magnetic Flux in Decaying Sunspots as
Observed with the Hinode/SOT
Authors: Kubo, M.; Lites, B. W.; Ichimoto, K.; Shimizu, T.; Suematsu,
Y.; Katsukawa, Y.; Tarbell, T. D.; Shine, R. A.; Title, A. M.; Nagata,
S.; Tsuneta, S.
Bibcode: 2008AGUSMSP31B..01K
Altcode:
Continuous observations of sunspot penumbrae with the Solar Optical
Telescope aboard Hinode clearly show that the outer boundary of the
penumbra fluctuates around its averaged position. The penumbral outer
boundary moves inward when granules appear in the outer penumbra. We
discover that such granules appear one after another while moving
magnetic features (MMFs) are separating from the penumbral "spines"
(penumbral features having fields that are stronger and more vertical
than their surroundings). These granules that appear in the outer
penumbra often merge with bright features inside the penumbra that move
with spines as they elongate toward the moat region. This suggests that
convective motions around the penumbral outer boundary are related to
disintegration of magnetic flux in the sunspot. We also find that dark
penumbral filaments frequently elongate into the moat region in the
vicinity of MMFs that detach from penumbral spines. Such elongating
dark penumbral filaments correspond to nearly horizontal fields
extending from the penumbra. Pairs of MMFs with positive and negative
polarities are sometimes observed along the elongating dark penumbral
filaments. This strongly supports the notion that such elongating dark
penumbral filaments have magnetic fields with a "sea serpent"-like
structure. Evershed flows, which are associated with the penumbral
horizontal fields, may be related to detachment of the MMFs from the
penumbral spines, as well as to the formation of the MMFs along the
dark penumbral filaments that elongate into the moat region.
Title: Formation of Solar Magnetic Flux Tubes with Kilogauss Field
Strength Induced by Convective Instability
Authors: Nagata, Shin'ichi; Tsuneta, Saku; Suematsu, Yoshinori;
Ichimoto, Kiyoshi; Katsukawa, Yukio; Shimizu, Toshifumi; Yokoyama,
Takaaki; Tarbell, Theodore D.; Lites, Bruce W.; Shine, Richard A.;
Berger, Thomas E.; Title, Alan M.; Bellot Rubio, Luis R.; Orozco
Suárez, David
Bibcode: 2008ApJ...677L.145N
Altcode:
Convective instability has been a mechanism used to explain
the formation of solar photospheric flux tubes with kG field
strength. However, the turbulence of the Earth's atmosphere has
prevented ground-based observers from examining the hypothesis
with precise polarimetric measurement on the subarcsecond scale
flux tubes. Here we discuss observational evidence of this scenario
based on observations with the Solar Optical Telescope (SOT) aboard
Hinode. The cooling of an equipartition field strength flux tube
precedes a transient downflow reaching 6 km s-1 and the
intensification of the field strength to 2 kG. These observations
agree very well with the theoretical predictions.
Title: Transient horizontal magnetic fields in solar plage regions
Authors: Ishikawa, R.; Tsuneta, S.; Ichimoto, K.; Isobe, H.; Katsukawa,
Y.; Lites, B. W.; Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu,
Y.; Tarbell, T. D.; Title, A. M.
Bibcode: 2008A&A...481L..25I
Altcode: 2008arXiv0802.1769I
Aims:We report the discovery of isolated, small-scale emerging
magnetic fields in a plage region with the Solar Optical Telescope
aboard Hinode.
Methods: Spectro-polarimetric observations were
carried out with a cadence of 34 s for the plage region located near
disc center. The vector magnetic fields are inferred by Milne-Eddington
inversion.
Results: The observations reveal widespread occurrence
of transient, spatially isolated horizontal magnetic fields. The
lateral extent of the horizontal magnetic fields is comparable to
the size of photospheric granules. These horizontal magnetic fields
seem to be tossed about by upflows and downflows of the granular
convection. We also report an event that appears to be driven by the
magnetic buoyancy instability. We refer to buoyancy-driven emergence
as type 1 and convection-driven emergence as type 2. Although both
events have magnetic field strengths of about 600 G, the filling
factor of type 1 is a factor of two larger than that of type 2.
Conclusions: Our finding suggests that the granular convection in
the plage regions is characterized by a high rate of occurrence of
granular-sized transient horizontal fields.
Title: Net circular polarization of sunspots in high spatial
resolution
Authors: Ichimoto, K.; Tsuneta, S.; Suematsu, Y.; Katsukawa, Y.;
Shimizu, T.; Lites, B. W.; Kubo, M.; Tarbell, T. D.; Shine, R. A.;
Title, A. M.; Nagata, S.
Bibcode: 2008A&A...481L...9I
Altcode:
Context: Net circular polarization (NCP) of spectral lines in
sunspots has been most successfully explained by the presense of
discontinuities in the magnetic field inclination and flow velocity
along the line-of-sight in the geometry of the embedded flux tube model
of penumbrae (Δγ-effect).
Aims: The fine scale structure of
NCP in a sunspot is examined with special attention paid to spatial
relations of the Evershed flow to confirm the validity of the present
interpretation of the NCP of sunspots.
Methods: High resolution
spectro-polarimetric data of a positive-polarity sunspot obtained
by the Solar Optical Telescope aboard Hinode are analysed.
Results: A positive NCP is associated with the Evershed flow
channels in both limb-side and disk center-side penumbrae and with
upflows in the penumbra at disk center. The negative NCP in the disk
center-side penumbra is generated in inter-Evershed flow channels.
Conclusions: The first result is apparently inconsistent with the
current explanation of NCP with the Δγ-effect but rather suggests a
positive correlation between the magnetic field strength and the flow
velocity as the cause of the NCP. The second result serves as strong
evidence for the presence of gas flows in inter-Evershed flow channels.
Title: Changes of Magnetic Structure in Three Dimensions Associated
with the X3.4 Flare of 2006 December 13
Authors: Jing, Ju; Wiegelmann, Thomas; Suematsu, Yoshinori; Kubo,
Masahito; Wang, Haimin
Bibcode: 2008ApJ...676L..81J
Altcode:
Recent observations demonstrated that sunspot structure can change
rapidly and irreversibly after flares. One of the most puzzling results
is the increase in magnetic shear around the flaring magnetic polarity
inversion line after flares. However, all these observations were
made at the photosphere level. In this Letter, we study the altitude
variation of the nonpotentiality of the magnetic fields associated
with the 4B/X3.4 flare of 2006 December 13. The vector magnetograms
with unprecedented quality from Hinode before and after the flare are
used as the boundary conditions to extrapolate the three-dimensional
nonlinear force-free magnetic fields and the potential fields. The
former are computed with the optimization algorithm and the latter with
the Green's function method. At the photosphere boundary, magnetic shear
increases after the flare in a local area close to the flaring magnetic
polarity inversion line. Two measures of the magnetic nonpotentiality,
the weighted mean shear θw and the total magnetic shear
θwB, are calculated in this area at progressively higher
altitude. By comparing their altitude variation profiles before and
after the flare, we find that the nonpotentiality of the local area
increases after the flare below ~8 Mm and decreases from that height
to ~70 Mm. Beyond 70 Mm, the magnetic fields approach potential for
both times.
Title: Hinode SOT Observations of Solar Quiescent Prominence Dynamics
Authors: Berger, Thomas E.; Shine, Richard A.; Slater, Gregory L.;
Tarbell, Theodore D.; Title, Alan M.; Okamoto, Takenori J.; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Suematsu, Yoshinori; Tsuneta, Saku; Lites,
Bruce W.; Shimizu, Toshifumi
Bibcode: 2008ApJ...676L..89B
Altcode:
We report findings from multihour 0.2'' resolution movies of
solar quiescent prominences (QPs) observed with the Solar Optical
Telescope (SOT) on the Hinode satellite. The observations verify
previous findings of filamentary downflows and vortices in QPs. SOT
observations also verify large-scale transverse oscillations in QPs,
with periods of 20-40 minutes and amplitudes of 2-5 Mm. The upward
propagation speed of several waves is found to be ~10 km s-1,
comparable to the sound speed of a 10,000 K plasma, implying that
the waves are magnetoacoustic in origin. Most significantly, Hinode
SOT observations reveal that dark, episodic upflows are common in
QPs. The upflows are 170-700 km in width, exhibit turbulent flow,
and rise with approximately constant speeds of ~20 km s-1
from the base of the prominence to heights of ~10-20 Mm. The upflows
are visible in both the Ca II H-line and Hα bandpasses of SOT. The new
flows are seen in about half of the QPs observed by SOT to date. The
dark upflows resemble buoyant starting plumes in both their velocity
profile and flow structure. We discuss thermal and magnetic mechanisms
as possible causes of the plumes.
Title: Emergence of a Helical Flux Rope under an Active Region
Prominence
Authors: Okamoto, Takenori J.; Tsuneta, Saku; Lites, Bruce W.; Kubo,
Masahito; Yokoyama, Takaaki; Berger, Thomas E.; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shibata, Kazunari; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
Bibcode: 2008ApJ...673L.215O
Altcode: 2008arXiv0801.1956O
Continuous observations were obtained of NOAA AR 10953 with the Solar
Optical Telescope (SOT) on board the Hinode satellite from 2007 April
28 to May 9. A prominence was located over the polarity inversion
line (PIL) to the southeast of the main sunspot. These observations
provided us with a time series of vector magnetic fields on the
photosphere under the prominence. We found four features: (1) The
abutting opposite-polarity regions on the two sides along the PIL first
grew laterally in size and then narrowed. (2) These abutting regions
contained vertically weak but horizontally strong magnetic fields. (3)
The orientations of the horizontal magnetic fields along the PIL on
the photosphere gradually changed with time from a normal-polarity
configuration to an inverse-polarity one. (4) The horizontal magnetic
field region was blueshifted. These indicate that helical flux rope
was emerging from below the photosphere into the corona along the PIL
under the preexisting prominence. We suggest that this supply of a
helical magnetic flux to the corona is associated with evolution and
maintenance of active region prominences.
Title: The Horizontal Magnetic Flux of the Quiet-Sun Internetwork
as Observed with the Hinode Spectro-Polarimeter
Authors: Lites, B. W.; Kubo, M.; Socas-Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa, Y.;
Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ApJ...672.1237L
Altcode:
Observations of very quiet Sun using the Solar Optical
Telescope/Spectro-Polarimeter (SOT/SP) aboard the Hinode spacecraft
reveal that the quiet internetwork regions are pervaded by horizontal
magnetic flux. The spatial average horizontal apparent flux density
derived from wavelength-integrated measures of Zeeman-induced linear
polarization is BTapp = 55 Mx cm -2, as
compared to the corresponding average vertical apparent flux density of
| BLapp| = 11 Mx cm -2. Distributions
of apparent flux density are presented. Magnetic fields are organized on
mesogranular scales, with both horizontal and vertical fields showing
"voids" of reduced flux density of a few granules spatial extent. The
vertical fields are concentrated in the intergranular lanes, whereas the
stronger horizontal fields are somewhat separated spatially from the
vertical fields and occur most commonly at the edges of the bright
granules. High-S/N observations from disk center to the limb help
to constrain possible causes of the apparent imbalance between |
BLapp| and BTapp, with
unresolved structures of linear dimension on the surface smaller by at
least a factor of 2 relative to the SOT/SP angular resolution being one
likely cause of this discrepancy. Other scenarios for explaining this
imbalance are discussed. The horizontal fields are likely the source of
the "seething" fields of the quiet Sun discovered by Harvey et al. The
horizontal fields may also contribute to the "hidden" turbulent flux
suggested by studies involving Hanle effect depolarization of scattered
radiation.
Title: Hinode Observations of Flux Emergence in Quiet and Active
Regions
Authors: Lites, B. W.; Centeno, R.; Kubo, M.; Socas-Navarro, H. Berger,
T.; Frank, Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.;
Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2008ASPC..383...71L
Altcode:
We review briefly the observational understanding of emergence of
flux in both the quiet Sun and active regions in the light of first
results from the joint Japan/US/UK Hinode mission. That spacecraft
is now providing us with our first continuous, high resolution
measurements of the photospheric vector magnetic field, along with
high resolution observations of the thermal and dynamic properties
of the chromosphere and corona. This review is intended to present a
few very early results and to highlight the potential for discovery
offered by this extraordinary new mission. The discovery of ubiquitous
horizontal magnetic flux in the quiet internetwork regions is presented.
Title: Mangetic field properties at the footpoints of solar
microflares (active-region transient brightenings)
Authors: Shimizu, T.; Kano, R.; Katsukawa, Y.; Kubo, M.; Deluca, E.;
Ichimoto, K.; Lites, B.; Nagata, S.; Sakao, T.; Shine, R.; Suematsu,
Y.; Tarbell, T.; Title, A.; Tsuneta, S.
Bibcode: 2007AGUFMSH52C..06S
Altcode:
Solar active regions produce numerous numbers of small-scale explosive
energy releases, i.e., microflares, which are captured by imaging
observations in soft X-rays as transient brightenings of small-scale
coronal loops. Thanks to advanced performance of X-Ray Telescope (XRT)
onboard the Hinode satellite, we can investigate finer structure
of the brightening X-ray sources in more details than we did with
Yohkoh data. One of important questions on microflares is what causes
microflares. The simultaneous visible-light observations by the Solar
Optical Telescope (SOT) allow us to explore magnetic activities
and magnetic field configuration at the photospheric footpoints
of brightening loops, giving key observations to investigate the
question. For our investigations of corona-photosphere magnetic
coupling, we have established co-alignment between SOT and XRT
with accuracy better than 1 arcsec (Shimizu et al. 2007, PASJ in
press). It turns out that Ca II H observations are very useful
to identify the exact positions of footpoints of X-ray transient
brightening loops. Small "Kernels" are sometimes observed in Ca II H
and they may be signature of highly accelerated non-thermal particles
impinging on chromosphere. As already shown in Shimizu et al.(2002),
frequent transient brightenings are observed at the locations where
emerging activities are on going. However, another type of brightening
triggering mechanism should exist to explain some observed multiple-loop
brightenings. In the multiple-loop brightenings, multiple loops are
magnetically in parallel with each other and no apparent magnetic
activities, such as emerging and canceling, are observed at and near
the footpoints. This paper will present SOT observations of some
microflares observed with XRT.
Title: Small-Scale Jetlike Features in Penumbral Chromospheres
Authors: Katsukawa, Y.; Berger, T. E.; Ichimoto, K.; Lites, B. W.;
Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.;
Title, A. M.; Tsuneta, S.
Bibcode: 2007Sci...318.1594K
Altcode:
We observed fine-scale jetlike features, referred to as penumbral
microjets, in chromospheres of sunspot penumbrae. The microjets
were identified in image sequences of a sunspot taken through a Ca II
H-line filter on the Solar Optical Telescope on board the Japanese solar
physics satellite Hinode. The microjets’ small width of 400 kilometers
and short duration of less than 1 minute make them difficult to identify
in existing observations. The microjets are possibly caused by magnetic
reconnection in the complex magnetic configuration in penumbrae and
have the potential to heat the corona above a sunspot.
Title: Chromospheric Alfvénic Waves Strong Enough to Power the
Solar Wind
Authors: De Pontieu, B.; McIntosh, S. W.; Carlsson, M.; Hansteen,
V. H.; Tarbell, T. D.; Schrijver, C. J.; Title, A. M.; Shine, R. A.;
Tsuneta, S.; Katsukawa, Y.; Ichimoto, K.; Suematsu, Y.; Shimizu, T.;
Nagata, S.
Bibcode: 2007Sci...318.1574D
Altcode:
Alfvén waves have been invoked as a possible mechanism for the heating
of the Sun's outer atmosphere, or corona, to millions of degrees and
for the acceleration of the solar wind to hundreds of kilometers per
second. However, Alfvén waves of sufficient strength have not been
unambiguously observed in the solar atmosphere. We used images of
high temporal and spatial resolution obtained with the Solar Optical
Telescope onboard the Japanese Hinode satellite to reveal that the
chromosphere, the region sandwiched between the solar surface and
the corona, is permeated by Alfvén waves with strong amplitudes on
the order of 10 to 25 kilometers per second and periods of 100 to
500 seconds. Estimates of the energy flux carried by these waves and
comparisons with advanced radiative magnetohydrodynamic simulations
indicate that such Alfvén waves are energetic enough to accelerate
the solar wind and possibly to heat the quiet corona.
Title: Chromospheric Anemone Jets as Evidence of Ubiquitous
Reconnection
Authors: Shibata, Kazunari; Nakamura, Tahei; Matsumoto, Takuma; Otsuji,
Kenichi; Okamoto, Takenori J.; Nishizuka, Naoto; Kawate, Tomoko;
Watanabe, Hiroko; Nagata, Shin'ichi; UeNo, Satoru; Kitai, Reizaburo;
Nozawa, Satoshi; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi;
Shimizu, Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.; Berger,
Thomas E.; Lites, Bruce W.; Shine, Richard A.; Title, Alan M.
Bibcode: 2007Sci...318.1591S
Altcode: 2008arXiv0810.3974S
The heating of the solar chromosphere and corona is a long-standing
puzzle in solar physics. Hinode observations show the ubiquitous
presence of chromospheric anemone jets outside sunspots in active
regions. They are typically 3 to 7 arc seconds = 2000 to 5000 kilometers
long and 0.2 to 0.4 arc second = 150 to 300 kilometers wide, and their
velocity is 10 to 20 kilometers per second. These small jets have an
inverted Y-shape, similar to the shape of x-ray anemone jets in the
corona. These features imply that magnetic reconnection similar to that
in the corona is occurring at a much smaller spatial scale throughout
the chromosphere and suggest that the heating of the solar chromosphere
and corona may be related to small-scale ubiquitous reconnection.
Title: Twisting Motions of Sunspot Penumbral Filaments
Authors: Ichimoto, K.; Suematsu, Y.; Tsuneta, S.; Katsukawa, Y.;
Shimizu, T.; Shine, R. A.; Tarbell, T. D.; Title, A. M.; Lites, B. W.;
Kubo, M.; Nagata, S.
Bibcode: 2007Sci...318.1597I
Altcode:
The penumbra of a sunspot is composed of numerous thin, radially
extended, bright and dark filaments carrying outward gas flows
(the Evershed flow). Using high-resolution images obtained by the
Solar Optical Telescope aboard the solar physics satellite Hinode, we
discovered a number of penumbral bright filaments revealing twisting
motions about their axes. These twisting motions are observed only
in penumbrae located in the direction perpendicular to the symmetry
line connecting the sunspot center and the solar disk center, and
the direction of the twist (that is, lateral motions of intensity
fluctuation across filaments) is always from limb side to disk-center
side. Thus, the twisting feature is not an actual twist or turn of
filaments but a manifestation of dynamics of penumbral filaments with
three-dimensional radiative transfer effects.
Title: Hinode SOT observations of plume upflows and cascading
downflows in quiescent solar prominences
Authors: Berger, T.; Shine, R.; Slater, G.; Tarbell, T.; Title, A.;
Lites, B.; Tsuneta, S.; Okamoto, T. J.; Ichimoto, K.; Katsukawa, Y.;
Sekii, T.; Suematsu, Y.; Shimizu, T.
Bibcode: 2007AGUFMSH53A1065B
Altcode:
We present several Hinode SOT filtergram movies of quiescent solar
prominences that show newly discovered "plume-like" upflows and
cascading "waterfall-like" downflows that persist for the entire
multi-hour duration of the observations. The flow speeds are on the
order of 10 km/sec with typical widths of 400-700 km. Preliminary
calculations show that if the upflows are buoyancy driven, the
associated thermal perturbation is on the order of 10,000 K, sufficient
to explain the dark appearance of the upflows in the interference
filter passbands. In addition we observe rotational vortices and
body oscillations within the prominences. These new observations
challenge current magnetostatic models of solar prominences by showing
that prominence plasmas are in constant motion, often in directions
perpendicular to the magnetic field lines proposed by the models. TRACE,
Hinode/EIS, and Hinode/XRT observations are used to investigate the
differential topology of the flows across temperature regimes.
Title: Coronal Transverse Magnetohydrodynamic Waves in a Solar
Prominence
Authors: Okamoto, T. J.; Tsuneta, S.; Berger, T. E.; Ichimoto, K.;
Katsukawa, Y.; Lites, B. W.; Nagata, S.; Shibata, K.; Shimizu, T.;
Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title, A. M.
Bibcode: 2007Sci...318.1577O
Altcode: 2008arXiv0801.1958O
Solar prominences are cool 104 kelvin plasma clouds
supported in the surrounding 106 kelvin coronal plasma by
as-yet-undetermined mechanisms. Observations from Hinode show fine-scale
threadlike structures oscillating in the plane of the sky with periods
of several minutes. We suggest that these represent Alfvén waves
propagating on coronal magnetic field lines and that these may play
a role in heating the corona.
Title: Quiet-Sun Internetwork Magnetic Fields from the Inversion of
Hinode Measurements
Authors: Orozco Suárez, D.; Bellot Rubio, L. R.; del Toro Iniesta,
J. C.; Tsuneta, S.; Lites, B. W.; Ichimoto, K.; Katsukawa, Y.; Nagata,
S.; Shimizu, T.; Shine, R. A.; Suematsu, Y.; Tarbell, T. D.; Title,
A. M.
Bibcode: 2007ApJ...670L..61O
Altcode: 2007arXiv0710.1405O
We analyze Fe I 630 nm observations of the quiet Sun at disk center
taken with the spectropolarimeter of the Solar Optical Telescope aboard
the Hinode satellite. A significant fraction of the scanned area,
including granules, turns out to be covered by magnetic fields. We
derive field strength and inclination probability density functions from
a Milne-Eddington inversion of the observed Stokes profiles. They show
that the internetwork consists of very inclined, hG fields. As expected,
network areas exhibit a predominance of kG field concentrations. The
high spatial resolution of Hinode's spectropolarimetric measurements
brings to an agreement the results obtained from the analysis of
visible and near-infrared lines.
Title: Center-to-Limb Variation of Stokes V Asymmetries in Solar
Pores Observed with the Hinode Spectro-Polarimeter
Authors: Morinaga, Shuji; Nagata, Shin'ichi; Ichimoto, Kiyoshi;
Suematsu, Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimizu,
Toshifumi; Shine, Richard A.; Tarbell, Theodore D.; Title, Alan M.;
Lites, Bruce; Kubo, Masahito; Sakurai, Takashi
Bibcode: 2007PASJ...59S.613M
Altcode:
Here we present spectro-polarimetric measurements of several pores
and the surrounding regions taken with the Solar Optical Telescope
aboard Hinode at various viewing angles. We analyzed the Stokes V
area asymmetry, and confirmed that it is depressed at the center of
the pores, while it shows large positive values (a blue lobe larger
than a red lobe) in the surrounding area; this is consistent with a
previous report. In addition to this ring of positive asymmetry, we
found regions of alternating positive and negative area asymmetries
when weak V regions were observed near the solar limb. The positive
asymmetry occurs on the disk-center side and the negative asymmetry
on the limb side of the magnetic concentrations. These center-to-limb
variations of the Stokes V area asymmetry can be interpreted as being
a systematic inflow of plasma into the magnetic concentrations from
their surroundings.
Title: Initial Results on Line-of-Sight Field Calibrations of SP/NFI
Data Taken by SOT/Hinode
Authors: Chae, Jongchul; Moon, Yong-Jae; Park, Young-Deuk; Ichimoto,
Kiyoshi; Sakurai, Takashi; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Shimizu, Toshifumi; Shine, Richard A.; Tarbell,
Theodore D.; Title, Alan M.; Lites, Bruce; Kubo, Masahito; Nagata,
Shin'ichi; Yokoyama, Takaaki
Bibcode: 2007PASJ...59S.619C
Altcode:
We present initial results on the line-of-sight field calibration
of the two kinds of Stokes I and V data taken by the Solar Optical
Telescope on the satellite Hinode: spectral profiles of Stokes I and V
parameters recorded on the Spectro-polarimeter (SP), and monochromatic
images of the same parameters recorded on the Narrow-band Filter Imager
(NFI). By applying the center-of-gravity method to the SP data of
AR10930 taken on 2006 December 11, we determined the line-of-sight field
at every location in the active region. As a result, we found that the
line-of-sight field strength ranges up to 2kG in plages, even without
taking into account the filling factor, and up to 3.5kG or higher values
inside the umbra of the major sunspot. We calibrated the NFI data in
reference to the field determined from the SP data. In regions outside
the sunspots and the penumbral regions, we adopted a linear relation,
B|| = βV / I, between the circular polarization, V / I,
and the line-of-sight field strength, B||, and obtained β =
23.5kG in regions outside the sunspots, and β = 12.0kG in penumbral
regions. In umbral regions of sunspots, a first-order polynomial was
adopted to model the reversal of the polarization signal over the
field strength.
Title: Response of the Solar Atmosphere to Magnetic Flux Emergence
from Hinode Observations
Authors: Li, Hui; Sakurai, Takashi; Ichimito, Kiyoshi; Suematsu,
Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimizu, Toshifumi; Shine,
Richard A.; Tarbell, Theodore D.; Title, Alan M.; Lites, Bruce; Kubo,
Masahito; Nagata, Shin'ichi; Kotoku, Jun; Shibasaki, Kiyoto; Saar,
Steven H.; Bobra, Monica
Bibcode: 2007PASJ...59S.643L
Altcode:
No abstract at ADS
Title: Initial Helioseismic Observations by Hinode/SOT
Authors: Sekii, Takashi; Kosovichev, Alexander G.; Zhao, Junwei;
Tsuneta, Saku; Shibahashi, Hiromoto; Berger, Thomas E.; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu,
Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell, Theodore
D.; Title, Alan M.
Bibcode: 2007PASJ...59S.637S
Altcode: 2007arXiv0709.1806S
Results from initial helioseismic observations by the Solar Optical
Telescope on-board Hinode are reported. It has been demonstrated
that intensity oscillation data from the Broadband Filter Imager
can be used for various helioseismic analyses. The k - ω power
spectra, as well as the corresponding time-distance cross-correlation
function, which promise high-resolution time-distance analysis below
the 6-Mm travelling distance, were obtained for G-band and CaII-H
data. Subsurface supergranular patterns were observed from our first
time-distance analysis. The results show that the solar oscillation
spectrum is extended to much higher frequencies and wavenumbers, and
the time-distance diagram is extended to much shorter travel distances
and times than were observed before, thus revealing great potential
for high-resolution helioseismic observations from Hinode.
Title: Hinode Observations of Horizontal Quiet Sun Magnetic Flux
and the ``Hidden Turbulent Magnetic Flux''
Authors: Lites, Bruce; Socas-Navarro, Hector; Kubo, Masahito; Berger,
Thomas; Frank, Zoe; Shine, Richard A.; Tarbell, Theodore D.; Title,
Alan M.; Ichimoto, Kiyoshi; Katsukawa, Yukio; Tsuneta, Saku; Suematsu,
Yoshinori; Shimizu, Toshifumi
Bibcode: 2007PASJ...59S.571L
Altcode:
We present observations of magnetic fields of the very quiet Sun
near disk center using the Spectro-Polarimeter of the Solar Optical
Telescope aboard the Hinode satellite. These observations reveal for
the first time the ubiquitous presence of horizontal magnetic fields in
the internetwork regions. The horizontal fields are spatially distinct
from the vertical fields, demonstrating that they are not arising mainly
from buffeting of vertical flux tubes by the granular convection. The
horizontal component has an average ``apparent flux density'' of
55Mxcm-2 (assuming the horizontal field structures are
spatially resolved), in contrast to the average apparent vertical flux
density of 11Mxcm-2. The vertical fields reside mainly in
the intergranular lanes, whereas the horizontal fields occur mainly
over the bright granules, with a preference to be near the outside
edge of the bright granules. The large apparent imbalance of vertical
and horizontal flux densities is discussed, and several scenarios are
presented to explain this imbalance.
Title: Strategy for the Inversion of Hinode Spectropolarimetric
Measurements in the Quiet Sun
Authors: Orozco Suárez, David; Bellot Rubio, Luis R.; Del Toro
Iniesta, Jose Carlos; Tsuneta, Saku; Lites, Bruce; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.
Bibcode: 2007PASJ...59S.837O
Altcode: 2007arXiv0709.2033O
In this paper we propose an inversion strategy for the analysis of
spectropolarimetric measurements taken by Hinode in the quiet Sun. The
Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode records
the Stokes spectra of the FeI line pair at 630.2nm with unprecendented
angular resolution, high spectral resolution, and high sensitivity. We
discuss the need to consider a local stray-light contamination to
account for the effects of telescope diffraction. The strategy is
applied to observations of a wide quiet Sun area at disk center. Using
these data we examine the influence of noise and initial guess models
in the inversion results. Our analysis yields the distributions of
magnetic field strengths and stray-light factors. They show that quiet
Sun internetwork regions consist mainly of hG fields with stray-light
contamination of about 0.8.
Title: Hinode Observations of a Vector Magnetic Field Change
Associated with a Flare on 2006 December 13
Authors: Kubo, Masahito; Yokoyama, Takaaki; Katsukawa, Yukio; Lites,
Bruce; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu,
Toshifumi; Nagata, Shin'ichi; Tarbell, Theodore D.; Shine, Richard A.;
Title, Alan M.; Elmore David
Bibcode: 2007PASJ...59S.779K
Altcode: 2007arXiv0709.2397K
Continuous observations of the flare productive active region 10930
were successfully carried out with the Solar Optical Telescope aboard
the Hinode spacecraft during 2006 December 6 to 19. We focused on the
evolution of photospheric magnetic fields in this active region, and the
magnetic field properties at the site of the X3.4 class flare, using
a time series of vector field maps with high spatial resolution. The
X3.4 class flare occurred on 2006 December 13 at the apparent
collision site between the large, opposite polarity umbrae. Elongated
magnetic structures with alternatingly positive and negative polarities
resulting from flux emergence appeared one day before the flare in the
collision site penumbra. Subsequently, the polarity inversion line
at the collision site became very complicated. The number of bright
loops in CaII H increased during the formation of these elongated
magnetic structures. Flare ribbons and bright loops evolved along
the polarity inversion line and one footpoint of the bright loop was
located in a region having a large departure of the field azimuth angle
with respect to its surroundings. SOT observations with high spatial
resolution and high polarization precision revealed temporal change in
the fine structure of magnetic fields at the flare site: some parts of
the complicated polarity inversion line then disappeared, and in those
regions the azimuth angle of the photospheric magnetic field changed by
about 90°, becoming more spatially uniform within the collision site.
Title: The Analysis of Penumbral Fine Structure Using an Advanced
Inversion Technique
Authors: Jurcák, Jan; Bellot Rubio, Luis; Ichimoto, Kiyoshi;
Katsukawa, Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi;
Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.; Tsuneta,
Saku
Bibcode: 2007PASJ...59S.601J
Altcode: 2007arXiv0707.1560J
We present a method to study the penumbral fine structure using data
obtained by the spectropolarimeter on board Hinode. For the first
time, the penumbral filaments can be considered as being resolved in
spectropolarimetric measurements. This enables us to use inversion
codes with only one-component model atmospheres, and thus to assign
the obtained stratifications of the plasma parameters directly to the
penumbral fine structure. This approach was applied to the limb-side
part of the penumbra in the active region NOAA10923. Preliminary results
show a clear dependence of the plasma parameters on the continuum
intensity in the inner penumbra, i.e., a weaker and horizontal magnetic
field along with an increased line-of-sight velocity are found in the
low layers of the bright filaments. The results in the mid penumbra
are ambiguous, and future analyses are necessary to unveil the magnetic
field structure and other plasma parameters there.
Title: Fine-Scale Structures of the Evershed Effect Observed by the
Solar Optical Telescope aboard Hinode
Authors: Ichimoto, Kiyoshi; Shine, Richard A.; Lites, Bruce; Kubo,
Masahito; Shimizu, Toshifumi; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Tarbell, Theodore D.; Title, Alan M.; Nagata,
Shin'ichi; Yokoyama, Takaaki; Shimojo, Masumi
Bibcode: 2007PASJ...59S.593I
Altcode:
The small-scale structure of the Evershed effect is being studied
using data obtained by the Spectropolarimeter and the Broadband Filter
Imager of the Solar Optical Telescope aboard Hinode. We find that the
Evershed flow starts at the leading edge of inwardly migrating bright
penumbral grains, and turns to nearly a horizontal flow preferentially
in the dark lanes of the penumbra. A number of small elongated regions
that have an upward motion of ∼ 1kms-1 are found in the
deep photosphere distributed over the penumbra. They are cospatial
with bright grains and have relatively horizontal magnetic fields. A
number of patches having a strong downward motion associated with the
opposite magnetic polarity from the sunspot are also found in the mid
and outer penumbra. They could be identified as foot points of the
Evershed flow channels, though the identification of individual pairs
is not straightforward. Our results provide strong support for some
recent findings from ground-based high-resolution observations, and
are in general agreement with the well-known picture of the uncombed
structure of the penumbra, in which the penumbrae consist of rising
flux tubes carrying nearly horizontal Evershed flows embedded in more
vertical background magnetic fields.
Title: Flare Ribbons Observed with G-band and FeI 6302Å, Filters
of the Solar Optical Telescope on Board Hinode
Authors: Isobe, Hiroaki; Kubo, Masahito; Minoshima, Takashi; Ichimoto,
Kiyoshi; Katsukawa, Yukio; Tarbell, Theodore D.; Tsuneta, Saku; Berger,
Thomas E.; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Title, Alan M.
Bibcode: 2007PASJ...59S.807I
Altcode: 2007arXiv0711.3946I
The Solar Optical Telescope (SOT) on board the Hinode satellite observed
an X3.4 class flare on 2006 December 13. A typical two-ribbon structure
was observed, not only in the chromospheric CaII H line, but also in
the G-band and FeI 6302Å line. The high-resolution, seeing-free images
achieved by SOT revealed, for the first time, sub-arcsec fine structures
of the ``white light'' flare. The G-band flare ribbons on sunspot
umbrae showed a sharp leading edge, followed by a diffuse inside,
as well as a previously known core-halo structure. The underlying
structures, such as umbral dots, penumbral filaments, and granules,
were visible in the flare ribbons. Assuming that the sharp leading
edge was directly heated by a particle beam and the diffuse parts were
heated by radiative back-warming, we estimated the depth of the diffuse
flare emission using an intensity profile of the flare ribbon. We found
that the depth of the diffuse emission was about 100km or less from
the height of the source of radiative back-warming. The flare ribbons
were also visible in the Stokes-V images of FeI 6302Å, as a transient
polarity reversal. This is probably related to a ``magnetic transient''
reported in the literature. The intensity increase in Stokes-I images
indicates that the FeI 6302Å line was significantly deformed by the
flare, which may cause such a magnetic transient.
Title: Small-Scale Magnetic-Flux Emergence Observed with Hinode
Solar Optical Telescope
Authors: Otsuji, Kenichi; Shibata, Kazunari; Kitai, Reizaburo; Ueno,
Satoru; Nagata, Shin'ichi; Matsumoto, Takuma; Nakamura, Tahei;
Watanabe, Hiroko; Tsuneta, Saku; Suematsu, Yoshinori; Ichimoto,
Kiyoshi; Shimizu, Toshifumi; Katsukawa, Yukio; Tarbell, Theodore D.;
Lites, Bruce; Shine, Richard A.; Title Alan M.
Bibcode: 2007PASJ...59S.649O
Altcode: 2007arXiv0709.3207O
We observed small-scale magnetic-flux emergence in a sunspot moat region
by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We
analyzed filtergram images observed at wavelengths of Fe 6302Å, G band,
and CaII H. In Stokes I images of Fe 6302Å, emerging magnetic flux was
recognized as dark lanes. In the G band, they showed to be their shapes
almost the same as in Stokes I images. These magnetic fluxes appeared
as dark filaments in CaII H images. Stokes V images of Fe 6302Å showed
pairs of opposite polarities at footpoints of each filament. These
magnetic concentrations were identified to correspond to bright points
in G band/CaII H images. From an analysis of time-sliced diagrams, we
derived the following properties of emerging flux, which are consistent
with those of previous studies: (1) Two footpoints separate each other
at a speed of 4.2kms-1 during the initial phase of evolution,
and decrease to about 1kms-1 10minutes later. (2) CaII H
filaments appear almost simultaneously with the formation of dark lanes
in Stokes I in an observational cadence of 2minutes. (3) The lifetime
of the dark lanes in the Stokes I and G band is 8minutes, while that
of Ca filament is 12minutes. An interesting phenomena was observed,
that an emerging flux tube expanded laterally in the photosphere with a
speed of 3.8kms-1. A discussion on the horizontal expansion
of the flux tube is given with refernce to previous simulation studies.
Title: Observations of Sunspot Oscillations in G Band and CaII H
Line with Solar Optical Telescope on Hinode
Authors: Nagashima, Kaori; Sekii, Takashi; Kosovichev, Alexander G.;
Shibahashi, Hiromoto; Tsuneta, Saku; Ichimoto, Kiyoshi; Katsukawa,
Yukio; Lites, Bruce; Nagata, Shin'ichi; Shimizu, Toshifumi; Shine,
Richard A.; Suematsu, Yoshinori; Tarbell, Theodore D.; Title, Alan M.
Bibcode: 2007PASJ...59S.631N
Altcode: 2007arXiv0709.0569N
Exploiting high-resolution observations made by the Solar Optical
Telescope on board Hinode, we investigate the spatial distribution
of the power spectral density of the oscillatory signal in and around
the active region NOAA 10935. The G-band data show that in the umbra
the oscillatory power is suppressed in all frequency ranges. On
the other hand, in CaII H intensity maps oscillations in the umbra,
so-called umbral flashes, are clearly seen with the power peaking around
5.5mHz. The CaII H power distribution shows the enhanced elements with
the spatial scale of the umbral flashes over most of the umbra, but
there is a region with suppressed power at the center of the umbra. The
origin and property of this node-like feature remain unexplained.
Title: Hinode SP Vector Magnetogram of AR10930 and Its
Cross-Comparison with MDI
Authors: Moon, Yong-Jae; Kim, Yeon-Han; Park, Young-Deuk; Ichimoto,
Kiyoshi; Sakurai, Takashi; Chae, Jongchul; Cho, Kyung Suk; Bong,
Suchan; Suematsu, Yoshinori; Tsuneta, Saku; Katsukawa, Yukio; Shimojo,
Masumi; Shimizu, Toshifumi; Shine, Richard A.; Tarbell, Theodore D.;
Title, Alan M.; Lites, Bruce; Kubo, Masahito; Nagata, Shin'ichi;
Yokoyama, Takaaki
Bibcode: 2007PASJ...59S.625M
Altcode:
We present one Hinode Spectropolarimeter (SP) magnetogram of AR 10930
that produced several major flares. The inversion from Stokes profiles
to magnetic field vectors was made using the standard Milne-Eddington
code. We successfully applied the Uniform Shear Method for resolving
the 180° ambiguity to the magnetogram. The inversion gave very strong
magnetic field strengths (near 4500 gauss) for a small portion of area
in the umbra. Considering that the observed V-profile of 6301.5Å was
well-fitted as well as a direct estimation of the Zeeman splitting
results in 4300-4600 gauss, we think that the field strengths
should not be far from the actual value. A cross-comparison of the
Hinode SP and SOHO MDI high resolution flux densities shows that the
MDI flux density could be significantly underestimated by about a
factor of two. In addition, it has a serious negative correlation
(the so-called Zeeman saturation effect) with the Hinode SP flux
density for umbral regions. Finally, we could successfully obtain
a recalibrated MDI magnetogram that has been corrected for the
Zeeman saturation effect using not only a pair of MDI intensity and
magnetogram data simultaneously observed, but also the relationship
from the cross-comparison between the Hinode SP and MDI flux densities.
Title: Formation Process of a Light Bridge Revealed with the Hinode
Solar Optical Telescope
Authors: Katsukawa, Yukio; Yokoyama, Takaaki; Berger, Thomas E.;
Ichimoto, Kiyoshi; Kubo, Masahito; Lites, Bruce; Nagata, Shin'ichi;
Shimizu, Toshifumi; Shine, Richard A.; Suematsu, Yoshinori; Tarbell,
Theodore D.; Title, Alan M.; Tsuneta, Saku
Bibcode: 2007PASJ...59S.577K
Altcode: 2007arXiv0709.2527K
The Solar Optical Telescope (SOT) on-board Hinode successfully and
continuously observed the formation process of a light bridge in a
matured sunspot of the NOAA active region 10923 for several days with
high spatial resolution. During its formation, many umbral dots were
observed to be emerging from the leading edges of penumbral filaments,
and rapidly intruding into the umbra. The precursor of the light bridge
formation was also identified as a relatively slow inward motion of
the umbral dots, which emerged not near the penumbra, but inside the
umbra. The spectro-polarimeter on SOT provided physical conditions in
the photosphere around the umbral dots and the light bridges. We found
that the light bridges and the umbral dots had significantly weaker
magnetic fields associated with upflows relative to the core of the
umbra, which implies that there was hot gas with weak field strength
penetrating from the subphotosphere to near the visible surface inside
those structures. There needs to be a mechanism to drive the inward
motion of the hot gas along the light bridges. We suggest that the
emergence and the inward motion are triggered by a buoyant penumbral
flux tube as well as subphotospheric flow crossing the sunspot.
Title: Umbral Fine Structures in Sunspots Observed with Hinode Solar
Optical Telescope
Authors: Kitai, Reizaburo; Watanabe, Hiroko; Nakamura, Tahei; Otsuji,
Ken-ichi; Matsumoto, Takuma; UeNo, Satoru; Nagata, Shin'ichi; Shibata,
Kazunari; Muller, Richard; Ichimoto, Kiyoshi; Tsuneta, Saku; Suematsu,
Yoshinori; Katsukawa, Yukio; Shimizu, Toshifumi; Tarbell, Theodore D.;
Shine, Richard A.; Title, Alan M.; Lites, Bruce
Bibcode: 2007PASJ...59S.585K
Altcode: 2007arXiv0711.3266K
A high resolution imaging observation of a sunspot umbra was made with
the Hinode Solar Optical Telescope. Filtergrams at wavelengths of the
blue and green continua were taken during three consecutive days. The
umbra consisted of a dark core region, several diffuse components,
and numerous umbral dots. We derived basic properties of umbral dots
(UDs), especially their temperatures, lifetimes, proper motions,
spatial distribution, and morphological evolution. The brightness
of UDs is confirmed to depend on the brightness of their surrounding
background. Several UDs show fission and fusion. Thanks to the stable
condition of the space observation, we could for the first time follow
the temporal behavior of these events. The derived properties of the
internal structure of the umbra are discussed from the viewpoint of
magnetoconvection in a strong magnetic field.
Title: On Connecting the Dynamics of the Chromosphere and Transition
Region with Hinode SOT and EIS
Authors: Hansteen, Viggo H.; de Pontieu, Bart; Carlsson, Mats;
McIntosh, Scott; Watanabe, Tetsuya; Warren, Harry P.; Harra, Louise K.;
Hara, Hirohisa; Tarbell, Theodore D.; Shine, Dick; Title, Alan M.;
Schrijver, Carolus J.; Tsuneta, Saku; Katsukawa, Yukio; Ichimoto,
Kiyoshi; Suematsu, Yoshinori; Shimizu, Toshifumi
Bibcode: 2007PASJ...59S.699H
Altcode: 2007arXiv0711.0487H
We use coordinated Hinode SOT/EIS observations that include
high-resolution magnetograms, chromospheric, and transition region
(TR) imaging, and TR/coronal spectra in a first test to study how
the dynamics of the TR are driven by the highly dynamic photospheric
magnetic fields and the ubiquitous chromospheric waves. Initial
analysis shows that these connections are quite subtle and require a
combination of techniques including magnetic field extrapolations,
frequency-filtered time-series, and comparisons with synthetic
chromospheric and TR images from advanced 3D numerical simulations. As a
first result, we find signatures of magnetic flux emergence as well as
3 and 5mHz wave power above regions of enhanced photospheric magnetic
field in both chromospheric, transition region, and coronal emission.
Title: Can High Frequency Acoustic Waves Heat the Quiet Sun
Chromosphere?
Authors: Carlsson, Mats; Hansteen, Viggo H.; de Pontieu, Bart;
McIntosh, Scott; Tarbell, Theodore D.; Shine, Dick; Tsuneta, Saku;
Katsukawa, Yukio; Ichimoto, Kiyoshi; Suematsu, Yoshinori; Shimizu,
Toshifumi; Nagata, Shin'ichi
Bibcode: 2007PASJ...59S.663C
Altcode: 2007arXiv0709.3462C
We use Hinode/SOT Ca II H-line and blue continuum broadband observations
to study the presence and power of high frequency acoustic waves at
high spatial resolution. We find that there is no dominant power at
small spatial scales; the integrated power using the full resolution of
Hinode (0.05'' pixels, 0.16'' resolution) is larger than the power in
the data degraded to 0.5'' pixels (TRACE pixel size) by only a factor
of 1.2. At 20 mHz the ratio is 1.6. Combining this result with the
estimates of the acoustic flux based on TRACE data of Fossum &
Carlsson (2006), we conclude that the total energy flux in acoustic
waves of frequency 5-40 mHz entering the internetwork chromosphere of
the quiet Sun is less than 800 W m$^{-2}$, inadequate to balance the
radiative losses in a static chromosphere by a factor of five.
Title: Formation of Moving Magnetic Features and Penumbral Magnetic
Fields with Hinode/SOT
Authors: Kubo, Masahito; Ichimoto, Kiyoshi; Shimizu, Toshifumi;
Tsuneta, Saku; Suematsu, Yoshinori; Katsukawa, Yukio; Nagata,
Shin'ichi; Tarbell, Theodore D.; Shine, Richard A.; Title, Alan M.;
Frank, Zoe A.; Lites, Bruce; Elmore, David
Bibcode: 2007PASJ...59S.607K
Altcode: 2007arXiv0709.1853K
Vector magnetic fields of moving magnetic features (MMFs) were well
observed with the Solar Optical Telescope (SOT) aboard the Hinode
satellite. We focused on the evolution of three MMFs with the SOT in
this study. We found that an MMF having relatively vertical fields
with the same polarity as the sunspot was detached from the penumbra
around the granules appearing in the outer penumbra. This suggests
that granular motions in the outer penumbra are responsible for
disintegration of the sunspot. Two MMFs with polarity opposite to
the sunspot are located around the outer edge of horizontal fields
extending from the penumbra. This is evidence that the MMFs with
polarity opposite to the sunspot are the prolongation of penumbral
horizontal fields. Redshifts larger than the sonic velocity in the
photosphere are detected for some of the MMFs with polarity opposite
to the sunspot.
Title: A Tale of Two Spicules: The Impact of Spicules on the Magnetic
Chromosphere
Authors: de Pontieu, Bart; McIntosh, Scott; Hansteen, Viggo H.;
Carlsson, Mats; Schrijver, Carolus J.; Tarbell, Theodore D.; Title,
Alan M.; Shine, Richard A.; Suematsu, Yoshinori; Tsuneta, Saku;
Katsukawa, Yukio; Ichimoto, Kiyoshi; Shimizu, Toshifumi; Nagata,
Shin'ichi
Bibcode: 2007PASJ...59S.655D
Altcode: 2007arXiv0710.2934D
We use high-resolution observations of the Sun in CaIIH (3968Å)
from the Solar Optical Telescope on Hinode to show that there are
at least two types of spicules that dominate the structure of the
magnetic solar chromosphere. Both types are tied to the relentless
magnetoconvective driving in the photosphere, but have very different
dynamic properties. ``Type-I'' spicules are driven by shock waves
that form when global oscillations and convective flows leak into
the upper atmosphere along magnetic field lines on 3--7minute
timescales. ``Type-II'' spicules are much more dynamic: they form
rapidly (in ∼ 10s), are very thin (≤ 200 km wide), have lifetimes
of 10-150s (at any one height), and seem to be rapidly heated to
(at least) transition region temperatures, sending material through
the chromosphere at speeds of order 50--150kms-1. The
properties of Type II spicules suggest a formation process that is
a consequence of magnetic reconnection, typically in the vicinity
of magnetic flux concentrations in plage and network. Both types of
spicules are observed to carry Alfvén waves with significant amplitudes
of order 20kms-1.
Title: Estimate on SOT Light Level in Flight with Throughput
Measurements in SOT Sun Tests
Authors: Shimizu, T.; Kubo, M.; Tarbell, T. D.; Berger, T. E.;
Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Miyashita, M.; Noguchi,
M.; Nakagiri, M.; Tsuneta, S.; Elmore, D. F.; Lites, B. W.
Bibcode: 2007ASPC..369...51S
Altcode:
The SOT (Solar Optical Telescope, e.g., Shimizu 2004) optical
system consists of 50cm-aperture optical telescope (OTA) and focal
plane instrument (FPP). The solar light into the telescope penetrates
through many optical elements located in OTA and FPP before illuminating
CCDs. Natural solar light was fed to the integrated SOT in sun tests for
verifying various optical aspects including the confirmation of photon
throughput. CCD exposures provide the number of photons accumulated
in an exposure duration with a clean-room test condition. To estimate
the absolute intensity of the solar light at the telescope entrance
in the clean-room test condition, we developed a pinhole-PSD sensor
for simultaneous monitoring the solar light outside the clean room
and measured the transmission of light through two flat mirrors of
the heliostat and clean-room entrance window glass as a function of
wavelength. The PSD sensor was pre-calibrated with continuous monitoring
the solar light in a day long under a clear constant sky condition,
determining the earth atmospheric attenuation and the PSD output for
the solar light on orbit. These throughput measurements have provided
an estimate on photon throughput for the SOT flight model. The results
confirm suitable number of photons without saturation for proper CCD
exposures in flight.
Title: Performance Characteristics of the Solar-B Spectro-Polarimeter
Authors: Lites, B. W.; Elmore, D. F.; Streander, K. V.; Hoffmann,
C. M.; Tarbell, T. D.; Title, A. M.; Shine, R. A.; Ichimoto, K.;
Tsuneta, S.; Shimizu, T.; Suematsu, Y.
Bibcode: 2007ASPC..369...55L
Altcode:
The Focal Plane Package (FPP) of the Solar Optical Telescope (SOT)
includes the first precision Spectro-Polarimeter (SP) for solar space
observations. The FPP/SP will provide high precision measures of
the vector magnetic field in the solar photosphere. Here we present
some as-built performance specifications for the entire system of
telescope + polarimeter. The FPP-SP system represents significant
gains in several aspects over existing spectro-polarimetric systems;
notably, angular resolution, polarimetric accuracy, spectral purity,
and most importantly, temporal continuity of stable, high angular
resolution. In this short summary of the poster, a few of the
performance characteristics of the SP are presented.
Title: Calibration of the SOT Polarization
Authors: Ichimoto, K.; Suematsu, Y.; Shimizu, T.; Katsukawa, Y.;
Noguchi, M.; Nakagiri, M.; Miyashita, M.; Tsuneta, S.; Tarbell, T. D.;
Shine, R. A.; Hoffmann, C. M.; Cruz, T.; Lites, B. W.; Elmore, D. F.
Bibcode: 2007ASPC..369...39I
Altcode:
Calibration of SOT polarization property was performed using natural
sunlight and well calibrated sheet polarizer (linear and circular)
placed on the entrance of the telescope. The polarimeter response
matrices were determined for the spectropolarimeter (SP) and the
narrowband filter imager (NFI), and it is shown that they are well
behave as predicted and constant over the field of view. The crosstalk
between I,Q,U,V will be suppressed to the negligible level at the
photometric accuracy of 10^{-3} after the calibration with the obtained
matrices. The sensitivity of SOT on linear and circular polarizations
at each wavelength observed by NFI are also obtained.
Title: Calibration of SOT Dopplergrams
Authors: Katsukawa, Y.; Ichimoto, K.; Sekii, T.; Suematsu, Y.; Tsuneta,
S.; Shine, R. A.; Tarbell, T. D.
Bibcode: 2007ASPC..369...43K
Altcode:
Narrow-band Filter Imager on SOT provides Dopplergrams (DGs) which
are images of Doppler (line- of-sight) velocities. Observations with
DGs are critically important in studies of photospheric dynamics and
helioseismology. The primary photospheric line used for DGs is Fe I 5576
Å which is a line insensitive to Zeeman effect. We made a calibration
function for the 5576 Å DGs to get actual Doppler velocities from
velocity indexes using an atlas spectrum and simulated transmission
profiles for the tunable filter (TF) on SOT. Using data sets taken
in the natural sun-light test, we quantitatively evaluated accuracy
of the DGs by comparing the rotational speed of the Sun measured
with DGs with the expected one. There was a little systematic error
in the velocity obtained by SOT, but the error was less than 20 %
of the predicted velocities.
Title: Examinations of the Relative Alignment of the Instruments
on SOT
Authors: Okamoto, T. J.; Katsukawa, Y.; Shimizu, T.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Tarbell, T. D.
Bibcode: 2007ASPC..369...47O
Altcode:
We report the results of the examination about the relative alignment
among the instruments on SOT. We employ a test data set obtained in the
natural sun-light test in May 2005, which has had a grid pattern over
the entire FOV. SOT has the filtergraph (FG) and the spectro-polarimeter
(SP). The FG consists of six broadband filter imagers (BFI) and six
narrowband filter imagers (NFI). We examined the displacements among
the images taken with different filters to an accuracy of better than
0.1 pixel corresponding to 0.02''. It is important to know relative
displacements and plate scales of these instruments for accurate
alignment of observational data. We note that the values measured in
our work are relative and it is needed to decide the absolute values
with another way.
Title: Vector Spectropolarimetry of Dark-cored Penumbral Filaments
with Hinode
Authors: Bellot Rubio, L. R.; Tsuneta, S.; Ichimoto, K.; Katsukawa,
Y.; Lites, B. W.; Nagata, S.; Shimizu, T.; Shine, R. A.; Suematsu,
Y.; Tarbell, T. D.; Title, A. M.; del Toro Iniesta, J. C.
Bibcode: 2007ApJ...668L..91B
Altcode: 2007arXiv0708.2791B
We present spectropolarimetric measurements of dark-cored penumbral
filaments taken with Hinode at a resolution of 0.3". Our observations
demonstrate that dark-cored filaments are more prominent in polarized
light than in continuum intensity. Far from disk center, the Stokes
profiles emerging from these structures are very asymmetric and show
evidence for magnetic fields of different inclinations along the
line of sight, together with strong Evershed flows of at least 6-7 km
s-1. In sunspots closer to disk center, dark-cored penumbral
filaments exhibit regular Stokes profiles with little asymmetries due
to the vanishing line-of-sight component of the horizontal Evershed
flow. An inversion of the observed spectra indicates that the magnetic
field is weaker and more inclined in the dark cores as compared with
the surrounding bright structures. This is compatible with the idea
that dark-cored filaments are the manifestation of flux tubes carrying
hot Evershed flows.
Title: Emergence of Small-Scale Magnetic Loops in the Quiet-Sun
Internetwork
Authors: Centeno, R.; Socas-Navarro, H.; Lites, B.; Kubo, M.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Tsuneta, S.;
Katsukawa, Y.; Suematsu, Y.; Shimizu, T.; Nagata, S.
Bibcode: 2007ApJ...666L.137C
Altcode: 2007arXiv0708.0844C
We study the emergence of magnetic flux at very small spatial
scales (less than 2") in the quiet-Sun internetwork. To this aim,
a time series of spectropolarimetric maps was taken at disk center
using the instrument SP/SOT on board Hinode. The LTE inversion of
the full Stokes vector measured in the Fe I 6301 and 6302 Å lines
allows us to retrieve the magnetic flux and topology in the region
of study. In the example presented here, the magnetic flux emerges
within a granular structure. The horizontal magnetic field appears
prior to any significant amount of vertical field. As time goes on,
the traces of the horizontal field disappear, while the vertical dipoles
drift-carried by the plasma motions-toward the surrounding intergranular
lanes. These events take place within typical granulation timescales.
Title: The Hinode (Solar-B) Mission: An Overview
Authors: Kosugi, T.; Matsuzaki, K.; Sakao, T.; Shimizu, T.; Sone,
Y.; Tachikawa, S.; Hashimoto, T.; Minesugi, K.; Ohnishi, A.; Yamada,
T.; Tsuneta, S.; Hara, H.; Ichimoto, K.; Suematsu, Y.; Shimojo, M.;
Watanabe, T.; Shimada, S.; Davis, J. M.; Hill, L. D.; Owens, J. K.;
Title, A. M.; Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Golub, L.
Bibcode: 2007SoPh..243....3K
Altcode:
The Hinode satellite (formerly Solar-B) of the Japan Aerospace
Exploration Agency's Institute of Space and Astronautical Science
(ISAS/JAXA) was successfully launched in September 2006. As the
successor to the Yohkoh mission, it aims to understand how magnetic
energy gets transferred from the photosphere to the upper atmosphere
and results in explosive energy releases. Hinode is an observatory
style mission, with all the instruments being designed and built to
work together to address the science aims. There are three instruments
onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer
(EIS), and the X-Ray Telescope (XRT). This paper provides an overview
of the mission, detailing the satellite, the scientific payload, and
operations. It will conclude with discussions on how the international
science community can participate in the analysis of the mission data.
Title: Chromospheric Micro-jets Discovered Above Sunspot Penumbrae
Authors: Katsukawa, Yukio; Tsuneta, S.; Suematsu, Y.; Ichimoto, K.;
Shimizu, T.; Kubo, M.; Nagata, S.; Berger, T.; Tarbell, T.; Shine,
R.; Title, A.
Bibcode: 2007AAS...210.9413K
Altcode: 2007BAAS...39..219K
The Solar Optical Telescope (SOT) aboard HINODE allows us to observe
dynamical activities in the solar photosphere and the chromosphere
with high and stable image quality of 0.2 arcseconds. This superior
performance of SOT provides new findings of fine-scale transient
activities occurring in the chromosphere. In this paper, we report
discovery of fine-scale jet-like phenomena ubiquitously observed
above sunspot penumbrae. The jets are identified in image sequences
of a sunspot taken through a Ca II H line filter at 3968A. The Ca II
H line is sensitive to about 10^4 K plasma in the chromosphere. Their length is typically between 3000 and 10000km, and their
width is smaller than 500km. It is notable that their lifetime
is shorter than 1 minute. Those small spatial and temporal scale
possibly makes it difficult to identify the phenomena in existing
ground-based observations. The jets are easily identified when a
sunspot is located far from the disk center, and motion of the bright
features suggests that mass is erupted from lower chromosphere to upper
atmosphere. Velocities of the motion are estimated to be 50 to 100 km/s
from their lateral motion of intensity patterns. The velocities are much
faster than sound speeds in the chromosphere. A possible cause of such
high-speed jets is magnetic reconnection at the lower chromosphere
resulted from fluted magnetic configuration in penumbrae which is
suggested by vector magnetic field measurements in the photosphere.
Title: Hinode Data Calibration For Precise Image Co-alignment:
XRT vs. SOT
Authors: Shimizu, Toshifumi; DeLuca, E. E.; Lundquist, L.; Sakao,
T.; Kubo, M.; Narukage, N.; Kano, R.; Katsukawa, Y.; Ichimoto, K.;
Suematsu, Y.; Tsuneta, S.; Tarbell, T.; Shine, D.; Hinode Team
Bibcode: 2007AAS...210.9417S
Altcode: 2007BAAS...39Q.220S
From late October in 2006, Hinode solar optical telescope (SOT) has
started to produce series of 0.2-0.3 arcsec visible-light images,
revealing dynamical behaviors of solar magnetic fields on the
solar surface. Simultaneously, Hinode X-ray telescope (XRT) has been
providing 1 arcsec resolution X-ray images of the solar corona, giving
the location of heating and dynamics occuring in the corona. Precise
image co-alignment of SOT data on XRT data with sub-arcsec accuracy is
required to provide new information regarding connecting the corona to
the photosphere. This presentation will give an introduction of Hinode
between-telescopes' image co-alignment to SPD participants. For active
region observations with sunspots, sunspots can be used as fiducial to
co-align the data from the two telescopes each other. Satellite jitter
in order of 1 arcsec or less is included in the series of XRT data,
whereas image stabilization system (correlation tracker) removes the
satellite jitter from the series of SOT images. Telescope pointings show
orbital variation in order of a few arcsec, which can be well predicted
from Hinode orbit information. Modeling co-alignment is under study
and it is the only precise method for quiet Sun and limb observations.
Title: Magnetic Patches in Internetwork Quiet Sun
Authors: De Wijn, Alfred; Lites, B.; Berger, T.; Shine, R.; Title,
A.; Katsukawa, Y.; Tsuneta, S.; Suematsu, Y.; Shimizu, T.; Hinode Team
Bibcode: 2007AAS...210.9412D
Altcode: 2007BAAS...39Q.219D
We study strong flux elements in the quiet sun in the context of
the nature of quiet-sun magnetism, its coupling to chromospheric,
transition-region and coronal fields, and the nature of a local
turbulent dynamo. Strong, kilogauss flux elements show up intermittently
as small bright points in G-band and Ca II H images. Although
bright points have been extensively studied in the magnetic network,
internetwork magnetism has only come under scrutiny in recent years. A
full spectrum of field strengths seems to be ubiquitously present in
the internetwork at small spatial scales, with the stronger elements
residing in intergranular lanes. De Wijn et al. (2005) found that bright
points in quiet sun internetwork areas appear recurrently with varying
intensity and horizontal motion within long-lived patches that outline
cell patterns on mesogranular scales. They estimate that the "magnetic
patches" have a mean lifetime of nine hours, much longer than granular
timescales. We use multi-hour sequences of G-band and Ca II H images
as well as magnetograms recorded by the Hinode satellite to follow up
on their results. The larger field of view, the longer sequences, the
addition of magnetograms, and the absence of atmospheric seeing allows
us to better constrain the patch lifetime, to provide much improved
statistics on IBP lifetime, to compare IBPs to network bright points,
and to study field polarity of IBPs in patches and between nearby
patches. Hinode is an international project supported by JAXA,
NASA, PPARC and ESA. We are grateful to the Hinode team for all their
efforts in the design, build and operation of the mission.
Title: Hinode/SOT Observations Of Apparent "Thermal Plume" Motions
In A Solar Prominence
Authors: Berger, Thomas; Tarbell, T.; Slater, G.; Tsuneta, S.;
Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.; Shimizu, T.; Kubo, M.;
Nagata, S.
Bibcode: 2007AAS...210.9433B
Altcode: 2007BAAS...39..222B
We present 396.8 nm Ca II H-line observations of a large
hedgerow, or "sheet", prominence seen on the solar western limb
on 30-November-2006. The 16 second cadence observations show dark
channels rising vertically at speeds of approximately 10 km/sec to
heights of about 15 Mm above the limb. Many of the motions end in
vortical overturning near the top of the sheet . Bright downflows of
similar speed are also seen within the sheet, often in association
with a dark channel that has risen to the top of the sheet. The dark
channels are suggestive of hot material rising in thermal plumes
within the prominence sheet. Similarly, the bright material motions
appear to be density enhanced regions of turbulent downflow. Current
models of sheet prominences do not include the observed dynamics. In
these models, the prominence plasma is in a low-beta state and is
constrained to move only along magnetic field lines. However the
motions observed here are extremely complex, implying either that the
magnetic field lines are undergoing turbulent motion, thus tangling
and reconnecting constantly, or that the plasma is not constrained
by the field and is in a high-beta convective state. We measure the
motion of several representative "plumes" and downflows, estimate the
density and temperature of the prominence plasma, and suggest several
avenues for further investigation. This work was supported by
NASA under the Hinode/SOT contract NNM07AA01C.
Title: High Resolution Observation of Spicules in Ca II H with
Hinode/SOT
Authors: Suematsu, Yoshinori; Katsukawa, Y.; Ichimoto, K.; Tsuneta, S.;
Okamoto, T.; Nagata, S.; Shimizu, T.; Tarbell, T.; Shine, R.; Title, A.
Bibcode: 2007AAS...210.9411S
Altcode: 2007BAAS...39..219S
High cadence observation with a Ca II H broadband filtergraph
(passband of 0.25 nm) of the Solar Optical Telescope (SOT) aboard
HINODE has revealed dynamical nature of solar limb spicules. Thanks to a
diffraction-limited and low-scattered light property of the instrument,
we can track the detailed evolution of individual spicules for the first
time with a spatial resolution of 0.2 arcsec. The spicules in Ca II
H are typically several arcsec tall and have multi-thread structure;
each threads are a few tenth of arcsec wide. It should be stressed
that most spicules do not show a simple up-and-down motion along a
rigid path line. They start with bright structure emanating from Ca II
H bright region, get widen and diffused with time and ascent, showing
expansion with lateral or even helical motion in tall events. Small and
short lived spicules tend to fade out after ascent. We will present
new findings of spicule dynamics in different magnetic environments
and discuss about long standing controversy of its motion and evolution.
Title: Hinode/SOT Observation of Fine Structure of the Evershed Flow
Authors: Ichimoto, Kiyoshi; Suematsu, Y.; Tsuneta, S.; Katsukawa, Y.;
Shimojo, M.; Kubo, M.; Shimizu, T.; Shine, R.; Tarbell, T.; Title,
A.; Lites, B.; Elmore, D.; Yokoyama, T.; Nagaka, S.
Bibcode: 2007AAS...210.9408I
Altcode: 2007BAAS...39..218I
Small scale structure of the Evershed effect was studied using the
Spectropolarimeter (SP) and Broadband Filter Imager (BFI) of SOT aboard
Hinode. SP maps and high cadence continuum images of BFI coverting
entire sunspots are used to investigate the spatial distribution of
the flow field, brightness and magnetic fields. It is revealed that the
Evershed flow starts at the front edge of inwardly migrating penumbral
grains with an upward velocity component and turns to nearly holizontal
flow preferentially in dark lanes (or dark core of filaments) of the
penumbra. Our results are in general agreement with the well known
uncombed penumbral concept in which the Evershed flow takes place
in nearly holizontal field channels. We discovered a number of tiny
elongated regions in deep photosphere in which there is an obvious
upward motion of 1-1.5km/s distributing over the penumbra. They
could be identified as the 'foot points' of the individual Evershed
flow channels. Cross-correlation among the flow speed, intensity,
magnetic field strength and inclination, and distribution of string
down flows in and around the penumbra will also be discussed.
Title: Magnetic Flux Emergence In The Quiet Sun Photosphere
Authors: Centeno, Rebecca; Lites, B.; Socas-Navarro, H.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Tsuneta, S.;
Katsukawa, Y.; Suematsu, Y.; Kubo, M.; Shimizu, T.
Bibcode: 2007AAS...210.9406C
Altcode: 2007BAAS...39..218C
We study the emergence of magnetic flux at very small spacial scales
(less than 1 arcsec) in the quiet Sun internetwork. To this aim, several
time series of spectropolarimetric maps were taken at disk center using
the instrument SP/SOT on board Hinode. The LTE inversion of the full
Stokes vector measured in the Fe I 6301 and 6302 lines will allow us
to retrieve the magnetic flux and topology in the region of study. We
find that the magnetic flux emerges typically within the granular
structures. In many cases, the horizontal magnetic field appears
prior to any significant amount of vertical field. As time goes on,
the traces of the horizontal field dissapear while the the vertical
dipoles drift -carried by the plasma motions- towards the surrounding
intergranular lanes. Sometimes they stay trapped there for a while
but they eventually either disappear by disgregation/cancelation
or agregate to other magnetic field concentrations giving rise to
larger flux elements. The time scale of these events is of the order
of 10-20 minutes.
Title: Formation of Moving Magnetic Features and Penumbral Magnetic
Fields
Authors: Kubo, Masahito; Ichimoto, K.; Shimizu, T.; Tsuneta, S.;
Suematsu, Y.; Katsukawa, Y.; Nagata, S.; Lites, B. W.; Frank, Z.;
Tarbell, T. D.; Shine, R. A.; Title, A. M.
Bibcode: 2007AAS...210.9410K
Altcode: 2007BAAS...39..218K
We investigate the formation process of Moving Magnetic Features
(MMFs) observed with Hinode/SOT. Moving magnetic features are small
magnetic elements moving outward in the moat region surrounding
mature sunspots. We derive vector magnetic fields of MMFs around
simple sunspots near the disk center. Most of MMFs with polarity
opposite to the sunspot have large redshift around the penumbral outer
boundary. We find that some of them have Doppler velocities of about
10 km/s and such large Doppler motion is observed only in the Stokes
V profile. The Stokes Q and U profiles in the same pixel do not have
any significant Doppler motions. Horizontal magnetic fields of the
penumbra frequently extend to the moat region and the MMFs having
horizontal fields with polarity same as the sunspot are formed. The
MMFs with polarity opposite to the sunspot appear around the outer
edge of the extending penumbral fields. We also find penumbral spines,
which have more vertical magnetic fields than the surroundings, branch
off at their outer edge and MMFs having relatively vertical fields
with polarity same as the sunspot are detached from the outer edge
of the branch. The branch of penumbral spine is formed when granular
cells in the moat region go into the penumbra.
Title: Ubiquitous Horizontal Magnetic Fields in the Quiet Solar
Photosphere as Revealed by HINODE Meaurements
Authors: Lites, Bruce W.; Socas Navarro, H.; Berger, T.; Frank,
Z.; Shine, R.; Tarbell, T.; Title, A.; Ichimoto, K.; Katsukawa,
Y.; Tsuneta, S.; Suematsu, Y.; Kubo, M.; Shimizu, T.; Nagata, S.;
Hinode Team
Bibcode: 2007AAS...210.6303L
Altcode: 2007BAAS...39..171L
Measurements with the HINODE Spectro-Polarimeter (SP) of the quiet
Sun allow characterization of the weak, mixed-polarity magnetic
flux at the highest angular resolution to date (0.3"), and with good
polarimetric sensitivity(0.025% relative to the continuum). The image
stabilization of the HINODE spacecraft allows long integrations with
degradation of the image quality only by the evolution of the solar
granulation. From the Stokes V profile measurements we find an average
solar "Apparent Flux Density" of 14 Mx cm-2, with significant Stokes V
signals at every position on the disk at all times. However, there are
patches of meso-granular size (5-15") where the flux is very weak. At
this high sensitivity, transverse fields produce measurable Stokes
Q,U linear polarization signals over a majority of the area, with
apparent transverse flux densities in the internetwork significantly
larger than the corresponding longitudinal flux densities. When viewed
at the center of the solar disk, the Stokes V signals (longitudinal
fields) show a preference for occurrence in the intergranular lanes,
and the Q,U signals occur preferably over the granule interiors,
but neither association is exclusive. Hinode is an international
project supported by JAXA, NASA, PPARC and ESA. We are grateful to the
Hinode team for all their efforts in the design, build and operation
of the mission.
Title: Attempt to detect Aflven waves with Solar Optical Telescope
aboard Hinode
Authors: Tsuneta, Saku; Suematsu, Y.; Ichimoto, K.; Katsukawa, Y.;
Shimizu, T.; Nagata, S.; Orozco Suárez, D.; Lites, B.; Shine, D.;
Tarbell, T.; Title, A.
Bibcode: 2007AAS...210.9428T
Altcode: 2007BAAS...39..222T
Flux tube on the sun may carry linear and torsional Alfven waves
generated by photospheric motion. Photospheric motion of 2 km/s would
provide magnetic fluctuation of 40G for 1KG tube and for the Alfven
speed of 50km/s. This may be close to the detection limit of the Stokes
Q and U signals for flux tubes located in the sun center. However,
for flux tubes located near the limb, the fluctuation would be seen in
the Stokes V signal, and can be detectable. We also may be able
to confirm the 90 degree phase shift between magnetic fluctuation and
velocity fluctuation, which is easier to observe for flux tubes near
the limb. Detection of waves would be important in terms of coronal
heating and solar wind acceleration. An attempt to detect waves along
flux tubes will be reported.
Title: Discovery Of Cool Cloud-like Structures In The Corona With
Hinode Solar Optical Telescope
Authors: Okamoto, Takenori; Tsuneta, S.; Katsukawa, Y.; Ichimoto,
K.; Suematsu, Y.; Shimizu, T.; Nagata, S.; Shibata, K.; Tarbell, T.;
Shine, R.; Berger, T.; Lites, B.; Myers, D.
Bibcode: 2007AAS...210.9426O
Altcode: 2007BAAS...39..221O
A solar observation satellite Hinode (Japanese for sun rise) was
launched in September 2006.Hinode carried 3 advanced solar telescopes,
visible light telescope, EUV imaging spectrometer, and X-ray telescope
to simultaneously observe the photosphere, chromosphere, transition
region, and corona. In the performance verification phase of the Hinode
spacecraft with its telescopes, we observed an active region AR10921
near the west limb of the solar disk on November 9 2006. At this point,
we planned to observe spicules on the limb with a broadband filter
dedicated to Ca II H line (3968A). Ca II-H emission line (3968A) comes
from plasma with temperature of approx. 10(4) K, which is much lower
than the coronal temperature of 10(6-7) K. In addition to spectacular
spicules, we find a large cloud-like structure located 10,000-20,000
km above the limb. The cloud has a very complex fine structure with
dominant horizontal thread-like structure. Some features are moving
horizontally and also have clear vertical oscillatory motions. The
periods and amplitudes of these oscillations are 130-250 seconds and
200-850 km, respectively. The vertical oscillatory motion sometimes
has a coherence length as long as 16,000 km. We conclude that from
various observational features this vertical oscillation is a signature
of Alfven waves propagating along the horizontal magnetic fields. We
will discuss their origin and implications.
Title: Discovery Of Small-scale Horizontal Magnetic Structures On
The Solar Photosphere
Authors: Ishikawa, Ryohko; Tsuneta, S.; Suematsu, Y.; Ichimoto, K.;
Katsukawa, Y.; Nagata, S.; Ishobe, H.; Tarbell, T.; Lites, B. W.;
Title, A.
Bibcode: 2007AAS...210.9404I
Altcode: 2007BAAS...39..217I
We discover two different types of episodes on the appearance
of horizontal magnetic fields with Solar Optical Telescope aboard
Hinode. The first episode is an emergence of strong thin horizontal
magnetic fields associated with separating vertical components on
both ends. Its size is about two granules. We also detect strong area
asymmetry of the environment Stokes Vprofile for the bout 8 minutes
before the first emergence of the horizontal component. One of the
footpoints has very strong downflows (several km/s), while the region
with strong linear polarization signal has small blue shift, indicating
an upward-moving horizontal flux. The second episode appears to be
more ubiquitous. Linear polarization signals appear inside granules (not
in inter-granules). Their size is smaller than granules, and lifetime
is longer than several minutes. We will summarize the nature of the
two types of the horizontal magnetic fluxes, and discuss their origin.
Title: Hinode/SOT Observations of Sunspot Penumbral Dynamics and
Evolution
Authors: Shine, Richard A.; Hagenaar, M.; Tarbell, T.; Title, A.;
Lites, B.; Ichimoto, K.; Tsuneta, S.; Katsakawa, Y.; Suematsu, Y.;
Nagata, S.; Kubo, M.; Shimizu, T.
Bibcode: 2007AAS...210.9407S
Altcode: 2007BAAS...39..218S
The Solar Optical Telescope (SOT) on the Hinode satellite (launched
October 2006) has obtained long and nearly continuous time series of
several large sunspots including those in NOAA AR's 10923, 10925,
and 10930. Here we use high resolution movies taken primarily with
the broad band Ca II (396.8nm) and G band (430.5nm) channels and
magnetograms taken with the 630.2nm narrow band channel to study
the details and short term evolution of penumbral fine structures
as well as the long term evolution of the sunspots. We compute flow
maps and use space/time slices to track motions of Evershed clouds,
penumbral grains, and visualize oscillations. The data contain examples
of penumbral formation and disintegration including "orphan" penumbra
(i.e., penumbra without an obvious umbra). There is also an interesting
instance of "colliding" penumbra in AR 10930 as two sunspots of opposite
polarity converged. The zone of apparent shear was associated with
several flares. This work was supported by NASA contract NNM07AA01C
Title: Optical Performance of the Solar Optical Telescope aboard
HINODE
Authors: Suematsu, Yoshinori; Ichimoto, K.; Katsukawa, Y.; Otsubo,
M.; Tsuneta, S.; Nakagiri, M.; Noguchi, M.; Tamura, T.; Kato, Y.;
Hara, H.; Miyashita, M.; Shimizu, T.; Kubo, M.; Sakamoto, Y.
Bibcode: 2007AAS...210.9402S
Altcode: 2007BAAS...39Q.217S
The Solar Optical Telescope (SOT) carried by HINODE was designed
to perform a high-precision polarimetric observation of the Sun
in visible light spectra with a spatial resolution of 0.2 - 0.3
arcseconds. The SOT is a sophistcated instrument and consists of two
separate optical parts; the Optical Telescope Assembly (OTA) which is
50 cm aperture Gregorian telescope feeding the light into following
observing instruments which is called the focal plane package (FPP)
made of two filtergraphs and a spectro-polarimeter. The performance
of the OTA is important because a spatial resolution and its temporal
stability is mainly determined by this component. To keep the OTA in
moderate temperature and optical thermal deformation small, it equipped
newly designed components such as a heat dump and a secondary field stop
aluminum mirror with high reflectivity silver coating and a temperature
low-sensitive apochromatic collimataing lens unit with a UV/IR cut
coating on the first surface. In addition, the SOT has an active image
stabilization system consisting of correlation tracker, tip-tilt mirror
and its controller against satellite pointing jitter. It was confirmed
that this system freezes residual motion to the 0.01 arcsecond level
on orbit. The image of sub-arcsecond G-band (430.5 nm) bright points
clearly indicates that the SOT achieves the diffraction-limit on orbit;
this is also confirmed using a phase diversity method. In this paper,
we describe details of the design and on-orbit performance of the OTA.
Title: Magnetic Landscape Of Solar Polar Region With Solar Optical
Telescope Aboard Hinode
Authors: Tsuneta, Saku; Suematsu, Y.; Ichimoto, K.; Shimizu, T.;
Katsukawa, Y.; Nagata, S.; Orozco Suárez, D.; Lites, B.; Shine, D.;
Tarbell, T.; Title, A.
Bibcode: 2007AAS...210.9405T
Altcode: 2007BAAS...39..218T
Solar polar region is the final destination for remnant magnetic
fields due to meridional flow and granular diffusion, and is very
important for the global solar dynamo. Hinode satellite carried out
high-resolution spectro-polarimetric observations for the Northern
pole on 2006 November 22 as a part of its performance verification
program. We find ubiquitous isolated (positive and negative) patches
in the Stokes V map (i.e. fields horizontal to local surface) all over
the Arctic circle. The Q (vertical to local surface) map indicates
scattered vertical flux tubes, which have bipolar feature in the U and
V maps. This suggests canopy-like structure of the strong isolated flux
tubes. This will be compared with equatorial landscape with similar
distance from the sun center. Strong flux tube and weaker ubiquitous
horizontal fields as represented by Stokes V would have implication
to the current understanding of the global and local dynamo.
Title: Magnetic Field Diagnostic Capability of Solar-B/SOT:
Filtergraph Instrument
Authors: Ichimoto, K.; Suematsu, Y.; Shimizu, T.; Katsukawa, Y.;
Tsuneta, S.; Tarbell, T. D.; Shine, R. A.; Hoffmann, C. M.; Title,
A. M.; Lites, B. W.; Elmore, D. F.; Streander, K. V.
Bibcode: 2006ASPC..358..189I
Altcode:
The Narrowband Filter Instrument (NFI) of the Solar Optical Telescope
onboard Solar-B provides 2D magnetograms/Dopplergrams with a tunable
Lyot filter (width ∼ 0.1 Å) in 6 selected wavelength bands, and
spatial sampling of 0.08 arcsec/px. The Zeeman-effect sensitivity of
NFI and the detection limits of weak magnetic fields are evaluated for
2 photospheric and 3 chromospheric lines. Magnetic-field retrievability
from the NFI observables is studied using synthetic Stokes profiles
of Fe I 5250 Å. We find that, with optimized wavelength sampling at 4
positions, the inferred magnetic field is sufficiently accurate under
the hypothesis of constant magnetic field and velocity along the LOS.
Title: The Proper Motion of Sunspot and Its Relation to the Flare
Onset
Authors: Yatini, C. Y.; Suematsu, Y.
Bibcode: 2006apri.meet...34Y
Altcode:
No abstract at ADS
Title: Completion of Solar-B/Optical Telescope flight model
Authors: Suematsu, Yoshinori; Ichimoto, Kiyosi; Shimizu, Toshifumi;
Otsubo, Masashi; Nakagiri, Masao; Noguchi, Motokazu; Tamura, Tomonori;
Katsukawa, Yukio; Kato, Yoshihiro; Hara, Hirohisa; Miyashita, Masakuni;
Tsuneta, Saku; Kubo, Masahito; Sakamoto, Yasushi
Bibcode: 2005ARAOJ...7...52S
Altcode:
No abstract at ADS
Title: Solar-B/Optical Telescope flight model is coming up
Authors: Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu, Toshifumi;
Otsubo, Masashi; Nakagiri, Masao; Noguchi, Motokazu; Tamura, Tomonori;
Kato, Yoshihiro; Hara, Hirohisa; Miyashita, Masakuni; Tsuneta, Saku;
Katsukawa, Yukio; Kubo, Masahito; Sakamoto, Yasushi
Bibcode: 2005naoj.book....4S
Altcode:
No abstract at ADS
Title: New clean room for space instrumentation
Authors: Noguchi, Motokazu; Nakagiri, Masao; Suematsu, Yoshinori;
Tsuneta, Saku; Kubo, Masahito
Bibcode: 2005naoj.book...37N
Altcode:
No abstract at ADS
Title: The first build-up of the Solar-B flight models
Authors: Hara, Hirohisa; Ichimoto, Kiyoshi; Otsubo, Masashi; Katsukawa,
Yukio; Kato, Yoshihiro; Kano, Ryohei; Kumagai, Kazuyoshi; Shibasaki,
Kiyoto; Shimizu, Toshifumi; Shimojo, Masumi; Suematsu, Yoshinori;
Tamura, Tomonori; Tsuneta, Saku; Noguchi, Motokazu; Nakagiri, Masao;
Miyashita, Masakuni; Watanabe, Tesuya; Kosuchi, Takeo; Sakao, Taro;
Matsuzaki, Keiichi; Kitakoshi, Yasunori; Kubo, Masahito; Sakamoto,
Yasushi
Bibcode: 2005ARAOJ...7...46H
Altcode:
No abstract at ADS
Title: Asymmetric Stokes-V Profiles at the Penumbral Boundary of
a Sunspot
Authors: Choudhary, D. P.; Balasubramaniam, K. S.; Suematsu, Y.
Bibcode: 2004ASPC..325..137C
Altcode:
We present the spectropolarimetric measurements of a sunspot
situated near central meridian disk passage. The sunspot was of
positive polarity with several opposite polarity magnetic elements
at and beyond the penumbral boundary. The Hα images of the sunspot
show bright emission regions near the penumbral boundary towards the
sun-center, which was of opposite polarity to the main spot. Doppler
velocities determined by measuring the center-of-gravity (COG) of the
Stokes-I profile, in general, agree with Evershed flow. In addition,
it shows strong flows in the penumbra. The velocities derived from
zero-crossing wavelengths of Stokes-V profiles show strong downflows
at the penumbral boundary. Double-lobed Stokes-V profiles are observed
at locations where penumbral fibrils terminate coinciding with Hα
plages. Double lobed profiles have an unshifted component similar to
the Stokes-V profiles of the sunspot penumbra and a shifted component
with a velocity of about 5 kmps. The amplitude of the second component
increases along the penumbral fibril as a function of the distance from
the center of the sunspot. In this paper we present the preliminary
results and propose to observe with the SolarB Solar Optical Telescope
(SOT) for understanding the nature of emerging flux near the sunspots.
Title: Image stabilization system on SOLAR-B Solar Optical Telescope
Authors: Shimizu, Toshifumi; Nagata, Shin'ichi; Edwards, Chris;
Tarbell, Theodore; Kashiwagi, Yasuhiro; Kodeki, Kazuhide; Ito,
Osamu; Miyagawa, Hiroyuki; Nagase, Masayuki; Inoue, Syunsaku; Kaneko,
Kazumasa; Sakamoto, Yasushi; Ichimoto, Kiyoshi; Tsuneta, Saku; Miki,
Shiro; Endo, Makoto; Tabata, Masaki; Nakaoji, Toshitaka; Matsuzaki,
Keiichi; Kobayashi, Ken; Otsubo, Masashi; Suematsu, Yoshinori; Kumagai,
Kazuyoshi; Noguchi, Motokazu; Tamura, Tomonori; Nakagiri, Masao
Bibcode: 2004SPIE.5487.1199S
Altcode:
Extremely stable pointing of the telescope is required for images on the
CCD cameras to accurately measure the nature of magnetic field on the
sun. An image stabilization system is installed to the Solar Optical
Telescope onboard SOLAR-B, which stabilizes images on the focal plane
CCD detectors in the frequency range lower than about 20Hz. The system
consists of a correlation tracker and a piezo-based tip-tilt mirror with
servo control electronics. The correlation tracker is a high speed CCD
camera with a correlation algorithm on the flight computer, producing
a pointing error from series of solar granule images. Servo control
electronics drives three piezo actuators in the tip-tilt mirror. A
unique function in the servo control electronics can put sine wave
form signals in the servo loop, allowing us to diagnose the transfer
function of the servo loop even on orbit. The image stabilization
system has been jointly developed by collaboration of National
Astronomical Observatory of Japan/Mitsubishi Electronic Corp. and
Lockheed Martin Advanced Technology Center Solar and Astrophysics
Laboratory. Flight model was fabricated in summer 2003, and we measured
the system performance of the flight model on a laboratory environment
in September 2003, confirming that the servo stability within 0-20 Hz
bandwidth is 0.001-0.002 arcsec rms level on the sun.
Title: The Solar Optical Telescope onboard the Solar-B
Authors: Ichimoto, Kiyoshi; Tsuneta, Saku; Suematsu, Yoshinori;
Shimizu, Toshifumi; Otsubo, Masashi; Kato, Yoshihiro; Noguchi,
Motokazu; Nakagiri, Masao; Tamura, Tomonori; Katsukawa, Yukio; Kubo,
Masahito; Sakamoto, Yasushi; Hara, Hirohisa; Minesugi, Kenji; Ohnishi,
Akira; Saito, Hideo; Kawaguchi, Noboru; Matsushita, Tadashi; Nakaoji,
Toshitaka; Nagae, Kazuhiro; Sakamoto, Joji; Hasuyama, Yoshihiro;
Mikami, Izumi; Miyawaki, Keizo; Sakurai, Yasushi; Kaido, Nobuaki;
Horiuchi, Toshihida; Shimada, Sadanori; Inoue, Toshio; Mitsutake,
Masaaki; Yoshida, Norimasa; Takahara, Osamu; Takeyama, Norihide;
Suzuki, Masaharu; Abe, Shunichi
Bibcode: 2004SPIE.5487.1142I
Altcode:
The solar optical telescope onboard the Solar-B is aimed to perform a
high precision polarization measurements of the solar spectral lines
in visible wavelengths to obtain, for the first time, continuous
sets of high spatial resolution (~0.2arcsec) and high accuracy
vector-magnetic-field map of the sun for studying the mechanisms
driving the fascinating activity phenomena occurring in the solar
atmosphere. The optical telescope assembly (OTA) is a diffraction
limited, aplanatic Gregorian telescope with an aperture of Φ500mm. With
a collimating lens unit and an active folding mirror, the OTA provides
a pointing-stabilized parallel beam to the focal plane package (FPP)
with a field of view of about 360x200arcsec. In this paper we identify
the key technical issues of OTA for achieving the mission goal and
describe the basic concepts in its optical, mechanical and thermal
designs. The strategy to verify the in-orbit performance of the
telescope is also discussed.
Title: Spectroscopic studies of the solar corona using Fe X, XIII,
XIV lines
Authors: Singh, Jagdev; Sakurai, Takashi; Ichimoto, Kiyoshi; Suematsu,
Yoshinori; Takeda, Aki
Bibcode: 2004naoj.book...46S
Altcode:
No abstract at ADS
Title: Thermo-optical testing of the solar optical telescope of
the Solar-B
Authors: Ichimoto, Kiyoshi; Nakagiri, Masao; Suematsu, Yoshinori;
Tamura, Tomonori; Tsuneta, Saku; Noguchi, Motokazu; Kato, Yoshihiro;
Otsubo, Seiji; Katsukawa, Yukio; Kubo, Masahito
Bibcode: 2004naoj.book....6I
Altcode:
No abstract at ADS
Title: The source of magnetic field twist in solar active regions
Authors: Bao, Shudong; Sakurai, Takashi; Suematsu, Yoshinori
Bibcode: 2004naoj.book...48B
Altcode:
No abstract at ADS
Title: Solar-B: Status of Project
Authors: Suematsu, Y.
Bibcode: 2003ASPC..289...37S
Altcode: 2003aprm.conf...37S
The Solar-B spacecraft, currently under development for a planned
launch in the summer of 2005, carries the Solar Optical Telescope
(SOT) to make precise measurements of magnetic fields of the solar
photosphere with a high spatial resolution, the X-Ray Telescope
(XRT) to observe the dynamics of the high temperature corona, and
the EUV Imaging Spectrometer (EIS) to observe plasma motions in the
transition region and corona. The aim of Solar-B is to investigate
the physical coupling between the photosphere (engine) and the corona
(dissipater) to ultimately understand the mechanism of coronal dynamics
and heating. The magnetic field maps with 0.2-0.3 arcsecond resolution,
the images of the high temperature corona with 1arcsec resolution,
and the precise coronal velocity maps provided by these telescopes
will all be new, and unprecedented scientific outcomes are expected.
Title: Development of the Solar-B spacecraft
Authors: Tsuneta, Saku; Ichimoto, Kiyoshi; Suematsu, Yoshinori;
Shimizu, Toshifumi; Hara, Hirohisa; Kano, Ryohei; Nagata, Shin'ichi;
Tamura, Tomonori; Nakagiri, Masao; Noguchi, Motokazu; Kato, Yoshihiro;
Watanabe, Tetsuya; Hanaoka, Yoichiro; Sawa, Masaki; Otsubo, Masashi;
Kosugi, Takeo; Yamada, Takahiro; Sakao, Taro; Matsuzaki, Keiichi;
Minesugi, Kenji; Onishi, Akira; Katsukawa, Yukio; Kobayashi, Ken;
Kubo, Masahito
Bibcode: 2003naoj.book....3T
Altcode:
No abstract at ADS
Title: Development of Solar-B solar optical telescope
Authors: Suematsu, Yoshinori; Ichimoto, Kiyoshi; Shimizu, Toshifumi;
Nagata, Shin'ichi; Tamura, Tomonori; Tsuneta, Saku; Noguchi, Motokazu;
Kato, Yoshihiro; Nakagiri, Masao; Otsubo, Masashi; Hanaoka, Yoichiro;
Katsukawa, Yukio; Kobayashi, Ken; Kubo, Masahito
Bibcode: 2003naoj.book....5S
Altcode:
No abstract at ADS
Title: Observational Study of the Three-Dimensional Magnetic Field
Structure and Mass Motion in Active Regions
Authors: Choudhary, Debi Prasad; Suematsu, Yoshinori; Ichimoto, Kiyoshi
Bibcode: 2002SoPh..209..349C
Altcode:
Spectro-polarimetric observations of active regions were carried
out in the spectral lines of Si i 10827.1 Å and He i 10830 Å to
study the three-dimensional magnetic field structure and associated
plasma flow properties. Comparison of Si i and He i magnetograms
with the potential field model shows that a large fraction of the
magnetic field is consistent with the potential field structure,
by assuming that the height difference between the origin of the two
lines is about 1200 km. The slope of the scatter plot between Si i
and He i magnetograms is 0.5, 0.76 in an emerging flux and a larger
active region, respectively. These values are lower than the scatter
plot slopes obtained from Kitt Peak photospheric and chromospheric
magnetograms, in which case the corresponding values are 0.83 and 0.9,
respectively. Considering the height difference between these two sets
of chromospheric magnetograms, this implies that the magnetic field
spreads out faster near the transition region heights. Dopplergrams
obtained by determining the centroid of the asymmetric line profiles
show that, in case of emerging flux region, the chromospheric upflow
regions are located in the magnetic neutral line areas.
Title: Spectroscopic Studies of the Solar Corona II. Properties of
Green and Red Emission Lines in Open and Closed Coronal Structures
Authors: Singh, Jagdev; Sakurai, Takashi; Ichimoto, Kiyoshi; Suematsu,
Yoshinori; Takeda, Aki
Bibcode: 2002PASJ...54..793S
Altcode:
We obtained profiles of the green (Fe <FONT SIZE="-2">XIV
5303Å) and red (Fe <FONT SIZE="-2">X 6374Å) emission lines
simultaneously on 1998 July18-19 for about 4hours with a cadence
of 10minutes, covering an area of about 200'' × 500'' in the
solar corona. The line width (FWHM), intensity, and Doppler shift
for both lines were computed using Gaussian fits to the observed
line profiles. We then studied any systematic differences in these
parameters between closed and open field structures, and their time
variations. The derived line widths indicate that the FWHM of the red
line increases with height above the limb at a rate of 0.5 - 2.6 mÅ
arcsec-1 and the green-line width decreases with height
at a rate of 1.2 - 3.4 mÅ arcsec-1. The difference in
the time-averaged values of the widths of the green line in open and
closed coronal structures at a given height above the limb is small,
whereas the width of the red line in open structures is substantially
larger than that in the closed loop-like coronal structures.
Title: The Sources of Magnetic Field Twist in Solar Active Regions
Authors: Bao, S. D.; Sakurai, T.; Suematsu, Y.
Bibcode: 2002ApJ...573..445B
Altcode:
Observations have revealed that a hemispheric preference of magnetic
chirality (handedness) exists throughout the solar atmosphere. For
example, the current helicity of active regions is predominantly
negative (left-handed twist) in the northern hemisphere and
positive (right-handed twist) in the southern. The explanation
of this hemispheric tendency is still open to question. In this
paper we first review several possible mechanisms and clarify some
misunderstandings. In our views, in the photosphere, the differential
rotation acting on already emerged sunspot magnetic fields will lead to
negative current helicity in the northern hemisphere and positive in the
southern, but the same effect caused by the Coriolis force is opposite
in sign. In the turbulent convection zone, the Coriolis force acting on
the rising magnetic flux tubes will result in negative/positive helicity
in the northern/southern hemisphere, but the corresponding action by the
differential rotation will give rise to a reversed result. Moreover,
in this region the α-effect will produce the wrong sign to explain
the observed sense of magnetic twist. It should be noteworthy that
the two current helicities generated by the α-effect, that in the
mean field and that in the fluctuations, have opposite signs, and the
former is positive/negative in the northern/southern hemisphere while
the latter is negative/positive in the northern/southern hemisphere. In
the overshoot region at the base of the convection zone, the current
helicity created by the α-effect has the sign needed. Finally,
we suggest that some surface flows (e.g., converging flows that can
lead to cancellation of opposite-polarity flux in the photosphere)
and magnetic reconnection are also important to the redistribution
(or regeneration) of magnetic twist in active regions.
Title: Observational studies of the solar cycle at the National
Astronomical Observatory of Japan
Authors: Sakurai, T.; Suematsu, Y.
Bibcode: 2002AdSpR..29.1565S
Altcode:
Instrumentation for observational studies of the solar activity cycle,
using ground-based optical telescopes at the National Astronomical
Observatory of Japan, is described. A newly-built 10-cm telescope for
sunspot observations is explained in detail. A future instrumentation
plan for long-term studies of the sun, called the Solar Cycle Telescope,
is presented. This will be composed of a 30-cm Makustov telescope
equipped with an infrared Stokes polarimeter, and a 15-cm refractor
for precise Doppler-shift measurements.
Title: Commission 12: Solar Radiation and Structure (Radiation et
Structure Solaires)
Authors: Foukal, Peter; Solanki, Sami; Mariska, J.; Baliunas, S.;
Dravins, D.; Duvall, T.; Fang, C.; Gaizauskas, V.; Heinzel, P.;
Kononovich, E.; Koutchmy, S.; Melrose, D.; Stix, M.; Suematsu, Y.;
Deubner, F.
Bibcode: 2000IAUTA..24...73F
Altcode:
No abstract at ADS
Title: Development of New Solar Optical Observation Systems at
Mitaka, NAOJ
Authors: Suematsu, Y.
Bibcode: 1999spro.proc..443S
Altcode:
We briefly describe three optical observation systems of the Sun being
developed at Mitaka, NAOJ.
Title: Derivation of the correction coefficient k in the relative
sunspot number for a new sunspot observing system at Mitaka.
Authors: Miyashita, M.; Suematsu, Y.; Irie, M.
Bibcode: 1999RNAOJ...4..149M
Altcode:
A new sunspot observing system using a CCD of 2k×2k pixels has started
at Mitaka, since April 1998. To determine the personal correction
coefficient k in the formula for the relative sunspot number, the
authors compared the sunspot numbers from the new system with those
from conventional hand-drawing observations at their observatory and
from S.I.D.C. (Sunspot Index Data Center). As a result, they obtained
k = 1.0 on the average for the new system. There were, however, some
cases in which the k-value largely deviates from the average.
Title: Simultaneous 2-D Spatial Spectra Using a Microlens Array
Authors: Balasubramaniam, K. S.; Suematsu, Y.; Smaldone, L. A.;
Yoshimura, K.; Hegwer, S.; Otani, H.
Bibcode: 1999AAS...194.9306B
Altcode: 1999BAAS...31R.989B
Simultaneous spatial spectra of extended solar structures, at a high
spatial resolution and temporal cadence is important to track and
understand the physics of dynamical evolutionary phenomena. Replacing
the slit of a conventional spectrograph with a micro-lens array will
then help to capture simultaneous spatial spectra using a large format
CCD camera. Such a technique will be useful to study small structures
(a few arcseconds across) such as Ellerman bombs, kernels of flares,
filamentary evolution and spicules. At the NSO/Richard B. Dunn Solar
Telescope, we have used a micro-lens array (0.6 mm pitch, 50 x 50
lens-lets) to observe structures with a spatial sampling of 0.24
arcseconds in Hα \ spectral line. The spectral sampling is 0.93
Angstroms/pixel over a 10- Angstroms bandwidth. The field-of-view
is however limited to about 12 arcseconds. We have also explored the
microlens array the observations to magnetic spectral lines such as
FeI 6301.5 and FeI 6302.5 Angstroms for variation of line-of-sight
of subarcsecond magnetic fields. We present initial results from an
engineering observational experiment at the Dunn Solar Telescope.
Title: Characteristic curves of photographic data made with a film
scanner.
Authors: Iizuka, Y.; Yamasaki, T.; Suematsu, Y.
Bibcode: 1999RNAOJ...4..107I
Altcode: 1999RNOAJ...4..107I
Thanks to the development of CCD camera and digital technologies,
photographic observations in astronomy has been getting less
popular and hence facilities to analyze the photographic data such as
micro-densitometers are disappearing. Instead, a film scanning device
with a linear CCD array (a film scanner), which can be controlled by
a personal computer, becomes available and much more popular for a
personal use. Hence, it is worth while examining the digitization
accuracy of the commercial-based film scanner and seeking the
possibility to replace the micro-densitometer with it. The authors
found that the film scanner gives good accuracy in comparison with
the micro-densitometer if the data are handled properly. They describe
the method and technique how to calibrate photographic data using the
film scanner.
Title: Scientific Objectives and Design Concepts of the Optical
Telescope and its Observing Instruments aboard Solar-B
Authors: Suematsu, Y.; Solar-B Working Group
Bibcode: 1999ASPC..183..198S
Altcode: 1999hrsp.conf..198S
No abstract at ADS
Title: Tridimensional Spectroscopic Observations of the Sun with a
Microlens-Array Spectrograph
Authors: Suematsu, Y.; Imai, H.; Yoshimura, K.; Ishigaki, T.; Ueno,
S.; Hayashi, T.; Ohtani, H.
Bibcode: 1999ASPC..183..303S
Altcode: 1999hrsp.conf..303S
No abstract at ADS
Title: Development of automatic detection and reduction system for
sunspots and faculae.
Authors: Imai, H.; Suematsu, Y.; Miyashita, M.; Kumagai, K.
Bibcode: 1998RNAOJ...4....1I
Altcode: 1998RNOAJ...4....1I
The authors describe an acquisition and data processing system
of full-disk digitial solar images at the National Astronomical
Observatory. The system aimes at an automated detection and
data reduction of sunspots and faculae, and will replace the
conventional hand drawing observation being continued since 1930's
at the observatory. Full-disk digital images of the sun are taken
and processed daily to provide automatic drawings of sunspots and
faculae. The number and parameters of sunspots such as the position,
area, and darkness are also derived. Data processing techniques used
for the images are briefly described, which include the method of limb
fitting, the production of solar contrast map by limb-darkening removal,
and the detection of sunspots and faculae.
Title: Radiation testing of optical glasses and crystals for Solar-B
optical instruments.
Authors: Nishino, Y.; Suematsu, Y.; Tsuneta, S.; Ichimoto, K.; Kobiki,
T.; Takeyama, N.
Bibcode: 1998RNAOJ...3..145N
Altcode: 1998RNOAJ...3..145N
This report gives some results of γ-ray irradiation (Co60
source) testing on optical glasses and crystals which may be used
in the next Japanese solar space mission Solar-B. Ordinary optical
glasses darken when exposed to high-energy radiation which is present
in natural space environment. In case of Solar-B, whose orbit will be
polar-sun-synchronous, the satellite will undergo the total dose of
more than 1000 krad in five years. Hence it is very crucial for the
success of the mission to know the feasibility of transmitting optical
elements in space. The authors tested two kinds of fused silica, a
fluorite, and ten kinds of UV transmitting glasses. Calcite was also
tested. It was found that the fused silica is radiation-resistant but
the other glasses and the fluorite are nonresistant and become quite
opaque in UV and visible wavelength regions after the irradiation.
Title: Solar Spicules: A brief review of recent high-resolution
observations
Authors: Suematsu, Y.
Bibcode: 1998ESASP.421...19S
Altcode: 1998sjcp.conf...19S
No abstract at ADS
Title: Properties of Hα spicules from disk and limb high-resolution
observations
Authors: Dara, H. C.; Koutchmy, S.; Suematsu, Y.
Bibcode: 1998ESASP.421..255D
Altcode: 1998sjcp.conf..255D
No abstract at ADS
Title: SXR Coronal Polar Jets and Recurrent Flashes
Authors: Koutchmy, S.; Hara, H.; Shibata, K.; Suematsu, Y.; Reardon, K.
Bibcode: 1998ASSL..229...87K
Altcode: 1998opaf.conf...87K
No abstract at ADS
Title: Horseshoe Shaped Hα Solar Flares on 13 Oct 1995 and Emerging
Flux Model of Flares
Authors: Suematsu, Y.; Nishino, Y.; Yan, Y.; Sato, J.
Bibcode: 1998ASSL..229..209S
Altcode: 1998opaf.conf..209S
No abstract at ADS
Title: On the correlation between line width and line depth of the
solar HeI 1083 NM line
Authors: Venkatakrishnan, P.; Sakurai, T.; Suematsu, Y.; Ichimoto, K.
Bibcode: 1997BASI...25..527V
Altcode:
No abstract at ADS
Title: SXR Coronal Flashes.
Authors: Koutchmy, S.; Hara, H.; Suematsu, Y.; Reardon, K.
Bibcode: 1997A&A...320L..33K
Altcode:
We provide evidence for the existence of a new type of soft X-ray
(SXR) brightening event that we call coronal flashes. The phenomenon
was observed on deep time series taken with the SXT of Yohkoh in the
north polar coronal hole, near the sunspot minimum. Events last as
short as 1.5 mn and the corresponding SXR flux span the range of
energies, from single pixel brightenings corresponding to fluxes
of about 10^24^erg but barely surpassing the level of the noise,
to higher and more smeared multiple px brightenings still orders
of magnitude smaller than the known small SXR bright points and/or
transient brightenings. The typical occurrence rate of flashes is
1-event/arcmin^2^/5mn with a 1/2mn integration time. At least part of
the coronal flashes are recurrent and some of them could be associated
with a SXR jet; it is not clear what is their optical counterpart.
Title: Spectroscopic Observation of the Solar Active Regions in Hel
10830 A Line
Authors: Tohmura, Ichirah; Kitai, Reizaburo; Suematsu, Yoshinori;
Soltau, Dirk
Bibcode: 1996JKASS..29..333T
Altcode:
No abstract at ADS
Title: Coordinated SPDE rocket, YOHKOH and ground observations of
an emerging flux region and a filament
Authors: Damé, L.; Martic, M.; Brown, W. A.; Bruner, M. E.; Strong,
K.; Suematsu, Y.; Tsuneta, S.; Schmieder, B.
Bibcode: 1996AdSpR..17d.189D
Altcode: 1996AdSpR..17..189D
During the first flight of the Solar Plasma Diagnostic Experiment
(SPDE), May 12, 1992, we obtained UV filtergrams at high resolution
(full Sun 0.82'' spatial resolution in the 160 nm continuum, the
CIV lines and Lyman alpha) with the Ultraviolet Filtergrap Camera
(UVFC). Closely coordinated observations were obtained with the Soft
X-ray Telescope (SXT) of the Yohkoh satellite and from dedicated ground
programs in particular at Sacramento Peak, La Palma and Pic-du-Midi
observatories. With this unique set of data we cover the solar
atmosphere as a whole, from the temperature minimum to the high corona
with essential steps in the chromosphere and transition region. After
the necessary calibrations of the data set, we present the first results
of the multitemperature development of an emerging flux region and of
a filament that rapidly changed right during the rocket short lifetime.
Title: Enhanced He{I} Absorption at the Feet of Solar X-Ray Loops
Authors: Venkatakrishnan, P.; Sakurai, Takashi; Suematsu, Yoshinori;
Ichimoto, Kiyoshi
Bibcode: 1996PASJ...48L...1V
Altcode:
A comparison of He{I} spectroheliograms and Yohkoh soft X-ray images
of active regions indicates that He{I} absorption is enhanced at
the feet of hot X-ray loops. It is suggested that the conduction of
heat from the loops into the transition region at their feet would
produce enhanced transition-region emission around 50 eV that would
in turn cause enhanced excitation of He{I} leading to the excess He{I}
absorption that is observed.
Title: High Resolution Observation of Solar Spicules and Their
Kinematic Modelling
Authors: Suematsu, Y.
Bibcode: 1996mpsa.conf..439S
Altcode: 1996IAUCo.153..439S
No abstract at ADS
Title: Statistical Studies of Solar H alpha Brightening Events and
Their Relation to Soft X-ray Events
Authors: Yatini, C. Y.; Suematsu, Y.
Bibcode: 1996mpsa.conf..453Y
Altcode: 1996IAUCo.153..453Y
No abstract at ADS
Title: He I 10830 Angstroms in Solar Active Regions and its
Correlation with Chromospheric Lines
Authors: Kitai, R.; Tohmura, I.; Suematsu, Y.; Akioka, M.; Soltau, D.
Bibcode: 1996mpsa.conf..435K
Altcode: 1996IAUCo.153..435K
No abstract at ADS
Title: High-Resolution Observation of Disk Spicules. I. Evolution
and Kinematics of Spicules in the Enhanced Network
Authors: Suematsu, Yoshinori; Wang, Haimin; Zirin, Harold
Bibcode: 1995ApJ...450..411S
Altcode:
We present measurements of a 75 minute sequence of CCD spicule
observations at Hα -0.65 Å, line center, and +0.65 Å. The
observations were made in a region of enhanced network near disk
center, where most spicules are longer and tilted further from the
vertical than those in truly quiet Sun. Images were reregistered with
a correlation coefficient greater than 0.9. We identify the spicules
as those elongated jets that radiate from elements of the magnetic
network and are the main chromospheric features seen in the wing of
Hα. Doppler images produced by red-blue subtraction show an upward
radial velocity during the extension phase and a downward velocity
during contraction for most spicules. Therefore, the spicules are
truly moving up and down. There were a few plagelike cells filled
with weak Hα emission, weak magnetic fields, and no spicules. We
also found many multiple spicules. The data are presented with
commentary on the accompanying videotape. We analyzed the
data to understand the spicule lifetimes and trajectories. We found
that the entire set of wavelengths and Dopplergrams was required to
separate overlapping spicules. Seventy-six of the 96 spicules studied
appear in complete upward and downward trajectories The evidence on
motions is not conclusive. Some proper motions are well represented
by ballistic trajectories with initial injection velocity about 40 km
s-1 for highly inclined spicules. The small decelerations
would require the spicules to be tilted typically 60°-70° from
the line of sight. Since limb observations favor tilts around 30°,
our observations must favor spicules tilted greatly from the radial,
as one finds in these enhanced field regions. The positive correlation
of lifetimes with projected lengths supports this model. However, the
Dopplergrams show that the entire spicule rises and falls as a whole,
which favors a fountain jet or some acceleration in the flux tube. The
downward trajectory may be slightly offset toward the network center
from the upward path. Bright points often appear at the bases of
spicules at Hα -0.65 Å, but during the peak extension or receding
phase of the spicule rather than the beginning; therefore, the spicule
is not a surgelike phenomenon (surges are usually initiated by Hα
brightening or a subflare, invariably in a bipolar feature). Further,
the magnetic elements, which match the Hα bright points exactly,
show no change associated with the brightening. The geometry creates
a problem for coronal heating models, as the spicule tops are at least
10" displaced from the bright-point bases, but no such offset appears
in the K line, for example. There is some evidence that the spicule
is generated several hundred kilometers above the photosphere.
Title: He I λ1083nm Observations and Chromospheric and Coronal
Activities
Authors: Suematsu, Y.; Ichimoto, K.; Sakurai, T.
Bibcode: 1995itsa.conf..413S
Altcode:
No abstract at ADS
Title: Peculiar magnetic field evolution of active region NOAA 7562
in August 1993 - results from campaign observation with Yohkoh
Authors: Sakurai, T.; Suematsu, Y.; Ichimoto, K.; Kurokawa, H.; Kitai,
R.; Akioka, M.; Tohmura, I.; Soltau, D.; Mickey, D. L.; Zhang, H.;
Li, W.; Zirin, H.; Tang, F.
Bibcode: 1994ESASP.373..337S
Altcode: 1994soho....3..337S
No abstract at ADS
Title: XV NSO/Sac Peak Solar workshop
Authors: Suematsu, Y.
Bibcode: 1994suns.work...19S
Altcode:
We present some results on studies of line profile fitting analysis
of He I 1083-nm line spectra which were obtained with a 25-cm aperture
coronagraph at the Norikura Solar Observatory.
Title: A Very Small Two-Ribbon Flare of GOES X-ray Class B6.7
Authors: Suematsu, Y.
Bibcode: 1994kofu.symp..135S
Altcode:
No abstract at ADS
Title: Small-Scale Brightening Events Found with Mitaka Hα Patrol
System and Their Soft X-Ray Signatures from YOHKOH SXT
Authors: Suematsu, Y.; Shimizu, T.; Tanaka, N.
Bibcode: 1994xspy.conf...39S
Altcode:
No abstract at ADS
Title: On the Coronal and Prominence Structures Observed at the
Total Solar Eclipse of 11 July 1991
Authors: Suematsu, Y.; Fukushima, H.; Nishino, Y.
Bibcode: 1994IAUS..154..205S
Altcode:
No abstract at ADS
Title: Small-Scale Brightening Events in H alpha and Soft X-rays in
Active Regions
Authors: Suematsu, Yoshinori
Bibcode: 1994ASPC...68..412S
Altcode: 1994sare.conf..412S
No abstract at ADS
Title: Improvement of camera mechanism for Hα monochromatic
heliograph at Mitaka.
Authors: Tanaka, N.; Yamaguchi, K.; Suematsu, Y.
Bibcode: 1993RNAOJ...1..361T
Altcode: 1993RNOAJ...1..361T
A monochromatic heliograph has been in operation since 1957 at
Mitaka. Recently the authors installed an automatic EE shutter control
and a video monitor. Owing to this upgrade, the quality of solar images
recorded on film has been improved significantly.
Title: Solar Flare Telescope project.
Authors: Ichimoto, K.; Sakurai, T.; Hiei, E.; Nishino, Y.; Shinoda, K.;
Noguchi, M.; Imai, H.; Irie, M.; Miyashita, M.; Tanaka, N.; Kumagai,
K.; Sano, I.; Suematsu, Y.; Okamoto, T.; Miyazaki, H.; Fukushima,
H.; Yose, Y.; Zhao, Z. W.
Bibcode: 1993RNAOJ...1..375I
Altcode: 1993RNOAJ...1..375I
The Solar Flare Telescope was built at Mitaka in 1989. This instrument
comprises four telescopes which observe (1) Hα images, (2) continuum
images, (3) vector magnetic fields, and (4) Doppler velocities,
respectively. The instrument aims at the study of energy build-up
and energy release in solar flares, in cooperation with the Solar-A
satellite (Yohkoh). The Solar Flare Telescope has been in operation
since 1990 December.
Title: Development of automatic detection system for solar Hα flares.
Authors: Tanaka, N.; Suematsu, Y.; Yamaguchi, K.
Bibcode: 1993RNAOJ...1..365T
Altcode: 1993RNOAJ...1..365T
A new solar Hα flare patrol system was installed at National
Astronomical Observatory, Mitaka and has been in operation since
September, 1991. The new system consists of a φ 4 cm doublet, an Hα
Lyot filter (pass band =0.5 Å), a 2/3 inch CCD camera, and a digital
image analysis and storage unit. In the new system, Hα flares can
be detected and be analyzed in real time by a computer. The authors
describe the performance of the system and the methods of Hα flare
detection and analysis.
Title: Magnetic Field Observation with the Solar Flare Telescope
Authors: Ichimoto, K.; Sakurai, T.; Nishino, Y.; Shinoda, K.; Noguchi,
M.; Kumagai, K.; Imai, H.; Irie, M.; Miyashita, M.; Tanaka, N.; Sano,
I.; Suematsu, Y.; Hiei, E.
Bibcode: 1993ASPC...46..166I
Altcode: 1993IAUCo.141..166I; 1993mvfs.conf..166I
No abstract at ADS
Title: Kinematics and Lifetimes of Solar Spicules
Authors: Suematsu, Y.; Wang, H.; Zirin, H.
Bibcode: 1992AAS...180.0702S
Altcode: 1992BAAS...24..738S
We present the dynamical evolution of spicules seen on the solar disk
and the relationship between the spicule formation and Hα bright point
at its footpoint. We used filtergrams in Hα -0.65 Angstroms, 0.0,
and +0.65 Angstroms, (passband = 0.25 Angstroms) obtained at BBSO on
Sep. 16, 1991, with the OSL CCD camera. The observations were made in
a region of enhanced network for one and half hours. The resolution
was 0.4 arcsec/pixel. The time resolution for the filtergrams of
same wavelength was about 20 sec. These filtergrams were carefully
registered with a cross-correlation technique, in order to follow the
time evolution of fine structures. We investigated both proper motions
and line-of-sight Doppler velocities of spicules; the latter were
obtained from the subtraction of Hα -0.65 from +0.65 filtergrams. About
2/3 of the spicules could be traced through up and down phases. For
most short-lived spicules, both their apparent motions and Doppler
velocities indicate that the motion of a spicule is real and it follows
nearly a ballistic trajectory. For some long-lived spicules, we can
see periodic rising motion. In these cases, we can see the lower part
of the spicule showing downward motion even in the rising phase. The
bright points, which are prominent in Hα blue wing, tend to appear or
reach their maximum intensity at about the maximum phase of spicules,
and to be accompanied with downward motions. It is likely that the
Hα bright point does not initiate the spicule formation but rather
it appears as a by-products of the spicule formation. These results
seem to suggest that the spicules are generated by an impulsive upward
force on the chromosphere such as a shock wave propagating upward,
and its seed perturbation might take place at a layer deeper than the
chromosphere, or might be a kinematic process with less heating if it
occurs in the chromosphere.
Title: Numerical Simulations of Microflare Evolution in the Solar
Transition Region and Corona
Authors: Sterling, Alphonse C.; Mariska, John T.; Shibata, Kazunari;
Suematsu, Yoshinori
Bibcode: 1991ApJ...381..313S
Altcode:
Several observers report transient ultraviolet brightenings, often
referred to as microflares, in the solar atmosphere. In this paper,
the results are presented of a series of one-dimensional numerical
simulations examining possible relationships between microflares
and the generation of dynamical chromospheric and transition region
features. Low-energy and medium-energy microflares eject long-lived
cool, dense gas plugs into the corona, with the gas plug traversing
the loop apex in the medium energy case. In the case of high-energy
microflares, the gas plug is rapidly heated to the temperature of the
surrounding corona, and the results resemble the dynamics occurring
in standard solar flare thick-target electron beam models.
Title: Chromospheric and Coronal Activities in the Quiet Sun
Originating from Photospheric 5-Minute Oscillations
Authors: Suematsu, Yoshinori; Takeuchi, Akitsugu
Bibcode: 1991LNP...387..259S
Altcode: 1991fpsa.conf..259S
We numerically investigated the non-linear response of the solar
atmosphere to 5-min oscillations, assuming that atmospheric motions
are restricted to flow along magnetic field lines. It was found that
5-min oscillations can generate shock waves along magnetic field
lines with inclination angles of about 50 degrees from vertical in
the chromosphere. It is suggested that coronal activities driven by
the shock waves might be observable with the Soft X-ray Telescope on
board Solar-A.
Title: Solar Flare Telescope and 10-cm New Coronagraph
Authors: Ichimoto, K.; Sakurai, T.; Yamaguchi, A.; Kumagai, K.;
Nishino, Y.; Suematsu, Y.; Hiei, E.; Hirayama, T.
Bibcode: 1991LNP...387..320I
Altcode: 1991fpsa.conf..320I
Two new telescopes were built at the National Astronomical
Observatory of Japan, i.e. the Solar Flare Telescope and the 10-cm New
Coronagraph. The Solar Flare Telescope was constructed at Mitaka to make
observations of photospheric velocity fields, vector magnetic fields,
and H and continuum images of active regions simultaneously. The whole
system will be completed in 1991. The 10-cm new coronagraph, which
was developed to make precise measurements of the coronal intensity in
several wavelengths, has already been in operation for one year at the
Norikura Solar Observatory. At present the accuracy of about 10-6 of
the solar disk intensity is achieved in continuum light, but further
improvement in the photometric accuracy remains to be done.
Title: Oscillatory and Transient Features Detected Simultaneously
in the CA II K and Hβ Line Spectra of a Quiescent Prominence
Authors: Suematsu, Yoshinori; Yoshinaga, Reiko; Terao, Naoko;
Tsubaki, Tokio
Bibcode: 1990PASJ...42..187S
Altcode:
Oscillatory time variations have been found in the line of sight Doppler
velocity both in the Ca II K and Hβ lines at a faint edge-region of a
quiescent prominence. The periods are about 240 and 830 s. Long-period
variations of about 1 hr have also been detected at the same region in
the Doppler velocity, integrated intensity, and line width. Moreover,
a transient velocity variation of about 10 min time-span and 6 km
s(-1) amplitude has been found at a region between the main bodies
of the prominence. There is evidence that the temperature starts to
increase before the Doppler velocity starts to increase in the case
of the long-period variation, while the increases of temperature and
Doppler velocity occur at the same time in the case of the transient
feature. The possibility is suggested that some of the long-period
oscillations might result from recurrent activation with heating in
some part of the prominence, although short-period oscillations are
not inconsistent with Alfven-wave-like ones.
Title: Influence of Photospheric 5-Minute Oscillations on the
Formation of Chromospheric Fine Structures
Authors: Suematsu, Yoshinori
Bibcode: 1990LNP...367..211S
Altcode: 1990psss.conf..211S
We present a basic idea how 5-minute oscillations can disturb the
solar chromosphere significantly and show some results of numerical
simulations in which the idea was examined.
Title: A coronal condensation observed at the total solar eclipse
of June 11, 1983 and a related transient prominence
Authors: Suematsu, Yoshinori; Saito, Sumisaburo; Funakoshi, Yasuhiro;
Kurokawa, Hiroki
Bibcode: 1988SoPh..116..285S
Altcode:
A coronal condensation was observed simultaneously with Fexiv λ5303,
Fex λ6374, Fe XI λ7892, and Hα filtergraphs. The size and shape
of the condensation in λ5303 are different from those in other
filtergrams. Hα filtergrams taken around the eclipse time show that a
small transient prominence exists in close proximity to the condensation
core and behaves like a post-flare loop system, though the appearance
is quite different and no flare-report exists. A small-scale energetic
phenomenon seems to have occurred at the top of magnetic loops.
Title: New evidence for oscillatory motions in a quiescent prominence
Authors: Tsubaki, Tokio; Toyoda, Minoru; Suematsu, Yoshinori; Gamboa,
Guillermo A. R.
Bibcode: 1988PASJ...40..121T
Altcode:
Detailed line-profile analyses have been carried out for Ca II K-line
time-series spectra successively obtained at two graded heights in
a quiescent prominence. Line-of-sight velocity variations of around
10-min period, with amplitudes of 1.2 - 3.0 km s-1, have
been detected successively over some 5,000 km at the corresponding
locations of the both heights along the spectrograph slit, hereby
providing new evidence for reconfirming the earlier result that there
are some specific regions in prominences where periodic oscillations
or waves can be amplified.
Title: Short-period oscillations found in a quiescent prominence
Authors: Tsubaki, Tokio; Ohnishi, Yumiko; Suematsu, Yoshinori
Bibcode: 1987PASJ...39..179T
Altcode:
For the purpose of detecting periodic oscillations or waves in a
quiescent prominence, time-series observations of Ca II K line spectra
were carried out at the Hida Observatory. Detailed line-profile analyses
followed by power spectral analyses have led to the conclusion that
nearly the same phase of periodic oscillations, having a period of 160
s and an amplitude of 0.8-1.4 km/s, were found in the line-of-sight
Doppler velocity at successive locations over 15,000 km along the
spectrograph slit. The intensity showed a slight indication for
periodic fluctuations with a period of 240 s. In the line width,
however, no periodicity was detected from the direct inspection of
temporal variations from the power spectral analysis.
Title: Observational study for detecting periodic oscillations in
the inner solar corona
Authors: Tsubaki, T.; Saito, Y.; Suematsu, Y.; Nakagomi, Y.
Bibcode: 1986PASJ...38..251T
Altcode:
For the purpose of detecting periodic oscillations or waves in the inner
corona, time series observations of Fe XIV λ5303 emission-line spectra
were made at the Norikura Solar Observatory. Detailed line-profile
analyses followed by power spectral analyses have provided the
conclusion that periodic intensity fluctuations of nearly the same
phase existed over some 100,000 km along the spectrograph slit with
the same period of 235 s, and with the wavelength of 30,000 - 40,000
km, while no periodicity was detected both for the line width and the
line-of-sight Doppler velocity.
Title: Mass Motions due to Shock Propagations Along Low-Lying Loops
in the Solar Atmosphere - on the Formation of Fibrils
Authors: Suematsu, Y.
Bibcode: 1985SoPh...98...67S
Altcode:
The formation of fibrils in low-lying loops is investigated by
performing one-dimensional nonlinear hydrodynamic calculations. The
loops have the height of 3000-5000 km and have an atmosphere extending
from the photosphere to the corona. A shock wave is generated from a
pressure pulse in the photosphere and it ejects the chromosphere-corona
transition region along the loop, expanding the underlying chromosphere
into the corona. This expanding chromospheric material in a loop is
regarded as a fibril. The shock propagates in the corona and collides
with another transition region where a reflected shock and a penetrating
shock are generated. The effect of the reflected shock on the motion
of the fibril is weak. The fibril shows a nearly ballistic motion as
observations suggest, if it does not extend beyond the summit of the
loop. The corona in the loop is compressed nearly adiabatically by the
fibril, and the enhanced coronal pressure leads the fibril finally to a
retracting motion even if the fibril goes beyond the summit of the loop.
Title: Weakening of the Solar Extreme Ultraviolet Line Emission by
Lyman Continuum Absorption as Derived from Line Ratios
Authors: Kanno, M.; Suematsu, Y.; Nishikawa, T.
Bibcode: 1984SoPh...91...71K
Altcode:
The intensity ratios of NIII, OIII, OIV, and OV lines observed by
the HCO experiment on Skylab are compared with the results of recent
multilevel calculations. It is found that solar transition-region
spectra require Lyman continuum absorption. The equivalent optical
thickness of the absorbers causing the weakening is found to be 1.6-1.7
for a quiet area, 1.4-1.9 for a coronal hole, and 2.4-2.5 for active
regions. These values are consistent with previous estimates from
different methods.
Title: Why are spicules absent over plages and long under coronal
holes?
Authors: Shibata, K.; Suematsu, Y.
Bibcode: 1982SoPh...78..333S
Altcode:
One-dimensional hydrodynamic simulations are performed in order
to examine the influence of initial atmospheric structures on the
dynamics of spicules. This is an extended version of our previous
spicule theory: spicules are produced by the shock wave (MHD slow
mode shock) which originates from a bright point appearance (sudden
pressure increase) at the network in the photosphere or in the low
chromosphere. Simulation results well reproduce the observational
facts that spicules are absent over plages and long under coronal
holes. The physical reason is that the growth of a shock wave during
its propagation through the chromosphere is small in plage regions and
large in coronal hole regions, since the growth of a shock is determined
by the density ratio (ϱh0/ϱc) between
the bright point and the corona. An empirical formula ΔHmax
∼ (ϱh0/ϱc)0.46 is
obtained, where ΔHmax is the maximum height of spicules
above the transition region. The cross-section of the vertical magnetic
flux tube is assumed to be constant in the numerical simulations.
Title: Numerical Hydrodynamics of the Jet Phenomena in the Solar
Atmosphere - Part Two - Surges
Authors: Shibata, K.; Nishikawa, T.; Kitai, R.; Suematsu, Y.
Bibcode: 1982SoPh...77..121S
Altcode:
One-dimensional hydrodynamic simulations of surges are performed in
order to make clear their origin and structure. Surges are regarded as
the jets resulting from a sudden pressure increase at the base of the
model atmosphere. The height of the explosion (h0), which
is measured from the level of τ5000 = 1, is regarded as a
free parameter. Another free parameter is the strength of the sudden
pressure increase (p/p0) at h0. Simulations
are performed for values in the ranges of 540 km ≤ h0
≤ 1920 km and 3 ≤ p/p0 ≤ 30. It was found that for a
fixed p/p0 there exists a critical height (hc)
in h0, which separates the jet (surge) models into two
types. For h0 > hc, jets are produced directly
by the pressure gradient force near h0, and made of the
matter ejected from the explosion itself. The essential hydrodynamic
structure of this type is the same as that in a shock tube (this type
is called `shock tube' type). For h0 < hc,
jets are not the direct results of the pressure enhancement, but
are produced by the shock wave which are generated by the pressure
enhancement and which has propagated through the chromosphere (this type
is called the `crest shock' type). It is shown that the critical height
(hc) ranges from 1000 km to 1500 km for 3 ≤ p/p0
≤ 30. General properties of both types are investigated in detail. The
results are compared with observations and it is concluded that small
surges associated with Ellerman bombsbelong to the `crest shock' type,
i.e. they are produced by the shock wave.
Title: Wavelength Dependence of the Weakening of the Solar Extreme
Ultraviolet Line Emission
Authors: Kanno, M.; Suematsu, Y.
Bibcode: 1982PASJ...34..449K
Altcode:
The solar EUV emission from transition-region lines with wavelengths
less than 912 Å is weakened by Lyman continuum absorption. Absorbers
causing the weakening have not been detected in spatially resolved
EUV and Hα observations. Two suggestions have been made on the
origin of the weakening: the cloud model (Schmahl and Orrall 1979)
and the overlapping model (Kanno 1979). In this paper the
empirical wavelength dependence of the weakening is studied for
several types of regions of the solar atmosphere in order to know
which of the models is consistent with observations. It is found that
observations can be reasonably explained in terms of the cloud model
where EUV emitting regions are overlain by clouds consisting of cool
material. The optical thickness of the clouds at the Lyman continuum
head ranges from 3 to 4 for the atmospheric regions discussed here;
it implies that the geometrical thickness of the clouds is less than
100 km, if the number density of neutral hydrogen in the clouds is
some 1011 cm-3. It is suggested that the clouds
correspond to the remnants of cool chromospheric materials jetted into
the corona such as Hα spicules.
Title: Numerical Hydrodynamics of the Jet Phenomena in the Solar
Atmosphere - Part One - Spicules
Authors: Suematsu, Y.; Shibata, K.; Neshikawa, T.; Kitai, R.
Bibcode: 1982SoPh...75...99S
Altcode:
We present a spicule model whose eruption occurs as a result of the
sudden pressure enhancement at the bright point located at the root of
the spicule. To show this, one dimensional (constant cross sectional)
and time dependent hydrodynamic equations are solved numerically in
the realistic solar atmosphere extending from the photosphere to
the corona. Adiabatic motion is assumed. The pressure enhancement
by a bright point at the base of the model atmosphere generates a
shock wave. The shock gets stronger as it passes upward through the
chromosphere and eventually collides with the chromosphere-corona
interface which is a kind of a contact discontinuity. As the result,
the interface begins to move upward. We identify the matter following
behind this interface as the solar spicule. The model explains many
observed features, such as the height and the density of the spicules,
although such features have been hitherto considered not to be explained
easily by shock theories.
Title: Numerical Hydrodynamic Simulations of Spicules
Authors: Suematsu, Y.
Bibcode: 1980jfss.conf...66S
Altcode:
No abstract at ADS