explanation blue bibcodes open ADS page with paths to full text
Author name code: anan
ADS astronomy entries on 2022-09-14
=author:"Anan, Tetsu"
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Title: Development of Integral Field Spectrographs to Revolutionize
Spectroscopic Observations of Solar Flares and other Energetic
Solar Eruptions
Authors: Lin, Haosheng; Anan, Tetsu; Cauzzi, Gianna; Fletcher, Lyndsay;
Huang, Pei; Kowalski, Adam; Kramar, Maxim; Qiu, Jiong; Samra, Jenna;
Spittler, Constance; Sukegawa, Takashi; Wirth, Gregory
2022arXiv220900788L Altcode:
The Sun's proximity offers us a unique opportunity to study in detail
the physical processes on a star's surface; however, the highly dynamic
nature of the stellar surface -- in particular, energetic eruptions
such as flares and coronal mass ejections -- presents tremendous
observational challenges. Spectroscopy probes the physical state of
the solar atmosphere, but conventional scanning spectrographs and
spectrometers are unable to capture the full evolutionary history of
these dynamic events with a sufficiently wide field of view and high
spatial, spectral, and temporal resolution. Resolving the physics of the
dynamic sun requires gathering simultaneous spectra across a contiguous
area over the full duration of these events, a goal now tantalizingly
close to achievable with continued investment in developing powerful
new Integral Field Spectrographs to serve as the foundation of both
future ground- and space-based missions. This technology promises to
revolutionize our ability to study solar flares and CMEs, addressing
NASA's strategic objective to "understand the Sun, solar system, and
universe." Since such events generate electromagnetic radiation and
high-energy particles that disrupt terrestrial electric infrastructure,
this investment not only advances humanity's scientific endeavors
but also enhances our space weather forecasting capability to protect
against threats to our technology-reliant civilization.
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Title: Ground-based instrumentation and observational techniques
Authors: Rimmele, Thomas; Kuhn, Jeff; Woeger, Friedrich; Tritschler,
. Alexandra; Lin, Haosheng; Casini, Roberto; Schad, Thomas; Jaeggli,
Sarah; de Wijn, Alfred; Fehlmann, Andre; Anan, Tetsu; Schmidt, Dirk
2022cosp...44.2507R Altcode:
We'll review the current state-of-the-art for ground-based
instrumentation and techniques to achieve high-resolution
observations. We'll use the 4m Daniel K. Inouye Solar Telescope
(DKIST), the European Solar Telescope (EST) and other ground-based
instrumentation as examples to demonstrate instrument designs
and observing techniques. Using adaptive optics and post-facto
image processing techniques, the recently completed DKIST provides
unprecedented resolution and high polarimetric sensitivity that
enables astronomers to unravel many of the mysteries the Sun presents,
including the origin of solar magnetism, the mechanisms of coronal
heating and drivers of flares and coronal mass ejections. Versatile
ground-based instruments provide highly sensitive measurements of solar
magnetic fields, that in the case of DKIST, also include measurements
of the illusive magnetic field of the faint solar corona. Ground-based
instruments produce large and diverse data sets that require complex
calibration and data processing to provide science-ready to a broad
community. We'll briefly touch on ongoing and future instrumentation
developments, including multi-conjugate adaptive optics.
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Title: Science Commissioning of the Diffraction-Limited Near-IR
Spectropolarimter for the Daniel K. Inouye Solar Telescope
Authors: Lin, Haosheng; Schad, Thomas; Kramar, Maxim; Jaeggli, Sarah;
Anan, Tetsu; Onaka, Peter
2022cosp...44.2508L Altcode:
The Diffraction-Limited Near-IR Spectropolarimeter (DL-NIRSP) is one
of the first-generation facility instruments of the Daniel K. Inouye
Solar Telescope (DKIST, or The Inouye Solar Telescope). It is a near-IR
spectropolarimeter optimized to study the magnetism of the dynamic solar
atmosphere, from the photosphere to the corona. DL-NIRSP is equipped
with two integral field units (IFUs) coupled to a high-resolution
grating spectrograph, and is capable of simultaneous measurements
of the full polarized spectra of a 2-dimensional spatial field
without scanning. Large field of view observations are supported by
mosaicking. DL-NIRSP observes simultaneously at three spectral windows,
enabling simultaneous coverage of different atmospheric layers with
carefully selected spectral lines. It can also observe the Sun with
three resolution modes, from diffraction-limited observations with
a spatial sampling of 0.03" to wide-field mode covering a 32"x15"
instantaneous FOV with 0.5" sampling. This paper will present results
from science commissioning observations conducted in late 2021.
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Title: Chromospheric Heating Mechanisms in a Plage Region Constrained
by Comparison of Magnetic Field and Mg II h & k Flux Measurements
with Theoretical Studies
Authors: Anan, Tetsu; Schad, Thomas; Kitai, Reizaburo; Dima, Gabriel;
Jaeggli, Sarah; Tarr, Lucas; Collados, Manuel; Dominguez-Tagle,
Carlos; Kleint, Lucia
2021AGUFMSH44A..05A Altcode:
The strongest quasi-steady heating in the solar atmosphere from the
photosphere through the corona occurs in plage regions. As many
chromospheric heating mechanisms have been proposed, important
discriminators of the possible mechanisms are the location of the
heating and the correlation between the magnetic field properties in
the chromosphere and the local heating rate. We observed a plage region
with the He I 1083.0 nm and Si I 1082.7 nm lines on 2018 October 3
using the integral field unit mode of the GREGOR Infrared Spectrograph
(GRIS) installed at the GREGOR telescope. During the GRIS observation,
the Interface Region Imaging Spectrograph (IRIS) obtained spectra of the
ultraviolet Mg II h & k doublet emitted from the same region. In
the periphery of the plage region, within the limited field of view
seen by GRIS, we find that the Mg II radiative flux increases with the
magnetic field in the chromosphere. The positive correlation implies
that magnetic flux tubes can be heated by Alfvén wave turbulence
or by collisions between ions and neutral atoms relating to Alfvén
waves. Within the plage region itself, the radiative flux was large
between patches of strong magnetic field strength in the photosphere, or
at the edges of magnetic patches. On the other hand, we do not find any
significant spatial correlation between the enhanced radiative flux and
the chromospheric magnetic field strength or the electric current. In
addition to the Alfvén wave turbulence or collisions between ions
and neutral atoms relating to Alfvén waves, other heating mechanisms
related to magnetic field perturbations produced by interactions of
magnetic flux tubes could be at work in the plage chromosphere.
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Title: Measurements of Photospheric and Chromospheric Magnetic
Field Structures Associated with Chromospheric Heating over a Solar
Plage Region
Authors: Anan, Tetsu; Schad, Thomas A.; Kitai, Reizaburo; Dima,
Gabriel I.; Jaeggli, Sarah A.; Tarr, Lucas A.; Collados, Manuel;
Dominguez-Tagle, Carlos; Kleint, Lucia
2021ApJ...921...39A Altcode: 2021arXiv210807907A
In order to investigate the relation between magnetic structures and
the signatures of heating in plage regions, we observed a plage region
with the He I 1083.0 nm and Si I 1082.7 nm lines on 2018 October 3
using the integral field unit mode of the GREGOR Infrared Spectrograph
(GRIS) installed at the GREGOR telescope. During the GRIS observation,
the Interface Region Imaging Spectrograph obtained spectra of the
ultraviolet Mg II doublet emitted from the same region. In the periphery
of the plage region, within the limited field of view seen by GRIS,
we find that the Mg II radiative flux increases with the magnetic
field in the chromosphere with a factor of proportionality of 2.38 ×
10<SUP>4</SUP> erg cm<SUP>-2</SUP> s<SUP>-1</SUP> G<SUP>-1</SUP>. The
positive correlation implies that magnetic flux tubes can be heated
by Alfvén wave turbulence or by collisions between ions and neutral
atoms relating to Alfvén waves. Within the plage region itself,
the radiative flux was large between patches of strong magnetic field
strength in the photosphere or at the edges of magnetic patches. On
the other hand, we do not find any significant spatial correlation
between the enhanced radiative flux and the chromospheric magnetic
field strength or the electric current. In addition to the Alfvén
wave turbulence or collisions between ions and neutral atoms relating
to Alfvén waves, other heating mechanisms related to magnetic field
perturbations produced by interactions of magnetic flux tubes could
be at work in the plage chromosphere.
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Title: He I Spectropolarimetry of a Supersonic Coronal Downflow
Within a Sunspot Umbra
Authors: Schad, Thomas A.; Dima, Gabriel I.; Anan, Tetsu
2021ApJ...916....5S Altcode:
We report spectropolarimetric observations of a supersonic
downflow impacting the lower atmosphere within a large sunspot
umbra. This work is an extension of Schad et al. using observations
acquired in the He I 10830 Å triplet by the Facility Infrared
Spectropolarimeter. Downflowing material accelerating along a cooled
coronal loop reaches peak speeds near 200 km s<SUP>-1</SUP> and exhibits
both high speed emission and absorption within the umbra, which we
determine to be a consequence of the strong height dependence of the
radiatively controlled source function above the sunspot umbra. Strong
emission profiles close to the rest wavelengths but with long redshifted
tails are also observed at the downflow terminus. From the polarized
spectra, we infer longitudinal magnetic field strengths of ~2.4 kG in
the core portion of the He I strong emission, which we believe is the
strongest ever reported in this line. Photospheric field strengths along
the same line of sight are ~2.8 kG as inferred using the Ca I 10839 Å
spectral line. The temperatures of the highest speed He I absorption
and the near-rest emission are similar (~10 kK), while a differential
emission measure analysis using Solar Dynamics Observatory/Atmospheric
Imaging Assembly data indicates significant increases in radiative
cooling for temperatures between ~0.5 and 1 MK plasma associated with
the downflow terminus. Combined we interpret these observations in the
context of a strong radiative shock induced by the supersonic downflow
impacting the low sunspot atmosphere.
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Title: He I spectropolarimetry of a supersonic coronal downflow
within a sunspot umbra
Authors: Schad, Thomas A.; Dima, Gabriel I.; Anan, Tetsu
2021arXiv210512853S Altcode:
We report spectropolarimetric observations of a supersonic downflow
impacting the lower atmosphere within a large sunspot umbra. This
work is an extension of Schad et al. 2016 using observations
acquired in the He I 10830 Angstrom triplet by the Facility Infrared
Spectropolarimeter. Downflowing material accelerating along a cooled
coronal loop reaches peak speeds near 200 km s$^{-1}$ and exhibits
both high speed emission and absorption within the umbra, which
we determine to be a consequence of the strong height dependence
of the radiatively-controlled source function above the sunspot
umbra. Strong emission profiles close to the rest wavelengths but with
long red-shifted tails are also observed at the downflow terminus. From
the polarized spectra, we infer longitudinal magnetic field strengths of
${\sim}2.4$ kG in the core portion of the He I strong emission, which we
believe is the strongest ever reported in this line. Photospheric field
strengths along the same line-of-sight are ${\sim}2.8$ kG as inferred
using the Ca I 10839 Angstrom spectral line. The temperatures of the
highest speed He I absorption and the near rest emission are similar
(${\sim}$10 kK), while a differential emission measure analysis using
SDO/AIA data indicates significant increases in radiative cooling for
temperatures between $\sim$0.5 and 1 MK plasma associated with the
downflow terminus. Combined we interpret these observations in the
context of a strong radiative shock induced by the supersonic downflow
impacting the low sunspot atmosphere.
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Title: Sunrise Chromospheric Infrared spectroPolarimeter (SCIP)
for SUNRISE III: polarization modulation unit
Authors: Kubo, Masahito; Shimizu, Toshifumi; Katsukawa, Yukio;
Kawabata, Yusuke; Anan, Tetsu; Ichimoto, Kiyoshi; Shinoda, Kazuya;
Tamura, Tomonori; Nodomi, Yoshifumi; Nakayama, Satoshi; Yamada, Takuya;
Tajima, Takao; Nakata, Shimpei; Nakajima, Yoshihito; Okutani, Kousei;
Feller, Alex; del Toro Iniesta, Jose Carlos
2020SPIE11447E..A3K Altcode:
Polarization measurements of the solar chromospheric lines at
high precision are key to present and future solar telescopes for
understanding magnetic field structures in the chromosphere. The
Sunrise Chromospheric Infrared spectroPolarimeter (SCIP) for Sunrise
III is a spectropolarimeter with a polarimetric precision of 0.03 %
(1 σ). The key to high-precision polarization measurements using
SCIP is a polarization modulation unit that rotates a waveplate
continuously at a constant speed. The rotating mechanism is a DC
brushless motor originally developed for a future space mission, and
its control logic was originally developed for the sounding rocket
experiment CLASP. Because of our requirement on a speed of rotation
(0.512 s/rotation) that was 10 times faster than that of CLASP, we
optimized the control logic for the required faster rotation. Fast
polarization modulation is essential for investigating the fine-scale
magnetic field structures related to the dynamical chromospheric
phenomena. We have verified that the rotation performance can achieve
the polarization precision of 0.03 % (1 σ) required by SCIP and such
a significant rotation performance is maintained under thermal vacuum
conditions by simulating the environment of the Sunrise III balloon
flight. The waveplate was designed as a pair of two birefringent
plates made of quartz and sapphire to achieve a constant retardation
in a wide wavelength range. We have confirmed that the retardation
is almost constant in the 770 nm and 850nm wavelength bands of SCIP
under the operational temperature conditions.
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Title: The Daniel K. Inouye Solar Telescope - Observatory Overview
Authors: Rimmele, Thomas R.; Warner, Mark; Keil, Stephen L.; Goode,
Philip R.; Knölker, Michael; Kuhn, Jeffrey R.; Rosner, Robert R.;
McMullin, Joseph P.; Casini, Roberto; Lin, Haosheng; Wöger, Friedrich;
von der Lühe, Oskar; Tritschler, Alexandra; Davey, Alisdair; de Wijn,
Alfred; Elmore, David F.; Fehlmann, André; Harrington, David M.;
Jaeggli, Sarah A.; Rast, Mark P.; Schad, Thomas A.; Schmidt, Wolfgang;
Mathioudakis, Mihalis; Mickey, Donald L.; Anan, Tetsu; Beck, Christian;
Marshall, Heather K.; Jeffers, Paul F.; Oschmann, Jacobus M.; Beard,
Andrew; Berst, David C.; Cowan, Bruce A.; Craig, Simon C.; Cross,
Eric; Cummings, Bryan K.; Donnelly, Colleen; de Vanssay, Jean-Benoit;
Eigenbrot, Arthur D.; Ferayorni, Andrew; Foster, Christopher; Galapon,
Chriselle Ann; Gedrites, Christopher; Gonzales, Kerry; Goodrich, Bret
D.; Gregory, Brian S.; Guzman, Stephanie S.; Guzzo, Stephen; Hegwer,
Steve; Hubbard, Robert P.; Hubbard, John R.; Johansson, Erik M.;
Johnson, Luke C.; Liang, Chen; Liang, Mary; McQuillen, Isaac; Mayer,
Christopher; Newman, Karl; Onodera, Brialyn; Phelps, LeEllen; Puentes,
Myles M.; Richards, Christopher; Rimmele, Lukas M.; Sekulic, Predrag;
Shimko, Stephan R.; Simison, Brett E.; Smith, Brett; Starman, Erik;
Sueoka, Stacey R.; Summers, Richard T.; Szabo, Aimee; Szabo, Louis;
Wampler, Stephen B.; Williams, Timothy R.; White, Charles
2020SoPh..295..172R Altcode:
We present an overview of the National Science Foundation's Daniel
K. Inouye Solar Telescope (DKIST), its instruments, and support
facilities. The 4 m aperture DKIST provides the highest-resolution
observations of the Sun ever achieved. The large aperture of
DKIST combined with state-of-the-art instrumentation provide the
sensitivity to measure the vector magnetic field in the chromosphere
and in the faint corona, i.e. for the first time with DKIST we will
be able to measure and study the most important free-energy source
in the outer solar atmosphere - the coronal magnetic field. Over its
operational lifetime DKIST will advance our knowledge of fundamental
astronomical processes, including highly dynamic solar eruptions
that are at the source of space-weather events that impact our
technological society. Design and construction of DKIST took over two
decades. DKIST implements a fast (f/2), off-axis Gregorian optical
design. The maximum available field-of-view is 5 arcmin. A complex
thermal-control system was implemented in order to remove at prime
focus the majority of the 13 kW collected by the primary mirror and
to keep optical surfaces and structures at ambient temperature, thus
avoiding self-induced local seeing. A high-order adaptive-optics
system with 1600 actuators corrects atmospheric seeing enabling
diffraction limited imaging and spectroscopy. Five instruments, four
of which are polarimeters, provide powerful diagnostic capability
over a broad wavelength range covering the visible, near-infrared,
and mid-infrared spectrum. New polarization-calibration strategies
were developed to achieve the stringent polarization accuracy
requirement of 5×10<SUP>−4</SUP>. Instruments can be combined and
operated simultaneously in order to obtain a maximum of observational
information. Observing time on DKIST is allocated through an open,
merit-based proposal process. DKIST will be operated primarily in
"service mode" and is expected to on average produce 3 PB of raw
data per year. A newly developed data center located at the NSO
Headquarters in Boulder will initially serve fully calibrated data to
the international users community. Higher-level data products, such as
physical parameters obtained from inversions of spectro-polarimetric
data will be added as resources allow.
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Title: Shock Heating Energy of Umbral Flashes Measured with Integral
Field Unit Spectroscopy
Authors: Anan, Tetsu; Schad, Thomas A.; Jaeggli, Sarah A.; Tarr,
Lucas A.
2019ApJ...882..161A Altcode: 2019arXiv190710797A
Umbral flashes are periodic brightness increases routinely observed in
the core of chromospheric lines within sunspot umbrae and are attributed
to propagating shock fronts. In this work we quantify the shock heating
energy of these umbral flashes using observations in the near-infrared
He I triplet obtained on 2014 December 7 with the SpectroPolarimetric
Imager for the Energetic Sun, which is a novel integral field unit
spectrograph at the Dunn Solar Telescope. We determine the shock
properties (the Mach number and the propagation speed) by fitting
the measured He I spectral profiles with a theoretical radiative
transfer model consisting of two constant-property atmospheric slabs
whose temperatures and macroscopic velocities are constrained by the
Rankine-Hugoniot relations. From the Mach number, the shock heating
energy per unit mass of plasma is derived to be 2 × 10<SUP>10</SUP>
erg g<SUP>-1</SUP>, which is insufficient to maintain the umbral
chromosphere. In addition, we find that the shocks propagate upward with
the sound speed and the Mach number does not depend on the temperature
upstream of the shocks. The latter may imply suppression of the
amplification of the Mach number due to energy loss of the shocks.
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Title: Optical Alignment of DL-NIRSP Spectrograph
Authors: Jaeggli, Sarah A.; Anan, Tetsu; Kramar, Maxim; Lin, Haosheng
2019AAS...23410612J Altcode:
The Diffraction-Limited Near-Infrared Spectropolarimeter (DL-NIRSP)
will be delivered as part of the first light instrumentation for the
Daniel K. Inouye Solar Telescope (DKIST) and is currently undergoing
lab integration at the University of Hawai'i Institute for Astronomy's
Advanced Technology Research Center on Maui. An off-axis hyperbolic
mirror, with a focal length of 1250 mm, is used as both collimator
and camera in the spectrograph, and makes this system particularly
difficult to align. The optical axis, or vertex, of the parent surface
is located approximately 260 mm from the center of the off-axis
section of the mirror, but there is no direct physical or optical
reference for the location and orientation of the optical axis. We
have made use of vendor data and a coordinate measuring machine (CMM)
arm to transfer coordinates from the back and perimeter surfaces of
the mirror to locate the optical axis focus and place the other optical
components in reference to this mechanical model. In coordination, we
have conducted tests of the optical quality at various points during
the alignment to ensure that the mechanical tolerances maintain the
optical quality of the system so that the instrument will be able to
achieve excellent spectral resolution limited by the spectrograph slit
width (λ/Δλ 250,000), and preserve the diffraction limited spatial
resolution provided by the telescope and feed optics (0.06" at 1 μm).
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Title: Shock heating energy in an umbra of a sunspot with integral
field unit spectroscopy
Authors: Anan, Tetsu; Schad, Thomas A.; Jaeggli, Sarah A.; Tarr,
Lucas A.
2019AAS...23421705A Altcode:
On 2014 December 7 we used new integral field spectroscopy techniques
to observe umbral flashes, which are periodic brightness increases
routinely observed in the core of chromospheric lines within sunspot
umbrae and are attributed to propagating shock fronts. In this work
we quantify the shock heating energy of these umbral flashes using
observations in the near infrared HeI triplet obtained with the
SpectroPolarimetric Imager for the Energetic Sun (SPIES), which is
novel integral field unit spectrograph at the Dunn Solar Telescope. We
determine the shock properties (the Mach number and the propagation
speed) by fitting the measured HeI spectral profiles with a theoretical
radiative transfer model using two constant property atmospheric slabs
whose temperatures and macroscopic velocities are constrained by the
Rankine-Hugoniot relations. From the Mach number, the shock heating
energy per unit mass of plasma is derived as 2 x 10<SUP>10</SUP>
erg/g. We conclude that the estimated shock heating energy rate is
less than the amount required to maintain the umbral chromosphere.
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Title: Shock Heating Energy in an umbra of a sunspot
Authors: Anan, Tetsu; Schad, Tom; Jaeggli, Sarah
2019EGUGA..2113543A Altcode:
In December 7, 2014, umbral flashes, which are periodic brightness
increases in chromospheric spectral lines of the umbrae due to shocks,
were observed in near infrared He I triplet with an integral-field-unit
spectrometer, SPIES (SpectroPolarimetric Imager for the Energetic Sun)
on the Dunn Solar Telescope with a cadence of 14 seconds. The SPIES is
a prototype instruments of a facility instrument of the Daniel K. Inouye
Solar Telescope. In order to determine Mach number at upstream of shock
waves, we fit the measured spectral profiles in the He I 1083 nm triplet
with theoretical profiles computed with a radiative transfer equation
using an atmospheric model based on two constant property slabs, of
which temperatures and macroscopic velocities are constrained by the
Rankine-Hugoniot relations. From the Mach number and the temperature,
shock heating energy per unit mass of plasma is derived as 2.0 x 10 ^
{10} erg/g. Finding a positive correlation between a spatial variation
of the chromospheric temperature and shock speed, we concluded that
prominent heating mechanism can be related with the shock, although
estimated shock heating energy rate is less than the required amount
of energy to maintain the umbral chromosphere.
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Title: Developments of a multi-wavelength spectro-polarimeter on
the Domeless Solar Telescope at Hida Observatory
Authors: Anan, Tetsu; Huang, Yu-Wei; Nakatani, Yoshikazu; Ichimoto,
Kiyoshi; UeNo, Satoru; Kimura, Goichi; Ninomiya, Shota; Okada,
Sanetaka; Kaneda, Naoki
2018PASJ...70..102A Altcode: 2018arXiv180302094A; 2018PASJ..tmp...66A
To obtain full Stokes spectra in multi-wavelength windows
simultaneously, we developed a new spectro-polarimeter on the Domeless
Solar Telescope at Hida Observatory. The new polarimeter consists of
a 60 cm aperture vacuum telescope on an altazimuth mounting, an image
rotator, a high-dispersion spectrograph, and a polarization modulator
and an analyzer composed of a continuously rotating waveplate with
a retardation that is nearly constant at around 127° in 500-1100
nm. There are also a polarizing beam splitter located close behind
the focus of the telescope, fast and large format CMOS cameras, and
an infrared camera. A slit spectrograph allows us to obtain spectra in
as many wavelength windows as the number of cameras. We characterized
the instrumental polarization of the entire system and established a
polarization calibration procedure. The cross-talks among the Stokes Q,
U, and V have been evaluated to be about 0.06%-1.2%, depending on the
degree of the intrinsic polarizations. In a typical observing setup,
a sensitivity of 0.03% can be achieved in 20-60 seconds for 500-1100
nm. The new polarimeter is expected to provide a powerful tool for
diagnosing the 3D magnetic field and other vector physical quantities
in the solar atmosphere.
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Title: Measurement of vector magnetic field in a flare kernel with
a spectropolarimetric observation in He I 10830 Å
Authors: Anan, Tetsu; Yoneya, Takurou; Ichimoto, Kiyoshi; UeNo, Satoru;
Shiota, Daikou; Nozawa, Satoshi; Takasao, Shinsuke; Kawate, Tomoko
2018PASJ...70..101A Altcode: 2018arXiv180806821A; 2018PASJ..tmp..113A
A flare kernel associated with a C4 class flare was observed in a
spectral window including the He I triplet 10830 Å and Si I 10827
Å with a spectropolarimeter on the Domeless Solar Telescope at
Hida Observatory on 2015 August 9. The observed Stokes profiles of
the He I triplet in the flare kernel in its post-maximum phase are
well reproduced through inversions considering the Zeeman and the
Paschen-Back effects with a three-slab model of the flare kernel,
in which two slabs which have upward and downward velocities produce
emissions and one slab produces an absorption. The magnetic field
strength inferred from the emission components of the He I line is 1400
G, which is significantly stronger than 690 G that is observed at the
same location in the same line 6.5 hr before the flare. In addition,
the photospheric magnetic field vector derived from the Si I10827 Å is
similar to that of the flare kernel. To explain this result, we suggest
that the emission in the He I triplet during the flare is produced in
the deep layer, around which bombardment of non-thermal electrons leads
to the formation of a coronal temperature plasma. Assuming a hydrogen
column density at the location where the He I emissions are formed,
and a power-law index of non-thermal electron energy distribution, we
derived the low-energy cutoff of the non-thermal electron as 20-30 keV,
which is consistent with that inferred from hard X-ray data obtained
by RHESSI.
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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
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).
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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
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.
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Title: Developments of the wideband spectropolarimeter of the Domeless
Solar Telescope at Hida Observatory
Authors: Anan, Tetsu; Ichimoto, Kiyoshi; Oi, Akihito; Kimura, Goichi;
Nakatani, Yoshikazu; Ueno, Satoru
2012SPIE.8446E..1CA Altcode:
We developed a new universal spectropolarimeter on the Domeless Solar
Telescope at Hida Observatory to realize precise spectropolarimetric
observations in a wide range of wavelength in visible and near
infrared. The system aims to open a new window of plasma diagnostics by
using Zeeman effect, Hanle effect, Stark effect, and impact polarization
to measure the external magnetic field, electric field, and anisotropies
in atomic excitation in solar atmosphere. The polarimeter consists of a
60 cm aperture vacuum telescope, a high dispersion vacuum spectrograph,
polarization modulator and analyser composed of a continuously rotating
waveplate whose retardation is constant in 400 - 1100 nm and Wallaston
prisms located closely behind the focus of the telescope, and a fast
and high sensitive CCD camera or a infrared camera. The duration for
this polarimeter's achieving photometric accuracy of 10<SUP>-3</SUP>
is 30 - 60 s. Instrumental polarization of the telescope is calibrated
by using a remotely controllable turret accommodating linear polarizer
attached at the entrance window of the telescope to induce well known
polarized light into the telescope. Thus a Mueller matrix model of the
telescope is established to compensate the instrumental polarization
included in observed data within the required accuracy.
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Title: Spicule Dynamics over a Plage Region
Authors: Anan, Tetsu; Kitai, Reizaburo; Kawate, Tomoko; Matsumoto,
Takuma; Ichimoto, Kiyoshi; Shibata, Kazunari; Hillier, Andrew; Otsuji,
Kenichi; Watanabe, Hiroko; Ueno, Satoru; Nagata, Shin'ichi; Ishii,
Takako T.; Komori, Hiroyuki; Nishida, Keisuke; Nakamura, Tahei; Isobe,
Hiroaki; Hagino, Masaoki
2010PASJ...62..871A Altcode: 2010arXiv1002.2288A
We studied spicular jets over a plage area and derived their
dynamic characteristics using Hinode Solar Optical Telescope (SOT)
high-resolution images. A target plage region was near to the west limb
of the solar disk. This location permitted us to study the dynamics
of spicular jets without any overlapping effect of spicular structures
along the line of sight. In this work, to increase the ease with which
we could identify spicules on the disk, we applied the image processing
method `MadMax' developed by Koutchmy et al. (1989). It enhances fine,
slender structures (like jets), over a diffuse background. We identified
169 spicules over the target plage. This sample permited us to derive
statistically reliable results regarding spicular dynamics. The
properties of plage spicules can be summarized as follows: (1) In a
plage area, we clearly identified spicular jet features. (2) They were
shorter in length than the quiet region limb spicules, and followed a
ballistic motion under constant deceleration. (3) The majority (80%)
of the plage spicules showed a cycle of rise and retreat, while 10% of
them faded out without a complete retreat phase. (4) The deceleration
of the spicule was proportional to the velocity of ejection (i.e.,
the initial velocity).
