Author name code: hara
ADS astronomy entries on 2022-09-14
author:"Hara, Hirohisa"
------------------------------------------------------------------------
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: Development of Fast and Precise Scan Mirror Mechanism for an
Airborne Solar Telescope
Authors: Oba, Takayoshi; Shimizu, Toshifumi; Katsukawa, Yukio; Kubo,
Masahito; Kawabata, Yusuke; Hara, Hirohisa; Uraguchi, Fumihiro;
Tsuzuki, Toshihiro; Tamura, Tomonori; Shinoda, Kazuya; Kodeki,
Kazuhide; Fukushima, Kazuhiko; Morales Fernández, José Miguel;
Sánchez Gómez, Antonio; Balaguer Jimenéz, María; Hernández
Expósito, David; Gandorfer, Achim
Bibcode: 2022arXiv220713864O
Altcode:
We developed a scan mirror mechanism (SMM) that enable a slit-based
spectrometer or spectropolarimeter to precisely and quickly map
an astronomical object. The SMM, designed to be installed in the
optical path preceding the entrance slit, tilts a folding mirror
and then moves the reflected image laterally on the slit plane,
thereby feeding a different one-dimensional image to be dispersed by
the spectroscopic equipment. In general, the SMM is required to scan
quickly and broadly while precisely placing the slit position across
the field-of-view (FOV). These performances are highly in demand for
near-future observations, such as studies on the magnetohydrodynamics of
the photosphere and the chromosphere. Our SMM implements a closed-loop
control system by installing electromagnetic actuators and gap-based
capacitance sensors. Our optical test measurements confirmed that the
SMM fulfils the following performance criteria: i) supreme scan-step
uniformity (linearity of 0.08%) across the wide scan range (${\pm}$1005
arcsec), ii) high stability (3${\sigma}$ = 0.1 arcsec), where the
angles are expressed in mechanical angle, and iii) fast stepping speed
(26 ms). The excellent capability of the SMM will be demonstrated
soon in actual use by installing the mechanism for a near-infrared
spectropolarimeter onboard the balloon-borne solar observatory for
the third launch, Sunrise III.
Title: A spectral solar irradiance monitor (SoSpIM) on the JAXA
Solar-C (EUVST) space mission
Authors: Harra, Louise K.; Watanabe, Kyoko; Haberreiter, Margit;
Hori, Tomoaki; Hara, Hirohisa; Kretzschmar, Matthieu; Woods, Thomas;
Shimizu, Toshifumi; Krucker, Samuel; Berghmans, David; Jin, Hidekatsu;
Dominique, Marie; Eparvier, Francis G.; Gissot, Samuel; Leng Yeo, Kok;
Pfiffner, Dany; Milligan, Ryan; Thiemann, Edward; Miyoshi, Yoshizumi;
Imada, Shinsuke; Kawate, Tomoko; Chamberlin, Phillip; Rozanov, Eugene;
Silvio Koller, -.; Barczynski, Krzysztof; Nozomu; Nishitani; Ieda,
Akimasa; Langer, Patrick; Meier, Leandro; Tye, Daniel; Alberti, Andrea
Bibcode: 2022cosp...44..834H
Altcode:
The JAXA Solar-C (EUVST) mission (Shimizu et al., 2020) is designed
to comprehensively understand how mass and energy are transferred
throughout the solar atmosphere. The EUV High-Throughput Spectroscopic
Telescope (EUVST) onboard does this by observing all the temperature
regimes of the atmosphere from the chromosphere to the corona
simultaneously. To enhance the EUVST scientific capabilities,
there will be a Solar Spectral Irradiance Monitor (SoSpIM). SoSpIM
will work hand-in-hand scientifically with EUVST, by providing the
full Sun irradiance at sub-second time cadence combined with the
spatially resolved spectroscopy from EUVST. The SoSPIM instrument
will specifically address two aspects. These are: · Understand how
the solar atmosphere becomes unstable, releasing the energy that
drives solar flares - achieved through probing fast time cadence
solar flare variations. · Measuring solar irradiance that impacts
the Earth's thermosphere and the mesosphere, linking to spatially
resolved measurements of the solar atmosphere with EUVST. SoSpIM will
provide high time resolution measurements in 2 channels (a) in the
corona through channel 1 (EUV) and (b) in the lower atmosphere through
channel 2 (Lyman alpha). Each channel impacts different layers of the
Earth's atmosphere.
Title: How Can Solar-C/SOSPIM Contribute to the Understanding of
Quasi-Periodic Pulsations in Solar Flares?
Authors: Dominique, Marie; Harra, Louise K.; Watanabe, Kyoko; Hara,
Hirohisa; Zhukov, Andrei; Shimizu, Toshifumi; Berghmans, David;
Dolla, Laurent; Gissot, Samuel; Pfiffner, Dany; Imada, Shinsuke;
Silvio Koller, -.; Meier, Leandro; Tye, Daniel; Alberti, Andrea
Bibcode: 2022cosp...44.2524D
Altcode:
Quasi-periodic pulsations (QPPs) refer to nearly-periodic oscillations
that are often observed in irradiance time series during solar flares
and have also been reported in several stellar flares. In the last
years, several statistical studies based on Soft X-ray measurements
have reached the conclusion that QPPs are present in most solar
flares of class M and above. Still, as of today, we are still unsure
of what causes QPPs. Several models could explain the presence of
QPPs with periods matching the ones observed. More detailed analysis
of the observational signatures of QPPs might help determine which
of those models are actually playing a role in the generation of
QPPs. However, as QPPs is a small timescale process (the period of
QPPs is often reported to be less than a minute), such an analysis
requires instruments with a good signal-to-noise and high sampling
rate. In this context, the spectral solar irradiance monitor SOSPIM,
that will be part of the JAXA SOLAR C mission and that will complement
the EUVST spectrograph measurements, could be a valuable asset. SOSPIM
will observe the solar chromosphere and corona in the Lyman-alpha
and EUV spectral ranges at high cadence. In this presentation, we
review the current knowledge of QPPs and describe what could be the
contribution of SOSPIM to push their understanding one step forward.
Title: Probing Upflowing Regions in the Quiet Sun and Coronal Holes
Authors: Schwanitz, Conrad; Harra, Louise; Raouafi, Nour E.; Sterling,
Alphonse C.; Moreno Vacas, Alejandro; del Toro Iniesta, Jose Carlos;
Orozco Suárez, David; Hara, Hirohisa
Bibcode: 2021SoPh..296..175S
Altcode: 2021arXiv211012753S
Recent observations from Parker Solar Probe have revealed that the
solar wind has a highly variable structure. How this complex behaviour
is formed in the solar corona is not yet known, since it requires
omnipresent fluctuations, which constantly emit material to feed
the wind. In this article we analyse 14 upflow regions in the solar
corona to find potential sources for plasma flow. The upflow regions
are derived from spectroscopic data from the EUV Imaging Spectrometer
(EIS) on board Hinode determining their Doppler velocity and defining
regions which have blueshifts stronger than −6 kms−1. To
identify the sources of these blueshift data from the Atmospheric
Imaging Assembly (AIA) and the Helioseismic and Magnetic Imager (HMI),
on board the Solar Dynamics Observatory (SDO), and the X-ray Telescope
(XRT), on board Hinode, are used. The analysis reveals that only 5 out
of 14 upflows are associated with frequent transients, like obvious
jets or bright points. In contrast to that, seven events are associated
with small-scale features, which show a large variety of dynamics. Some
resemble small bright points, while others show an eruptive nature, all
of which are faint and only live for a few minutes; we cannot rule out
that several of these sources may be fainter and, hence, less obvious
jets. Since the complex structure of the solar wind is known, this
suggests that new sources have to be considered or better methods used
to analyse the known sources. This work shows that small and frequent
features, which were previously neglected, can cause strong upflows in
the solar corona. These results emphasise the importance of the first
observations from the Extreme-Ultraviolet Imager (EUI) on board Solar
Orbiter, which revealed complex small-scale coronal structures.
Title: How Can Solar-C/SOSPIM Contribute to the Understanding of
Quasi-Periodic Pulsations in Solar Flares?
Authors: Dominique, Marie; Dolla, Laurent; Zhukov, Andrei; Alberti,
Andrea; Berghmans, David; Gissot, Samuel; Hara, Hirohisa; Harra,
Louise; Imada, Shinsuke; Koller, Silvio; Meier, Leandro; Pfiffner,
Daniel; Shimizu, Toshifumi; Tye, Daniel; Watanabe, Kyoko
Bibcode: 2021AGUFMSH25E2124D
Altcode:
Quasi-periodic pulsations (QPPs) refer to nearly-periodic oscillations
that are often observed in irradiance time series during solar flares
and have also been reported in several stellar flares. In the last
years, several statistical studies based on Soft X-ray measurements
have reached the conclusion that QPPs are present in most solar flares
of class M and above. Still, the mechanism at the origin of QPPs is
under debate. Are they caused by waves or periodic fluctuations of the
magnetic reconnection driving the flare? Analyzing the characteristics
of QPPs and their evolution during the flare could help identifying
their origin. However, QPPs sometimes exhibit very different
periodicities, and do not always happen during the same phase of the
flare. All this could point to the coexistence of QPPs with different
origin mechanism, and indicates the need for more observations. In this
context, the spectral solar irradiance monitor SOSPIM, that will be
part of the JAXA SOLAR C mission and that will complement the EUVST
spectrograph measurements, could be a valuable asset. SOSPIM will
observe the solar chromosphere and corona in the Lyman-alpha and EUV
spectral ranges at high cadence. In this presentation, we review the
current knowledge of QPPs and describe what could be the contribution
of SOSPIM to push their understanding one step forward.
Title: Electron Density Dependence of Extreme Ultraviolet Line
Intensity Ratios in Ar XIV
Authors: Nakamura, Nobuyuki; Numadate, Naoki; Kono, Yasutaka; Murakami,
Izumi; Kato, Daiji; Sakaue, Hiroyuki A.; Hara, Hirohisa
Bibcode: 2021ApJ...921..115N
Altcode:
We report the electron density dependence of extreme ultraviolet line
intensity ratios in Ar XIV studied using a well-defined electron beam
ion trap plasma. The purpose of this study is to examine the potential
of the Ar XIV lines in diagnosing the electron density of solar corona
active regions with a temperature higher than 3 MK. The experimentally
obtained dependence is in good agreement with collisional-radiative
model calculations, which ensures the usability of the Ar XIV lines.
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: GRB 210308A: MITSuME Okayama optical upper limits
Authors: Ogata, S.; Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano,
M.; Ogawa, F.; Nakamura, N.; Ito, N.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29621....1O
Altcode:
We observed the field of GRB 210308A (D'Elia et al.,GCN Circular #29619)
with the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Okayama Astrophysical Observatory,
Okayama, Japan. The observation with a series of 60 sec exposures
started at 2021-03-08 11:03:59 UT.(4.5 hours after Swift BAT trigger)
We stacked the images with good conditions. We did not detect the
optical afterglow reported previously (D'Elia et al.,GCN Circular
#29619) in all three bands. We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
4.5 11:51:53 4440 g'>17.6, Rc>17.8, Ic>17.8
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73,
Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
Title: GRB 210306A: MITSuME Akeno optical observation
Authors: Hosokawa, R.; Adachi, R.; Murata, K. L.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29608....1H
Altcode:
We observed the field of GRB 210306A (D'Elia et al. GCN #29597,
Watson et al. GCN 29598, Romanov GCN #29599, Strausbaugh et al. GCN
#29600, Ohno et al. GCN #29602, Hentunen et al. GCN #29603, Stecklum
et al. GCN #29604, Veres et al. GCN #29605, Lipunov et al. GCN
#29606, Zhu et al. GCN #29607) with the optical three color (g',
Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope
of Akeno Observatory, Yamanashi, Japan. The observation with
a series of 60 sec exposures started at 2021-03-06 09:12:03 UT
(5.3 hours after Swift BAT trigger). We stacked the images with
good conditions. We marginally detected the point source at the
position consistent with the afterglow detected previously(D'Elia
et al. GCN #29597, Watson et al. GCN 29598, Romanov GCN #29599,
Strausbaugh et al. GCN #29600, Hentunen et al. GCN #29603,
Stecklum et al. GCN #29604, Zhu et al. GCN #29607). We measured the
magnitudes as follows. T0+[hour] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
5.3 11:38:10 8160 g'=20.0+/-0.4, Rc=20.2+/-0.4, Ic=19.0+/-0.3
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
PS1 catalog for flux calibration. The magnitudes are expressed in the
AB system. The images were processed in real-time through the MITSuME
GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1,
Pages 4-24; https://github.com/MNiwano/Eclaire).
Title: GRB 210318B: MITSuME Okayama optical upper limits
Authors: Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29675....1H
Altcode:
We observed the field of GRB 210318B (Troja et al. GCN Circular #29663,
Svinkin et al. GCN Circular #29664, Stamatikos et al. GCN Circular
#29666, Lipunov et al. GCN Circular #29667, Malacaria et al. GCN
Circular #29668) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Okayama Astrophysical
Observatory, Okayama, Japan. The observation with a series of 60 sec
exposures started at 2021-03-19 19:11:03 UT.(40.4 hours after Swift BAT
trigger) We stacked the images with good conditions. We did not find any
new point sources within the Swift XRT circle (Troja et al. GCN Circular
#29663) in all three bands. We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
40.4 19:50:32 2040 g'>14.3, Rc>14.2, Ic>13.4
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
the UCAC4 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73,
Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
Title: GRB 210212A: MITSuME Akeno optical upper limits
Authors: Murata, K. L.; Adachi, R.; Hosokawa, R.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29496....1M
Altcode:
We observed the field of GRB 210212A (Troja et al. GCN #29487,
Beardmore et al. GCN #29489, Palmer et al. GCN #29491, Kuin et
al. GCN #29492, Hu et al. GCN #29494, Tohuvavohu et al. GCN #29495)
with the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi,
Japan. The observation with a series of 60 sec exposures started at
2021-02-12 08:51:45 UT(4.43 hours after the Swift BAT trigger). We
stacked the images with good conditions. We did not find any new point
sources within the enhanced Swift XRT circle (Beardmore et al. GCN
#29489) in all three bands. We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
8.6 13:05:08 5400 g'>18.6, Rc>18.5, Ic>17.8
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73,
Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
Title: GRB 210222B: MITSuME Akeno optical upper limits
Authors: Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29565....1H
Altcode:
We observed the field of GRB 210222B (Lipunov et al. GCN #29544, Gropp
et al. GCN #29545, Hu et al. GCN #29546, Strausbaugh et al. GCN #29547,
Mong et al. GCN #29548, Perley et al. GCN #29549, Mong et al. GCN
#29550, Zhu et al. GCN #29551, Fernandez et al. GCN #29552, Lipunov et
al. GCN #29554, Jelinek et al. GCN #29557, Zheng et al. GCN #29558,
Siegel et al. GCN #29559, Page et al. GCN #29560, Ukwatta et al. GCN
#29561, Gokuldass et al. GCN #29562, Belkin et al. GCN #29563) with
the optical three color (g', Rc, and Ic) CCD cameras attached to the
MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The
observation with a series of 60 sec exposures started at 2021-02-23
11:00:13 UT(12.4hours after the Swift BAT trigger). We stacked the
images with good conditions. We did not detect the optical afterglow
reported previously (Gropp et al. GCN #29545, Hu et al. GCN #29546,
Strausbaugh et al. GCN #29547, Mong et al. GCN #29548, Perley et al. GCN
#29549, Mong et al. GCN #29550, Zhu et al. GCN #29551, Fernandez et
al. GCN #29552, Lipunov et al. GCN #29554, Jelinek et al. GCN #29557,
Siegel et al. GCN #29559, Gokuldass et al. GCN #29562, Belkin et al. GCN
#29563) in all three bands. We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
12.4 15:18:25 14100 g'>19.6, Rc>19.9, Ic>19.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73,
Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
Title: GRB 210209A: MITSuME Akeno optical upper limits
Authors: Hosokawa, R.; Adachi, R.; Murata, K. L.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29455....1H
Altcode:
We observed the field of GRB 210209A (Laha et al. GCN #29442, Evans et
al. GCN #29443, Perri et al. GCN #29449, Breeveld et al. GCN #29453)
with the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi,
Japan. The observation with a series of 60 sec exposures started at
2021-02-10 08:49:41 UT(11.2 hour after the Swift BAT trigger). Since
the first 17 images were taken under high airmass conditions, we
stacked the images with good conditions. We did not find any new
point sources within the enhanced Swift XRT circle (Evans et al. GCN
#29443) in all three bands. We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
11.2 09:14:41 600 g'>17.2, Rc>17.6, Ic>17.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73,
Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
Title: GRB 210218A: MITSuME Akeno optical upper limits
Authors: Ogawa, F.; Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano,
M.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29532....1O
Altcode:
We observed the field of GRB 210218A (Sbarufatti et al. GCN #29529, Zhu
et al. GCN #29530, Xin et al. GCN #29531) with the optical three color
(g', Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of
Akeno Observatory, Yamanashi, Japan. The observation with a series of
10 sec exposures started at 2021-02-18 13:36:05 UT(46 seconds after the
Swift BAT trigger). We stacked the images with good conditions. We did
not find any new point sources within the Swift BAT circle (Sbarufatti
et al. GCN #29529) in all three bands. We obtained the 5-sigma limits of
the stacked images as follows. T0+[sec] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
46 14:03:01 1220 g'>17.3, Rc>17.5, Ic>16.7
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
the UCAC4 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al. 2021, PASJ, Vol.73,
Issue 1, Pages 4-24; https://github.com/MNiwano/Eclaire).
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: GRB 210104A: MITSuME Akeno optical observation
Authors: Hosokawa, R.; Adachi, R.; Niwano, M.; Murata, K. L.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2021GCN.29237....1H
Altcode:
We observed the field of GRB 210104A (The Fermi GBM team , GCN 29232,
E. Troja et al., GCN 29233, B. Biltzinger et al., GCN 29234) with
the optical three color (g', Rc, and Ic) CCD cameras attached to the
MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The
observation started at 2021-01-04 11:27:54 UT (55s after Swift BAT
trigger). We detected the point source at the position consistent with
the afterglow detected previously(E. Troja et al., GCN 29233, L. P. Xin
et al., GCN 29235, Y.-D. Hu et al., GCN 29236). We measured the
magnitudes as follows. T0+[sec] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
55 11:28:24 60 g'=14.6+/-0.1, Rc=14.2+/-0.1, Ic=13.8+/-0.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
PS1 catalog for flux calibration. The magnitudes are expressed in the AB
system. The images were processed in real-time through the MITSuME GPU
reduction pipeline (Niwano et al., https://doi.org/10.1093/pasj/psaa091,
https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).
Title: Multicolor-optical observations of the flat-spectrum radio
quasar Ton 599 and quasar 3C279
Authors: Hosokawa, R.; Murata, K. L.; Niwano, M.; Wang, S.; Adachi,
R.; Ogawa, F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara,
H.; Yatsu, Y.; Kawai, N.
Bibcode: 2021ATel14353....1H
Altcode:
We monitor the flat-spectrum radio quasar Ton 599 with three optical
bands (g', Rc, and Ic) using the MITSuME 50 cm Telescopes at Akeno
Observatory and Okayama Astrophysical Observatory in Japan.
Title: Multicolor-optical observation of the flaring blazar BL
Lacertae
Authors: Hosokawa, R.; Murata, K. L.; Niwano, M.; Wang, S.; Adachi,
R.; Ogawa, F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara,
H.; Yatsu, Y.; Kawai, N.
Bibcode: 2021ATel14334....1H
Altcode:
The flaring blazar BL Lacertae was in the bright state in optical,
X-ray and gamma-ray around August 2020 (ATel #13930, #13933, #13956,
#13958, #13963, #13964) and in another bright state around October 2020
(ATel #14065, #14069, #14072, #14081, #14096).
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: GRB 201203A: MITSuME Okayama optical upper limits
Authors: Niwano, M.; Hosokawa, R.; Murata, K. L.; Adachi, R.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28992....1N
Altcode:
We observed the field of GRB 201203A (S. Dichiara et al.,
GCN Circular #28985) with the optical three color (g', Rc,
and Ic) CCD cameras attached to the MITSuME 50 cm telescope
of Okayama Astrophysical Observatory, Okayama, Japan. The
observation started at 12:02:06 UT. We did not find any new
point sources within the Swift-XRT circle ( V. D'Elia et
al., GCN Circular #28990) in all three bands. We obtained the
5-sigma limits as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
6.9 13:45:28.19 9000 g'>17.9, Rc>18.6, Ic>17.7
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through the
MITSuME GPU reduction pipeline (Niwano et al., 10.1093/pasj/psaa091,
arXiv:2008.11486; https://github.com/MNiwano/Eclaire).
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: GRB 201223A: MITSuME Akeno optical observation
Authors: Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.29164....1H
Altcode:
We observed the field of GRB 201223A (J.D. Gropp et al., GCN #29158,
J. Wood et al., GCN #29161) with the optical three color (g', Rc,
and Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno
Observatory, Yamanashi, Japan. The observation started at 2020-12-23
17:59:18 UT (52s after Swift BAT trigger). We detected the point source
at the position consistent with the afterglow detected previously
(Lipunov et al. GCN #29157, Gropp et al., GCN #29158, Z.P. Zhu
et al. GCN #29159, Y.-D. Hu et al. GCN #29160). We measured the
magnitudes as follows. T0+[sec] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
52 17:59:48 60 g'=15.45+/-0.05, Rc=15.04+/-0.03, Ic=14.77+/-0.04
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
PS1 catalog for flux calibration. The magnitudes are expressed in the AB
system. The images were processed in real-time through the MITSuME GPU
reduction pipeline (Niwano et al., https://doi.org/10.1093/pasj/psaa091,
https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).
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: GRB 201214B: MITSuME Akeno optical upper limits
Authors: Nakamura, N.; Hosokawa, R.; Murata, K. L.; Adachi, R.;
Niwano, M.; Ogawa, F.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.;
Yatsu, Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.29056....1N
Altcode:
We observed the field of GRB 201214B (The Fermi GBM team, GCN
#29039, P. Evans et al., GCN #29043, V. Lipunov et al., GCN #29044,
D. Palmer et al., GCN #29045, B. Sbarufatti et al., GCN #29052 )
with the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi,
Japan. The observation with a series of 60 sec exposures started at
2020-12-15 18:51:41 UT(28.8 hour after trigger). We did not find any
new point sources within the enhanced Swift BAT circle (D. Palmer et
al., GCN #29045) in all three bands. We obtained the 5-sigma limits of
the stacked images as follows T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
28.8 18:51:41 10380 g'>20.9, Rc>21.0, Ic>20.3
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration. The magnitudes
are expressed in the AB system. The images were processed in
real-time through the MITSuME GPU reduction pipeline (Niwano et al.,
https://doi.org/10.1093/pasj/psaa091, https://arxiv.org/abs/2008.11486;
https://github.com/MNiwano/Eclaire).
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: GRB 201104B: MITSuME Akeno optical observation
Authors: Hosokawa, R.; Adachi, R.; Murata, K. L.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28870....1H
Altcode:
We observed the field of GRB 201104B (B. Sbarufatti et al., GCN #28825)
with the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi,
Japan. The observation with a series of 60 sec exposures started at
2020-11-05 08:14:33 UT. The first 29 images were heavily affected
by twilight at Akeno Observatory. We marginally detected the point
source at the position consistent with the afterglow detected
previously (Marshall et al., GCN #28827, Vielfaure et al., GCN
#28840, Oates et al., GCN #28851, Belkin et al., GCN #28852, Belkin
et al., GCN #28856, and Gupta et al., GCN #28860). We measured the
magnitudes as follows. T0+[hour] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
15.2 2020-11-05 12:59:59 21360
g'=21.5+/-0.3, Rc=20.7+/-0.2, Ic=20.3+/-0.3
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration. The magnitudes
are expressed in the AB system. The images were processed in
real-time through the MITSuME GPU reduction pipeline (Niwano et al.,
https://doi.org/10.1093/pasj/psaa091, https://arxiv.org/abs/2008.11486;
https://github.com/MNiwano/Eclaire).
Title: GRB 201017A: MITSuME Akeno optical upper limits
Authors: Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28684....1H
Altcode:
We observed the field of GRB 201017A (The Fermi GBM team, GCN
#28665, A. D'Ai et al., GCN #28666, V. Lipunov et al., GCN #28667,
L. P. Xin et al., GCN #28672, S. Belkin et al., GCN #28679) with
the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi,
Japan. The observation started at 2020-10-17 12:53:15 UT.(186
min after trigger) Since some images were heavily affected by bad
weather, we stacked the images with good conditions. We did not
find any new point sources within the enhanced Swift/XRT circle
(M. R. Goad et al., GCN #28671) in all three bands. We obtained
the 5-sigma limits as follows T0+[min] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
296 17:53:37 9480 g'>20.0,Rc>19.9,Ic>19.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration. The magnitudes
are expressed in the AB system. The images were processed in
real-time through the MITSuME GPU reduction pipeline (Niwano et al.,
accepted for publication in PASJ, https://arxiv.org/abs/2008.11486;
https://github.com/MNiwano/Eclaire).
Title: GRB 201020A: MITSuME Akeno optical observation
Authors: Adachi, R.; Hosokawa, R.; Murata, K. L.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28697....1A
Altcode:
We observed the field of GRB 201020A (E. Ambrosi et al.,GCN Circular
#28696) with the optical three color (g', Rc, and Ic) CCD cameras
attached to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi,
Japan. The observation started at 2020-10-20 08:31:00 UT. The first
28 images were heavily affected by twilight at Akeno Observatory. We
detected the point source at the position consistent with the afterglow
detected previously (E. Ambrosi et al. GCN #28696). We measured the
magnitudes as follows. T0+[min] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
196 09:15:39 1260 g'=19.4+/-0.2, Rc=18.4+/-0.1, Ic=18.4+/-0.2
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We
used GSC2.3 and PS1 catalog for flux calibration. The magnitudes
are expressed in the AB system. The images were processed in
real-time through the MITSuME GPU reduction pipeline (Niwano et al.,
accepted for publication in PASJ, https://arxiv.org/abs/2008.11486;
https://github.com/MNiwano/Eclaire).
Title: GRB 201024A: MITSuME Akeno optical upper limits
Authors: Niwano, M.; Murata, K. L.; Hosokawa, R.; Adachi, R.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28779....1N
Altcode:
We observed the field of GRB 201024A (F. E. Marshall et al.,GCN
Circular #28761) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan. We observed for two nights. The observation with a
series of 60 sec exposures started at 2020-10-24 16:04:04UT for the
first night and 2020-10-25 15:56:17UT for the second night. We stacked
the images with good conditions each night. We did not detect the
point source reported by other telescopes (Lipunov et al. GCN Circular
#28760, Fernandez-Garcia et al. #28763, de Ugarte Postigo et al. #28764,
Martin Jelinek et al. #28766). We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
13.78 2020-10-24T18:27:11 11520 g'>20.2, Rc>20.4, Ic>19.7
38.48 2020-10-25T17:17:59 1980 g'>19.4, Rc>19.6, Ic>18.8
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst T-EXP: Total Exposure time We used the
PS1 catalog for flux calibration. The magnitudes are expressed in the
AB system. The images were processed in real-time through the MITSuME
GPU reduction pipeline (Niwano et al., accepted for publication in PASJ,
https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).
Title: GRB 201027A: MITSuME Akeno optical upper limits
Authors: Hosokawa, R.; Hara, H.; Adachi, R.; Niwano, M.; Ogawa, F.;
Murata, K. L.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28802....1H
Altcode:
We observed the field of GRB 201027A (V. Lipunov et al., GCN #28787,
S. B. Cenko et al., GCN #28788, Y.-D. Hu et al., GCN #28794 )
with the optical three color (g', Rc, and Ic) CCD cameras attached
to the MITSuME 50 cm telescope of Akeno Observatory, Yamanashi,
Japan. The observation with a series of 60 sec exposures started at
2020-10-27 18:43:12 UT(17.2 hour after trigger). Since the first
18 images were taken under high airmass conditions, we stacked
the images with good conditions. We did not find any new point
sources within the enhanced Swift/XRT circle (J.P. Osborne et al.,
GCN #28792) in all three bands. We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
17.6 19:19:32 3180 g'>19.5,Rc>20.0,Ic>19.1
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time
We used the PS1 catalog for flux calibration. The magnitudes
are expressed in the AB system. The images were processed in
real-time through the MITSuME GPU reduction pipeline (Niwano et al.,
https://doi.org/10.1093/pasj/psaa091, https://arxiv.org/abs/2008.11486;
https://github.com/MNiwano/Eclaire).
Title: GRB 201001A: MITSuME Akeno optical upper limits
Authors: Hosokawa, R.; Ogata, S.; Murata, K. L.; Adachi, R.; Niwano,
M.; Ogawa, F.; Nakamura, N.; Ito, N.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28548....1H
Altcode:
We observed the field of GRB 201001A(Fermi GBM Team, GCN 28538;
David et al., GCN 28539) with the optical three color (g', Rc, and
Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno
Observatory, Yamanashi, Japan. The observation with a series of 60
sec exposures started at 2020-10-01 16:44:38UT. Since some images
were heavily affected by the moon, we stacked the images with good
conditions. We did not find any new point sources within the enhanced
Swift/XRT error circle (Evans et al., GCN 28540) in the 60 sec exposure
images and the stacked images. We obtained the 5-sigma limits of the
stacked images as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
6.8 2020-10-01T19:06:10.46 4020 g'>19.0, Rc>19.3, Ic>18.9
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through
the MITSuME GPU reduction pipeline (Niwano et al., accepted
for publication in PASJ, https://arxiv.org/abs/2008.11486;
https://github.com/MNiwano/Eclaire). --
＿＿＿＿＿＿＿＿＿＿＿＿ 東京工業大学
河合研究室 修士1年 細川稜平 hosokawa@hp.phys.titech.ac.jp
Title: GRB 201006A: MITSuME Akeno optical upper limits
Authors: Ito, N.; Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano,
M.; Ogawa, F.; Nakamura, N.; Ogata, S.; Takamatsu, H.; Hara, H.;
Yatsu, Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28571....1I
Altcode:
We observed the field of GRB 201006A (J.D. Gropp et al.,GCN
#28560, S.Mereghetti et al., GCN #28561, R. Hamburg et al., GCN #
28564) with the optical three color (g', Rc, and Ic) CCD cameras
attached to the MITSuME 50 cm telescope of Akeno Observatory,
Yamanashi, Japan. The observation started at 13:31:53 UT. Since
some images were heavily affected by bad weather and the moon,
we stacked the images with good conditions. We did not find
any new point sources within the enhanced Swift/XRT circle
(M.R. Goad et al., GCN #28562) in all three bands. We obtained the
5-sigma limits as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
12.2 16:27:01 4020.0 g'>19.5,Rc>19.4,Ic>18.9
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst T-EXP: Total Exposure time We used
PS1 catalog for flux calibration. The magnitudes are expressed in the
AB system. The images were processed in real-time through the MITSuME
GPU reduction pipeline (Niwano et al., accepted for publication in PASJ;
arXiv2008.11486 https://github.com/MNiwano/Eclaire)
Title: GRB 200907B: MITSuME Okayama optical upper limits
Authors: Hosokawa, R.; Murata, K. L.; Adachi, R.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28393....1H
Altcode:
We observed the field of GRB 200907B (Beardmore et al., GCN 28384;
Evans et al., GCN 28385,28391) with the optical three color (g',
Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of
Okayama Astrophysical Observatory, Okayama, Japan. The observation
with a series of 60 sec exposures started at 2020-09-07 18:52:16UT. We
did not find any new point sources within the enhanced Swift/XRT
error circle (Evans et al., GCN 28391) in the 60 sec exposure
images and the stacked images. We obtained the 5-sigma limits of
the stacked images as follows. T0+[sec] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
65 2020-09-07T19:19:48 2100 g'>17.1, Rc>17.9, Ic>17.3
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst T-EXP: Total Exposure time We used the
PS1 catalog for flux calibration. The magnitudes are expressed in the
AB system. The images were processed in real-time through the MITSuME
GPU reduction pipeline (Niwano et al., accepted for publication in PASJ,
https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).
Title: GRB 200819A: MITSuME Akeno optical upper limits
Authors: Murata, K. L.; Hosokawa, R.; Adachi, R.; Niwano, M.;
Ogawa, F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara,
H.; Yatsu, Y.; Kawai, N.; Horiuchi, Takashi; Hanayama, Hidekazu;
MITSuME Collaboration
Bibcode: 2020GCN.28269....1M
Altcode:
We observed the field of GRB 200819A (Dichiara et al., GCN 28263;
Evans et al., GCN 28265) with the optical three color (g', Rc, and
Ic) CCD cameras attached to the MITSuME 50 cm telescope of Akeno
Observatory, Yamanashi, Japan. The observation with a series of
60 sec exposures started on 2020-08-19 15:45:44 UT. Some images
were heavily affected by bad weather conditions. We stacked
the images with good weather conditions. We did not find any
new point sources within the enhanced Swift/XRT error circle
(Evans et al., GCN 28265) of the stacked images. We obtained the
5-sigma limits as follows. T0+[sec] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
~290 2020-08-19T17:36:48 5640 g'>18.4, Rc>19.0, Ic>19.3
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through
the MITSuME GPU reduction pipeline (Niwano et al., submitted;
https://github.com/MNiwano/Eclaire)
Title: GRB 200806A: MITSuME Akeno optical upper limits
Authors: Murata, K. L.; Adachi, R.; Hosokawa, R.; Niwano, M.; Ogawa,
F.; Nakamura, N.; Ito, N.; Ogata, S.; Takamatsu, H.; Hara, H.; Yatsu,
Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.28215....1M
Altcode:
We observed the field of GRB 200806A (Ambrosi et al., GCN 28211;
Beardmore et al., GCN 28214) with the optical three color (g',
Rc, and Ic) CCD cameras attached to the MITSuME 50 cm telescope of
Akeno Observatory, Yamanashi, Japan. The observation with a series
of 60 sec exposures started on 2020-08-06 15:30:34 UT. The first
15 images were heavily affected by the presence of the moon. We
stacked the images excluding the 15 images and did not find any
new point sources within the enhanced Swift/XRT error circle
(Beardmore et al., GCN 28214) of the stacked images. We obtained
the 5-sigma limits as follows. T0+[min] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
19 2020-08-06T15:57:10 960 g'>16.7, Rc>16.7, Ic>16.9
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through
the MITSuME GPU reduction pipeline (Niwano et al., submitted;
https://github.com/MNiwano/Eclaire)
Title: Resonant electron impact excitation of highly charged Fe ions
studied with a compact electron beam ion trap
Authors: Monobe, Masashi; Sakaue, Hiroyuki A.; Kato, Daiji; Murakami,
Izumi; Hara, Hirohisa; Watanabe, Tetsuya; Nakamura, Nobuyuki
Bibcode: 2020XRS....49..511M
Altcode:
No abstract at ADS
Title: GRB 200613A: MITSuME Akeno optical upper limits
Authors: Murata, K. L.; Ito, N.; Hosokawa, R.; Adachi, R.; Niwano,
M.; Ogawa, F.; Nakamura, N.; Ogata, S.; Takamatsu, H.; Hara, H.;
Yatsu, Y.; Kawai, N.; MITSuME Collaboration
Bibcode: 2020GCN.27962....1M
Altcode:
We observed the field of GRB 200613A (Fermi GBM team, GCN 27926;
Bissaldi et al., GCN 27930; Ohno et al., GCN 27931) with the
optical three color (g', Rc, and Ic) CCD cameras attached to the
MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan. The
observation started on 2020-06-15 11:33. We did not detect the
optical afterglow (Kann et al., GCN 27935; Kennea et al., GCN 27936;
Pozanenko et al., GCN 27937; Izzo et al., GCN 27939; Zhu et al.,
GCN 27943; Marshall et al., GCN 27944; Liu et al., GCN 27949;
Belkin et al., GCN 27958) in the stacked image. We obtained the
5-sigma limits as follows. T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
54 2020-06-15T12:29:27 2040 g'>19.3, Rc>19.5, Ic>18.6
------------------------------------------------------------------------------------------------
T0+: Elapsed time after the burst T-EXP: Total Exposure time We used
the PS1 catalog for flux calibration. The magnitudes are expressed
in the AB system. The images were processed in real-time through
the MITSuME GPU reduction pipeline (Niwano et al., submitted;
https://github.com/MNiwano/Eclair)
Title: A Solar Magnetic-fan Flaring Arch Heated by Nonthermal
Particles and Hot Plasma from an X-Ray Jet Eruption
Authors: Lee, Kyoung-Sun; Hara, Hirohisa; Watanabe, Kyoko; Joshi,
Anand D.; Brooks, David H.; Imada, Shinsuke; Prasad, Avijeet; Dang,
Phillip; Shimizu, Toshifumi; Savage, Sabrina L.; Moore, Ronald;
Panesar, Navdeep K.; Reep, Jeffrey W.
Bibcode: 2020ApJ...895...42L
Altcode: 2020arXiv200509875L
We have investigated an M1.3 limb flare, which develops as a magnetic
loop/arch that fans out from an X-ray jet. Using Hinode/EIS, we
found that the temperature increases with height to a value of over
107 K at the loop top during the flare. The measured Doppler
velocity (redshifts of 100-500 km s-1) and the nonthermal
velocity (≥100 km s-1) from Fe XXIV also increase with
loop height. The electron density increases from 0.3 × 109
cm-3 early in the flare rise to 1.3 × 109
cm-3 after the flare peak. The 3D structure of the loop
derived with Solar TErrestrial RElations Observatory/EUV Imager
indicates that the strong redshift in the loop-top region is due to
upflowing plasma originating from the jet. Both hard X-ray and soft
X-ray emission from the Reuven Ramaty High Energy Solar Spectroscopic
Imager were only seen as footpoint brightenings during the impulsive
phase of the flare, then, soft X-ray emission moved to the loop top in
the decay phase. Based on the temperature and density measurements and
theoretical cooling models, the temperature evolution of the flare arch
is consistent with impulsive heating during the jet eruption followed
by conductive cooling via evaporation and minor prolonged heating in
the top of the fan loop. Investigating the magnetic field topology and
squashing factor map from Solar Dynamics Observatory/HMI, we conclude
that the observed magnetic-fan flaring arch is mostly heated from low
atmospheric reconnection accompanying the jet ejection, instead of from
reconnection above the arch as expected in the standard flare model.
Title: Locating Hot Plasma in Small Flares using Spectroscopic
Overlappogram Data from the Hinode EUV Imaging Spectrometer
Authors: Harra, Louise; Matthews, Sarah; Long, David; Hasegawa,
Takahiro; Lee, Kyoung-Sun; Reeves, Katharine K.; Shimizu, Toshifumi;
Hara, Hirohisa; Woods, Magnus
Bibcode: 2020SoPh..295...34H
Altcode: 2020arXiv200302908H
One of the key processes associated with the "standard" flare model is
chromospheric evaporation, a process during which plasma heated to high
temperatures by energy deposition at the flare footpoints is driven
upwards into the corona. Despite several decades of study, a number
of open questions remain, including the relationship between plasma
produced during this process and observations of earlier "superhot"
plasma. The Extreme ultraviolet Imaging Spectrometer (EIS) onboard
Hinode has a wide slot, which is often used as a flare trigger in the
He II emission-line band. Once the intensity passes a threshold level,
the study will switch to one focussed on the flaring region. However,
when the intensity is not high enough to reach the flare trigger
threshold, these datasets are then available during the entire flare
period and provide high-cadence spectroscopic observations over a
large field of view. We make use of data from two such studies of a
C4.7 flare and a C1.6 flare to probe the relationship between hot Fe
XXIV plasma and plasmas observed by the Reuven Ramaty High Energy Solar
Spectroscopic Imager (RHESSI) and the X-ray Telescope (XRT) to track
where the emission comes from and when it begins. The flare trigger
slot data used in our analysis has one-minute cadence. Although the
spatial and spectral information are merged in the wide-slot data,
it is still possible to extract when the hot plasma appears, through
the appearance of the Fe Xxiv spectral image. It is also possible
to derive spectrally pure Fe XXIV light curves from the EIS data,
and compare them with those derived from hard X-rays, enabling a full
exploration of the evolution of hot emission. The Fe XXIV emission
peaks just after the peak in the hard X-ray lightcurve; consistent with
an origin in the evaporation of heated plasma following the transfer
of energy to the lower atmosphere. A peak was also found for the C4.7
flare in the RHESSI peak temperature, which occurred before the hard
X-rays peaked. This suggests that the first peak in hot-plasma emission
is likely to be directly related to the energy-release process.
Title: Nonthermal Motions in a Polar Coronal Hole Measured with
Hinode/EIS during an on-Orbit Partial Solar Eclipse on 2017 August 21
Authors: Hara, Hirohisa
Bibcode: 2019ApJ...887..122H
Altcode:
We have performed a spectroscopic observation over the south polar
coronal hole (PCH) with the Hinode Extreme-ultraviolet (EUV) Imaging
Spectrometer (EIS) during an on-orbit partial solar eclipse. In this
partial eclipse, the Moon passed through the EIS observing area that
was set in the south PCH at the height of 0.9-1.4 solar radii. Using
the lunar occultation, we have corrected for the scattered light
contamination from bright regions of the Sun that is present in the
dark PCH emission line profiles. The nonthermal width of the corrected
emission line profile in the PCH increases from the limb toward the
high-altitude corona. It has also been confirmed that the nonthermal
width tends to decrease beyond ∼1.2 solar radii. These results
are consistent with the model in which outward-propagating Alfvén
waves start being dissipated at ∼1.2 solar radii, as previously
reported. The reduced energy within ∼1.4 solar radii contributes to
atmospheric heating and the initial acceleration for the solar wind
in the low corona. The remaining energy flux at 1.4 solar radii may
be dissipated in the distant corona and is sufficient to provide the
additional acceleration required to drive the fast solar wind.
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: 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: Structure and dynamics of the hot flaring loop-top source
observed by Hinode, SDO, RHESSI, and STEREO
Authors: Lee, Kyoung-Sun; Hara, Hirohisa; Watanabe, Kyoko; Joshi,
Anand D.; Imada, Shinsuke; Brooks, David H.; Dang, Phillip; Shimizu,
Toshifumi; Savage, Sabrina
Bibcode: 2019AAS...23421605L
Altcode:
We have investigated an M1.3 flare on 2014 January 13 around
21:48 UT observed at the west limb using the Hinode, SDO, RHESSI,
and STEREO. Especially, the Hinode/EIS scanned the flaring loop
covering the loop-top region over the limb, which is a good target to
investigate the dynamics of the flaring loop with their height. Using
the multi-wavelength observations from the Hinode/EIS and SDO/AIA,
we found a very hot emission above the loop-top observed in Fe XXIV
and 131Å channel. Measuring the intensity, Doppler velocity and line
width for the flaring loop, we found that hot emission observed at
the cusp-like shape of the loop-top region which shows strong redshift
about 500 km s-1 in Doppler velocity and strong enhancement
of the non-thermal velocity (line width enhancement) larger than 100
km s-1. Combining with the STEREO observation, we have
examined the 3D structure with loop tilt angle and have investigated
the velocity distribution of the loop-top region. With the loop tilt
angle, we could identify the strong redshift at the loop-top region
may indicate an up-flow along the loop-top region. From RHESSI hard
X-ray (HXR), and soft X-ray (SXR) emission, we found that the footpoint
brightening region at the beginning of the flare has a both HXR (25-50
keV) and SXR (12-25 keV) emission in which imply that the region has
non-thermal emission or accelerated particles. Then, within 10 minutes
the soft X-ray (SXR) emission observed near the cusp shape region at
loop top. The temporal variation of the HXR and SXR emissions and the
Doppler velocity variation of the hot plasma component at the loop-top
imply that the strong flow in a hot component near loop-top could be
the evaporation flows which detected at the corona along the tilted
loop. Moreover, The temporal evolution of the temperature observed
by SDO/AIA and Hinode/EIS also shows the cooling process of the flare
plasma which is consistent with the impulsively heated flare model.
Title: Comparison of Scattering Polarization Signals Observed by
CLASP: Possible Indication of the Hanle Effect
Authors: Ishikawa, R.; Trujillo Bueno, J.; Uitenbroek, H.; Kubo, M.;
Tsuneta, S.; Goto, M.; Kano, R.; Narukage, N.; Bando, T.; Katsukawa,
Y.; Ishikawa, S.; Giono, G.; Suematsu, Y.; Hara, H.; Shimizu, T.;
Sakao, T.; Winebarger, A.; Kobayashi, K.; Cirtain, J.; Champey, P.;
Auchère, F.; Štěpán, J.; Belluzzi, L.; Asensio Ramos, A.; Manso
Sainz, R.; De Pomtieu, B.; Ichimoto, K.; Carlsson, M.; Casini, R.
Bibcode: 2019ASPC..526..305I
Altcode:
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP; Kano et
al. 2012; Kobayashi et al. 2012; Kubo et al. 2014) observed, for the
first time, the linear polarization produced by scattering processes
in the hydrogen Lyman-α (121.57 nm) and Si III (120.56 nm) lines of
the solar disk radiation. The complexity of the observed scattering
polarization (i.e., conspicuous spatial variations in Q/I and U/I
at spatial scales of 10″-20″ and the absence of center-to- limb
variation at the Lyman-α center; see Kano et al. 2017) motivated us
to search for possible hints of the operation of the Hanle effect by
comparing: (a) the Lyman-α line center signal, for which the critical
field strength (BH) for the onset of the Hanle effect is
53 G, (b) the Lyman-α wing, which is insensitive to the Hanle effect,
and (c) the Si III line, whose BH = 290 G. We focus on four
regions with different total unsigned photospheric magnetic fluxes
(estimated from SDO/HMI observations), and compare the corresponding
U/I spatial variations in the Lyman-α wing, Lyman-α center, and Si III
line. The U/I signal in the Lyman-α wing shows an antisymmetric spatial
distribution, which is caused by the presence of a bright structure in
all the selected regions, regardless of the total unsigned photospheric
magnetic flux. In an internetwork region, the Lyman-α center shows an
antisymmetric spatial variation across the selected bright structure,
but it does not show it in other more magnetized regions. In the Si III
line, the spatial variation of U/I deviates from the above-mentioned
antisymmetric shape as the total unsigned photospheric magnetic flux
increases. We argue that a plausible explanation of this differential
behavior is the operation of the Hanle effect. This work, presented
in an oral contribution at this Workshop, has been published on The
Astrophysical Journal (Ishikawa et al. 2017).
Title: CLASP Constraints on the Magnetization and Geometrical
Complexity of the Chromosphere-Corona Transition Region
Authors: Trujillo Bueno, J.; Štěpán, J.; Belluzzi, L.; Asensio
Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Ishikawa,
R.; Kano, R.; Winebarger, A.; Auchère, F.; Narukage, N.; Kobayashi,
K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...866L..15T
Altcode: 2018arXiv180908865T
The Chromospheric Lyman-Alpha Spectro-Polarimeter (CLASP) is a
suborbital rocket experiment that on 2015 September 3 measured
the linear polarization produced by scattering processes in the
hydrogen Lyα line of the solar disk radiation. The line-center
photons of this spectral line radiation mostly stem from the
chromosphere-corona transition region (TR). These unprecedented
spectropolarimetric observations revealed an interesting surprise,
namely that there is practically no center-to-limb variation (CLV) in
the Q/I line-center signals. Using an analytical model, we first show
that the geometric complexity of the corrugated surface that delineates
the TR has a crucial impact on the CLV of the Q/I and U/I line-center
signals. Second, we introduce a statistical description of the solar
atmosphere based on a 3D model derived from a state-of-the-art radiation
magnetohydrodynamic simulation. Each realization of the statistical
ensemble is a 3D model characterized by a given degree of magnetization
and corrugation of the TR, and for each such realization we solve the
full 3D radiative transfer problem taking into account the impact
of the CLASP instrument degradation on the calculated polarization
signals. Finally, we apply the statistical inference method presented
in a previous paper to show that the TR of the 3D model that produces
the best agreement with the CLASP observations has a relatively weak
magnetic field and a relatively high degree of corrugation. We emphasize
that a suitable way to validate or refute numerical models of the upper
solar chromosphere is by confronting calculations and observations
of the scattering polarization in ultraviolet lines sensitive to the
Hanle effect.
Title: A Statistical Inference Method for Interpreting the CLASP
Observations
Authors: Štěpán, J.; Trujillo Bueno, J.; Belluzzi, L.; Asensio
Ramos, A.; Manso Sainz, R.; del Pino Alemán, T.; Casini, R.; Kano, R.;
Winebarger, A.; Auchère, F.; Ishikawa, R.; Narukage, N.; Kobayashi,
K.; Bando, T.; Katsukawa, Y.; Kubo, M.; Ishikawa, S.; Giono, G.; Hara,
H.; Suematsu, Y.; Shimizu, T.; Sakao, T.; Tsuneta, S.; Ichimoto, K.;
Cirtain, J.; Champey, P.; De Pontieu, B.; Carlsson, M.
Bibcode: 2018ApJ...865...48S
Altcode: 2018arXiv180802725S
On 2015 September 3, the Chromospheric Lyman-Alpha SpectroPolarimeter
(CLASP) successfully measured the linear polarization produced by
scattering processes in the hydrogen Lyα line of the solar disk
radiation, revealing conspicuous spatial variations in the Q/I and U/I
signals. Via the Hanle effect, the line-center Q/I and U/I amplitudes
encode information on the magnetic field of the chromosphere-corona
transition region, but they are also sensitive to the three-dimensional
structure of this corrugated interface region. With the help of a simple
line-formation model, here we propose a statistical inference method
for interpreting the Lyα line-center polarization observed by CLASP.
Title: 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: Probing the evolution of a coronal cavity within a solar
coronal mass ejection.
Authors: Harra, Louise K.; Doschek, G. A.; Hara, Hirohisa; Long,
David; Warren, Harry; Matthews, Sarah; Lee, Kyoung-Sun; Jenkins, Jack
Bibcode: 2018cosp...42E1381H
Altcode:
On the 10 September 2017, an X-class solar flare erupted at the solar
limb. The associated coronal mass ejection (CME) had the classic three
part structure with a bright core surrounded by a dark cavity. This
event was captured perfectly by the Hinode EUV imaging spectrometer
(EIS). The EIS instrument captured spectroscopically the flaring
loops, the current sheet and the cavity for the first time. In the
'standard flare model', magnetic reconnection of coronal loops occurs
following the eruption of a magnetic flux rope. The flux rope is a key
element of the flare process and eruption but is inherently difficult
to observe. Dark cavities observed within a CME are assumed to be
flux ropes. The observations we describe here, provide an insight
into the characteristics of a cavity, and how the rapid injection of
energy from the flare underneath forces the rapid expansion of the
flux rope resulting in the eruption. Doppler shifts of over 200 km/s
are measured at either end of the cavity. There is mixed temperature
plasma - cool material in the centre that also has strong flows, and
hot FeXXIV emission being observed. SDO Atmospheric Imaging Assembly
(AIA) data shows that the cavity erupts rapidly, and is being driven
by the non-thermal energy input from the flare below as measured from
Fermi data.
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: Optical alignment of the high-precision UV spectro-polarimeter
(CLASP2)
Authors: Song, Donguk; Ishikawa, Ryohko; Kano, Ryouhei; Yoshida,
Masaki; Tsuzuki, Toshihiro; Uraguchi, Fumihiro; Shinoda, Kazuya;
Hara, Hirohisa; Okamoto, Takenori J.; Auchère, Frédéric; McKenzie,
David E.; Rachmeler, Laurel A.; Trujillo Bueno, Javier
Bibcode: 2018SPIE10699E..2WS
Altcode:
Chromospheric LAyer Spectro-Polarimeter (CLASP2) is our next sounding
rocket experiment after the success of Chromospheric Lyman-Alpha
Spectro-Polarimeter (CLASP1). CLASP2 is scheduled to launch in 2019,
and aims to achieve high precision measurements (< 0.1 %) of the
linear and circular polarizations in the Mg ii h and k lines near the
280 nm, whose line cores originate in the upper solar chromosphere. The
CLASP2 spectro-polarimeter follows very successful design concept of
the CLASP1 instrument with the minimal modification. A new grating was
fabricated with the same radius of curvature as the CLASP1 grating, but
with a different ruling density. This allows us to essentially reuse
the CLASP1 mechanical structures and layout of the optics. However,
because the observing wavelength of CLASP2 is twice longer than that
of CLASP1, a magnifier optical system was newly added in front of the
cameras to double the focal length of CLASP2 and to maintain the same
wavelength resolution as CLASP1 (0.01 nm). Meanwhile, a careful optical
alignment of the spectro-polarimeter is required to reach the 0.01 nm
wavelength resolution. Therefore, we established an efficient alignment
procedure for the CLASP2 spectro-polarimeter based on an experience
of CLASP1. Here, we explain in detail the methods for achieving the
optical alignment of the CLASP2 spectro-polarimeter and discuss our
results by comparing with the performance requirements.
Title: Plasma Evolution within an Erupting Coronal Cavity
Authors: Long, David M.; Harra, Louise K.; Matthews, Sarah A.; Warren,
Harry P.; Lee, Kyoung-Sun; Doschek, George A.; Hara, Hirohisa; Jenkins,
Jack M.
Bibcode: 2018ApJ...855...74L
Altcode: 2018arXiv180201391L
Coronal cavities have previously been observed to be associated
with long-lived quiescent filaments and are thought to correspond
to the associated magnetic flux rope. Although the standard flare
model predicts a coronal cavity corresponding to the erupting flux
rope, these have only been observed using broadband imaging data,
restricting an analysis to the plane-of-sky. We present a unique set of
spectroscopic observations of an active region filament seen erupting
at the solar limb in the extreme ultraviolet. The cavity erupted and
expanded rapidly, with the change in rise phase contemporaneous with an
increase in nonthermal electron energy flux of the associated flare. Hot
and cool filamentary material was observed to rise with the erupting
flux rope, disappearing suddenly as the cavity appeared. Although
strongly blueshifted plasma continued to be observed flowing from
the apex of the erupting flux rope, this outflow soon ceased. These
results indicate that the sudden injection of energy from the flare
beneath forced the rapid eruption and expansion of the flux rope,
driving strong plasma flows, which resulted in the eruption of an
under-dense filamentary flux rope.
Title: Photospheric and Coronal Abundances in an X8.3 Class Limb Flare
Authors: Doschek, G. A.; Warren, H. P.; Harra, L. K.; Culhane, J. L.;
Watanabe, T.; Hara, H.
Bibcode: 2018ApJ...853..178D
Altcode:
We analyze solar elemental abundances in coronal post-flare
loops of an X8.3 flare (SOL2017-09-10T16:06) observed on the west
limb on 2017 September 10 near 18 UT using spectra recorded by
the Extreme-ultraviolet Imaging Spectrometer (EIS) on the Hinode
spacecraft. The abundances in the corona can differ from photospheric
abundances due to the first ionization potential (FIP) effect. In
some loops of this flare, we find that the abundances appear to be
coronal at the loop apices or cusps, but steadily transform from
coronal to photospheric as the loop footpoint is approached. This
result is found from the intensity ratio of a low-FIP ion spectral
line (Ca XIV) to a high-FIP ion spectral line (Ar XIV) formed at
about the same temperature (4-5 MK). Both lines are observed close in
wavelength. Temperature, which could alter the interpretation, does
not appear to be a factor based on intensity ratios of Ca XV lines
to a Ca XIV line. We discuss the abundance result in terms of the
Laming model of the FIP effect, which is explained by the action of
the ponderomotive force in magnetohydrodynamic (MHD) waves in coronal
loops and in the underlying chromosphere.
Title: Coronal Heating: Issues Revealed from Hinode Observations
Authors: Hara, Hirohisa
Bibcode: 2018ASSL..449...65H
Altcode:
No abstract at ADS
Title: From Hinode to the Next-Generation Solar Observation Missions
Authors: Ichimoto, Kiyoshi; Hara, Hirohisa; Katsukawa, Yukio;
Ishikawa, Ryoko
Bibcode: 2018ASSL..449..231I
Altcode:
No abstract at ADS
Title: Resonant Electron Impact Excitation of 3d Levels in
Fe14+ and Fe15+
Authors: Tsuda, Takashi; Shimizu, Erina; Ali, Safdar; Sakaue, Hiroyuki
A.; Kato, Daiji; Murakami, Izumi; Hara, Hirohisa; Watanabe, Tetsuya;
Nakamura, Nobuyuki
Bibcode: 2017ApJ...851...82T
Altcode: 2017arXiv171003548T
We present laboratory spectra of the 3p-3d transitions in
Fe14+ and Fe15+ excited with a mono-energetic
electron beam. In the energy-dependent spectra obtained by
sweeping the electron energy, resonant excitation is confirmed
as an intensity enhancement at specific electron energies. The
experimental results are compared with theoretical cross sections
calculated based on fully relativistic wave functions and the
distorted wave approximation. Comparisons between the experimental
and theoretical results show good agreement for the resonance
strength. A significant discrepancy is, however, found for the
non-resonant cross section in Fe14+. This discrepancy is
considered to be the fundamental cause of the previously reported
inconsistency of the model with the observed intensity ratio between
the {}3{P}2{--}{}3{D}3
and {}1{P}1{--}{}1{D}2
transitions.
Title: SOLARIS: Solar Sail Investigation of the Sun
Authors: Appourchaux, Thierry; Auchère, Frédéric; Antonucci, Ester;
Gizon, Laurent; MacDonald, Malcolm; Hara, Hirohisa; Sekii, Takashi;
Moses, Daniel; Vourlidas, Angelos
Bibcode: 2017arXiv170708193A
Altcode:
In this paper, we detail the scientific objectives and outline
a strawman payload of the SOLAR sail Investigation of the Sun
(SOLARIS). The science objectives are to study the 3D structure
of the solar magnetic and velocity field, the variation of total
solar irradiance with latitude, and the structure of the corona. We
show how we can meet these science objective using solar-sail
technologies currently under development. We provide a tentative
mission profile considering several trade-off approaches. We also
provide a tentative mass budget breakdown and a perspective for a
programmatic implementation.
Title: Measuring Velocities in the Early Stage of an Eruption:
Using “Overlappogram” Data from Hinode EIS
Authors: Harra, Louise K.; Hara, Hirohisa; Doschek, George A.;
Matthews, Sarah; Warren, Harry; Culhane, J. Leonard; Woods, Magnus M.
Bibcode: 2017ApJ...842...58H
Altcode:
In order to understand the onset phase of a solar eruption, plasma
parameter measurements in the early phases are key to constraining
models. There are two current instrument types that allow us to make
such measurements: narrow-band imagers and spectrometers. In the
former case, even narrow-band filters contain multiple emission lines,
creating some temperature confusion. With imagers, however, rapid
cadences are achievable and the field of view can be large. Velocities
of the erupting structures can be measured by feature tracking. In the
spectrometer case, slit spectrometers can provide spectrally pure images
by “rastering” the slit to build up an image. This method provides
limited temporal resolution, but the plasma parameters can be accurately
measured, including velocities along the line of sight. Both methods
have benefits and are often used in tandem. In this paper we demonstrate
for the first time that data from the wide slot on the Hinode EUV
Imaging Spectrometer, along with imaging data from AIA, can be used to
deconvolve velocity information at the start of an eruption, providing
line-of-sight velocities across an extended field of view. Using He
II 256 Å slot data at flare onset, we observe broadening or shift(s)
of the emission line of up to ±280 km s-1. These are seen at
different locations—the redshifted plasma is seen where the hard X-ray
source is later seen (energy deposition site). In addition, blueshifted
plasma shows the very early onset of the fast rise of the filament.
Title: Neon-like Iron Ion Lines Measured in NIFS/Large Helical Device
(LHD) and Hinode/EUV Imaging Spectrometer (EIS)
Authors: Watanabe, Tetsuya; Hara, Hirohisa; Murakami, Izumi; Kato,
Daiji; Sakaue, Hiroyuki A.; Morita, Shigeru; Suzuki, Chihiro; Tamura,
Naoki; Yamamoto, Norimasa; Nakamura, Nobuyuki
Bibcode: 2017ApJ...842...12W
Altcode:
Line intensities emerging from the Ne-sequence iron ion (Fe XVII) are
measured in the laboratory, by the Large Helical Device at the National
Institute for Fusion Science, and in the solar corona by the EUV Imaging
Spectrometer (EIS) on board the Hinode mission. The intensity ratios of
Fe XVII λ 204.6/λ 254.8 are derived in the laboratory by unblending
the contributions of the Fe XIII and XII line intensities. They are
consistent with theoretical predictions and solar observations, the
latter of which endorses the in-flight radiometric calibrations of the
EIS instrument. The still remaining temperature-dependent behavior of
the line ratio suggests the contamination of lower-temperature iron
lines that are blended with the λ 204.6 line.
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: Measurements of density dependent intensity ratios of extreme
ultraviolet line emission from Fe X, XI, and XII
Authors: Shimizu, Erina; Ali, Safdar; Tsuda, Takashi; Sakaue, Hiroyuki
A.; Kato, Daiji; Murakami, Izumi; Hara, Hirohisa; Watanabe, Tetsuya;
Nakamura, Nobuyuki
Bibcode: 2017A&A...601A.111S
Altcode:
We report high-resolution density dependent intensity ratio measurements
for middle charge states of iron in the extreme ultraviolet (EUV)
spectral wavelength range of 160-200 Å. The measurements were
performed at the Tokyo EBIT laboratory by employing a flat-field
grazing incidence spectrometer installed on a low energy compact
electron beam ion trap. The intensity ratios for several line pairs
stemming from Fe X, Fe XI and Fe XII were extracted from spectra
collected at the electron beam energies of 340 and 400 eV by varying
the beam current between 7.5 and 12 mA at each energy. In addition,
the effective electron densities were obtained experimentally by imaging
the electron beam profile and ion cloud size with a pinhole camera and
visible spectrometer, respectively. In this paper, the experimental
results are compared with previous data from the literature and with the
present calculations performed using a collisional-radiative model. Our
experimental results show a rather good agreement with the calculations
and previous reported results.
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: UV/EUV High-Throughput Spectroscopic Telescope: A Next
Generation Solar Physics Mission white paper
Authors: Imada, S.; Shimizu, T.; Kawate, T.; Hara, H.; Watanabe, T.
Bibcode: 2017arXiv170104972I
Altcode:
The origin of the activity in the solar corona is a long-standing
problem in solar physics. Recent satellite observations, such as Hinode,
Solar Dynamics Observatory (SDO), Interface Region Imaging Spectrograph
(IRIS), show the detail characteristics of the solar atmosphere and
try to reveal the energy transfer from the photosphere to the corona
through the magnetic fields and its energy conversion by various
processes. However, quantitative estimation of energy transfer along
the magnetic field is not enough. There are mainly two reason why it is
difficult to observe the energy transfer from photosphere to corona; 1)
spatial resolution gap between photosphere (a few 0.1 arcsec) and corona
(a few arcsec), 2) lack in temperature coverage. Furthermore, there
is not enough observational knowledge of the physical parameters in
the energy dissipation region. There are mainly three reason why it is
difficult to observe in the vicinity of the energy dissipation region;
1) small spatial scale, 2) short time scale, 3) low emission. It is
generally believed that the energy dissipation occurs in the very small
scale and its duration is very short (10 second). Further, the density
in the dissipation region might be very low. Therefore, the high spatial
and temporal resolution UV/EUV spectroscopic observation with wide
temperature coverage is crucial to estimate the energy transport from
photosphere to corona quantitatively and diagnose the plasma dynamics
in the vicinity of the energy dissipation region. Main Science Target
for the telescope is quantitative estimation for the energy transfer
from the photosphere to the corona, and clarification of the plasma
dynamics in the vicinity of the energy dissipation region, where is the
key region for coronal heating, solar wind acceleration, and/or solar
flare, by the high spatial and temporal resolution UV/EUV spectroscopy.
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: The Characteristics of Solar X-Class Flares and CMEs: A
Paradigm for Stellar Superflares and Eruptions?
Authors: Harra, Louise K.; Schrijver, Carolus J.; Janvier, Miho;
Toriumi, Shin; Hudson, Hugh; Matthews, Sarah; Woods, Magnus M.; Hara,
Hirohisa; Guedel, Manuel; Kowalski, Adam; Osten, Rachel; Kusano,
Kanya; Lueftinger, Theresa
Bibcode: 2016SoPh..291.1761H
Altcode: 2016SoPh..tmp..111H
This paper explores the characteristics of 42 solar X-class flares that
were observed between February 2011 and November 2014, with data from
the Solar Dynamics Observatory (SDO) and other sources. This flare
list includes nine X-class flares that had no associated CMEs. In
particular our aim was to determine whether a clear signature could
be identified to differentiate powerful flares that have coronal
mass ejections (CMEs) from those that do not. Part of the motivation
for this study is the characterization of the solar paradigm for
flare/CME occurrence as a possible guide to the stellar observations;
hence we emphasize spectroscopic signatures. To do this we ask the
following questions: Do all eruptive flares have long durations? Do
CME-related flares stand out in terms of active-region size vs. flare
duration? Do flare magnitudes correlate with sunspot areas, and, if so,
are eruptive events distinguished? Is the occurrence of CMEs related to
the fraction of the active-region area involved? Do X-class flares with
no eruptions have weaker non-thermal signatures? Is the temperature
dependence of evaporation different in eruptive and non-eruptive
flares? Is EUV dimming only seen in eruptive flares? We find only one
feature consistently associated with CME-related flares specifically:
coronal dimming in lines characteristic of the quiet-Sun corona,
i.e. 1 - 2 MK. We do not find a correlation between flare magnitude
and sunspot areas. Although challenging, it will be of importance to
model dimming for stellar cases and make suitable future plans for
observations in the appropriate wavelength range in order to identify
stellar CMEs consistently.
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: 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: MAVEN observations of the Cycle 24 solar wind conditions at
1.5 AU
Authors: Lee, Christina O.; Halekas, J.; Espley, J.; Thiemann, E.;
Luhmann, J. G.; Hara; Lillis, R. J.; Larson, D.; Eparvier, F.; Jakosky,
B. M.
Bibcode: 2016shin.confE.177L
Altcode:
The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft went
into orbit around Mars on 21 September 2014. The mission was designed
in part to study the response of the upper atmosphere, ionosphere,
and magnetosphere of Mars to solar and solar wind inputs. When MAVEN
is on the Martian dayside and orbiting around its apoapsis altitude
of 6200 km, the suite of instruments onboard can measure the upstream
solar wind plasma (density, velocity), interplanetary magnetic field
(magnitude and direction) and particle counts of SEP protons and
electrons, as well as the EUV solar irradiance. Given the suite of
plasma, particles, and field instruments onboard MAVEN, these 1.5 AU
observations provide a unique and comprehensive data set that may be
used to study the heliospheric conditions beyond the orbits of Earth
and STEREO. Such studies may include understanding the dynamics and
evolution of ICMEs and CIRs from the Sun out to 1.5 AU, or comparing
the space weather effects observed at 1 AU and 1.5 AU for a given
solar-heliospheric event period. We will present an overview of the
space weather conditions observed thus far by MAVEN and highlight a
number of space weather events at Mars triggered by CMEs, SEPs, flares,
and CIRs of cycle 24. Numerical 3D simulations from WSA-Enlil-cone as
well as observations from SOHO/LASCO, SDO/AIA, STEREO, and ACE will
also be presented to provide global context to the events discussed.
Title: Recent progress of SPAN towards neutrino mass spectroscopy
Authors: Masuda, T.; Hara, H.; Miyamoto, Y.; Sasao, N.; Tanaka, M.;
Uetake, S.; Yoshimi, A.; Yoshimura, K.; Yoshimura, M.
Bibcode: 2016JPhCS.718f2043M
Altcode:
SPAN (Spectroscopy of Atomic Neutrino) project aims to determine the
absolute neutrino mass. The process we plan to use is a cooperative
de-excitation of atoms in a metastable level emitting a neutrino pair
associated with a photon. The photon energy spectrum of this process
contains information on the absolute mass of neutrino. Key items of this
experiment are a rate amplification using macro-coherence in a target
medium in case of plural particles emission and an external triggering
of the emission in order to scan the spectrum. We have demonstrated the
rate amplification in two-photon emission from para-hydrogen gas which
was coherently excited to its first vibrationally excited state. The
coherence in the medium was generated by irradiating two driving laser
pulses. The emission was stimulated by irradiating a mid-infrared
laser pulse. The enhancement factor of more than 1018 with
respect to the spontaneous emission was achieved. This paper briefly
summarizes the results.
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: Doppler Shift of the Quiet Region Measured by Meridional
Scans with the EUV Imaging Spectrometer on board Hinode
Authors: Kitagawa, N.; Hara, H.; Yokoyama, T.
Bibcode: 2016ApJ...816...14K
Altcode: 2015arXiv151105213K
Spatially averaged (> 50") EUV spectral lines in the transition
region of solar quiet regions are known to be redshifted. Because
the mechanism underlying this phenomenon is unclear, we require
additional physical information on the lower corona in order to
limit the theoretical models. To acquire this information, we
measured the Doppler shifts over a wide coronal temperature range
({log}T[{{K}}]=5.7-6.3) using the spectroscopic data taken by the Hinode
EUV Imaging Spectrometer. By analyzing the data over the center-to-limb
variations covering the meridian from the south to the north pole,
we successfully measured the velocity to an accuracy of 3 {{km}}
{{{s}}}-1. Below {log}T [{{K}}]=6.0, the Doppler shifts
of the emission lines were almost zero with an error of 1-3 {{km}}
{{{s}}}-1; above this temperature, they were blueshifted
with a gradually increasing magnitude, reaching -6.3+/- 2.1 {{km}}
{{{s}}}-1 at {log}T [{{K}}]=6.25.
Title: A Study of the Coronal Non-thermal Velocity in Polar Regions
During the Rise from Solar Minimum to Solar Maximum in Cycle 24
Authors: Harra, L.; Baker, D.; Edwards, S. J.; Hara, H.; Howe, R.;
van Driel-Gesztelyi, L.
Bibcode: 2015SoPh..290.3203H
Altcode: 2015SoPh..tmp....8H
We explore the changes in coronal non-thermal velocity (Vnt)
measurements at the poles from solar minimum to solar maximum using
Hinode EUV Imaging Spectrometer data. We find that although the
intensity in the corona at the poles does tend to increase with
the cycle, there are no significant changes in the Vnt
values. The locations of enhanced Vnt values measured do not
always have a counterpart in intensity, and they are sometimes located
in weak emission regions. Unipolar magnetic streams, created through
diffusion of the following polarity of the decaying active regions,
slowly progress towards the poles. These streams are expected to
be related to magnetic nulls as locations that indicate an increased
likelihood for magnetic reconnection to occur. Through global potential
field source-surface modelling, we determine how the number of nulls
varied during the cycle and find that those that lie at < 1.1
solar radii vary significantly. We search for a correlation between
the variation of the magnetic nulls and the Vnt values,
as it may be expected that with an increasing number of nulls, the
Vnt values in the corona increase as well. There is no
correlation with the Vnt values, however. This indicates
that the magnetic structures that create the enhanced Vnt
behaviour are small-scale features and hence not easily measurable at
the poles. Because they do not change during the solar cycle, they are
likely to be created by a local dynamo. The variation of the upper
range of Vnt is reduced, which highlights that strongly
dynamic behaviour is reduced as the solar maximum approaches. This
is likely to be due to the reduced area of the polar coronal hole,
which allows fewer opportunities for reconnection to occur between
open and closed magnetic fields.
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: 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 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: New developments in rotating and linear motion mechanisms
used in contamination sensitive space telescopes
Authors: Shimizu, Toshifumi; Watanabe, Kyoko; Nakayama, Satoshi;
Tajima, Takao; Obara, Shingo; Imada, Shinsuke; Nishizuka, Naoto;
Ishikawa, Shin-nosuke; Hara, Hirohisa
Bibcode: 2014SPIE.9151E..38S
Altcode:
We have been developing a rotating mechanism and a linear motion
mechanism for their usage in contamination sensitive space
telescopes. They both are needed for ~1.4 meter optical telescope
and its focal plane instrument onboard SOLAR-C, the next-generation
spaceborne solar observatory following Hinode. Highly reliable long life
performance, low outgassing properties, and low level of micro-vibration
are required along with their scientific performance. With the
proto-type mechanisms, the long life performance and outgassing
properties of the mechanisms have been evaluated in vacuum chambers. The
level of micro-vibration excited during the operations of the rotating
mechanism was measured by operating it on the Kestler table. This
paper provides the overall descriptions of our mechanism developments.
Title: RHESSI and EIS observations of an above-the-looptop
reconnection region
Authors: Glesener, Lindsay; Hara, Hirohisa; Krucker, Sam
Bibcode: 2014AAS...22410406G
Altcode:
A variety of solar flare observations suggest particle acceleration in
the corona, at or above the flare looptop. Hard X-ray (HXR) studies,
for example, occasionally reveal accelerated electrons above flare
looptops, in some cases suggesting the location of the acceleration
region. However, since coronal HXR sources are faint and the structure
of the flare as seen in extreme ultraviolet (EUV) images is complicated,
it is difficult to say where these sources lie with respect to,
for example, the reconnection region.HXR and EUV observations can
provide complementary information for investigating this topic. EUV
imaging spectroscopy reveals bulk flows and locations of line-broadened
(potentially turbulent) sources. Such observations can, for example,
identify outflows from the reconnection region. HXR imaging places
the flare-accelerated electrons in the context of the overall flare
geometry, allowing comparison of the locations of accelerated electrons,
the reconnection region, and the flare loop.In this work, data from
RHESSI and Hinode/EIS are used to investigate above-the-looptop sources
in the 2013 May 15 X-class flare. Above-the-looptop EIS flows and
loop-top line-broadening are compared with RHESSI HXR sources in the
preimpulsive phase of the flare.
Title: The SOLAR-C Mission
Authors: Hara, Hirohisa
Bibcode: 2014cosp...40E1153H
Altcode:
The SOLAR-C is a planned satellite mission that is led by the JAXA
SOLAR-C working group as the 4th Japanese space solar observatory
that follows the 3rd satellite mission, Hinode. Hinode equips three
major science payloads to cover from the photosphere to the corona
simultaneously and has revealed the ubiquitous emergence/submergence
of small-scale bipolar fields and the formation of kilo Gauss magnetic
flux tubes from vector magnetic field measurements on the photosphere,
unexpected dynamical phenomena in the chromosphere, spectral signatures
of small-scale coronal heating events near the chromosphere below its
spatial resolution, and so forth. These are the universal magnetized
plasma activity in the nearest star, and the essential energy source
of the phenomena is of magnetic-field origin coupled with photospheric
convective motion. To elucidate the newly-found solar active phenomena
and the problems that have been tackled for a long time in solar
physics, we try to understand the causal linkage between solar
magnetic fields and active phenomena on the Sun in the true sense
by high-resolution (0.1-0.3 arcsecs) instruments in space. SOLAR-C
will observe photospheric and chromospheric activity by imaging
and measure chromospheric magnetic fields by spectropolarimetry,
in addition to photospheric magnetic fields. It visualizes the site
of dynamical events for chromospheric and coronal heating by imaging
and spectroscopy with comparable resolution and by high-resolution
chromospheric magnetometry. In addition, SOLAR-C essentially contributes
to space weather by estimating the stored magnetic energy in the
corona via measurements of chromospheric magnetic fields. The coming
sounding-rocket program CLASP and the further satellite mission SOLAR-D
that may follow the SOLAR-C mission are also briefly mentioned.
Title: Velocity structure of solar flare plasmas
Authors: Watanabe, Tetsuya; Watanabe, Kyoko; Hara, Hirohisa; Imada,
Shinsuke
Bibcode: 2014cosp...40E3606W
Altcode:
Thanks to its increased sensitivity and spectral resolution, EIS
enabled emission line profile analysis for the first time in solar
EUV spectroscopy, and it found detailed structures in velocity and
temperature in solar flares. A widely accepted model for solar flares
incorporates magnetic reconnection in the corona which results
in local heating as well as acceleration of nonthermal particle
beams. The standard model of solar flares is called the CSHKP model,
arranging the initials of model proposers. We find loop-top hot source,
fast outflows nearby, inflow structure flowing to the hot source that
appeared in the impulsive phase of long-duration eruptive flares. From
the geometrical relationships of these phenomena, we conclude that
they provide evidence for magnetic reconnection that occurs near the
loop-top region. The reconnection rate is estimated to 0.05 - 0.1,
which supports the Petschek-type magnetic reconnection. The nonthermal
particle beams will travel unimpeded until they reach the cold, dense
chromosphere, where the energy of the beam is predominantly used to
heat the chromosphere at the foot points of flaring loops. Explosive
chromospheric evaporation happens when the beam energy is high enough
that the chromosphere cannot radiate away energy fast enough and
hence expands at high velocities into the corona. Spatially resolved
observations of chromopheric evaporation during the initial phases of
impulsive flares, a few bright points of Fexxiii and Fexxiv emission
lines at the footpoints of flaring loops present dominated blue-shifted
components of 300 - 400 kms (-1) , while Fexv/xvi lines are nearly
stationary, and Feviii and Sivii lines present +50 kms (-1) red
shifts. We will review these new views on dynamical structure in flares.
Title: Spectroscopy of Reconnection Inflow and Outflow in Solar Flares
Authors: Hara, Hirohisa
Bibcode: 2014cosp...40E1154H
Altcode:
We report reconnection inflow and outflow structures in a type of solar
flares that were observed by spectroscopic observations with the Hinode
EUV Imaging Spectrometer. A dark outflow has been found by EIS raster
scan observations in hot emission lines like Fe XXIII and Fe XXIV as a
structure extended from a site above a bright flare loop. The outflow
structure is heated to ~10 MK, and the electron density of the outflow
is enhanced by about a factor of 2 from the surrounding corona. The
hot emission lines in the outflow structure show a large excess width,
which may imply the presence of an internal flow structure or the plasma
in a turbulent state. A high-density blob structure that appears above
the loop-top region where the reconnection outflow collides shows the
Doppler motion toward the low-altitude direction. The reconnection
rate is estimated to be 0.01-0.1 in combination with the signature of
reconnection inflow from the Doppler velocity measurement.
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: Hot Plasma Associated with a Coronal Mass Ejection
Authors: Landi, E.; Miralles, M. P.; Raymond, J. C.; Hara, H.
Bibcode: 2013ApJ...778...29L
Altcode:
We analyze coordinated observations from the EUV Imaging Spectrometer
(EIS) and X-Ray Telescope (XRT) on board Hinode of an X-ray Plasma
Ejection (XPE) that occurred during the coronal mass ejection (CME)
event of 2008 April 9. The XPE was trailing the CME core from behind,
following the same trajectory, and could be identified both in EIS
and XRT observations. Using the EIS spectrometer, we have determined
the XPE plasma parameters, measuring the electron density, thermal
distribution, and elemental composition. We have found that the XPE
composition and electron density were very similar to those of the
pre-event active region plasma. The XPE temperature was higher, and its
thermal distribution peaked at around 3 MK also, typical flare lines
were absent from EIS spectra, indicating that any XPE component with
temperatures in excess of 5 MK was likely either faint or absent. We
used XRT data to investigate the presence of hotter plasma components
in the XPE that could have gone undetected by EIS and found that—if
at all present—these components have small emission measure values
and their temperature is in the 8-12.5 MK range. The very hot plasma
found in earlier XPE observations obtained by Yohkoh seems to be
largely absent in this CME, although plasma ionization timescales
may lead to non-equilibrium ionization effects that could make bright
lines from ions formed in a 10 MK plasma not detectable by EIS. Our
results supersede the XPE findings of Landi et al., who studied the
same event with older response functions for the XRT Al-poly filter;
the differences in the results stress the importance of using accurate
filter response functions.
Title: Evidence for Hot Fast Flow above a Solar Flare Arcade
Authors: Imada, S.; Aoki, K.; Hara, H.; Watanabe, T.; Harra, L. K.;
Shimizu, T.
Bibcode: 2013ApJ...776L..11I
Altcode: 2013arXiv1309.3401I
Solar flares are one of the main forces behind space weather
events. However, the mechanism that drives such energetic phenomena is
not fully understood. The standard eruptive flare model predicts that
magnetic reconnection occurs high in the corona where hot fast flows are
created. Some imaging or spectroscopic observations have indicated the
presence of these hot fast flows, but there have been no spectroscopic
scanning observations to date to measure the two-dimensional structure
quantitatively. We analyzed a flare that occurred on the west solar
limb on 2012 January 27 observed by the Hinode EUV Imaging Spectrometer
(EIS) and found that the hot (~30MK) fast (>500 km s-1)
component was located above the flare loop. This is consistent with
magnetic reconnection taking place above the flare loop.
Title: The Location of Non-thermal Velocity in the Early Phases of
Large Flares—Revealing Pre-eruption Flux Ropes
Authors: Harra, Louise K.; Matthews, Sarah; Culhane, J. L.; Cheung,
Mark C. M.; Kontar, Eduard P.; Hara, Hirohisa
Bibcode: 2013ApJ...774..122H
Altcode:
Non-thermal velocity measurements of the solar atmosphere, particularly
from UV and X-ray emission lines have demonstrated over the decades
that this parameter is important in understanding the triggering of
solar flares. Enhancements have often been observed before intensity
enhancements are seen. However, until the launch of Hinode, it has
been difficult to determine the spatial location of the enhancements to
better understand the source region. The Hinode EUV Imaging Spectrometer
has the spectral and spatial resolution to allow us to probe the early
stages of flares in detail. We analyze four events, all of which
are GOES M- or X-classification flares, and all are located toward
the limb for ease of flare geometry interpretation. Three of the
flares were eruptive and one was confined. In all events, pre-flare
enhancement in non-thermal velocity at the base of the active region
and its surroundings has been found. These enhancements seem to be
consistent with the footpoints of the dimming regions, and hence may
be highlighting the activation of a coronal flux rope for the three
eruptive events. In addition, pre-flare enhancements in non-thermal
velocity were found above the looptops for the three eruptive events.
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: Properties of a Solar Flare Kernel Observed by Hinode and SDO
Authors: Young, P. R.; Doschek, G. A.; Warren, H. P.; Hara, H.
Bibcode: 2013ApJ...766..127Y
Altcode: 2012arXiv1212.4388Y
Flare kernels are compact features located in the solar chromosphere
that are the sites of rapid heating and plasma upflow during the rise
phase of flares. An example is presented from a M1.1 class flare in
active region AR 11158 observed on 2011 February 16 07:44 UT for which
the location of the upflow region seen by EUV Imaging Spectrometer (EIS)
can be precisely aligned to high spatial resolution images obtained by
the Atmospheric Imaging Assembly (AIA) and Helioseismic and Magnetic
Imager (HMI) on board the Solar Dynamics Observatory (SDO). A string
of bright flare kernels is found to be aligned with a ridge of strong
magnetic field, and one kernel site is highlighted for which an upflow
speed of ≈400 km s-1 is measured in lines formed at 10-30
MK. The line-of-sight magnetic field strength at this location is
≈1000 G. Emission over a continuous range of temperatures down to
the chromosphere is found, and the kernels have a similar morphology
at all temperatures and are spatially coincident with sizes at the
resolution limit of the AIA instrument (lsim400 km). For temperatures
of 0.3-3.0 MK the EIS emission lines show multiple velocity components,
with the dominant component becoming more blueshifted with temperature
from a redshift of 35 km s-1 at 0.3 MK to a blueshift of
60 km s-1 at 3.0 MK. Emission lines from 1.5-3.0 MK show a
weak redshifted component at around 60-70 km s-1 implying
multi-directional flows at the kernel site. Significant non-thermal
broadening corresponding to velocities of ≈120 km s-1 is
found at 10-30 MK, and the electron density in the kernel, measured
at 2 MK, is 3.4 × 1010 cm-3. Finally, the Fe
XXIV λ192.03/λ255.11 ratio suggests that the EIS calibration has
changed since launch, with the long wavelength channel less sensitive
than the short wavelength channel by around a factor two.
Title: SDO and Hinode observations of coronal heating at a flare
kernel site
Authors: Young, P. R.; Doschek, G. A.; Warren, H. P.; Hara, H.
Bibcode: 2013enss.confE..36Y
Altcode:
Flare kernels are compact features located in the chromosphere that
are the sites of rapid heating and plasma upflow during the rise phase
of flares. They provide an excellent opportunity for testing models of
energy transport and dissipation in the solar atmosphere as they are
very bright and emit over a wide temperature range. A M1.1 class flare
that peaked at 07:44 UT on 2011 February 16 was observed simultaneously
by SDO and Hinode, and one flare kernel observed prior to the flare
peak is highlighted. It is found to emit at all temperatures from
the chromosphere through to 30 MK, with all AIA channels brightening
simultaneously and rise times of only 1 minute. The kernel is located on
a ridge of strong magnetic field close to a neutral line in the active
region. The kernel is at the resolution limit of AIA, suggesting a size
of < 0.6 arcsec. Hinode/EIS allows velocity patterns in the kernel
to be tracked over a wide temperature range and reveals a dominant high
speed upflow of 400 km/s at temperatures of 10-30 MK, with both down
and upflows measured at cooler temperatures of 1.5-3.0 MK, suggesting
unresolved structures. All emission lines show evidence of significant
non-thermal broadening, and the electron density of the plasma is 3.4
x 10^10 cm-3. The observations are compared to models of chromospheric
evaporation and similarities and differences are highlighted.
Title: Observations from SDO, Hinode, and STEREO of a Twisting and
Writhing Start to a Solar-filament-eruption Cascade
Authors: Sterling, Alphonse C.; Moore, Ronald L.; Hara, Hirohisa
Bibcode: 2012ApJ...761...69S
Altcode:
We analyze data from SDO (AIA, HMI), Hinode (SOT, XRT, EIS), and STEREO
(EUVI) of a solar eruption sequence of 2011 June 1 near 16:00 UT,
with an emphasis on the early evolution toward eruption. Ultimately,
the sequence consisted of three emission bursts and two filament
ejections. SDO/AIA 304 Å images show absorbing-material strands
initially in close proximity which over ~20 minutes form a
twisted structure, presumably a flux rope with ~1029
erg of free energy that triggers the resulting evolution. A jump
in the filament/flux rope's displacement (average velocity ~20 km
s-1) and the first burst of emission accompanies the
flux-rope formation. After ~20 more minutes, the flux rope/filament
kinks and writhes, followed by a semi-steady state where the flux
rope/filament rises at (~5 km s-1) for ~10 minutes. Then
the writhed flux rope/filament again becomes MHD unstable and violently
erupts, along with rapid (50 km s-1) ejection of the filament
and the second burst of emission. That ejection removed a field that
had been restraining a second filament, which subsequently erupts as
the second filament ejection accompanied by the third (final) burst of
emission. Magnetograms from SDO/HMI and Hinode/SOT, and other data,
reveal several possible causes for initiating the flux-rope-building
reconnection, but we are not able to say which is dominant. Our
observations are consistent with magnetic reconnection initiating the
first burst and the flux-rope formation, with MHD processes initiating
the further dynamics. Both filament ejections are consistent with the
standard model for solar eruptions.
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: Production of High-Temperature Plasmas During the Early Phases
of a C9.7 Flare. II. Bi-directional Flows Suggestive of Reconnection
in a Pre-flare Brightening Region
Authors: Watanabe, T.; Hara, H.; Sterling, A. C.; Harra, L. K.
Bibcode: 2012SoPh..281...87W
Altcode: 2012SoPh..tmp..185W
The 6 June 2007 16:55 UT flare was well observed with high time-cadence
sparse raster scans by the EUV Imaging Spectrometer (EIS) on board
the Hinode spacecraft. The observation covers an active region area
of 240 arcsec × 240 arcsec with the 1 arcsec slit in about 160 seconds.
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: Flare Onset Observed with Hinode in the 2006 December 13 Flare
Authors: Asai, A.; Hara, H.; Watanabe, T.; Imada, S.
Bibcode: 2012ASPC..454..303A
Altcode:
We present a detailed examination of the preflare phenomena of
the X3.4 flare that occurred on 2006 December 13. This flare was
associated with a faint arc-shaped ejection, which is thought to be
an MHD fast-mode shock wave, seen in the soft X-ray images taken
with the Hinode X-Ray Telescope (XRT), just at the start of the
impulsive phase of the flare. Even before the ejection, we found many
preflare features, such as an S-shaped brightening (sigmoid) with XRT,
chromospheric brightening at the footpoints of the sigmoid loops with
the Solar Optical Telescope (SOT), a faint X-ray eruption with XRT,
and so on. The EUV Imaging Spectrometer (EIS) also observed the flare,
and therefore, enabled us to examine the spectroscopic features. We
discuss these phenomena and the energy release prosses.
Title: Propagating Slow Magnetoacoustic Waves along the Continuous
Outflows Observed with EIS/Hinode
Authors: Nishizuka, N.; Matsumoto, T.; Morita, S.; Hara, H.;
Shibata, K.
Bibcode: 2012ASPC..454..157N
Altcode:
The high temporal relation data obtained from EIS/Hinode has been
analyzed. In the ‘sit-and-stare’ mode observations, we focused
on continuous outflows at the edge of the active region NOAA 10942
on 2007 February 20. We found that the Doppler blueshift (∼20-50 km
s-1) components, in Fe XII 195 Å emission line, propagating
with the continuous plasma outflows from the edge of the active region,
with the transverse velocity ranging 140-160 km s-1. This
suggests slow magnetoacoustic wave propagation along the open field
line. We also found a jet around the active region, whose transverse
velocity ∼170 km s-1 and line-of-sight Doppler velocity
∼150 km s-1.
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: Post-Coronal Mass Ejection Plasma Observed by Hinode
Authors: Landi, E.; Raymond, J. C.; Miralles, M. P.; Hara, H.
Bibcode: 2012ApJ...751...21L
Altcode:
In the present work we study the evolution of an active region after
the eruption of a coronal mass ejection (CME) using observations from
the EIS and XRT instruments on board Hinode. The field of view includes
a post-eruption arcade, a current sheet, and a coronal dimming. The
goal of this paper is to provide a comprehensive set of measurements
for all these aspects of the CME phenomenon made on the same CME
event. The main physical properties of the plasma along the line of
sight—electron density, thermal structure, plasma composition, size,
and, when possible, mass—are measured and monitored with time for
the first three hours following the CME event of 2008 April 9. We find
that the loop arcade observed by EIS and XRT may not be related to the
post-eruption arcade. Post-CME plasma is hotter than the surrounding
corona, but its temperature never exceeds 3 MK. Both the electron
density and thermal structure do not show significant evolution with
time, while we found that the size of the loop arcade in the Hinode
plane of the sky decreased with time. The plasma composition is the same
in the current sheet, in the loop arcade, and in the ambient plasma,
so all these plasmas are likely of coronal origin. No significant
plasma flows were detected.
Title: Spectroscopic Observations of Continuous Outflows and
Propagating Waves in Active Region NOAA 10942 with Hinode/EIS
Authors: Nishizuka, N.; Hara, H.
Bibcode: 2012ASPC..455..219N
Altcode:
We analyze "sit-and-stare" mode observations of continuous outflows and
waves with the Extreme ultraviolet Imaging Spectrometer (EIS) on board
Hinode, whose slit was located along the open field lines at the edge of
active region NOAA 10942 on February 20, 2007. We found both intensity
and velocity disturbances in Fe xii 195.12 Å propagating along the
field lines with apparent speeds of 140 km s-1. The Doppler
shifts shows mean upward velocities of 30-50 km s-1 and
small velocity disturbances with amplitudes of 5-15 km s-1
in phase with intensity disturbances of 3-5% amplitude relative to
the mean intensity. Not only a quasi-periodicity of 10-13 minutes but
also “tad pole'' signatures—which may be evidence of propagating
waves—were observed at the footpoints of the loops. Covariation
of intensity and Doppler velocity is consistent with upward motion
of propagating slow-mode magnetoacoustic waves. The energy flux of
the waves was estimated to be 1-3× 105 erg s-1
cm-2, which is not enough to account for coronal heating but
sufficient for solar wind acceleration. High temporal spectroscopic
observation also revealed intermittent signatures of line broadening
at the footpoints of the loops. Each of them seems to correspond to
the footpoints of propagating disturbances. This may indicate that
the origins of flows and waves are unresolved explosive events at the
lower atmosphere, by analogy to spectroscopic observations of a jet.
Title: Photosphere-Corona Connection in Active-Region Plage
Authors: Hara, H.
Bibcode: 2012decs.confE..94H
Altcode:
We discuss the relationships between the temperature of coronal
loops and photospheric magnetic properties at their footpoints in
an active-region plage from observations by Hinode. The motion of
photospheric magnetic fields is tracked by the correlation tracking
of SOT FG Stokes-V maps to estimate the photospheric horizontal
velocity. We find that the horizontal velocity is anti-correlated
with the filling factor of photospheric magnetic fields estimated from
the SOT SP data. It is confirmed from high-resolution observations by
Hinode that the footpoints of hot (warm) coronal loops in X-ray (EUV)
observations are rooted at low (high) magnetic filing factor regions
within the plage. The distribution of energy flux to the corona in
the plage is calculated from observations according to a model in
Katsukawa & Tsuneta (2005). The distribution appears to explain
the footpoint position of hot and warm loops.
Title: One-dimensional Modeling for Temperature-dependent Upflow in
the Dimming Region Observed by Hinode/EUV Imaging Spectrometer
Authors: Imada, S.; Hara, H.; Watanabe, T.; Murakami, I.; Harra,
L. K.; Shimizu, T.; Zweibel, E. G.
Bibcode: 2011ApJ...743...57I
Altcode: 2011arXiv1108.5031I
We previously found a temperature-dependent upflow in the dimming region
following a coronal mass ejection observed by the Hinode EUV Imaging
Spectrometer (EIS). In this paper, we reanalyzed the observations along
with previous work on this event and provided boundary conditions for
modeling. We found that the intensity in the dimming region dramatically
drops within 30 minutes from the flare onset, and the dimming region
reaches the equilibrium stage after ~1 hr. The temperature-dependent
upflows were observed during the equilibrium stage by EIS. The
cross-sectional area of the flux tube in the dimming region does not
appear to expand significantly. From the observational constraints,
we reconstructed the temperature-dependent upflow by using a new method
that considers the mass and momentum conservation law and demonstrated
the height variation of plasma conditions in the dimming region. We
found that a super-radial expansion of the cross-sectional area is
required to satisfy the mass conservation and momentum equations. There
is a steep temperature and velocity gradient of around 7 Mm from
the solar surface. This result may suggest that the strong heating
occurred above 7 Mm from the solar surface in the dimming region. We
also showed that the ionization equilibrium assumption in the dimming
region is violated, especially in the higher temperature range.
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: Magnetic Reconnection in Non-equilibrium Ionization Plasma
Authors: Imada, S.; Murakami, I.; Watanabe, T.; Hara, H.; Shimizu, T.
Bibcode: 2011ApJ...742...70I
Altcode: 2011arXiv1108.5026I
We have studied the effect of time-dependent ionization and
the recombination processes on magnetic reconnection in the solar
corona. Petschek-type steady reconnection, in which the magnetic energy
is mainly converted at the slow-mode shocks, was assumed. We carried out
the time-dependent ionization calculation in the magnetic reconnection
structure. We only calculated the transient ionization of iron;
the other species were assumed to be in ionization equilibrium. The
intensity of line emissions at specific wavelengths was also calculated
for comparison with Hinode or other observations in future. We found
the following: (1) iron is mostly in non-equilibrium ionization in the
reconnection region; (2) the intensity of line emission estimated by
the time-dependent ionization calculation is significantly different
from that determined from the ionization equilibrium assumption;
(3) the effect of time-dependent ionization is sensitive to the
electron density in the case where the electron density is less than
1010 cm-3 (4) the effect of thermal conduction
lessens the time-dependent ionization effect; and (5) the effect of
radiative cooling is negligibly small even if we take into account
time-dependent ionization.
Title: Plasma Motions and Heating by Magnetic Reconnection in a 2007
May 19 Flare
Authors: Hara, Hirohisa; Watanabe, Tetsuya; Harra, Louise K.; Culhane,
J. Leonard; Young, Peter R.
Bibcode: 2011ApJ...741..107H
Altcode:
Based on scanning spectroscopic observations with the Hinode EUV
imaging spectrometer, we have found a loop-top hot source, a fast
jet nearby, and an inflow structure flowing to the hot source that
appeared in the impulsive phase of a long-duration flare at the
disk center on 2007 May 19. The hot source observed in Fe XXIII and
Fe XXIV emission lines has the electron temperature of 12 MK and
density of 1 × 1010 cm-3. It shows excess
line broadening, which exceeds the thermal Doppler width by ~100 km
s-1, with a weak redshift of ~30 km s-1. We have
also observed a blueshifted faint jet whose Doppler velocity exceeds
200 km s-1 with an electron temperature of 9 MK. Coronal
plasmas with electron temperature of 1.2 MK and density of 2.5 ×
109 cm-3 that flow into the loop-top region
with a Doppler velocity of 20 km s-1 have been identified
in the Fe XII observation. They disappeared near the hot source,
possibly by being heated to the hotter faint jet temperature. From
the geometrical relationships of these phenomena, we conclude that
they provide evidence for magnetic reconnection that occurs near the
loop-top region. The estimated reconnection rate is 0.05-0.1, which
supports the Petschek-type magnetic reconnection. Further supporting
evidence for the presence of the slow-mode and fast-mode MHD shocks
in the reconnection geometry is given based on the observed quantities.
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: Intensity Ratio of Density-sensitive Lines in Fe Ions Observed
with a Well-defined Laboratory Plasma
Authors: Nakamura, Nobuyuki; Watanabe, Etsushi; Sakaue, Hiroyuki A.;
Kato, Daiji; Murakami, Izumi; Yamamoto, Norimasa; Hara, Hirohisa;
Watanabe, Tetsuya
Bibcode: 2011ApJ...739...17N
Altcode:
We present spectra of highly charged Fe ions in the extreme ultraviolet
range observed using an electron beam ion trap equipped with a
flat-field grazing incidence spectrometer. The density dependence of
line intensity ratios is investigated for several density-sensitive
lines of Fe XIII, XIV, and XV. Unlike previous studies where the
electron density was estimated from theoretical considerations, here
it is derived from electron beam profile measurements. The experimental
data are compared with model calculations.
Title: Spectroscopic Observations of Continuous Outflows and
Propagating Waves from NOAA 10942 with Extreme Ultraviolet Imaging
Spectrometer/Hinode
Authors: Nishizuka, N.; Hara, H.
Bibcode: 2011ApJ...737L..43N
Altcode:
We focused on "sit-and-stare" observations of an outflow region at the
edge of active region NOAA 10942 on 2007 February 20 obtained by the
Extreme ultraviolet Imaging Spectrometer on board Hinode. We analyzed
the data above the base of the outflow and found both continuous
outflows and waves, which propagate from the base of the outflow. The
spectra at the base of the outflow and at higher locations show
different properties. The line profiles show blue-side asymmetry at the
base of the outflow where nonthermal broadening becomes large because of
fast upflows generated by heating events. On the other hand, at higher
locations line profiles are symmetric and the intensity disturbances
vary in phase with the velocity disturbances. The correlations
between the intensity and velocity disturbances become noticeable at
higher locations, so this indicates evidence of (at least locally)
upward propagating slow-mode waves along the outflow. We also found a
transient oscillation of different period in the wavelet spectrum. This
indicates that a different wave is additionally observed during
a limited period. High cadence spectroscopic observations revealed
intermittent signatures of nonthermal velocities. Each of them seems to
correspond to the base of the propagating disturbances. Furthermore, a
jet was captured by the sit-and-stare observations across the slit. The
similarity of line profiles of the outflow and the jet may indicate
that the flows and waves originate in unresolved explosive events in
the lower atmosphere of the corona.
Title: A Sounding Rocket Experiment for Spectropolarimetric
Observations with the Lyα Line at 121.6 nm (CLASP)
Authors: Ishikawa, R.; Bando, T.; Fujimura, D.; Hara, H.; Kano,
R.; Kobiki, T.; Narukage, N.; Tsuneta, S.; Ueda, K.; Wantanabe,
H.; Kobayashi, K.; Trujillo Bueno, J.; Manso Sainz, R.; Stepan, J.;
de Pontieu, B.; Carlsson, M.; Casini, R.
Bibcode: 2011ASPC..437..287I
Altcode:
A team consisting of Japan, USA, Spain, and Norway is developing a
high-throughput Chromospheric Lyman-Alpha SpectroPolarimeter (CLASP),
which is proposed to fly with a NASA sounding rocket in 2014. CLASP will
explore the magnetism of the upper solar chromosphere and transition
region via the Hanle effect of the Lyα line for the first
time. This experiment requires spectropolarimetric observations with
high polarimetric sensitivity (∼0.1%) and wavelength resolution
(0.1 Å). The final spatial resolution (slit width) is being discussed
taking into account the required high signal-to-noise ratio. We have
demonstrated the performance of the Lyα polarimeter by
extensively using the Ultraviolet Synchrotron ORbital Radiation Facility
(UVSOR) at the Institute for Molecular Sciences. In this contribution,
we report these measurements at UVSOR together with the current status
of the CLASP project.
Title: Coronal-Temperature-Diagnostic Capability of the Hinode/
X-Ray Telescope Based on Self-Consistent Calibration
Authors: Narukage, N.; Sakao, T.; Kano, R.; Hara, H.; Shimojo, M.;
Bando, T.; Urayama, F.; DeLuca, E.; Golub, L.; Weber, M.; Grigis,
P.; Cirtain, J.; Tsuneta, S.
Bibcode: 2011SoPh..269..169N
Altcode: 2010arXiv1011.2867N; 2011SoPh..tmp....1N
The X-Ray Telescope (XRT) onboard the Hinode satellite is an X-ray
imager that observes the solar corona with unprecedentedly high angular
resolution (consistent with its 1″ pixel size). XRT has nine X-ray
analysis filters with different temperature responses. One of the most
significant scientific features of this telescope is its capability
of diagnosing coronal temperatures from less than 1 MK to more than
10 MK, which has never been accomplished before. To make full use
of this capability, accurate calibration of the coronal temperature
response of XRT is indispensable and is presented in this article. The
effect of on-orbit contamination is also taken into account in the
calibration. On the basis of our calibration results, we review the
coronal-temperature-diagnostic capability of XRT.
Title: Ionization non-equilibrium plasma during magnetic reconnection
in solar corona
Authors: Imada, S.; Murakami, I.; Watanabe, T.; Hara, H.; Shimizu, T.
Bibcode: 2010AGUFMSH31A1788I
Altcode:
Hinode can provide us both of the stored magnetic field energy in
corona before magnetic reconnection and the most part of energy post
reconnection stage. On the other hand, there is not enough observational
knowledge of the physical parameters in the reconnection region. The
inflow into the reconnection region, the temperature of the plasma in
the reconnection region, and the temperatures and densities of the
plasma jets predicted by reconnection, have not been quantitatively
measured in sufficient. EIS on Hinode may provide some answers if
solar cycle 24 ever produces a solar maximum. But it is important
to answer why the most observation cannot detect the predicted flow
or temperature in the reconnection region. One of the reasons why we
cannot observe inside the magnetic reconnection region is due to its
darkness. Generally we can see the bright cusp-like structure during
solar flare, although the reconnection region is faint/blind. One may
think that the temperature in the reconnection region is enough higher
than that of cusp-like flare loops. Thus the wavelength of emission
from reconnection region is different from flare loops. However, this
is not entirely true. Magnetic reconnection causes rapid heating. Thus
ionization cannot reach to the equilibrium stage. We have calculated
the ionization process in the down stream of Petschek type magnetic
reconnection. From our result, we can clearly see that plasma cannot
reach the ionization equilibrium in the down stream of slow-mode
shock. The typical emissions from magnetic reconnection region are
FeIXX or FeXX, although the plasma temperature is equal to 40MK. The
typical temperature and density of post flare loops are 10 MK and 10^11
/cc, and the dominant emissions from post flare loops are from FeIXX
to FeXXIII. Thus the wavelength of emission from reconnection region
is not so much different from post flare loops. We will discuss how
the emissions from reconnection region looks like by using several
ionization calculations of magnetic reconnection.
Title: The Chromospheric Lyman Alpha SpectroPolarimeter (CLASP)
Authors: Kobayashi, K.; Tsuneta, S.; Trujillo Bueno, J.; Cirtain,
J. W.; Bando, T.; Kano, R.; Hara, H.; Fujimura, D.; Ueda, K.; Ishikawa,
R.; Watanabe, H.; Ichimoto, K.; Sakao, T.; de Pontieu, B.; Carlsson,
M.; Casini, R.
Bibcode: 2010AGUFMSH11B1632K
Altcode:
Magnetic fields in the solar chromosphere play a key role in the
energy transfer and dynamics of the solar atmosphere. Yet a direct
observation of the chromospheric magnetic field remains one of the
greatest challenges in solar physics. While some advances have been
made for observing the Zeeman effect in strong chromospheric lines,
the effect is small and difficult to detect outside sunspots. The
Hanle effect offers a promising alternative; it is sensitive to weaker
magnetic fields (e.g., 5-500 G for Ly-Alpha), and while its magnitude
saturates at stronger magnetic fields, the linear polarization signals
remain sensitive to the magnetic field orientation. The Hanle effect
is not only limited to off-limb observations. Because the chromosphere
is illuminated by an anisotropic radiation field, the Ly-Alpha line is
predicted to show linear polarization for on-disk, near-limb regions,
and magnetic field is predicted to cause a measurable depolarization. At
disk center, the Ly-Alpha radiation is predicted to be negligible
in the absence of magnetic field, and linearly polarized to an order
of 0.3% in the presence of an inclined magnetic field. The proposed
CLASP sounding rocket instrument is designed to detect 0.3% linear
polarization of the Ly-Alpha line at 1.5 arcsecond spatial resolution
(0.7’’ pixel size) and 10 pm spectral resolution. The instrument
consists of a 30 cm aperture Cassegrain telescope and a dual-beam
spectropolarimeter. The telescope employs a ``cold mirror’’ design
that uses multilayer coatings to reflect only the target wavelength
range into the spectropolarimeter. The polarization analyzer consists of
a rotating waveplate and a polarizing beamsplitter that comprises MgF2
plates placed at Brewster’s Angle. Each output beam of the polarizing
beamsplitter, representing two orthogonal linear polarizations, is
dispersed and focused using a separate spherical varied-line-space
grating, and imaged with a separate 512x512 CCD camera. Prototypes
of key optical components have been fabricated and tested. Instrument
design is being finalized, and the experiment will be proposed for a
2014 flight aboard a NASA sounding rocket.
Title: Hinode, STEREO and SOHO obervations of a CME event
Authors: Landi, E.; Raymond, J. C.; Miralles, M. P.; Hara, H.
Bibcode: 2010AGUFMSH31D..01L
Altcode:
Coronal Mass Ejections (CMEs) are among the most dramatic and violent
dynamic events occurring in the solar atmosphere, and have significant
impact on the near-Earth environment. So far, the physical processes
responsible for their release and acceleration have not been completely
understood, in part because of the lack of direct measurements of the
CME plasma phycical parameters and evolution during the CME onset. Here
we describe the analysis of multiwavelength observations from Hinode,
SOHO and STEREO of the very early phases of a CME observed during the
Whole Heliospheric Interval campaign. SECCHI/EUVI, SECCHI/COR1, SOHO/EIT
and SOHO/LASCO images are used to reconstruct the 3D trajectory,
velocity and acceleration up to 20 solar radii. Hinode/EIS, Hinode/XRT
and SOHO/UVCS high resolution EUV spectra and X-ray images are used to
measure the physical properties and the thermal structure of the core
of the CME ejecta as a function of time up to 2.0 solar radii. The
physical properties of the current sheet that formed after the CME
erupted are also measured as a function of time.
Title: Modeling of EIS Spectrum Drift from Instrumental Temperatures
Authors: Kamio, S.; Hara, H.; Watanabe, T.; Fredvik, T.; Hansteen,
V. H.
Bibcode: 2010SoPh..266..209K
Altcode: 2010SoPh..tmp..137K; 2010arXiv1003.3540K
An empirical model has been developed to reproduce the drift of the
spectrum recorded by the EIS on Hinode using instrumental temperatures
and relative motion of the spacecraft. The EIS spectrum shows an
artificial drift in wavelength dimension in sync with the revolution of
the spacecraft, which is caused by temperature variations inside the
spectrometer. The drift amounts to 70 km s−1 in Doppler
velocity and introduces difficulties in velocity measurements. An
artificial neural network is incorporated to establish a relationship
between the instrumental temperatures and the spectral drift. This
empirical model reproduces observed spectrum shift with an rms error
of 4.4 km s−1. This procedure is robust and applicable to
any spectrum obtained with EIS, regardless of the observing field. In
addition, spectral curvatures and spatial offset in the north - south
direction are determined to compensate for instrumental effects.
Title: Mode Identification of MHD Waves in an Active Region Observed
with Hinode/EIS
Authors: Kitagawa, N.; Yokoyama, T.; Imada, S.; Hara, H.
Bibcode: 2010ApJ...721..744K
Altcode: 2010arXiv1008.1823K
In order to better understand the possibility of coronal heating
by MHD waves, we analyze Fe XII 195.12Å data observed with the EUV
Imaging Spectrometer on board Hinode. We performed a Fourier analysis
of EUV intensity and Doppler velocity time series data in the active
region corona. Notable intensity and Doppler velocity oscillations were
found for two moss regions out of the five studied, while only small
oscillations were found for five apexes of loops. The amplitudes of the
oscillations were 0.4%-5.7% for intensity and 0.2-1.2 km s-1
for Doppler velocity. In addition, oscillations of only the Doppler
velocity were seen relatively less often in the data. We compared
the amplitudes of intensity and those of Doppler velocity in order to
identify MHD wave modes and calculated the phase delays between Fourier
components of intensity and those of Doppler velocity. The results
are interpreted in terms of MHD waves as follows: (1) few kink modes
or torsional Alfvén mode waves were seen in both moss regions and the
apexes of loops, (2) upwardly propagating and standing slow mode waves
were found in moss regions, and (3) consistent with previous studies,
estimated values of energy flux of the waves were several orders of
magnitude lower than that required for heating active regions.
Title: On Redshifts and Blueshifts in the Transition Region and Corona
Authors: Hansteen, V. H.; Hara, H.; De Pontieu, B.; Carlsson, M.
Bibcode: 2010ApJ...718.1070H
Altcode: 2010arXiv1001.4769H
Emission lines formed in the transition region (TR) of the Sun have long
been known to show pervasive redshifts. Despite a variety of proposed
explanations, these TR downflows (and the slight upflows in the low
corona) remain poorly understood. We present results from comprehensive
three-dimensional MHD models that span the upper convection zone up to
the corona, 15 Mm above the photosphere. The TR and coronal heating
in these models is caused by the stressing of the magnetic field by
photospheric and convection "zone dynamics," but also in some models by
the injection of emerging magnetic flux. We show that rapid, episodic
heating, at low heights of the upper chromospheric plasma to coronal
temperatures naturally produces downflows in TR lines, and slight
upflows in low coronal lines, with similar amplitudes to those observed
with EUV/UV spectrographs. We find that TR redshifts naturally arise
in episodically heated models where the average volumetric heating
scale height lies between that of the chromospheric pressure scale
height of 200 km and the coronal scale height of 50 Mm.
Title: Production of High-temperature Plasmas During the Early Phases
of a C9.7 Flare
Authors: Watanabe, Tetsuya; Hara, Hirohisa; Sterling, Alphonse C.;
Harra, Louise K.
Bibcode: 2010ApJ...719..213W
Altcode:
Explosive chromospheric evaporation is predicted from some current
solar flare models. In this paper, we analyze a flare with high time
cadence raster scans with the EUV Imaging Spectrometer (EIS) on board
the Hinode spacecraft. This observation covers an area of 240'' ×
240'', with the 1'' slit in about 160 s. The early phases of a C9.7
flare that occurred on 2007 June 6 were well observed. The purpose of
our analysis is to study for the first time the spatially resolved
spectra of high-temperature plasma, especially from Fe XXIII and Fe
XXIV, allowing us to explore the explosive chromospheric evaporation
scenario further. Sections of raster images obtained between 17:20:09
and 17:20:29 (UT) show a few bright patches of emission from Fe
XXIII/Fe XXIV lines at the footpoints of the flaring loops; these
footpoints were not clearly seen in the images taken earlier, between
17:17:30 and 17:17:49 (UT). Fe XXIII spectra at these footpoints show
dominating blueshifted components of -(300 to 400) km s-1,
while Fe XV/XIV lines are nearly stationary; Fe XII lines and/or
lower temperature lines show slightly redshifted features, and Fe
VIII and Si VII to He II lines show ~+50 km s-1 redshifted
components. The density of the 1.5-2 MK plasma at these footpoints is
estimated to be 3 × 1010 cm-3 by the Fe XIII/XIV
line pairs around the maximum of the flare. High-temperature loops
connecting the footpoints appear in the Fe XXIII/XXIV images taken over
17:22:49-17:23:08 (UT) which is near the flare peak. Line profiles of
these high-temperature lines at this flare peak time show only slowly
moving components. The concurrent cooler Fe XVII line at 254.8 Å is
relatively weak, indicating the predominance of high-temperature plasma
(>107 K) in these loops. The characteristics observed
during the early phases of this flare are consistent with the scenario
of explosive chromospheric evaporation.
Title: Physical Conditions in a CME from Hinode, STEREO, and SOHO
Observations
Authors: Landi, E.; Raymond, J. C.; Miralles, M. P.; Hara, H.
Bibcode: 2010ASPC..428..201L
Altcode:
In the present work we analyze multiwavelength observations from
Hinode, SOHO, and STEREO of the early phases of a CME. We use EIS,
UVCS, and XRT to measure the physical properties of the CME ejecta as
a function of time at 1.1 and 1.9 Rsun. EUVI, COR 1, EIT,
and LASCO images are used to measure the CME trajectory, velocity, and
acceleration in 3D up to 5 Rsun. The diagnostic results are
used to determine the energy budget of the CME plasma and the heating
rate, and to compare it to theoretical predictions.
Title: Response of the Solar Atmosphere to the Emergence of
`Serpentine' Magnetic Field
Authors: Harra, L. K.; Magara, T.; Hara, H.; Tsuneta, S.; Okamoto,
T. J.; Wallace, A. J.
Bibcode: 2010SoPh..263..105H
Altcode:
Active region magnetic flux that emerges to the photosphere from
below will show complexity in the structure, with many small-scale
fragmented features appearing in between the main bipole and then
disappearing. Some fragments seen will be absorbed into the main
polarities and others seem to cancel with opposite magnetic field. In
this paper we investigate the response of the corona to the behaviour
of these small fragments and whether energy through reconnection
will be transported into the corona. In order to investigate this we
analyse data from the Hinode space mission during flux emergence on
1 - 2 December 2006. At the initial stages of flux emergence several
small-scale enhancements (of only a few pixels size) are seen in the
coronal line widths and diffuse coronal emission exists. The magnetic
flux emerges as a fragmented structure, and coronal loops appear
above these structures or close to them. These loops are large-scale
structures - most small-scale features predominantly stay within the
chromosphere or at the edges of the flux emergence. The most distinctive
feature in the Doppler velocity is a strong ring of coronal outflows
around the edge of the emerging flux region on the eastern side which
is either due to reconnection or compression of the structure. This
feature lasts for many hours and is seen in many wavelengths. We
discuss the implications of this feature in terms of the onset of
persistent outflows from an active region that could contribute to
the slow solar wind.
Title: Physical Conditions in a Coronal Mass Ejection from Hinode,
Stereo, and SOHO Observations
Authors: Landi, E.; Raymond, J. C.; Miralles, M. P.; Hara, H.
Bibcode: 2010ApJ...711...75L
Altcode:
In the present work, we analyze multiwavelength observations from
Hinode, Solar and Heliospheric Observatory (SOHO), and STEREO of the
early phases of a coronal mass ejection (CME). We use Hinode/EIS
and SOHO/UVCS high-resolution spectra to measure the physical
properties of the CME ejecta as a function of time at 1.1 and 1.9
solar radii. Hinode/XRT images are used in combination with EIS
spectra to constrain the high temperature plasma properties of the
ejecta. SECCHI/EUVI, SECCHI/COR 1, SOHO/EIT, and SOHO/LASCO images are
used to measure the CME trajectory, velocity, and acceleration. The
combination of measurements of plane of the sky velocities from two
different directions allows us to determine the total velocity of the
CME plasma up to 5 solar radii. Plasma properties, dynamical status,
thermal structure, and brightness distributions are used to constrain
the energy content of the CME plasma and to determine the heating
rate. We find that the heating is larger than the kinetic energy,
and compare it to theoretical predictions from models of CME plasma
heating and acceleration.
Title: On red-shifts in the transition region and corona .
Authors: Hansteen, V. H.; Hara, H.; de Pontieu, B.; Carlsson, M.
Bibcode: 2010MmSAI..81..729H
Altcode:
We present evidence that transition region red-shifts are naturally
produced in episodically heated models where the average volumetric
heating scale height lies between that of the chromospheric
pressure scale height of 200 km and the coronal scale height of
50 Mm. In order to do so we present results from 3d MHD models
spanning the upper convection zone up to the corona, 15 Mm above the
photosphere. Transition region and coronal heating in these models
is due both the stressing of the magnetic field by photospheric and
convection `zone dynamics, but also in some models by the injection
of emerging magnetic flux.
Title: Flows in active regions revealed from Hinode EIS Observations
Authors: Hara, Hirohisa
Bibcode: 2010cosp...38.2930H
Altcode: 2010cosp.meet.2930H
Hinode EUV imaging spectrometer (EIS) has revealed the presence of
high-velocity upflow components of nearly coronal sound speed near
footpoints of coronal loops in quiescent active regions. The upflow
is detected as an enhancement with low emission at the blue wing of
the emission-line profile. The low-emission component suggests the
presence of spatially unresolved upflows and smallness of each heating
volume. Such fast flows are not observed in the high corona in general,
and are expected when the heat input to the loop system is concentrated
at the footpoints of coronal loops. We will discuss the implications
for coronal heating mechanisms from the EIS observations and other
observable such as photospheric magnetic fields.
Title: Plasma Heating and Velocity Fields nearby Magnetic Reconnection
Site Revealed from an EUV Emission-line Spectroscopy
Authors: Hara, Hirohisa
Bibcode: 2010cosp...38.2958H
Altcode: 2010cosp.meet.2958H
We report observational properties in the impulsive phase of a long
duration flare on 2007 May 19 from spectroscopic observations with the
Hinode EUV imaging spectrometer (EIS) with supplemental observations
of Hinode SOT XRT, TRACE, and RHESSI. We have found an isolated
hot source showing a largely enhanced nonthermal line broadening, a
fast jet nearby, and an inflow structure to the hot source. Magnetic
reconnection occurring above the loop-top region of the flare loop
can account for these observations.
Title: Characteristics of the Nonthermal Velocity Signature Observed
in the Impulsive Phase of the 2007 May 19 Flare
Authors: Hara, H.; Watanabe, T.; Bone, L. A.; Culhane, J. L.; van
Driel-Gesztelyi, L.; Young, P. R.
Bibcode: 2009ASPC..415..459H
Altcode:
The Hinode EUV Imaging Spectrometer (EIS) observed a long duration
flare with a weak impulsive phase that appears to conform to the
standard two-ribbon flare reconnection model. EIS scanned the flare
site during the impulsive phase and observed Fe XXIII and Fe XXIV line
emission that closely followed the flare hard X-ray emission while the
line profiles showed significant non-thermal broadening. We suggest
that a shock originating at the reconnection site which sweeps up and
heats the coronal plasma can account for our observations.
Title: Coronal Plasma Motions in Active Region Loops Observed with
Hinode EIS
Authors: Hara, H.
Bibcode: 2009ASPC..415..252H
Altcode:
The Hinode EUV Imaging Spectrometer (EIS) has revealed the presence
of high-velocity upflow components of nearly coronal sound speed
near the footpoints of active region loops in a quiescent active
region. The upflow is detected as subsonic line shifts with enhanced
line broadenings when the emission line fitting by a Gaussian function
is applied to the line-profile analysis for hot coronal emission lines,
and it contributes to the line broadening because of the multiple
components within the EIS spatial resolution, suggesting the presence of
spatially unresolved upflows and the smallness of each heating volume.
Title: Ion Temperature and Non-Thermal Velocity in a Solar Active
Region: Using Emission Lines of Different Atomic Species
Authors: Imada, S.; Hara, H.; Watanabe, T.
Bibcode: 2009ApJ...705L.208I
Altcode:
We have studied the characteristics of the ion thermal temperature
and non-thermal velocity in an active region observed by the EUV
Imaging Spectrometer onboard Hinode. We used two emission lines of
different atomic species (Fe XVI 262.98 Å and S XIII 256.69 Å) to
distinguish the ion thermal velocity from the observed full width at
half-maximum. We assumed that the sources of the two emission lines
are the same thermal temperature. We also assumed that they have the
same non-thermal velocity. With these assumptions, we could obtain
the ion thermal temperature, after noting that M sulfur ~
0.6M iron. We have carried out the ion thermal temperature
analysis in the active region where the photon counts are sufficient
(>4500). What we found is as follows: (1) the common ion thermal
temperatures obtained by Fe XVI and S XIII are ~2.5 MK, (2) the typical
non-thermal velocities are ~13 km s-1, (3) the highest
non-thermal velocities (>20 km s-1) are preferentially
observed between the bright points in Fe XVI, while (4) the hottest
material (>3 MK) is observed relatively inside the bright points
compared with the highest non-thermal velocity region.
Title: Distribution of jets and magnetic fields in a coronal hole
Authors: Kamio, S.; Hara, H.; Watanabe, T.; Curdt, W.
Bibcode: 2009A&A...502..345K
Altcode:
Context: Recent observations of ubiquitous jets in coronal holes suggest
that they play an important role in coronal heating and solar wind
acceleration.
Aims: The aim of our study is to understand the
magnetic connectivity and the formation of jets in coronal holes. The
study of jets also helps to understand the magnetic field configuration
in the coronal hole.
Methods: A coordinated observation between
EIS and SUMER was carried out in a polar coronal hole to investigate
both the transition region and the corona. Spectropolarimeter (SP)
data allowed us to examine the relationship between the distribution
of jets and magnetic fields in the photosphere.
Results: Coronal
jets as well as explosive events and cool upflows were identified from
EIS and SUMER data. The location of these events are correlated with
network fields in the photosphere.
Conclusions: Footpoints of
coronal jets are connected to patches of vertical kG fields in the
photosphere, which are thought to anchor open fields in the upper
corona. Explosive events and cool upflows occur in network regions
which harbor low-lying fields in the transition region.
Title: Differential Rotation Rate of X-ray Bright Points and Source
Region of their Magnetic Fields
Authors: Hara, Hirohisa
Bibcode: 2009ApJ...697..980H
Altcode:
The differential rotation rate of the solar corona has statistically
been estimated from the motion of X-ray bright points (XBPs) that
were observed with the Yohkoh soft X-ray telescope and the source
region of magnetic fields is discussed from the evaluated rotation
rate. The rotation rate of a pair of XBPs in a given latitude band is
calculated from the position of an XBP in an X-ray image and that of
an arbitrary-chosen XBP in a different X-ray image obtained with a
time lag Δt. We have made the histogram of rotation rate from such
samples in each latitude band for many X-ray images, and it shows a
symmetric distribution that is well fitted by a Voigt function, not
a Gaussian function, with a background. The modal rates at various
longitudes in a given latitude band become the same value when a
height is adopted as a characteristic height of XBPs, and we define
the modal value against latitude as the differential rotation rate
of XBPs in the present study. The differential rotation rate shows
a similar trend as that of photospheric magnetic fields evaluated
from the local correlation technique. We find that the differential
rotation rate changes with a parameter Δt that is associated with the
lifetime of XBPs, and that it becomes smaller in height for shorter
Δt with the lower end that approaches to the rotation rate determined
from the photospheric Doppler measurements. This trend suggests that
magnetic fields associated with XBPs with a short lifetime are rooted
just below the surface of the Sun at the top of the convection zone,
and that they have a different origin from active regions.
Title: The SOLAR-C Mission
Authors: Hara, Hirohisa; JAXA SOLAR-C Working Group
Bibcode: 2009SPD....40.1802H
Altcode:
The JAXA SOLAR-C Working Group is planning the next solar observing
satellite SOLAR-C that follows Hinode (SOLAR-B) in orbit. Two plans,
Plan-A and Plan-B, are concurrently examined. Plan-A is a plan by a
spacecraft that is in an out-of-ecliptic interplanetary orbit to observe
the polar regions of the Sun. In the Plan-A mission, the solar dynamo
and the dynamics of the solar interior by helioseismic and magnetic
field observations from an unprecedented vantage point are the central
topics. Plan-B is a plan by a spacecraft in a sun-synchronous low-earth
orbit or a geostationary orbit. It is a high-spatial resolution
mission by largely enhanced spectroscopic and spectro-polarimetric
observations. With these new capabilities, the fundamental physical
processes in the heating and the dynamics of solar atmosphere are
explored in the Plan-B. The SOLAR-C Science Definition Meeting was
held with the participation of foreign scientists under the support
of JAXA and ESA last November, and the mission is highly anticipated
by the solar physicists over the world. The SOLAR-C working group
wishes to realize the launch of spacecraft slightly after the middle
of the 2010's.
Title: Physical Properties of Cooling Plasma in Quiescent Active
Region Loops
Authors: Landi, E.; Miralles, M. P.; Curdt, W.; Hara, H.
Bibcode: 2009ApJ...695..221L
Altcode:
In the present work, we use SOHO/SUMER, SOHO/UVCS, SOHO/EIT, SOHO/LASCO,
STEREO/EUVI, and Hinode/EIS coordinated observations of an active
region (AR 10989) at the west limb taken on 2008 April 8 to study the
cooling of coronal loops. The cooling plasma is identified using the
intensities of SUMER spectral lines emitted at temperatures in the
4.15 <= log T <= 5.45 range. EIS and SUMER spectral observations
are used to measure the physical properties of the loops. We found that
before cooling took place these loops were filled with coronal hole-like
plasma, with temperatures in the 5.6 <= log T <= 5.9 range. SUMER
spectra also allowed us to determine the plasma temperature, density,
emission measure, element abundances, and dynamic status during the
cooling process. The ability of EUVI to observe the emitting region
from a different direction allowed us to measure the volume of the
emitting region and estimate its emission measure. Comparison with
values measured from line intensities provided us with an estimate
of the filling factor. UVCS observations of the coronal emission
above the active region showed no streamer structure associated with
AR 10989 at position angles between 242°and 253fdg EIT, LASCO, and
EUVI-A narrowband images and UVCS spectral observations were used to
discriminate between different scenarios and monitor the behavior
of the active region in time. The present study provides the first
detailed measurements of the physical properties of cooling loops,
a very important benchmark for theoretical models of loop cooling
and condensation.
Title: Fe XIII Density Diagnostics in the EIS Observing Wavelengths
Authors: Watanabe, T.; Hara, H.; Yamamoto, N.; Kato, D.; Sakaue,
H. A.; Murakami, I.; Kato, T.; Nakamura, N.; Young, P. R.
Bibcode: 2009ApJ...692.1294W
Altcode:
The diagnostic capability of Fe XIII line features seen in the
170-210 Å waveband of the EUV Imaging Spectrometer (EIS) on Hinode
is investigated, with emphasis on density diagnostics applied to
solar active regions. Four diagnostic line pairs are found to yield
consistent densities ranging from 108.5 to 109.5
cm-3 across an active region using a new theoretical model
of the ion. In separate EIS observations of a small flare, the widely
used line pair, Fe XIII λ203.8/λ202.0, is found to reach the high
density limit predicted by a new theoretical model of the iron ion.
Title: High-precision density measurements in the solar
corona. I. Analysis methods and results for Fe XII and Fe XIII
Authors: Young, P. R.; Watanabe, T.; Hara, H.; Mariska, J. T.
Bibcode: 2009A&A...495..587Y
Altcode: 2008arXiv0805.0958Y
Aims: The EUV Imaging Spectrometer (EIS) instrument on board the Hinode
satellite has access to some of the best coronal density diagnostics,
and the high sensitivity of the instrument now allows electron number
density, N_e, measurements to an unprecedented precision of up to
±5% in active regions. This paper gives a thorough overview of data
analysis issues for the best diagnostics of Fe XII and Fe XIII and
assesses the accuracy of the measurements.
Methods: Two density
diagnostics each from Fe XII (λ186.88/λ195.12 and λ196.64/λ195.12)
and Fe XIII (λ196.54/λ202.04 and λ203.82/λ202.04) are analysed in
two active region datasets from 2007 May 3 and 6 that yield densities
in the range 8.5≤ log (N_e/cm-3)≤ 11.0. The densities
are derived using v5.2 of the CHIANTI atomic database. Blending,
line fitting, and instrumental issues are discussed, and line fit
parameters presented.
Results: The Fe XII and Fe XIII diagnostics
show broadly the same trend in density across the active region,
consistent with their similar temperatures of formation. However,
the high precision of the EIS measurements demonstrates significant
discrepancies of up to 0.5 dex in derived log Ne values, with
Fe XII always giving higher densities than Fe XIII. The discrepancies
may partly be due to real physical differences between the emitting
regions of the two plasmas, but the dominant factor lies in the
atomic models of the two ions. Two specific problems are identified
for Fe XII λ196.64 and Fe XIII λ203.82: the former is found to
be underestimated in strength by the CHIANTI atomic model, while
the high-density limit of the λ203.82/λ202.04 ratio appears to be
inaccurate in the CHIANTI atomic model. The small grating tilt of the
EIS instrument is found to be very significant when deriving densities
from emission lines separated by more than a few angstroms. Revised
wavelengths of 196.518± 0.003 Å and 196.647± 0.003 Å are suggested
for the Fe XIII λ196.54 and Fe XII λ196.64 lines, respectively.
Title: Coronal Nonthermal Velocity Following Helicity Injection
Before an X-Class Flare
Authors: Harra, L. K.; Williams, D. R.; Wallace, A. J.; Magara, T.;
Hara, H.; Tsuneta, S.; Sterling, A. C.; Doschek, G. A.
Bibcode: 2009ApJ...691L..99H
Altcode:
We explore the "pre-flare" behavior of the corona in a three-day
period building up to an X-class flare on 2006 December 13 by analyzing
EUV spectral profiles from the Hinode EUV Imaging Spectrometer (EIS)
instrument. We found an increase in the coronal spectral line widths,
beginning after the time of saturation of the injected helicity as
measured by Magara & Tsuneta. In addition, this increase in line
widths (indicating nonthermal motions) starts before any eruptive
activity occurs. The Hinode EIS has the sensitivity to measure changes
in the buildup to a flare many hours before the flare begins.
Title: EIS/ Hinode Observations of Doppler Flow Seen through the
40-Arcsec Wide-Slit
Authors: Innes, D. E.; Attie, R.; Hara, H.; Madjarska, M. S.
Bibcode: 2008SoPh..252..283I
Altcode: 2008SoPh..tmp..174I; 2008arXiv0807.1185I
The Extreme ultraviolet Imaging Spectrometer (EIS) onboard Hinode
is the first solar telescope to obtain wide-slit spectral images
that can be used for detecting Doppler flows in transition region
and coronal lines on the Sun and to relate them to their surrounding
small-scale dynamics. We select EIS lines covering the temperature
range 6×104 to 2×106 K that give spectrally
pure images of the Sun with the 40-arcsec slit. In these images Doppler
shifts are seen as horizontal brightenings. Inside the image it is
difficult to distinguish shifts from horizontal structures but emission
beyond the image edge can be unambiguously identified as a line shift
in several lines separated from others on their blue or red side by
more than the width of the spectrometer slit (40 pixels). In the blue
wing of He II, we find a large number of events with properties (size
and lifetime) similar to the well-studied explosive events seen in
the ultraviolet spectral range. Comparison with X-Ray Telescope (XRT)
images shows many Doppler shift events at the footpoints of small X-ray
loops. The most spectacular event observed showed a strong blue shift
in the transition region and lower corona lines from a small X-ray
spot that lasted less than 7 min. The emission appears to be near
a cool coronal loop connecting an X-ray bright point to an adjacent
region of quiet Sun. The width of the emission implies a line-of-sight
velocity of 220 km s−1. In addition, we show an example
of an Fe XV shift with a velocity of about 120 km s−1,
coming from what looks like a narrow loop leg connecting a small X-ray
brightening to a larger region of X-ray emission.
Title: Flows and Nonthermal Velocities in Solar Active Regions
Observed with the EUV Imaging Spectrometer on Hinode: A Tracer of
Active Region Sources of Heliospheric Magnetic Fields?
Authors: Doschek, G. A.; Warren, H. P.; Mariska, J. T.; Muglach, K.;
Culhane, J. L.; Hara, H.; Watanabe, T.
Bibcode: 2008ApJ...686.1362D
Altcode: 2008arXiv0807.2860D
From Doppler velocity maps of active regions constructed from spectra
obtained by the EUV Imaging Spectrometer (EIS) on the Hinode spacecraft
we observe large areas of outflow (20-50 km s-1) that can
persist for at least a day. These outflows occur in areas of active
regions that are faint in coronal spectral lines formed at typical
quiet-Sun and active region temperatures. The outflows are positively
correlated with nonthermal velocities in coronal plasmas. The bulk
mass motions and nonthermal velocities are derived from spectral line
centroids and line widths, mostly from a strong line of Fe XII at
195.12 Å. The electron temperature of the outflow regions estimated
from an Fe XIII to Fe XII line intensity ratio is about (1.2-1.4) ×
106 K. The electron density of the outflow regions derived
from a density-sensitive intensity ratio of Fe XII lines is rather low
for an active region. Most regions average around 7 × 108
cm-3, but there are variations on pixel spatial scales
of about a factor of 4. We discuss results in detail for two active
regions observed by EIS. Images of active regions in line intensity,
line width, and line centroid are obtained by rastering the regions. We
also discuss data from the active regions obtained from other orbiting
spacecraft that support the conclusions obtained from analysis of the
EIS spectra. The locations of the flows in the active regions with
respect to the longitudinal photospheric magnetic fields suggest that
these regions might be tracers of long loops and/or open magnetic
fields that extend into the heliosphere, and thus the flows could
possibly contribute significantly to the solar wind.
Title: Overview of EIS Performance
Authors: Hara, H.
Bibcode: 2008ASPC..397...11H
Altcode:
The Hinode EUV Imaging Spectrometer (EIS) is a high-sensitivity
spectrometer to observe the solar transition region and corona in two
extreme-ultraviolet wavelength bands of 166-211 and 245-291 Å. Hinode
was successfully launched on 2006 Sep 23 06:36 JST and EIS has produced
high-quality EUV spectra since the First Light Operation on 2006 Oct
28. We report the on-orbit EIS performance after the launch in this
short paper.
Title: Velocity Structure of Bright Points in a Coronal Hole
Authors: Kamio, S.; Hara, H.; Watanabe, T.; Curdt, W.
Bibcode: 2008ASPC..397...35K
Altcode:
We present the velocity structure of bright points in the corona
and in the transition region. This is one of the first results from
the coordinated observation with Hinode/EIS and SOHO/SUMER in April
2007. Bright points in the corona are associated with bright patches in
the transition region network. The result suggests coronal bright points
are rooted in the magnetic field concentration of the network. No clear
connection is found between velocities in the corona and the transition
region, but observing time difference between EIS and SUMER could be
the cause of the dissociation.
Title: Coronal Plasma Motions Revealed from Spectroscopic Observations
with Hinode EIS
Authors: Hara, Hirohisa
Bibcode: 2008AstHe.101..497H
Altcode:
The author tries to understand why the solar corona is heated to a
temperature of 106K, in other words, how the energy of
photospheric granular motions is transferred via magnetic fields
and dissipated at the coronal height from observations with three
telescopes on the Hinode spacecraft. An initial result from Hinode
EUV spectroscopic observations on the motions of coronal plasmas near
footpoints of coronal loops is briefly introduced.
Title: Strongly Blueshifted Phenomena Observed with Hinode EIS in
the 2006 December 13 Solar Flare
Authors: Asai, Ayumi; Hara, Hirohisa; Watanabe, Tetsuya; Imada,
Shinsuke; Sakao, Taro; Narukage, Noriyuki; Culhane, J. L.; Doschek,
G. A.
Bibcode: 2008ApJ...685..622A
Altcode: 2008arXiv0805.4468A
We present a detailed examination of strongly blueshifted emission
lines observed with the EUV Imaging Spectrometer on board the Hinode
satellite. We found two kinds of blueshifted phenomenon associated
with the X3.4 flare that occurred on 2006 December 13. One was related
to a plasmoid ejection seen in soft X-rays. It was very bright in all
the lines used for the observations. The other was associated with the
faint arc-shaped ejection seen in soft X-rays. The soft X-ray ejection
is thought to be a magnetohydrodynamic (MHD) fast-mode shock wave. This
is therefore the first spectroscopic observation of an MHD fast-mode
shock wave associated with a flare.
Title: Long Duration Flare Observed with Hinode EIS
Authors: Culhane, J. L.; Hara, H.; Watanabe, T.; Matsuzaki, K.; Harra,
L. K.; Cargill, P.; Mariska, J. T.; Doschek, G. A.
Bibcode: 2008ASPC..397..121C
Altcode:
The first Long Duration Event (LDE) observed with Hinode EIS using
a high spectral resolution raster scan is described. The hot plasma
features include a cusp-shaped arcade associated with a thermal RHESSI
source, cooling post-flare loops, complex plasma flows and an EIT
observation that shows expanding loops and inflows characteristic of
the standard magnetic reconnection model for solar flares. A Coronal
Mass Ejection (CME) is also seen by LASCO. The cusp is well observed
in the Ca XVII line and we find enhanced line broadening above this
region. Doppler velocity observations for the post-flare loops show both
up-flows and down-flows that are interpreted as due to siphon flows.
Title: Long Duration Thermal Hard X-ray Sources Observed in Two
Eruptive Flares
Authors: Bone, L. A.; Culhane, J. L.; van Driel-Gesztelyi, L.; Hara, H.
Bibcode: 2008ASPC..397..160B
Altcode:
We present observations of two eruptive flares on 17 of December
2006 (C1.9) and 19 of May 2007 (B9.7) which had good coverage with
both Hinode and RHESSI. In these flares we see a long lived, gradual
thermal hard X-ray source of low emission measure and, relative to
the loops observed with GOES and XRT, high temperature. The lack of a
non-thermal hard X-ray component and impulsive behaviour is inconsistent
with electron beam driven chromospheric evaporation.
Title: Doppler Shifts in the Boundary of the Dimming Region
Authors: Imada, S.; Hara, H.; Watanabe, T.; Asai, A.; Kamio, S.;
Matsuzaki, K.; Harra, L. K.; Mariska, J. T.
Bibcode: 2008ASPC..397..102I
Altcode:
We present Hinode/EIS raster scan observations of the GOES X3.2
flare that occurred on 2006 December 13. There was a small transient
coronal hole which was located 200 arcsec east of the flare arcade. The
transient coronal hole was strongly affected by the X-class flare, and
the strong upflows were observed in Fe XV line 284.2 Å (log{T/{K}}
= 6.3) at the boundary of dimming region. In this paper, we discuss
how to obtain the velocity map by correcting the instrumental effects.
Title: Vertical Temperature Structures of the Solar Corona Derived
with the Hinode X-Ray Telescope
Authors: Kano, Ryouhei; Sakao, Taro; Narukage, Noriyuki; Tsuneta,
Saku; Kotoku, Jun'ichi; Bando, Takamasa; Deluca, Edward; Lundquist,
Loraine; Golub, Leon; Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo,
Masumi; Shibasaki, Kiyoto; Shimizu, Toshifumi; Nakatani, Ichiro
Bibcode: 2008PASJ...60..827K
Altcode:
We obtained temperature structures in faint coronal features
above and near the solar limb with the X-Ray Telescope aboard the
Hinode satellite by accurately correcting the scattered X-rays
from surrounding bright regions with occulted images during
the solar eclipses. Our analysis yields a polar coronal hole
temperature of about 1.0MK and an emission measure in the range of
1025.5-1026.0cm-5. In addition,
our methods allow us to measure the temperature and emission
measure of two distinct quiet-Sun structures: radial (plume-like)
structures near the boundary of the coronal-hole and diffuse quiet
Sun regions at mid-latitudes. The radial structures appear to have
increasing temperature with height during the first 100Mm, and
constant temperatures above 100Mm. For the diffuse quiet-Sun region
the temperatures are the highest just above the limb, and appear
to decrease with height. These differences may be due to different
magnetic configurations.
Title: Wavelengths and Intensities of Spectral Lines in the 171-211
and 245-291 Å Ranges from Five Solar Regions Recorded by the
Extreme-Ultraviolet Imaging Spectrometer (EIS) on Hinode
Authors: Brown, C. M.; Feldman, U.; Seely, J. F.; Korendyke, C. M.;
Hara, H.
Bibcode: 2008ApJS..176..511B
Altcode:
We present spectral line wavelengths, identifications, and intensities
in the 171-211 and 245-291 Å ranges from five solar plasma regions
recorded by the Extreme-Ultraviolet Imaging Spectrometer (EIS)
on Hinode. The recorded data were emitted from a quiet region,
two active areas on the solar disk, a limb region, and a region
20'' above the limb. The line list contains 500 lines of which 55%
were identified with previously known transitions. Although the EIS
spectral coverage is limited to two ranges approximately 40 Å wide,
the identified lines belong to a total of 56 ions from 15 elements.
Title: Non-Gaussian Line Profiles in a Large Solar Flare Observed
on 2006 December 13
Authors: Imada, S.; Hara, H.; Watanabe, T.; Asai, A.; Minoshima, T.;
Harra, L. K.; Mariska, J. T.
Bibcode: 2008ApJ...679L.155I
Altcode:
We have studied the characteristics of the non-Gaussian line profile
of the Fe XIV 274.20 Å line in and around a flare arcade. We found
that broad non-Gaussian line profiles associated with redshifts
are observed in the flare arcade. There were two typical types
of broad line profiles. One was a distorted line profile caused by
multiple flows, and the other was a symmetric line profile without any
additional component. We successfully distinguished those two types
using higher order statistical moments or M—the additional component
contribution—defined in this Letter. The distorted/symmetric broad
line profiles were preferentially observed in new/old flare loops,
respectively.
Title: The Hinode X-Ray Telescope (XRT): Camera Design, Performance
and Operations
Authors: Kano, R.; Sakao, T.; Hara, H.; Tsuneta, S.; Matsuzaki, K.;
Kumagai, K.; Shimojo, M.; Minesugi, K.; Shibasaki, K.; DeLuca, E. E.;
Golub, L.; Bookbinder, J.; Caldwell, D.; Cheimets, P.; Cirtain, J.;
Dennis, E.; Kent, T.; Weber, M.
Bibcode: 2008SoPh..249..263K
Altcode:
The X-ray Telescope (XRT) aboard the Hinode satellite is a grazing
incidence X-ray imager equipped with a 2048×2048 CCD. The XRT has
1 arcsec pixels with a wide field of view of 34×34 arcmin. It is
sensitive to plasmas with a wide temperature range from < 1 to 30
MK, allowing us to obtain TRACE-like low-temperature images as well as
Yohkoh/SXT-like high-temperature images. The spacecraft Mission Data
Processor (MDP) controls the XRT through sequence tables with versatile
autonomous functions such as exposure control, region-of-interest
tracking, flare detection, and flare location identification. Data are
compressed either with DPCM or JPEG, depending on the purpose. This
results in higher cadence and/or wider field of view for a given
telemetry bandwidth. With a focus adjust mechanism, a higher resolution
of Gaussian focus may be available on-axis. This paper follows the
first instrument paper for the XRT (Golub et al., Solar Phys.243, 63,
2007) and discusses the design and measured performance of the X-ray
CCD camera for the XRT and its control system with the MDP.
Title: The Solar Optical Telescope of Solar-B ( Hinode): The Optical
Telescope Assembly
Authors: Suematsu, Y.; Tsuneta, S.; Ichimoto, K.; Shimizu, T.; Otsubo,
M.; Katsukawa, Y.; Nakagiri, M.; Noguchi, M.; Tamura, T.; Kato, Y.;
Hara, H.; Kubo, M.; Mikami, I.; Saito, H.; Matsushita, T.; Kawaguchi,
N.; Nakaoji, T.; Nagae, K.; Shimada, S.; Takeyama, N.; Yamamuro, T.
Bibcode: 2008SoPh..249..197S
Altcode: 2008SoPh..tmp...26S
The Solar Optical Telescope (SOT) aboard the Solar-B satellite (Hinode)
is designed to perform high-precision photometric and polarimetric
observations of the Sun in visible light spectra (388 - 668 nm)
with a spatial resolution of 0.2 - 0.3 arcsec. The SOT consists of
two optically separable components: the Optical Telescope Assembly
(OTA), consisting of a 50-cm aperture Gregorian with a collimating lens
unit and an active tip-tilt mirror, and an accompanying Focal Plane
Package (FPP), housing two filtergraphs and a spectro-polarimeter. The
optomechanical and optothermal performance of the OTA is crucial to
attain unprecedented high-quality solar observations. We describe in
detail the instrument design and expected stable diffraction-limited
on-orbit performance of the OTA, the largest state-of-the-art solar
telescope yet flown in space.
Title: Coronal Plasma Motions near Footpoints of Active Region Loops
Revealed from Spectroscopic Observations with Hinode EIS
Authors: Hara, Hirohisa; Watanabe, Tetsuya; Harra, Louise K.; Culhane,
J. Leonard; Young, Peter R.; Mariska, John T.; Doschek, George A.
Bibcode: 2008ApJ...678L..67H
Altcode:
The solar active region 10938 has been observed from the disk center
to the west limb with the Hinode EUV Imaging Spectrometer. In the
disk-center observation, subsonic upflow motions of tens of km
s-1 and enhanced nonthermal velocities have been found
near the footpoints of the active region loops assuming a single
Gaussian approximation for the emission-line profiles. When the same
part of the active region is observed near the limb, both upflows
and enhanced nonthermal velocities essentially decrease. There
is a strong correlation between Doppler velocity and nonthermal
velocity. Significant deviations from a single Gaussian profile are
found in the blue wing of the line profiles for the upflows. These
suggest that there are unresolved high-speed upflows. We discuss the
implications for coronal heating mechanisms.
Title: Outflows at the Edges of Active Regions: Contribution to
Solar Wind Formation?
Authors: Harra, L. K.; Sakao, T.; Mandrini, C. H.; Hara, H.; Imada,
S.; Young, P. R.; van Driel-Gesztelyi, L.; Baker, D.
Bibcode: 2008ApJ...676L.147H
Altcode:
The formation of the slow solar wind has been debated for many years. In
this Letter we show evidence of persistent outflow at the edges of
an active region as measured by the EUV Imaging Spectrometer on board
Hinode. The Doppler velocity ranged between 20 and 50 km s-1
and was consistent with a steady flow seen in the X-Ray Telescope. The
latter showed steady, pulsing outflowing material and some transverse
motions of the loops. We analyze the magnetic field around the active
region and produce a coronal magnetic field model. We determine from
the latter that the outflow speeds adjusted for line-of-sight effects
can reach over 100 km s-1. We can interpret this outflow as
expansion of loops that lie over the active region, which may either
reconnect with neighboring large-scale loops or are likely to open to
the interplanetary space. This material constitutes at least part of
the slow solar wind.
Title: Observation and Modeling of Coronal "Moss" With the EUV
Imaging Spectrometer on Hinode
Authors: Warren, Harry P.; Winebarger, Amy R.; Mariska, John T.;
Doschek, George A.; Hara, Hirohisa
Bibcode: 2008ApJ...677.1395W
Altcode: 2007arXiv0709.0396W
Observations of transition region emission in solar active regions
represent a powerful tool for determining the properties of hot coronal
loops. We present the analysis of new observations of active region
moss taken with the Extreme Ultraviolet Imaging Spectrometer (EIS)
on the Hinode satellite. EIS observations of a density sensitive Fe
XII line ratio suggest moss densities of approximately 1010
cm-3 and pressures of 3 × 1016 cm-3
K. We find that the moss intensities predicted by steady, uniformly
heated loop models are too intense relative to the observations,
consistent with previous work. To bring the steady heating model into
agreement with the observations a filling factor is required. Our
analysis indicates that the filling factor in the moss is nonuniform
and varies inversely with the loop pressure. The intensities predicted
by steady uniform heating are generally consistent with the EIS moss
observations. There are, however, significant discrepancies for the
coolest emission line available in the data we analyze.
Title: 2006 December 17 Long Duration Flare Observed with the Hinode
EUV Imaging Spectrometer
Authors: Hara, Hirohisa; Watanabe, Tetsuya; Matsuzaki, Keiichi; Harra,
Louise K.; Culhane, J. Leonard; Cargill, Peter; Mariska, John T.;
Doschek, George A.
Bibcode: 2008PASJ...60..275H
Altcode:
A GOES C-class long-duration flare that occurred near the west limb on
2006 December 17 was observed with the Hinode EUV Imaging Spectrometer
(EIS) in raster-scan observations. Cusp-shaped arcades are prominent in
the spectroheliogram of the CaXVII emission line at 192.86Å. Spatial
relationships between hot flare loops with a cusp apex and cool post
flare loops with various temperatures are clearly shown in the EIS
observations. We find an enhanced line broadening above the bright
loop-top region in the CaXVII observation. The Doppler observations of
cooling post flare loops with coronal temperatures show both downflows
and upflows along the loops, and these are interpreted as a part of
siphon flows. Enhanced nonthermal line broadenings are identified at
the top of the post flare loops.
Title: Erratum: "Outflows at the Edges of Active Regions: Contribution
to Solar Wind Formation?" (ApJ, 676, L147 [2008])
Authors: Harra, L. K.; Sakao, T.; Mandrini, C. H.; Hara, H.; Imada,
S.; Young, P. R.; van Driel-Gesztelyi, L.; Baker, D.
Bibcode: 2008ApJ...677L.159H
Altcode:
No abstract at ADS
Title: An active region jet observed with Hinode
Authors: Chifor, C.; Young, P. R.; Isobe, H.; Mason, H. E.; Tripathi,
D.; Hara, H.; Yokoyama, T.
Bibcode: 2008A&A...481L..57C
Altcode:
Aims:We study the physical properties of an active region (AR) jet in
order to probe the mechanisms responsible for it.
Methods: We
report 2007 January 15/16 observations of a recurring jet situated on
the west side of NOAA AR 10938. Multi-wavelength data from all three
instruments onboard Hinode were analysed. This paper focuses on one
instance of a jet observed with the Hinode/EUV Imaging Spectrometer
(EIS). Using EIS raster data we measured the temperatures, Doppler
shifts, density, and filling factor.
Results: A strong
blue-shifted component and an indication of a weak red-shifted
component at the base of the jet was observed around Log Te
= 6.2. The up-flow velocities exceeded 150 km s-1. The
jet component was seen over a range of temperatures between 5.4 and
6.4 in Log T_e. Using Fe XII λ186 and λ195 line ratios, we measured
densities above Log Ne = 11 for the high-velocity up-flow
component. We found that the density of the high-velocity up-flow
increases with velocity. We estimate the filling factor in the jet
up-flow to be <0.03. With the Hinode/Solar Optical Telescope (SOT),
we observed recurrent (quasi periodic) magnetic flux cancelations just
before the recurrent jet emission was seen in images taken with the
X-ray Telescope (XRT).
Conclusions: The high-velocity up-flows,
together with the density dependence on velocity, support an evaporation
scenario for the acceleration of this jet. The high density and small
filling factor, coupled with the high Doppler velocities are strongly
suggestive of multiple small-scale magnetic reconnection events being
responsible for the production of both EUV and X-ray jets.
Title: Characteristics of Anemone Active Regions Appearing in Coronal
Holes Observed with the Yohkoh Soft X-Ray Telescope
Authors: Asai, Ayumi; Shibata, Kazunari; Hara, Hirohisa; Nitta,
Nariaki V.
Bibcode: 2008ApJ...673.1188A
Altcode: 2008arXiv0805.4474A
Coronal structure of active regions appearing in coronal holes is
studied, using data that were obtained with the Soft X-Ray Telescope
(SXT) aboard Yohkoh between 1991 November and 1993 March. The following
characteristics are found. Many of the active regions (ARs) appearing
in coronal holes show a structure that looks like a sea anemone. Such
active regions are called anemone ARs. About one-fourth of all active
regions that were observed with SXT from their births showed the
anemone structure. For almost all the anemone ARs, the order of the
magnetic polarities is consistent with the Hale-Nicholson polarity
law. These anemone ARs also showed, to a greater or lesser extent,
an east-west asymmetry in the X-ray intensity distribution, such that
the following (eastern) part of the AR was brighter than its preceding
(western) part. This, as well as the anemone shape itself, is consistent
with the magnetic polarity distribution around the anemone ARs. These
observations also suggest that an active region appearing in coronal
holes has a simpler (less sheared) and more preceding-spot-dominant
magnetic structure than those appearing in other regions.
Title: Hinode: A New Solar Observatory in Space
Authors: Hara, Hirohisa
Bibcode: 2008PFR.....2S1008H
Altcode:
The third Japanese solar observing satellite, SOLAR-B, was launched on
2006 Sep 23 from the Uchinoura Space Center of JAXA and it was named
“Hinode” (sunrise). Hinode carries three major telescopes: Solar
Optical Telescope (SOT), X-Ray Telescope (XRT), and Extreme-ultraviolet
Imaging Spectrometer (EIS). These telescopes have been built in an
international collaboration of Japan, US, and UK for understanding the
formation mechanism of the solar corona, mechanism of dynamic events
such as solar flares and coronal mass ejection, and general magnetic
activities on the sun. All telescopes have started their commissioning
activities after the successful launch of the spacecraft. The
performance of the spacecraft that supports the diffraction-limited
SOT observations and the first-light observation of each telescope
are briefly introduced.
Title: Molecular Contamination Assessments on
<i>Hinode</i> X-Ray Telescope
Authors: Urayama, Fumitaka; Bando, Takamasa; Kano, Ryouhei; Hara,
Hirohisa; Narukage, Noriyuki; Sakao, Taro
Bibcode: 2008JSASS..56..536U
Altcode:
The <i>Hinode</i> (Solar-B) was launched by M-V rocket on 22
September 2006 UT. The telemetry data of the <i>Hinode</i>
X-ray Telescope (XRT) showed that the X-ray count rate detected with
the XRT had decreased rapidly since the operational heaters on the
XRT telescope tube were turned on. This is attributed to the fact that
molecular contaminants accumulated onto the CCD with the temperature
of -60ºC resulting in the degradation of the XRT sensitivity. We baked
the CCD at the temperature of 35ºC in order to remove the contaminants
from the CCD surface. However many contaminant spots appeared on the
surface. We found that major contaminant source existed in the telescope
tube, and identified the contaminants as diethylhexyl phthalate (DEHP)
or DEHP-like organics. The mechanisms to yield the contaminant spots
were discussed.
Title: The relation between explosive events and photospheric
magnetic fields
Authors: Kamio, Suguru; Hara, Hirohisa; Watanabe, Tetsuya
Bibcode: 2008cosp...37.1434K
Altcode: 2008cosp.meet.1434K
The relationship between explosive events and photospheric magnetic
fields in a quiet region is studied by high resolution data obtained
with EIS and SOT on board Hinode. Data from quiet regions near the disk
center were selected and reduced in this paper. He II λ 256.32 (log Te
= 4.7) and other emission lines from the transition region were analyzed
to find a signature of explosive events. Many line-broadening features
are found in the transition region, while they are not found in the
coronal emission lines such as Fe XII λ 195.12. Spectropolarimeter (SP)
allowed us to study photospheric magnetic fields with unprecedentedly
high resolution. In addition, the evolution of magnetic fields was
captured by Narrowband filter imager (NFI). The result indicates that
explosive events occurred around magnetic field patches in the network.
Title: Flare and Erupting Filament of 19th May, 2007 - Sources of
a Magnetic Cloud Observed by Stereo
Authors: Culhane, J. Leonard; Bone, Laura; Hara, Hirohisa; Farrugia,
Charles; Galvin, Antoinette; van Driel-Gesztelyi, Lidia; Popecki,
Mark; Luhmann, Janet G.; Veronig, Astrid
Bibcode: 2008cosp...37..609C
Altcode: 2008cosp.meet..609C
A GOES Class B9.5 flare was observed on the Sun starting 19-May-2007
at 12:51 UT. Data obtained by the Hinode, TRACE, RHESSI, STEREO and
SOHO spacecraft will be discussed. The evolution and eventual eruption
of a related Halpha filament were monitored by patrol observations at
Kanzelhoehe. These observations and associated detection of EUV-emitting
filament material will also be presented. The flare energetics and
the possible role of the flare in the filament eruption will be
examined. Finally the relationship of the magnetic configuration
of the solar eruption along with the temperature and composition of
erupting material will be assessed in relation to the properties of
a magnetic cloud later detected by STEREO in-situ instruments near
Earth on 22-May-2007.
Title: FeXIII density diagnostics for solar coronal and flare plasmas
Authors: Watanabe, Tetsuya; Hara, Hirohisa; Yamamoto, Norimasa; Kato,
Takako; Young, Peter R.
Bibcode: 2008cosp...37.3434W
Altcode: 2008cosp.meet.3434W
Density sensitive FeXIII line ratios were obtained by EUV Imaging
Spectrometer (EUV) on Hinode for quiet-sun, active region, and
flare plasmas. Consistency of density estimates derived from various
density-sensitive line pairs appearing in the EIS observing wavelengths
will be discussed in comparison with theoretical models. The intensity
ratios of FeXIIIλ203.8A/202.0A in flaring active region show its
high-density limit, suggesting that densities at the foot points
of flaring looops exceed 1012 cm-3 , though the value itself is not
exactly consistent with the laboratory data.
Title: Coronal Plasma Motions near Footpoints of Active Region Loops
Revealed from Spectroscopic Observations with {it Hinode} EIS
Authors: Hara, Hirohisa; Watanabe, Tetsuya; Harra, Louise K.; Culhane,
J. Leonard; Young, Peter R.; Doschek, G. A.; Mariska, John
Bibcode: 2008cosp...37.1175H
Altcode: 2008cosp.meet.1175H
We have observed the solar active region 10938 from the disk center
to the west limb with the Hinode EUV Imaging Spectrometer. In the
disk center observation subsonic upflow motions of tens of km s-1 and
enhanced nonthermal velocities have been found near the footpoints of
the active-region loops assuming a single Gaussian approximation for
the emission-line profiles. When the same part of the active region
is observed near the limb, both upflows and enhanced nonthermal
velocities essentially decrease, clearly showing that the enhanced
nonthermal velocities in the disk center observation are mainly due to
line-of-sight motions, which are likely parallel to magnetic field lines
of the coronal loops. There is a strong correlation between Doppler
velocity and nonthermal velocity in the upflow regions. The enhancement
in the blue wing of the line profiles is found for the upflows as a
significant deviation from a single Gaussian profile. These suggest
that there are unresolved high-speed upflows near the footpoints of
active region loops. We discuss the implications for coronal heating
mechanisms.
Title: Differential Rotation Rate of the Solar Corona Estimated From
X-Ray Bright Points
Authors: Hara, Hirohisa
Bibcode: 2008cosp...37.1174H
Altcode: 2008cosp.meet.1174H
The differential rotation rate of the solar corona has statistically
been estimated from the motion of X-ray bright points (XBPs) that were
observed with the Yohkoh Soft X-ray Telescope (SXT). The statistical
height of XBP is estimated to be 10,000±2,000 km from the constraint
in which the same rotation rate has to be expected in different
longitudes. The differential rotation rate of the corona is finally
derived by considering the height. The estimated rotation rate shows
a similar trend for that of the photospheric magnetic fields that
are evaluated from the local correlation technique. We find that the
rotation rate on the equator changes with a parameter ∆t in the data
analysis that is associated with the lifetime of XBP and that it becomes
slower for shorter ∆t. This trend suggests that the magnetic fields
associated with XBPs with a short lifetime are rooted very shallow
part of the subsurface in the convection zone.
Title: Structures in flaring loops seen in FeXXIII 263.76A line
Authors: Watanabe, T.; Doschek, G. A.; Harra, L. K.; Hara, H.
Bibcode: 2007AGUFMSH52C..03W
Altcode:
EIS observed the highest temperature lines of FeXXIII263.76A,
FeXXIV192.10A, 255.10A in the EIS observing wavelengths during a C4.2
flare occurred on 16-Jan-07, as well as an FeXVII line at 254.83A. The
raster scan of the flaring area took place during 2:36 - 2:41 UT nearly
at the maximum phase of the flare. Comparing a monochromatic FeXXIII
raster image with the other high spatial resolution images taken by the
instruments on board the Hinode and those by Nobeyama Radio Heliograph,
electron precipitation cites are indentified. Foot points with fast
chromospheric evaporation are compact at the size of a few arcseconds,
and the turbulence still remain around the top of flaring loops. Down
flows are also seen in the lower temperature lines just outside the
flaring loops.
Title: Continuous Plasma Outflows from the Edge of a Solar Active
Region as a Possible Source of Solar Wind
Authors: Sakao, Taro; Kano, Ryouhei; Narukage, Noriyuki; Kotoku,
Jun'ichi; Bando, Takamasa; DeLuca, Edward E.; Lundquist, Loraine L.;
Tsuneta, Saku; Harra, Louise K.; Katsukawa, Yukio; Kubo, Masahito;
Hara, Hirohisa; Matsuzaki, Keiichi; Shimojo, Masumi; Bookbinder, Jay
A.; Golub, Leon; Korreck, Kelly E.; Su, Yingna; Shibasaki, Kiyoto;
Shimizu, Toshifumi; Nakatani, Ichiro
Bibcode: 2007Sci...318.1585S
Altcode:
The Sun continuously expels a huge amount of ionized material into
interplanetary space as the solar wind. Despite its influence on the
heliospheric environment, the origin of the solar wind has yet to
be well identified. In this paper, we report Hinode X-ray Telescope
observations of a solar active region. At the edge of the active region,
located adjacent to a coronal hole, a pattern of continuous outflow of
soft-x-ray emitting plasmas was identified emanating along apparently
open magnetic field lines and into the upper corona. Estimates of
temperature and density for the outflowing plasmas suggest a mass
loss rate that amounts to ~1/4 of the total mass loss rate of the
solar wind. These outflows may be indicative of one of the solar wind
sources at the Sun.
Title: Study of Two Long Duration Eruptive Flares with the Hinode
and RHESSI Spacecraft
Authors: Culhane, J. L.; Bone, L.; Williams, D. R.; Brooks, D. H.;
Vandriel-Gesztelyi, L.; Hara, H.; Veronig, A.
Bibcode: 2007AGUFMSH52C..05C
Altcode:
Two eruptive flares that occurred on 17 December 2006 and 19 May
2007 were observed by the instruments on the Hinode and RHESSI
spacecraft. Both share some of the characteristics of the well known
event observed with Yohkoh in February, 1992 (Tsuneta et al., 1992)
in that they seem largely thermal in character and exhibit many of
the features of the standard Carmichael, Hirayama, Sturrock, Kopp,
Pneuman (CHSKP) flare model. However for these events, much additional
(e.g. SOHO) data is available including the observation of an associated
erupting filament on 19th May that was seen at the Kanzelhoehe Solar
Observatory. In this talk the role of the outflow termination shock
in heating the flare plasma will be re-examined. In particular the
presence of plasma over a wide temperature range in the flare cusps
and the possibility of non-thermal effects following the shock heating,
will be assessed. The behaviour of the erupting filament material will
also be discussed.
Title: Solar Transition Region Features Observed with Hinode/EIS
Authors: Young, Peter R.; Del Zanna, Giulio; Mason, Helen E.; Doschek,
George A.; Culhane, Len; Hara, Hirohisa
Bibcode: 2007PASJ...59S.727Y
Altcode: 2007arXiv0706.1856Y
Two types of solar active region feature prominent at transition region
temperatures are identified in Hinode/EIS data of AR 10938 taken on
2007 January 20. The footpoints of 1 MK TRACE loops are shown to emit
strongly in emission lines formed at log T = 5.4-5.8, allowing the
temperature increase along the footpoints to be clearly seen. A density
diagnostic of Mg VII yields the density in the footpoints, with one
loop showing a decrease from 3 × 109 cm-3 at the
base to 1.5 × 109 cm-3 at a projected height
of 20 Mm. The second feature is a compact active region transition
region brightening which is particularly intense in O V emission
(log T = 5.4) but also has a signature at temperatures up to log T =
6.3. The Mg VII diagnostic gives a density of 4 × 1010
cm-3, and emission lines of Mg VI and Mg VII show line
profiles broadened by 50kms-1 and wings extending beyond
± 200kms-1. Continuum emission in the short wavelength
band is also found to be enhanced, and is suggested to be free-bound
emission from recombination onto He+.
Title: Hot and Cool Loops Composing the Corona of the Quiet Sun
Authors: Matsuzaki, Keiichi; Hara, Hirohisa; Watanabe, Tetsuya; Dere,
Kenneth P.; Brown, Charles M.; Culhane, Len
Bibcode: 2007PASJ...59S.683M
Altcode:
We performed a raster scan observation of the quiet Sun with the EUV
Imaging Spectrometer (EIS) aboard Hinode and simultaneously analyzed
observed emission lines of Fe VIII to XV. From a combined analysis,
radiance maps from the observed emission lines were deconvolved into
plasma components at five representative temperatures between 0.40MK and
2.63MK. While the lowest temperature component shows network structures
on spatial scales of between 10" and 20", the higher temperature
components show thread-like patterns on larger scales. A comparison of
emission measures at the different temperatures suggests that the lowest
temperature component is mainly composed of bodies of small loops,
rather than a collection of foot points of the higher temperature
loops. The difference in morphologies is interpreted as being due to
different magnetic field configurations, loops within super-granule
cells and fields extending beyond the boundaries of super-granule cells,
with distinct peak temperatures following a loop scaling law.
Title: Temperature and Density Structures of Solar Corona, A Test
of Iron Line Diagnostic Capability of EIS Instrument on Board Hinode
Authors: Watanabe, Tetsuya; Hara, Hirohisa; Culhane, Len; Harra,
Louise K.; Doschek, George A.; Mariska, John T.; Young, Peter R.
Bibcode: 2007PASJ...59S.669W
Altcode:
Increased diagnostic capability of the EUV Imaging Spectrometer
(EIS) aboard Hinode (former Solar-B) has been demonstrated with
a set of iron emission lines emerging in the two EIS observing
wavelength bands (170-210Å and 250-290Å) and their line-intensity
ratios. ``Abundance-uncertainty'' free relative emission measure
distributions as a function of temperature were deduced using only iron
emission lines of various ionization stages. First-light spectra of a
small active region show iron lines ranging from FeVIII (185.2Å and
186.6Å) through FeXVII (204.7Å, 254.9Å, and 269.4Å). Spectra of a
C-class flare confirms the presence of one of these higher temperature
lines (FeXVII at 254.9Å) more clearly, as well showing FeXXIV (192.0Å
and 255.1Å) and FeXXIII (263.8Å), which are normally only seen at
flare temperatures.
Title: Observations of Transient Active Region Heating with Hinode
Authors: Warren, Harry P.; Ugarte-Urra, Ignacio; Brooks, David H.;
Cirtain, Jonathan W.; Williams, David R.; Hara, Hirohisa
Bibcode: 2007PASJ...59S.675W
Altcode: 2007arXiv0711.0357W
We present observations of transient active region heating events
observed with the Extreme Ultraviolet Imaging Spectrometer (EIS) and
X-ray Telescope (XRT) on Hinode. This initial investigation focuses
on NOAA active region 10940 as observed by Hinode on 2007 February 1
between 12 and 19UT. In these observations we find numerous examples
of transient heating events within the active region. The high spatial
resolution and broad temperature coverage of these instruments allows
us to track the evolution of coronal plasma. The evolution of the
emission observed with XRT and EIS during these events is generally
consistent with loops that have been heated and are cooling. We have
analyzed the most energetic heating event observed during this period,
a small GOES B-class flare, in some detail and present some of the
spectral signatures of the event, such as relative Doppler shifts at
one of the loop footpoints and enhanced line widths during the rise
phase of the event. While the analysis of these transient events has
the potential to yield insights into the coronal heating mechanism,
these observations do not rule out the possibility that there is a
strong steady heating level in the active region. Detailed statistical
analysis will be required to address this question definitively.
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: EUV Emission Lines and Diagnostics Observed with Hinode/EIS
Authors: Young, Peter R.; Del Zanna, Giulio; Mason, Helen E.; Dere,
Ken P.; Landi, Enrico; Landini, Massimo; Doschek, George A.; Brown,
Charles M.; Culhane, Len; Harra, Louise K.; Watanabe, Tetsuya; Hara,
Hirohisa
Bibcode: 2007PASJ...59S.857Y
Altcode: 2007arXiv0706.1857Y
Quiet Sun and active region spectra from the Hinode/EIS instrument are
presented, and the strongest lines from different temperature regions
discussed. A list of emission lines recommended to be included in EIS
observation studies is presented based on analysis of blending and
diagnostic potential using the CHIANTI atomic database. In addition
we identify the most useful density diagnostics from the ions covered
by EIS.
Title: Hinode EUV Imaging Spectrometer Observations of Solar Active
Region Dynamics
Authors: Mariska, John T.; Warren, Harry P.; Ugarte-Urra, Ignacio;
Brooks, David H.; Williams, David R.; Hara, Hirohisa
Bibcode: 2007PASJ...59S.713M
Altcode: 2007arXiv0708.4309M
The EUV Imaging Spectrometer (EIS) on the Hinode satellite is capable of
measuring emission line center positions for Gaussian line profiles to a
fraction of a spectral pixel, resulting in relative solar Doppler-shift
measurements with an accuracy of a less than a km s-1 for
strong lines. We show an example of the application of that capability
to an active region sit-and-stare observation in which the EIS slit
is placed at one location on the Sun and many exposures are taken
while the spacecraft tracking keeps the same solar location within
the slit. For the active region examined (NOAA10930), we find that
significant intensity and Doppler-shift fluctuations as a function of
time are present at a number of locations. These fluctuations appear
to be similar to those observed in high-temperature emission lines
with other space-borne spectroscopic instruments. With its increased
sensitivity over earlier spectrometers and its ability to image many
emission lines simultaneously, EIS should provide significant new
constraints on Doppler-shift oscillations in the corona.
Title: Velocity Structure of Jets in a Coronal Hole
Authors: Kamio, Suguru; Hara, Hirohisa; Watanabe, Tetsuya; Matsuzaki,
Keiichi; Shibata, Kazunari; Culhane, Len; Warren, Harry P.
Bibcode: 2007PASJ...59S.757K
Altcode: 2007arXiv0711.2848K
The velocity structures of jets in a coronal hole have been derived
for the first time. Hinode observations revealed the existence
of many bright points in coronal holes. They are loop-shaped and
sometimes associated with coronal jets. Spectra obtained with the
Extreme-ultraviolet Imaging Spectrometer aboard Hinode were analyzed
to infer the Doppler velocity of bright loops and jets in a coronal
hole of the north polar region. Elongated jets above bright loops are
found to be blue-shifted by 30kms-1 at maximum, while foot
points of bright loops are red-shifted. Blue-shifts detected in coronal
jets are interpreted as being upflows produced by magnetic reconnection
between emerging flux and the ambient field in the coronal hole.
Title: Discovery of a Temperature-Dependent Upflow in the Plage
Region During a Gradual Phase of the X-Class Flare
Authors: Imada, Shinsuke; Hara, Hirohisa; Watanabe, Tetsuya; Kamio,
Suguru; Asai, Ayumi; Matsuzaki, Keiichi; Harra, Louise K.; Mariska,
John T.
Bibcode: 2007PASJ...59S.793I
Altcode:
We present Hinode/EIS raster scan observations of the plage region
taken during the gradual phase of the GOES X3.2 flare that occurred on
2006 December 13. The plage region is located 200" east of the flare
arcade. The plage region has a small transient coronal hole. The
transient coronal hole is strongly affected by an X-class flare,
and upflows are observed at its boundary. Multi-wavelength spectral
observations allow us to determine velocities from the Doppler shifts
at different temperatures. Strong upflows along with stationary plasma
have been observed in the FeXV line 284.2Å (log T / K = 6.3) in the
plage region. The strong upflows reach almost 150kms-1, which
was estimated by a two-component Gaussian fitting. On the other hand,
at a lower corona/transition region temperature (HeII, 256.3Å, log T /
K = 4.9), very weak upflows, almost stationary, have been observed. We
find that these upflow velocities clearly depend on the temperature
with the hottest line, FeXV, showing the fastest upflow velocity and the
second-highest line, FeXIV, showing the second-highest upflow velocity
(130kms-1). All velocities are below the sound speed. The
trend of the upflow dependence on temperature dramatically changes
at 1MK. These results suggest that heating may have an important role
for strong upflow.
Title: Coronal Dimming Observed with Hinode: Outflows Related to a
Coronal Mass Ejection
Authors: Harra, Louise K.; Hara, Hirohisa; Imada, Shinsuke; Young,
Peter R.; Williams, David R.; Sterling, Alphonse C.; Korendyke,
Clarence; Attrill, Gemma D. R.
Bibcode: 2007PASJ...59S.801H
Altcode:
Coronal dimming has been a signature used to determine the source
of plasma that forms part of a coronal mass ejection (CME) for many
years. Generally dimming is detected through imaging instruments such
as SOHO EIT by taking difference images. Hinode tracked active region
10930 from which there were a series of flares. We combined dimming
observations from EIT with Hinode data to show the impact of flares
and coronal mass ejections on the region surrounding the flaring
active region, and we discuss evidence that the eruption resulted in
a prolonged steady outflow of material from the corona. The dimming
region shows clear structure with extended loops whose footpoints are
the source of the strongest outflow (≈ 40 kms-1). This
confirms that the loops that are disrupted during the event do lose
plasma and hence are likely to form part of the CME. This is the
first time the velocity of the coronal plasma has been measured in an
extended dimming region away from the flare core. In addition there
was a weaker steady outflow from extended, faint loops outside the
active region before the eruption, which is also long lasting. These
were disturbed and the velocity increased following the flare. Such
outflows could be the source of the slow solar wind.
Title: Wavelength Determination for Solar Features Observed by the
EUV Imaging Spectrometer on Hinode
Authors: Brown, Charles M.; Hara, Hirohisa; Kamio, Suguru; Feldman,
Uri; Seely, John F.; Doschek, George A.; Mariska, John T.; Korendyke,
Clarence M.; Lang, James; Dere, Kenneth P.; Culhane, Len; Thomas,
Roger J.; Davila, Joseph M.
Bibcode: 2007PASJ...59S.865B
Altcode:
A wavelength calibration of solar lines observed by the high
resolution EUV Imaging Spectrometer (EIS) on the Hinode satellite
is reported. Spectral features of the quiet sun and of two mildly
active areas were measured and calibrated. A listing of the stronger
observed lines with identification of the leading contributor ions
is presented. 41 lines are reported, with 90% identified. Wavelength
precisions (2σ) of ±0.0031Å for the EIS short band and ±0.0029Å
for the EIS long band are obtained. These lines, typical of 1-2
×106 K plasmas, are recommended as standards for the
establishment of EIS wavelength scales. The temperature of EIS varies
by about 1D.5 C around the orbit and also with spacecraft pointing. The
correlation of these temperature changes with wavelength versus pixel
number scale changes is reported.
Title: Nonthermal Velocities in Solar Active Regions Observed with
the Extreme-Ultraviolet Imaging Spectrometer on Hinode
Authors: Doschek, G. A.; Mariska, J. T.; Warren, H. P.; Brown, C. M.;
Culhane, J. L.; Hara, H.; Watanabe, T.; Young, P. R.; Mason, H. E.
Bibcode: 2007ApJ...667L.109D
Altcode:
We discuss nonthermal velocities in an active region as revealed
by the Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Hinode
spacecraft. The velocities are derived from spectral line profiles in
the extreme-ultraviolet (EUV) from a strong line of Fe XII at 195.12 Å
by fitting each line profile to a Gaussian function. We compare maps
of the full width at half-maximum values, the Fe XII spectral line
intensity, the Fe XII Doppler shift, the electron temperature, and
electron density. We find that the largest widths in the active region
do not occur in the most intense regions, but seem to concentrate in
less intense regions, some of which are directly adjacent to coronal
loops, and some of which concentrate in regions which also exhibit
relative Doppler outflows. The increased widths can also occur over
extended parts of the active region.
Title: Comparison of solar spectra from the Hinode extreme-ultraviolet
imaging spectrometer (EIS) to preflight calibrations
Authors: Seely, John; Feldman, Uri; Brown, Charles; Doschek, George;
Hara, H.
Bibcode: 2007SPIE.6688E..0WS
Altcode: 2007SPIE.6688E..29S
The Extreme-Ultraviolet Imaging Spectrometer (EIS) on the Hinode
satellite records high-resolution solar spectra in the 170-210 Å
and 246-290 Å wavelength ranges. The EIS optics operate at near
normal incidence and consist of an off-axis parabolic mirror, a
toroidal diffraction grating, two CCD detectors, and two thin aluminum
filters. To increase the normal incidence efficiency, high-reflectance
multilayer interference coatings were deposited on the mirror and the
grating. Prior to launch, each of the optical components was calibrated
using synchrotron radiation, and the spectral and spatial resolution
of the complete instrument were measured. In this paper, we compare the
preflight calibrations with the first-light spectra recorded in space.
Title: The EUV Imaging Spectrometer for Hinode
Authors: Culhane, J. L.; Harra, L. K.; James, A. M.; Al-Janabi, K.;
Bradley, L. J.; Chaudry, R. A.; Rees, K.; Tandy, J. A.; Thomas, P.;
Whillock, M. C. R.; Winter, B.; Doschek, G. A.; Korendyke, C. M.;
Brown, C. M.; Myers, S.; Mariska, J.; Seely, J.; Lang, J.; Kent,
B. J.; Shaughnessy, B. M.; Young, P. R.; Simnett, G. M.; Castelli,
C. M.; Mahmoud, S.; Mapson-Menard, H.; Probyn, B. J.; Thomas, R. J.;
Davila, J.; Dere, K.; Windt, D.; Shea, J.; Hagood, R.; Moye, R.; Hara,
H.; Watanabe, T.; Matsuzaki, K.; Kosugi, T.; Hansteen, V.; Wikstol, Ø.
Bibcode: 2007SoPh..243...19C
Altcode:
The EUV Imaging Spectrometer (EIS) on Hinode will observe solar corona
and upper transition region emission lines in the wavelength ranges
170 - 210 Å and 250 - 290 Å. The line centroid positions and profile
widths will allow plasma velocities and turbulent or non-thermal line
broadenings to be measured. We will derive local plasma temperatures and
densities from the line intensities. The spectra will allow accurate
determination of differential emission measure and element abundances
within a variety of corona and transition region structures. These
powerful spectroscopic diagnostics will allow identification
and characterization of magnetic reconnection and wave propagation
processes in the upper solar atmosphere. We will also directly study
the detailed evolution and heating of coronal loops. The EIS instrument
incorporates a unique two element, normal incidence design. The optics
are coated with optimized multilayer coatings. We have selected highly
efficient, backside-illuminated, thinned CCDs. These design features
result in an instrument that has significantly greater effective area
than previous orbiting EUV spectrographs with typical active region
2 - 5 s exposure times in the brightest lines. EIS can scan a field
of 6×8.5 arc min with spatial and velocity scales of 1 arc sec and
25 km s−1 per pixel. The instrument design, its absolute
calibration, and performance are described in detail in this paper. EIS
will be used along with the Solar Optical Telescope (SOT) and the X-ray
Telescope (XRT) for a wide range of studies of the solar atmosphere.
Title: The Hinode (Solar-B) Mission: An Overview
Authors: Kosugi, T.; Matsuzaki, K.; Sakao, T.; Shimizu, T.; Sone,
Y.; Tachikawa, S.; Hashimoto, T.; Minesugi, K.; Ohnishi, A.; Yamada,
T.; Tsuneta, S.; Hara, H.; Ichimoto, K.; Suematsu, Y.; Shimojo, M.;
Watanabe, T.; Shimada, S.; Davis, J. M.; Hill, L. D.; Owens, J. K.;
Title, A. M.; Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Golub, L.
Bibcode: 2007SoPh..243....3K
Altcode:
The Hinode satellite (formerly Solar-B) of the Japan Aerospace
Exploration Agency's Institute of Space and Astronautical Science
(ISAS/JAXA) was successfully launched in September 2006. As the
successor to the Yohkoh mission, it aims to understand how magnetic
energy gets transferred from the photosphere to the upper atmosphere
and results in explosive energy releases. Hinode is an observatory
style mission, with all the instruments being designed and built to
work together to address the science aims. There are three instruments
onboard: the Solar Optical Telescope (SOT), the EUV Imaging Spectrometer
(EIS), and the X-Ray Telescope (XRT). This paper provides an overview
of the mission, detailing the satellite, the scientific payload, and
operations. It will conclude with discussions on how the international
science community can participate in the analysis of the mission data.
Title: The X-Ray Telescope (XRT) for the Hinode Mission
Authors: Golub, L.; DeLuca, E.; Austin, G.; Bookbinder, J.; Caldwell,
D.; Cheimets, P.; Cirtain, J.; Cosmo, M.; Reid, P.; Sette, A.; Weber,
M.; Sakao, T.; Kano, R.; Shibasaki, K.; Hara, H.; Tsuneta, S.; Kumagai,
K.; Tamura, T.; Shimojo, M.; McCracken, J.; Carpenter, J.; Haight,
H.; Siler, R.; Wright, E.; Tucker, J.; Rutledge, H.; Barbera, M.;
Peres, G.; Varisco, S.
Bibcode: 2007SoPh..243...63G
Altcode:
The X-ray Telescope (XRT) of the Hinode mission provides an
unprecedented combination of spatial and temporal resolution in solar
coronal studies. The high sensitivity and broad dynamic range of XRT,
coupled with the spacecraft's onboard memory capacity and the planned
downlink capability will permit a broad range of coronal studies over
an extended period of time, for targets ranging from quiet Sun to
X-flares. This paper discusses in detail the design, calibration, and
measured performance of the XRT instrument up to the focal plane. The
CCD camera and data handling are discussed separately in a companion
paper.
Title: Coronal dimming observed with Hinode
Authors: Harra, Louise; Hara, H.; Young, P.; Williams, D.; Sterling,
A.; Attrill, G.
Bibcode: 2007AAS...210.6305H
Altcode: 2007BAAS...39..172H
Coronal dimming has been a technique used to determine the source
of plasma that forms part of a coronal mass ejection. Generally
dimming is detected through imaging instruments such as SOHO EIT by
taking difference images. In a few cases the SOHO-CDS has been used
to determine outflowing material, and a decrease in density. Hinode
tracked active region 10930 from which there were a series of flares. We
combine dimming observations from EIT with Hinode data to show the
impact of flares and coronal mass ejections on the region surrounding
the flaring active region, and we discuss evidence that the eruption
resulted in a prolonged steady outflow of material from the corona.
Title: EIS/Hinode Look At Active Region Dynamics
Authors: Ugarte-Urra, Ignacio; Warren, H. P.; Brooks, D. H.; Williams,
D. R.; Cirtain, J. W.; McKenzie, D. E.; Weber, M.; Hara, H.; Harra,
L. K.
Bibcode: 2007AAS...210.9429U
Altcode: 2007BAAS...39..222U
We present some initial results from the Hinode EUV Imaging Spectrometer
(EIS) on the heating and cooling of active region loops. The events
we observe are part of the short term active region evolution within
the span of 50 hours of sit-and-stare observations. We investigate
the temporal evolution of the intensity and Doppler shift of spectral
lines formed at different temperatures. We then determine time lags
and cooling times at various temperature regimes and discuss the
results in the context of previous results provided by earlier space
missions. This effort is considered a first step into the hydrodynamic
modeling of the loop structures. The morphology of the structures is
obtained from X-Ray Telescope (XRT) and TRACE images.
Title: A Long-duration Flare Observed With Hinode EIS
Authors: Hara, Hirohisa; Watanabe, T.; Harra, L.; Culhane, L.; Cargill,
P.; Doschek, G.; Mariska, J.
Bibcode: 2007AAS...210.6802H
Altcode: 2007BAAS...39..175H
Long-duration solar flares generally have a cusp apex at the loop
top. The cusp shape reflects the topology of magnetic fields near
the flare-loop top and it is one of the indirect pieces of evidence
supporting the occurrence of the magnetic reconnection process above
flare loops. The Hinode EUV Imaging Spectrometer (EIS) observed a
long-duration flare that occurred on 2006 Dec 17. We present the first
EIS spectroscopic observation of cusp-shaped flare loops. We also
report velocity fields around the cusp structures and post-flare loops.
Title: Intercalibration of the X-ray Telescope and the EUV Imaging
Spectrometer on Hinode
Authors: Golub, Leon; Cirtain, J.; DeLuca, E. E.; Hara, H.; Warren,
H.; Weber, M.
Bibcode: 2007AAS...210.9418G
Altcode: 2007BAAS...39..220G
The X-Ray Telescope and the Extreme-Ultra Violet Imaging Spectrometer
on Hinode are designed to measure the emission of excited ions formed
at temperatures ranging from 104-108 K. The
temperature overlap of these two telescope is from 0.7 to 20 MK, and
an on-orbit calibration of the sensitivity of the two instruments
to solar features will provide a basis for future observational
comparisons. Using calibrated samples of data from each instrument,
and relying to a great extent on the CHIANTI spectral code, we have
derived an estimate of the inter-calibration of the two telescope
for a variety of different solar features and conditions. This is a
major step in enhancing our ability to use the instruments together
for providing quantitative diagnostics of the solar plasma.
Title: Continuous Upflow of Plasmas at the Edge of an Active Region
as Revealed by the X-ray Telescope (XRT) aboard Hinode
Authors: Sakao, Taro; Kano, R.; Narukage, N.; Kotoku, J.; Bando, T.;
DeLuca, E. E.; Lundquist, L. L.; Golub, L.; Kubo, M.; Katsukawa, Y.;
Tsuneta, S.; Hara, H.; Matsuzaki, K.; Shimojo, M.; Shibasaki, K.;
Shimizu, T.; Nakatani, I.
Bibcode: 2007AAS...210.7205S
Altcode: 2007BAAS...39Q.179S
We present X-ray imaging observations with Hinode X-Ray Telescope (XRT)
of an active region NOAA AR 10942 made in the period of 20-22 February
2007. A prominent feature that drew our particular attention is that
there revealed continuous upflow of soft-X-ray-emitting plasmas along
apparently-open field lines towards the outer corona emanating from the
edge of the active region. The field lines are originated from
an ensamble of small spots of following polarity, and are located at
a border between the active region and an adjacent equatorial coronal
hole(s) located to the east. The upflow was observed to be continuous
throughout the three days of observation intervals with projected
velocity of 140 km/s, accompanied with undulating motion of the field
lines. We assert that these upflowing plasmas would be a possible
source of slow solar wind material, which supports a foresighted
notion which grew out of interplanetary scintillation observations
that slow solar wind most likely has its origin in the vicinity of
active regions with large flux expansion (Kojima et al. 1999). A
preliminaty analysis indicates that the temperature of the upflowing
material near the base of the field lines is 1.3 MK with number density
of 2 × 109 /cm3. Assuming that all the material
is to escape to the interplanetary space, this leads to a mass loss
rate of 2 × 1011 g/s which amounts to a good fraction of
the total mass loss rate for solar wind. It is noteworthy that, even
apart from this unique upflow, we see continuous (up)flows of plasmas
anywhere around (surrounding) the active region. Details of the
upflow will be presented and their possible implication to slow solar
wind discussed.
Title: Iron Line Ratio Analysis in an Active Region
Authors: Watanabe, Tetsuya; Hara, H.; Culhane, J. L.; Harra, L. K.;
Doschek, G. A.; Mariska, J. T.; Young, P. R.; Hinode EIS Team
Bibcode: 2007AAS...210.7204W
Altcode: 2007BAAS...39..179W
Increased diagnostic capability of the EIS instrument on board Hinode
(Solar-B) is demonstrated with a set of iron emission lines appearing
in the two EIS observing wavelengths (170 - 210 A & 250 - 290
A) and their line intensity ratios. First-light spectra of a small
active region show iron lines at the ionization stages of FeVIII
(185.2 A & 186.6 A) through FeXVII (204.7 A, 254.9 A, & 269.4
A). Decay phase spectra of a C-class flare confirms the presence of
this higher temperature line; FeXVII at 254.9 A more clearly, as well
as those lines of flare temperatures; FeXXIV (192.0 A & 255.1 A)
and FeXXIII (263.8 A).
Title: Temperature Structures Above Coronal Hole and Quiet Sun
Authors: Kano, Ryouhei; Sakao, T.; Narukage, N.; Kotoku, J.; Bando,
T.; DeLuca, E. E.; Lundquist, L.; Golub, L.; Tsuneta, S.; Hara, H.;
Shibasaki, K.; Shimojo, M.
Bibcode: 2007AAS...210.9436K
Altcode: 2007BAAS...39..223K
The X-ray Telescope (XRT) on board Hinode satelite has the capability
to derive the temperature structure in the solar corona. We present
the hieght dependence of the temperature above the limb. Because X-ray
intensity above the limb is so faint, it is important to estimate the
scattered light from disk corona. The eclipses happened on February 17
and March 19 in 2007 at Hinode orbit. On February 17, we took X-ray
images above the south polar coronal hole, while Moon passed it. On
March 19, we took the data for quiet Sun in the same way. We
can estimated the scattered light from the eclipse data, and derived
the scatter-free X-ray images above the solar limb. In this meeting,
we will present the temperatures above coronal hole and quiet Sun,
based on the eclipse data.
Title: 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: Optics and mechanisms for the Extreme-Ultraviolet Imaging
Spectrometer on the Solar-B satellite
Authors: Korendyke, Clarence M.; Brown, Charles M.; Thomas, Roger J.;
Keyser, Christian; Davila, Joseph; Hagood, Robert; Hara, Hirohisa;
Heidemann, Klaus; James, Adrian M.; Lang, James; Mariska, John T.;
Moser, John; Moye, Robert; Myers, Steven; Probyn, Brian J.; Seely,
John F.; Shea, John; Shepler, Ed; Tandy, Jason
Bibcode: 2006ApOpt..45.8674K
Altcode:
The Extreme-Ultraviolet Imaging Spectrometer (EIS) is the first of a
new generation of normal-incidence, two-optical-element spectroscopic
instruments developed for space solar extreme-ultraviolet astronomy. The
instrument is currently mounted on the Solar-B satellite for a planned
launch in late 2006. The instrument observes in two spectral bands,
170-210 Å and 250-290 Å. The spectrograph geometry and grating
prescription were optimized to obtain excellent imaging while still
maintaining readily achievable physical and fabrication tolerances. A
refined technique using low ruling density surrogate gratings and
optical metrology was developed to align the instrument with visible
light. Slit rasters of the solar surface are obtained by mechanically
tilting the mirror. A slit exchange mechanism allows selection among
four slits at the telescope focal plane. Each slit is precisely located
at the focal plane. The spectrograph imaging performance was optically
characterized in the laboratory. The resolution was measured using
the Mg iii and Ne iii lines in the range of 171-200 Å. The He ii line
at 256 Å and Ne iii lines were used in the range of 251-284 Å. The
measurements demonstrate an equivalent resolution of ∼2 arc sec on
the solar surface, in good agreement with the predicted performance. We
describe the EIS optics, mechanisms, and measured performance.
Title: A Spectroscopic Observation of a Magnetic Reconnection Site
in a Small Flaring Event
Authors: Hara, Hirohisa; Nishino, Yohei; Ichimoto, Kiyoshi;
Delaboudinière, Jean-Pierre
Bibcode: 2006ApJ...648..712H
Altcode:
We have observed two types of coronal bidirectional flows in a flare
with a small energy release through a spectroscopic observation of
the Fe X emission line at 6374 Å with a ground-based coronagraph
at the Norikura Solar Observatory. We find a bidirectional flow of
+/-3 km s-1 above the top of a flare loop. Remarkable
increases of the line intensity and line width are not observed in
the flow. From the loop geometry and sign of the Fe X Doppler velocity
we conclude that the bidirectional flow is reconnection inflow above
the flare loop. We estimate the reconnection rate to be ~0.003 for
this event. The other bidirectional flow is observed along postflare
loops with significant increases of the line intensity and Doppler
velocity. This flow is interpreted as a cooling upflow having a velocity
of ~10 km s-1 along a postflare loop from its lower part. We
also find that the increase of the nonthermal line width in the loop-top
region starts when the line intensity reaches its peak. This supports
the presence of a mechanism to enhance turbulent plasma motions in
the loop-top region.
Title: The extreme UV imaging spectrometer for the JAXA Solar-B
mission
Authors: Culhane, J. L.; Doschek, G. A.; Watanabe, T.; Smith, A.;
Brown, C.; Hara, H.; Harra, L. K.; James, A. M.; al Janabi, K.;
Kent, B.; Korendyke, C.; Lang, J.; Mariska, J.; Myers, S.; Seely,
J.; Simnett, G.; Tandy, J.; Thomas, R.; Windt, D. L.
Bibcode: 2006SPIE.6266E..0TC
Altcode: 2006SPIE.6266E..22C
The ISAS/JAXA Solar-B mission includes an Extreme-UV Imaging
Spectrometer (EIS). It detects photons in the wavelength ranges 17 -
21 nm and 25 - 29 nm which include emission lines from several highly
ionised species that exist at temperatures log T = 4.7, 5.6, 5.8,
5.9 and 6.0 - 7.3 K. Instrument throughput is increased substantially
by the use of multilayer coatings optimized for maximum reflectance
in the two selected wavelength bands. The use of back-illuminated
CCDs provides significantly enhanced quantum efficiency over that
previously available from microchannel plate systems. In this paper we
will describe the design and operation of the instrument and present
its performance parameters e.g. spectral and spatial resolution and
sensitivity. Preliminary results of recent calibration measurements
will be described. The role of EIS in the Solar-B mission will be
illustrated with reference to the anticipated observing strategy for
the first three months of the mission which will be outlined.
Title: Contamination evaluation and thermal vacuum bakeout for
SOLAR-B visible-light and X-ray telescope
Authors: Tamura, Tomonori; Hara, Hirohisa; Tsuneta, Saku; Ichimoto,
Kiyoshi; Kumagai, Kazuyoshi; Nakagiri, Masao; Shimizu, Toshifumi;
Sakao, Taro; Kano, Ryouhei
Bibcode: 2005RNAOJ...8...21T
Altcode:
In the development of space telescopes, we are concerned about molecular
outgassing materials from telescope components. In particular, for
solar telescopes in space, the deposition of the outgassing materials
may lead to the increase of solar absorptance at a mirror surface
and it causes the thermal distortion due to the resultant temperature
increase. The mirror reflectivity at vacuum ultraviolet wavelengths
is very sensitive to molecular contamination. We have extensively
evaluated reflectance at 121.6nm (Lyman-alpha) of the contamination
witness mirrors exposed to the telescope testing environments in the
SOLAR-B visible-light telescope program. Thermal vacuum bakeout of
flight components is very effective process to reduce the outgassing
rate. We have severe contamination control program during the assembly
and testing of the SOLAR-B telescope up to launch of the satellite.
Title: Development of Heater control equipment for the Solar-B XRT
thermal vacuum test
Authors: Kumagai, Kazuyoshi; Kano, Ryohei; Hara, Hirohisa; Tamura,
Tomonori; Sawa, Masaki; Tsuneta, Saku; Sakao, Taro; Matsuzaki, Keiichi
Bibcode: 2005RNAOJ...8...29K
Altcode:
The thermal vacuum test of the X-ray Telescope (XRT) aboard the
Solar-B satellite was carried out at NASA/Goddard Space Flight Center
(GSFC) since January 2004. For this thermal test, we developed the
Heater Sensor GSE (HS-GSE). It is an equipment to record flight
temperature sensors in the X-ray camera and to control flight camera
heaters. During the GSFC thermal test, the HS-GSE successfully recorded
the camera temperatures every 10 seconds, and controlled the heaters
automatically. We report the system of the HS-GSE successfully recorded
the camera temperatures every 10 seconds, and controlled the heaters
automatically. We report the system of the HS-GSE with the results in
the thermal test.
Title: 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: The Solar-B EUV imaging spectrometer and its science goals
Authors: Culhane, J. L.; Harra, L. K.; Doschek, G. A.; Mariska, J. T.;
Watanabe, T.; Hara, H.
Bibcode: 2005AdSpR..36.1494C
Altcode:
The Solar-B mission includes an Extreme-UV Imaging Spectrometer
(EIS). It detects photons in the ranges 170-210 and 250-290 Å which
include emission lines from several highly ionised species that exist
at temperatures log T = 4.7, 5.6, 5.8, 5.9 and 6.0-7.3 K. In this
paper, we will describe the design and operation of the instrument
and present its performance parameters, e.g., spectral and spatial
resolution and sensitivity. Preliminary results of recent calibration
measurements will be described. Its role in the Solar-B mission will
be illustrated with reference to several key science topics that the
EIS is expected to address. The anticipated observing strategy for
the first three months of the mission will be outlined.
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: Variation of the X-ray Bright Point Number over the Solar
Activity Cycle
Authors: Hara, H.; Nakakubo-Morimoto, K.
Bibcode: 2004ASPC..325..307H
Altcode:
We have counted the number of X-ray bright points (XBPs) in the
quiet-Sun region from Yohkoh soft X-ray images during a period of
1993--2000. Since we define XBPs as a small region that is less than 60
arcsec with a significantly enhanced emission in soft X-ray intensity
compared with the adjacent background corona, the number of XBPs in the
whole Sun area is affected by the soft X-ray intensity of the background
corona and the presence of active regions. Under these conditions,
the number of XBPs in the whole Sun area is anti-correlated with the
sunspot number due to the change of background X-ray intensity and the
occultation by active regions during the 11-year activity cycle. In
order to estimate the real number variation with little artifact,
we have calculated the number of XBPs in a unit area by limiting the
X-ray intensity range of the background corona and by removing a bias
effect of a selected intensity threshold for the XBP counting. The
evaluated change of the XBP number density in the quiet Sun is less
than a factor of two over the period in the present study and there
is no clear enhancement in XBP number near the solar minimum. We
conclude that the number density of XBP is nearly independent of the
11-year solar activity cycle. Since an XBP found in the quiet Sun is
recognized to be an event which is produced through an interacting
process of opposite-polarity magnetic fields in the quiet Sun, the
low-amplitude variation of the XBP number density suggests that there
is a mechanism to create solar magnetic fields, which are different
from those associated with active regions, irrespective of the 11-year
solar activity cycle.
Title: SolarB X-Ray Telescope (XRT)
Authors: Kano, R.; Hara, H.; Shimojo, M.; Tsuneta, S.; Sakao, T.;
Matsuzaki, K.; Kosugi, T.; Golub, L.; Deluca, E. E.; Bookbinder,
J. A.; Cheimets, P.; Owens, J. K.; Hill, L. D.
Bibcode: 2004ASPC..325...15K
Altcode:
The Soft X-ray Telescope (XRT) aboard SolarB is a grazing incidence
X-ray telescope equipped with 2k × 2k CCD. XRT has 1 arcsec resolution
with wide field-of-view of 34 × 34 arcmin. It is sensitive to
<1 MK to 30 MK, allowing us to obtain TRACE-like low temperature
images as well. Co-alignment with SOT and EIS is realized through
the XRT visible light telescope and with temperature overlap with
EIS. Spacecraft mission data processor (MDP) controls XRT through
the sequence tables with versatile autonomous functions such as
exposure control, region-of-interest tracking, flare detection and
flare location identification. Data are compressed either with DPCM or
JPEG, depending on the purpose. This results in higher cadence and/or
wider field-of-view for given telemetry bandwidth. With focus adjust
mechanism, higher resolution of Gaussian focus may be available on-axis.
Title: SolarB EUV Imaging Spectrometer (EIS)
Authors: Hara, H.
Bibcode: 2004ASPC..325...27H
Altcode:
The Extreme-ultraviolet Imaging Spectrometer (EIS) onboard Solar-B
is designed and being developed under international collaboration
to execute spectroscopic observations of the dynamical solar upper
atmosphere in two extreme-ultraviolet wavelength ranges, 170--210 AA and
250--290 AA. These bands include strong emission lines that are formed
at 104.7--107.3 K. A high-cadence spectroscopic
observation with EIS is suitable for the studies of coronal heating
process and it will reveal dynamical plasma motions in/around solar
flares of all sizes. It is of particular importance to specify the key
physics of coronal heating process and solar dynamic events through
collaborative observations with SOT and XRT on the same spacecraft.
Title: Focal plane CCD camera for the X-Ray Telescope (XRT) aboard
SOLAR-B
Authors: Sakao, Taro; Kano, Ryouhei; Hara, Hirohisa; Matsuzaki,
Keiichi; Shimojo, Masumi; Tsuneta, Saku; Kosugi, Takeo; Shibasaki,
Kiyoto; Kumagai, Kazuyoshi; Sawa, Masaki; Tamura, Tomonori; Iwamura,
Satoru; Nakano, Mitsuhiko; Du, Zhangong; Hiyoshi, Kenji; Horii,
Michihiro; Golub, Leon; Bookbinder, Jay A.; Cheimets, Peter C.; Hill,
Lawrence D.; Owens, Jerry K.
Bibcode: 2004SPIE.5487.1189S
Altcode:
We present scientific as well as engineering overview of the X-Ray
Telescope (XRT) aboard the Japanese Solar-B mission to be launched in
2006, with emphasis on the focal plane CCD camera that employs a 2k
x 2k back-thinned CCD. Characterization activities for the flight CCD
camera made at the National Astronomical Observatory of Japan (NAOJ)
are discussed in detail with some of the results presented.
Title: The Solar Optical Telescope onboard the Solar-B
Authors: Ichimoto, Kiyoshi; Tsuneta, Saku; Suematsu, Yoshinori;
Shimizu, Toshifumi; Otsubo, Masashi; Kato, Yoshihiro; Noguchi,
Motokazu; Nakagiri, Masao; Tamura, Tomonori; Katsukawa, Yukio; Kubo,
Masahito; Sakamoto, Yasushi; Hara, Hirohisa; Minesugi, Kenji; Ohnishi,
Akira; Saito, Hideo; Kawaguchi, Noboru; Matsushita, Tadashi; Nakaoji,
Toshitaka; Nagae, Kazuhiro; Sakamoto, Joji; Hasuyama, Yoshihiro;
Mikami, Izumi; Miyawaki, Keizo; Sakurai, Yasushi; Kaido, Nobuaki;
Horiuchi, Toshihida; Shimada, Sadanori; Inoue, Toshio; Mitsutake,
Masaaki; Yoshida, Norimasa; Takahara, Osamu; Takeyama, Norihide;
Suzuki, Masaharu; Abe, Shunichi
Bibcode: 2004SPIE.5487.1142I
Altcode:
The solar optical telescope onboard the Solar-B is aimed to perform a
high precision polarization measurements of the solar spectral lines
in visible wavelengths to obtain, for the first time, continuous
sets of high spatial resolution (~0.2arcsec) and high accuracy
vector-magnetic-field map of the sun for studying the mechanisms
driving the fascinating activity phenomena occurring in the solar
atmosphere. The optical telescope assembly (OTA) is a diffraction
limited, aplanatic Gregorian telescope with an aperture of Φ500mm. With
a collimating lens unit and an active folding mirror, the OTA provides
a pointing-stabilized parallel beam to the focal plane package (FPP)
with a field of view of about 360x200arcsec. In this paper we identify
the key technical issues of OTA for achieving the mission goal and
describe the basic concepts in its optical, mechanical and thermal
designs. The strategy to verify the in-orbit performance of the
telescope is also discussed.
Title: Design and Performance of Tip-Tilt Mirror System for Solar
Telescope
Authors: Kodeki, Kazuhide; Fukushima, Kazuhiko; Hara, Hirohisa; Inoue,
Masao; Kano, Ryouhei; Kashiwase, Toshio; Nagata, Shin'ichi; Sakao,
Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi
Bibcode: 2004JSpRo..41..868K
Altcode:
No abstract at ADS
Title: Development of the Solar-B X-ray telescope focal plane camera
Authors: Kano, Ryouhei; Hara, Hirohisa; Kumagai, Kazuyoshi; Sawa,
Masaki; Tsuneta, Saku; Sakao, Taro; Matsuzaki, Keiichi
Bibcode: 2004naoj.book....5K
Altcode:
No abstract at ADS
Title: Variation of the X-Ray Bright Point Number over the Solar
Activity Cycle
Authors: Hara, H.; Nakakubo-Morimoto, K.
Bibcode: 2003ApJ...589.1062H
Altcode:
We have counted the number of X-ray bright points (XBPs) in the
quiet-Sun region from Yohkoh soft X-ray images during a period of
1993-2000. Since we define XBPs as a small region that is less than ~60"
with a significantly enhanced emission in soft X-ray intensity compared
with the adjacent background corona, the number of XBPs in the whole Sun
area is affected by the soft X-ray intensity of the background corona
and the presence of the solar active regions. Under these conditions,
the number of XBPs in the whole Sun area is anticorrelated with the
sunspot number owing to the change of background X-ray intensity and
the occultation by active regions during the 11 yr activity cycle. In
order to estimate the real number variation with little artifact,
we have calculated the number of XBPs in a unit area by limiting the
X-ray intensity range of the background corona and by removing a bias
effect of a selected intensity threshold for the XBP counting. The
evaluated change of the XBP number density in the quiet Sun is less
than a factor of 2 over the period in the present study, and there
is no clear enhancement in XBP number near the solar minimum. We
conclude that the number density of XBPs is nearly independent of
the 11 yr solar activity cycle. Since an XBP found in the quiet Sun
is believed to be an event that is produced through an interacting
process of opposite-polarity magnetic fields in the quiet Sun, the
low-amplitude variation of the XBP number density suggests that there
is a mechanism to create solar magnetic fields, which are different
from those associated with active regions, irrespective of the 11 yr
solar activity cycle.
Title: Spatial and Temporal Properties of Hot and Cool Coronal Loops
Authors: Nagata, Shin'ichi; Hara, Hirohisa; Kano, Ryouhei; Kobayashi,
Ken; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi;
Gurman, Joseph B.
Bibcode: 2003ApJ...590.1095N
Altcode:
A suite of images from the XUV Doppler Telescope (XDT), the Yohkoh Soft
X-ray Telescope (SXT), and the Extreme-Ultraviolet Imaging Telescope
(EIT) on the Solar and Heliospheric Observatory (SOHO) allow us to
see the whole (T>1 MK) temperature evolution of coronal loops. The
detailed morphological comparison of an active region shows that hot
loops seen in SXT (T>3 MK) and cool loops seen in the the EIT 195
Å band (T~1.5 MK) are located in almost alternating manner. The
anticoincidence of the hot and the cool loops is conserved for a
duration much longer than the estimated cooling timescale. However, both
hot and cool loops have counterparts in the intermediate-temperature
images. The cross-correlation coefficients are higher for neighboring
temperature pairs and lower for pairs with larger temperature
differences. These results suggest that loops are not isothermal but
rather have a differential emission measure distribution of modest but
finite width that peaks at different temperatures for different loops.
Title: 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: Contamination evaluation and control for SOLAR-B optical
telescope
Authors: Tamura, Tomonori; Hara, Hirohisa; Tsuneta, Saku; Ichimoto,
Kiyoshi; Kumagai, Kazuyoshi
Bibcode: 2002RNAOJ...6...49T
Altcode:
In space telescopes, the deposition of molecular outgassing from its
component parts may degrade the mirror reflectivity. In the case of the
SOLAR-B visible light telescope, the molecular contamination is even
more threatening since the deposited contaminants, when illuminated by
the ultraviolet light from the sun, not only blacken but also promote
further deposition. We thus started an extensive program to measure
outgassing from all the non-metal material candidates to be used
of the SOLAR-B telescope and to evaluate various chemical-cleaning
(de-oil) procedures for the metal parts. The evaluation is based on
NASA-MSFC-SPEC-1238 specification, and Thermoelectric Quartz Crystal
Microbalance is the primary apparatus for the measurement. We are
able to select the best possible adhesives and de-oil procedures for
the flight model, whenever there are multiple choices. Conditions
for the flight-model vacuum bakeout will also be established based on
the measurements. The program significantly mitigates the risk due to
molecular contamination the SOLAR-B program.
Title: The Temperature Analysis of Yohkoh/SXT Data using the CHIANTI
Spectral Database
Authors: Shimojo, M.; Hara, H.; Kano, R.
Bibcode: 2002mwoc.conf..419S
Altcode:
Since the CHIANTI database for astrophysical emission line spectroscopy
was extended to X-ray wavelengths below 50Å recently (Dere et
al. 2000), a temperature response of YOHKOH/SXT has been able to
calculate using the database. The functions of temperature responses of
SXT are very important for plasma diagnostic since we usually derive
the electron temperature of coronal plasma using the observed signal
counts and the ratio of the temperature responses. In this paper,
we present the properties of the SXT temperature responses which are
calculated from the CHIANTI database and also compare them with the
SXT temperature responses which are calculated using Mewe spectral
databases (Mewe, et al., 1985, 1986). We calculated the filter ratios
using CHIANTI database and compared them with the filter ratios which
are calculated from Mewe database. At the result, it is found that
the difference between temperatures which are derived using CHIANTI
and Mewe database is about 2 MK around 5 MK, if we use Al and Al12
filters for the plasma diagnostic. The result is the same as Schmelz
et al.(1999). In the paper, we also discuss the effect of the CHIANTI
spectral databases for previous works which used the filter ratios
based on Mewe database.
Title: Soft X-Ray High-Temperature Regions above Solar Flare Loops
Authors: Akiyama, S.; Hara, H.
Bibcode: 2002mwoc.conf..367A
Altcode:
We analyzed 141 solar flare dates that were observed with the Yohkoh
soft and hard X-ray telescopes to investigate general characteristics
of soft X-ray high-temperature regions above flare loops. Although
existence of the high-temperature region was first reported by Masuda
et al. (1994), it has been criticized by several authors because
the soft X-ray intensity of that region is weak and because it is
usually located near a relatively large intensity gradient. A careful
analysis is required for a systematic research that reveals general
characteristics of the region and roles in the flare energy release
mechanism. We carefully estimated the electron temperature of a flare
site with the filter ratio technique from the Yohkoh soft X-ray data
under an isothermal approximation after correcting the spacecraft
pointing jitter and scattered X-rays due to the mirror micro-roughness,
both of which are causes of the criticism. We have still found the
high-temperature regions of 15--35 million degrees above flare loops
for 64 flares in 141 events. A single flare event had single/multiple
high-temperature region of 1--3 times 104 km in size. The
region appeared at the hard X-ray impulsive phase and its temperature
reached a maximum before the soft X-ray peak time. The volume emission
measure of the region was 1047--48 cm3, which
was about ten times smaller than that of 10 million degree flare loops
beneath. The high-temperature regions tended to move outwards at a
speed of 10--20 km s-1, which was systematically faster
than the rising speed of flare loops of 4--6 km s-1. When
the high-temperature regions were located in asymmetrical point to the
two footpoints of flare loop, the regions were located at the side
of a weaker hard X-ray source measured with the Yohkoh hard X-ray
telescope, showing that the high-temperature regions appear at the
side of a footpoint with a weaker magnetic field than the other.
Title: On the Detection of Solar Coronal High-Velocity Fields Using
the XUV Doppler Telescope
Authors: Kobayashi, Ken; Hara, Hirohisa; Kano, Ryohei; Nagata,
Shin'ichi; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida,
Tsuyoshi; Harrison, Richard
Bibcode: 2000PASJ...52.1165K
Altcode:
The XUV Doppler Telescope (XDT) is a sounding rocket experiment
designed to detect flows in the solar corona using filter ratios. The
XDT, successfully launched on 1998 January 31, is a normal incidence
telescope composed of narrow-bandpass multilayer mirrors and capable
of obtaining images 2 Å\ above and 2 Å\ below the Fe XIV 211 Å\
(T = 1.7 MK) emission line. It has the potential to make a velocity map
of the entire solar disk with just a few minutes of observation. The
image ratio maps show features that translate to Doppler shifts of
200 km s-1 or more, including several `redshift' features
located near footpoints of coronal loops. However, no corresponding
velocity features were seen by the Solar and Heliospheric Observatory
(SOHO) Coronal Diagnostic Spectrometer (CDS) in the Mg IX 368 Å (T =
1 MK) line, suggesting that the features are not caused by Doppler
shift. Instead, the features seem to be related to contamination
of lower temperature (T < 1 MK) emission lines and the nearby
density-sensitive Fe XIII lines. We conclude that while no flows were
positively identified by the XDT, this observing technique is capable
of detecting flows of 1000 km s^{-1} independently, and 200 km s^{-1}$
when combined with simultaneous plasma diagnostic observation.
Title: Scalar curvature of massive ideal gases
Authors: Oshima, H.; Obata, T.; Hara, H.
Bibcode: 2000AIPC..519..732O
Altcode: 2000stph.conf..732O
.
Title: Fluctuations in human's walking
Authors: Obata, T.; Ohyama, T.; Shimada, J.; Oshima, H.; Hara, H.;
Fujita, S.
Bibcode: 2000AIPC..519..720O
Altcode: 2000stph.conf..720O
.
Title: The Occurrence Probability of X-rays Plasma Ejections by
Solar Flares
Authors: Akiyama, S.; Hara, H.
Bibcode: 2000ASPC..205..137A
Altcode: 2000ltse.conf..137A
We have investigated X-ray ejecta above flare loops, which were observed
before soft X-ray peak time, using the Yohkoh soft X-ray observations
in 1996 when the background corona was very weak. We found 35 plasma
ejecta out of 84 flares and studied soft X-ray data to discover the
probability to observe the plasma ejecta. On the other hand, we searched
for prominence eruptions using Solar-Geophysical Data in the same flare
series and found 16 prominence eruptions out of 29 flares having soft
x-ray plasma ejecta. As a result, 76% of flares have plasma ejecta
observed in either Hα or soft X-ray wavelength. It follows from this
that there are many flare associated ejecta.
Title: Active region dynamics
Authors: Harra, L. K.; Matthews, S. A.; Hara, H.; Ichimoto, K.
Bibcode: 2000ssls.work..109H
Altcode:
It has been frequently observed that in solar active regions the
measured line widths are larger than those based on thermal equilibrium
widths. This excess width (characterised as non-thermal velocity,
Vnt) has been proposed as a signature of the heating
mechanism. The behaviour of the Vnt at coronal temperatures
has not produced consistent results with values ranging from 0 to
100 km/s. We investigate this problem by using joint observations
from Norikura Solar Observatory, Japan and the Coronal Diagnostic
Spectrometer (CDS) on SOHO. We find that values of Vnt range
between 10-20 km/s. We analyse the dynamical bahaviour of different
temperature loops and find that for loops with log Te <
5.8, the variability ∝Te0.39. This is comparable
to the dependence of non-thermal velocity on temperature which we have
determined to be Vnt ∝ Te0.35. This
suggests that the excess line broadening is caused by highly dynamical
behaviour in the transition region for active regions. These results
have significant implications for potential heating mechanisms and
these are discussed.
Title: Variation of X-Ray Bright Point Number Over the Solar
Activity Cycle
Authors: Nakakubo, K.; Hara, H.
Bibcode: 2000AdSpR..25.1905N
Altcode:
X-ray bright points (XBPs) have been counted from Yohkoh/Soft X-ray
Telescope (SXT) images obtained during the period from 1992 December
to 1997 August. The number of XBPs did not change significantly until
about 1995. It then varied inversely with the sunspot number and reached
a maximum during the solar minimum. However, taking into account both
the XBP's intensity histogram and the background coronal intensity
histogram, it seems that the apparent observed increase of XBP number
near the solar minimum is due to a decrease of the background intensity,
not due to an actual increase. There appears to be little correlation
between XBP and sunspot numbers
Title: Temperatures of Pre-Flare and Flaring Loops Observed with
the Yohkoh Soft X-Ray Telescope
Authors: Yasuno, S.; Hiei, E.; Hara, H.; Watanabe, T.
Bibcode: 2000AdSpR..25.1805Y
Altcode:
We statistically investigate thermal characteristics of soft X-ray
coronal loops in the pre-flare and flaring stages using the data
observed between January 1992 and December 1992 with the soft X-ray
telescope on board the Yohkoh satellite. The data cover the pre-flare
phase in the periods of 30-90 minutes preceding the flares, the rising
phases, and the peaks of flares in X- ray intensity, and the beginnings
of the decay phases. We compare the thermal characteristics of soft
X-ray coronal loops before they flare and those at the peaks of flares,
and we find that the loops having higher temperatures in the pre-flare
stages produce bigger and higher temperature flares later
Title: Initial Results from the XUV Doppler Telescope
Authors: Kano, R.; Hara, H.; Kobayashi, K.; Kumagai, K.; Nagata, S.;
Sakao, T.; Shimizu, T.; Tsuneta, S.; Yoshida, T.
Bibcode: 2000AdSpR..25.1739K
Altcode:
We developed a unique telescope to obtain simultaneous XUV images and
the velocity maps by measuring the line-of-sight Doppler shifts of the
Fe XIV 211A&ring line (T = 1.8 MK): the Solar XUV Doppler Telescope
(hereafter XDT). The telescope was launched by the Institute of Space
and Astronautical Science with the 22nd S520 rocket on January 31,
1998, and took 14 XUV whole sun images during 5 minutes. Simultaneous
observations of XDT with Yohkoh (SXT), SOHO (EIT, CDS, LASCO and MDI)
were successfully carried out. The images taken with EIT, XDT and SXT
are able to cover the wide temperature ranging from 1 to 10 MK, and
clearly show the multi-temperature nature of the solar corona. Indeed,
we notice that both the cool (1-2 MK) loops observed with EIT and
XDT, and the hot (>3 MK) loops observed with SXT exist in the same
active regions but in a spatially exclusive way. The XDT red-blue ratio
between longer- and shorter-wavelength bands of Fe XIV 211A&ring
line indicates a possible down-flow of 1.8 MK plasma near the footpoints
of multiple cool loops
Title: X-Ray Eruptive Structures Associated with Small Flares
Authors: Akiyama, S.; Hara, H.
Bibcode: 2000AdSpR..26..465A
Altcode:
We searched for X-ray eruptive structures above the flare loops, whose
soft X-ray flux at the peak phase ranges from class A to C in the
GOES classification, using the Yohkoh soft X-ray observations in 1996
when the background corona was very weak. We found 12 plasmoid-like or
loop-like ejecta out of 43 flares studied. Existence of these eruptive
structures implies that the magnetic reconnection model, which was
strongly supported by Yohkoh observations of flares of a narrow range
of X-ray peak flux, can explain the solar flares covering more than
five orders of magnitude in the soft X-ray flux. We also found that
the projected outgoing velocities of the ejecta are systematically
slower in small flares than in large flares
Title: A Method for Characterizing Rotation Rates in the Soft
X-Ray Corona
Authors: Weber, M. A.; Acton, L. W.; Alexander, D.; Kubo, S.; Hara, H.
Bibcode: 1999SoPh..189..271W
Altcode:
Differential rotation rates of soft X-ray features in the solar
corona are quantified by a method of harmonic filtering using
the Lomb-Scargle periodogram. This approach leads reasonably to a
quantitative discrimination between uncertainty estimates and spectral
leakage of the fundamental rotation frequency due to the presence
of multiple rotating tracers. Mean rotation rates as a function of
latitude and year are calculated for the years 1992-1997 (roughly
the declining phase of the last solar activity cycle). The corona is
found to have a small but measurable latitudinal gradient in rotation
rate. The presence of multiple features places a lower bound of 1-2%
on the relative uncertainties with which a `mean' rotation rate can
be measured. The results are compared with autocorrelation estimates
and found to agree within 1σ.
Title: Narrow-Bandpass Multilayer Mirrors for an Extreme-Ultraviolet
Doppler Telescope
Authors: Hara, Hirohisa; Nagata, Shin'ichi; Kano, Ryouhei; Kumagai,
Kazuyoshi; Sakao, Taro; Shimizu, Toshifumi; Tsuneta, Saku; Yoshida,
Tsuyoshi; Ishiyama, Wakana; Oshino, Tetsuya; Murakami, Katsuhiko
Bibcode: 1999ApOpt..38.6617H
Altcode:
No abstract at ADS
Title: The XUV Doppler Telescope (XDT)
Authors: Sakao, T.; Tsuneta, S.; Hara, H.; Shimizu, T.; Kano, R.;
Kumagai, K.; Yoshida, T.; Nagata, S.; Kobayashi, K.
Bibcode: 1999SoPh..187..303S
Altcode:
We present an overview and instrumental details of the solar XUV Doppler
Telescope (XDT) launched in January 1998 with the S520CN-22 sounding
rocket of the Institute of Space and Astronautical Science. The XDT
observes nearly single-temperature solar corona at 1.8 MK with angular
resolution of ≈ 5'' pixel size, together with the ability to detect
the coronal velocity field with a full-Sun field of view. By use of
normal incidence optics whose primary and secondary mirrors are coated
with multilayer materials in two sectors, the XDT takes images of the
Sun in a set of shorter and longer wavelength bands around the Fe xiv
211.3 Å emission line. Summation of a pair of images in the two bands
provides an image of the 1.8 MK-corona while the difference between
the two provides velocity images of the Fe xiv-emitting plasma. A brief
description on the observation sequence together with the flight result
is also given.
Title: Dynamics of solar active region loops
Authors: Harra-Murnion, L. K.; Matthews, S. A.; Hara, H.; Ichimoto, K.
Bibcode: 1999A&A...345.1011H
Altcode:
It has been frequently observed that in solar active regions the
measured line widths are larger than those based on thermal equilibrium
widths. This excess width (characterised as non-thermal velocity,
Vnt) has been proposed as a signature of the heating
mechanism. The behaviour of the Vnt at coronal temperatures
has not produced consistent results with values ranging from 0 to 100
km s(-1) . We investigate this problem by using joint observations
from Norikura Solar Observatory, Japan and the Coronal Diagnostic
Spectrometer (CDS) on SOHO. With CDS we determine temperatures, and
with Norikura we obtain accurate line widths for Fe XIV (~2 MK). We
find that values of Vnt range between 10-20 km s(-1) . We
analyse the dynamical behaviour of different temperature loops and
find that for loops with Log T_e < 5.8, the variability ~ T_e(0.39)
. This is comparable to the dependence of non-thermal velocity on
temperature which we have determined to be Vnt ~ T_e(0.35)
. This suggests that the excess line broadening is caused by highly
dynamical behaviour in the transition region for active regions. These
results have significant implications for potential heating mechanisms
and these are discussed.
Title: Microscopic Nonthermal Plasma Motions of Coronal Loops in a
Solar Active Region
Authors: Hara, H.; Ichimoto, K.
Bibcode: 1999ApJ...513..969H
Altcode:
We present a spectroscopic observation of a solar active region NOAA
7590 with a coronagraph at the Norikura Solar Observatory, which
provides high-resolution spectra of the visible coronal emission lines
(Fe X λ6374, Fe XIV λ5303, Ca XV λ5694) with a spatial sampling
of 2.0"×2.3". Nonthermal velocities (ξ) estimated from Fe X λ6374,
Fe XIV λ5303, and Ca XV λ5694 in this observation are 14-20, 10-18,
and 16-26 km s-1, respectively. The first two results are
consistent with the results obtained by Cheng et al. and others. Even
in the Ca XV structures the present observation does not confirm the
large nonthermal velocity of 40-60 km s-1 to be typical
value. The hypothesis that the nonthermal width in coronal emission
lines is due to coronal Alfvén waves is tested by carefully examining
the relationship between the width of coronal emission lines and
orientation of coronal loops to the line-of-sight direction. From the
comparison between edge-on loops in which the direction of magnetic
field is nearly parallel to the line-of-sight direction and face-on
loops in which the magnetic field is almost perpendicular to the
line-of-sight direction, the full width at half-maximum (FWHM) of
coronal emission lines for the edge-on loop appears to become smaller
near the loop top than that for the face-on loops. The obvious decrease
of FWHM of 0.04-0.07 Å (Δξ=3-5 km s-1) is found in the
Fe XIV edge-on loops. Although this may be evidence for the Alfvén
waves in coronal loops, the velocity amplitude seems to be too small
to explain all the nonthermal velocity reported so far.
Title: Development and flight performance of tip-tilt mirror system
for a sounding rocket observation of the Sun.
Authors: Shimizu, T.; Yoshida, T.; Tsuneta, S.; Sakao, T.; Kano,
R.; Hara, H.; Nagata, S.; Kodeki, K.; Inoue, M.; Fukushima, K.;
Kashiwase, T.
Bibcode: 1999RNAOJ...4...43S
Altcode: 1999RNOAJ...4...43S
A tip-tilt mirror (TTM) system was developed for the XUV Doppler
telescope (XDT) on board an ISAS sounding rocket. The spatial resolution
of the telescope is about 5″ whereas the pointing stability is
only ±0.3° with the rocket pointing control system. To achieve
better than 5″stability on the focal plane of the telescope, the
TTM system controls the tilt of the secondary mirror with fixed-coil
magnetic actuators. The control signal to stabilize focal-plane images
is supplied by the position-sensitive detector (PSD) of a pin-hole
telescope equipped inside XDT. Closed-loop controls are made with
the on-board software on the DSP processor. The sounding rocket was
successfully launched on 31 January 1998 from the Kagoshima Space
Center of ISAS. TTM worked perfectly during the flight, and achieved
better than 5″stability on the focal plane during CCD exposures.
Title: Design of a High-Resolution Extreme-Ultraviolet Imaging
Spectrometer with Aberration-Corrected Concave Gratings
Authors: Harada, Tatsuo; Sakuma, Hideo; Takahashi, Kaoru; Watanabe,
Tetsuya; Hara, Hirohisa; Kita, Toshiaki
Bibcode: 1998ApOpt..37.6803H
Altcode:
No abstract at ADS
Title: Development of the tip-tilt mirror system for the solar
XUV telescope
Authors: Kodeki, Kazuhide; Fukushima, Kazuhiko; Kashiwase, Toshio;
Inoue, Masao; Shimizu, Toshifumi; Yoshida, Tsuyoshi; Sakao, Taro;
Hara, Hirohisa; Nagata, Shin'ichi; Kano, Ryouhei; Tsuneta, Saku
Bibcode: 1998SPIE.3356..922K
Altcode:
This paper describes the design and prelaunch performance of the
tip-tilt mirror (TTM) system developed for the XUV Cassegrain telescope
aboard the ISAS sounding rocket experiment. The spatial resolution
of the telescope is about 5 arcsec, whereas the rocket pointing is
only controlled to be within +/- 0.5 degree around the target without
stability control. The TTM is utilized to stabilize the XUV image
on the focal planes by tilting the secondary mirror with two-axes
fixed-coil type actuators. The two position- sensitive detectors in
the telescope optics and in the TTM mechanical structure from the
normal and local closed-loop modes. The TTM has four grain modes with
automatic transition among the modes. The low gain mode is used in
the initial acquisition, and in case the TTM loses the tracking. The
high gain mode is used in the normal tracking mode. This arrangement
provides us with the wide initial acquisition angle with single TTM
system as well as the high pointing accuracy once the tracking is
established. The TTM has a launch-lock mechanism against the launch
vibration of 16G. The closed-loop control with command and telemetry
interface is done by the flight software against the launch vibration
of 16G. The closed-loop control with command and telemetry interface
is done by the flight software on the DSP processor. The use of the
fast processor brings in the significant reduction in the weight and
size of the control- electronics, more flexible control system, and
shorter design and testing period.
Title: Using Strong Solar Coronal Emission Lines as Coronal Flux
Proxies
Authors: Falconer, David A.; Jordan, Stuart D.; Brosius, Jeffrey W.;
Davila, Joseph M.; Thomas, Roger J.; Andreatta, Vicenzo; Hara, Hirohisa
Bibcode: 1998SoPh..180..179F
Altcode:
We investigate the possibility that strong EUV lines observed with the
Goddard Solar EUV Rocket Telescope and Spectrograph (SERTS) provide
good proxies for estimating the total coronal flux over shorter
wavelength ranges. We use coordinated SERTS and Yohkoh observations
to obtain both polynomial and power-law fits relating the broad-band
soft X-ray fluxes to the intensities of Fexvi 335 Ú and 361 Ú, Fexv
284 Ú and 417 Ú, and Mgix 368 Ú measured with SERTS. We found that
the power-law fits best cover the full range of solar conditions from
quiet Sun through active region, though not surprisingly the `cooler'
Mgix 368 Ú line proves to be a poor proxy. The quadratic polynomial
fits yield fair agreement over a large range for all but the Mgix
line. However, the linear fits fail conspicuously when extrapolated
into the quiet-Sun regime. The implications of this work for the Heii
304 Ú line formation problem are also briefly considered.
Title: Solar Active Region: Heating and Dynamics
Authors: Harra-Murnion, L. K.; Matthews, S. A.; Hara, H.; Ichimoto, K.
Bibcode: 1998sxmm.confE..85H
Altcode:
No abstract at ADS
Title: XUV Doppler Telescope Aboard Sounding Rocket
Authors: Yoshida, T.; Kano, R.; Nagata, S.; Hara, H.; Sakao, T.;
Shimizu, T.; Tsuneta, S.
Bibcode: 1998ASSL..229..383Y
Altcode: 1998opaf.conf..383Y
No abstract at ADS
Title: Evolution of the Solar Corona from the Maximum to the Minimum
Authors: Hara, H.
Bibcode: 1998ASSL..229....3H
Altcode: 1998opaf.conf....3H
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: Joint Observations of an Active Region with Norikura and CDS
Authors: Harra-Murnion, L. K.; Matthews, S. A.; Hara, H.; Ichimoto, K.
Bibcode: 1998ASPC..155..346H
Altcode: 1998sasp.conf..346H
No abstract at ADS
Title: Erratum: "A High-Temperature Component in Coronal holes as
Confirmed by a Parial-Eclipse Observation"
Authors: Hara, Hirohisa
Bibcode: 1997PASJ...49..523H
Altcode:
No abstract at ADS
Title: XUV Doppler telescope with multilayer optics
Authors: Hara, Hirohisa; Kano, Ryouhei; Nagata, Shin'ichi; Sakao, Taro;
Shimizu, Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi; Kosugi, Takeo
Bibcode: 1997SPIE.3113..420H
Altcode:
We present an overview of a sounding-rocket experiment, which is
scheduled to be launched by the Institute of Space and Astronautical
Science (ISAS) in January 1998, the rising phase of the 11-year activity
cycle of the sun. The purpose of this experiment is (1) to obtain
whole-sun images taken in an XUV emission line, Fe XIV 211 angstrom,
using the normal incidence multilayer optics with a high spectral
resolution of (lambda) /(Delta) (lambda) approximately equals 40, and
(2) to carry out the velocity-field measurement with detection limit
as high as 100 km/s.
Title: Development of multilayer mirrors for the XUV Doppler telescope
Authors: Nagata, Shin'ichi; Hara, Hirohisa; Sakao, Taro; Shimizu,
Toshifumi; Tsuneta, Saku; Yoshida, Tsuyoshi; Ishiyama, Wakana;
Murakami, Katsuhiko; Oshino, Tetsuya
Bibcode: 1997SPIE.3113..193N
Altcode:
We present the development status of the normal incidence XUV multilayer
mirrors for XUV Doppler telescope, which observes coronal velocity
fields of the whole sun. The telescope has two narrow band-pass
multilayer mirrors tuned to slightly longer and shorter wavelengths
around the Fe XIV line at 211.3 Angstrom. From the intensity difference
of the images taken with these two bands, we can obtain Dopplergram of
1.8 MK plasma of the whole sun. It is required that the multilayer has
high wavelength-resolution ((lambda) /(Delta) (lambda) approximately
30 per mirror), anti-reflection coating for intense He II 304 angstrom
emission line and high d-spacing uniformity of approximately 1%.
Title: A High-Temperature Component in Coronal Holes as Confirmed
by a Partial-Eclipse Observation
Authors: Hara, Hirohisa
Bibcode: 1997PASJ...49..413H
Altcode:
We confirmed X-ray signals in coronal holes based upon a Yohkoh soft
X-ray observation of a partial eclipse on 1993 November 13. The
observed X-ray signals cannot be explained by those coming from
one-million-degree plasmas alone, which were observed with the Skylab
UV and EUV instruments. This suggests that higher-temperature plasmas
are necessary to explain the present observation.
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: The Structure and Properties of Solar Active Regions and
Quiet-Sun Areas Observed in Soft X-Rays with Yohkoh/SXT and in the
Extreme-Ultraviolet with SERTS
Authors: Brosius, Jeffrey W.; Davila, Joseph M.; Thomas, Roger J.;
Saba, Julia L. R.; Hara, Hirohisa; Monsignori-Fossi, Brunella C.
Bibcode: 1997ApJ...477..969B
Altcode:
We observed two solar active regions (NOAA regions 7563 and 7565),
quiet-Sun areas, and a coronal hole region simultaneously with Goddard
Space Flight Center's Solar EUV Rocket Telescope and Spectrograph
(SERTS) and with the Yohkoh Soft X-ray Telescope (SXT) on 1993 August
17. SERTS provided spatially resolved active region and quiet-Sun slit
spectra in the 280 to 420 Å wavelength range, and images in the lines
of He II λ303.8, Mg IX λ368.1, Fe XV λ284.1, and Fe XVI λλ335.4
and 360.8 SXT provided images through multiple broadband filters in both
the full-frame imaging mode and the partial-frame imaging mode. The
SERTS images in Fe XV (log Tmax = 6.33, where Tmax
is the temperature which maximizes the fractional ion abundance in
the available ionization equilibrium calculations, i.e., the formation
temperature) and Fe XVI (log Tmax = 6.43) exhibit remarkable
morphological similarity to the SXT images. Whereas the Fe XV and XVI
images outline the loop structures seen with SXT, the cooler He II
(log Tmax = 4.67) and Mg IX (log Tmax = 5.98)
images outline loop footpoints. In addition, the Mg IX emission
outlines other structures not necessarily associated with the hot
loops; these may be cool (T <~ 1 × 106 K) loops. From the spatially resolved slit spectra, we obtained emission-line
profiles for lines of He II λ303.8, Mg IX λ368.1, Fe XIII λ348.2,
Si XI λ303.3, Fe XIV λ334.2, Fe XV λ284.1, and Fe XVI λ335.4
for each spatial position. Based upon the spatial variations of the
line intensities, active region 7563 systematically narrows when
viewed with successively hotter lines, and appears narrowest in the
broadband soft X-ray emission. The active region width (full width at
half-maximum intensity) diminishes linearly with log Tmax;
the linear fit yields an extrapolated effective log Tmax
of 6.51 +/- 0.01 for the X-ray emission. The most intense, central core
straddles the magnetic neutral line. Active region and quiet-Sun
one-dimensional temperature scans were derived from intensity ratios
of spatially resolved SERTS slit spectral lines, and from coregistered
SXT filter ratios. The highest plasma temperatures were measured in the
most intense, central core of region 7563. The temperatures derived
from Fe XVI λ335.4/Fe XV λ284.1 and Fe XVI λ335.4/Fe XIV λ334.2
vary significantly (based upon the measurement uncertainties) but not
greatly (factors of less than 1.5) across the slit. The average log
T values derived from the above two ratios for region 7563 are 6.39
+/- 0.04 and 6.32 +/- 0.02, respectively. Somewhat larger systematic
variations were obtained from all available SXT filter ratios. The
average active region log T values derived from the SXT AlMgMn/thin
Al, thick Al/thin Al, and thick Al/AlMgMn filter ratios are 6.33 +/-
0.03, 6.45 +/- 0.02, and 6.49 +/- 0.03, respectively. Active
region and quiet-Sun one-dimensional density scans were derived from
intensity ratios of spatially resolved SERTS slit spectral lines of
Fe XIII and Fe XIV. The derived densities show neither systematic nor
significant variations along the slit in either the active region or
the quiet-Sun, despite the fact that the intensities themselves vary
substantially. This indicates that the product of the volume filling
factor and the path length (fΔl) must be greater by factors of 3-5 in
the active region core than in the outskirts. Furthermore, the derived
active region densities are ~2 times the quiet-Sun densities. This
density difference is adequate to explain the factor of ~4 intensity
difference in Fe XII and Fe XIII between the active and quiet areas,
but it is not adequate to explain the factor of ~8 intensity difference
in Fe XIV between the active and quiet areas. We attribute the latter
to a greater fΔl in the active regions. Statistically significant
Doppler shifts are not detected in region 7563 or in the quiet-Sun
with any of the EUV lines.
Title: VizieR Online Data Catalog: Tokyo meridian circle catalog of
O-B stars (Yasuda+ 1986)
Authors: Yasuda, H.; Hara, H.; Fukaya, R.; Ishii, H.
Bibcode: 1997yCat.1249....0Y
Altcode:
A catalog of the O-B stars, selected from "Blaauw-Parenago" list (1955,
First IAU Symposium, "Co-ordination of galactic research") and Rubin's
catalog (1962AJ.....67..491R, Cat. ), has been compiled on the FK4
system by the observations made with Gautier 8-inch Meridian Circle at
the Tokyo Astronomical Observatory during the period, 1971 to 1979. It
contains 1059 stars and was compiled for the future establishment of
high precision proper motions of O-B stars. (1 data file).
Title: Evolution of the solar corona from solar maximum to minimum
Authors: Hara, H.
Bibcode: 1997AdSpR..20.2279H
Altcode:
A study on solar coronal activities related to the 11-year activity
cycle is presented from the Yohkoh soft X-ray observations. Yohkoh was
launched in August 1991, just after the solar maximum of the cycle 22
and continues to observe the Sun in the declining phase of the magnetic
activity cycle toward the solar minimum. The soft X-ray flux from the
whole Sun in the declining phase essentially decreases with the size of
active regions. The X-ray intensity in quiet regions in the declining
phase decreases with the magnetic flux observed at the photosphere. The
whole-Sun soft X-ray flux does not monotonically decrease, but there are
periodic enhancements of the flux with about a one-year interval. The
activity appears as bright clusters in the butterfly diagram of the
soft X-ray intensity and corresponds to the emergence of complexes
of activity in the sunspot zones. The high-latitude activity is also
studied, and we find that the X-ray intensity of high-latitude regions
fluctuates with time scale of about one year.
Title: Japanese sounding rocket experiment with the solar XUV
Doppler telescope
Authors: Sakao, Taro; Tsuneta, Saku; Hara, Hirohisa; Kano, Ryouhei;
Yoshida, Tsuyoshi; Nagata, Shin'ichi; Shimizu, Toshifumi; Kosugi,
Takeo; Murakami, Katsuhiko; Wasa, Wakuna; Inoue, Masao; Miura,
Katsuhiro; Taguchi, Koji; Tanimoto, Kazuo
Bibcode: 1996SPIE.2804..153S
Altcode:
We present an overview of an ongoing Japanese sounding rocket project
with the Solar XUV Doppler telescope. The telescope employs a pair
of normal incidence multilayer mirrors and a back-thinned CCD, and is
designed to observe coronal velocity field of the whole sun by measuring
line- of-sight Doppler shifts of the Fe XIV 211 angstroms line. The
velocity detection limit is estimated to be better than 100 km/s. The
telescope will be launched by the Institute of Space and Astronautical
Science in 1998, when the solar activity is going to be increasing
towards the cycle 23 activity maximum. Together with the overview of
the telescope, the current status of the development of each telescope
components including multilayer mirrors, telescope structure, image
stabilization mechanism, and focal plane assembly, are reviewed. The
observation sequence during the flight is also briefly described.
Title: The Structure and Properties of Solar Active Regions and
Quiet Sun Areas Observed With SERTS and YOHKOH
Authors: Brosius, J. W.; Davila, J. M.; Thomas, R. J.; Hara, H.
Bibcode: 1996AAS...188.3715B
Altcode: 1996BAAS...28..880B
We observed solar active regions, quiet sun areas, and a coronal hole
simultaneously with Goddard Space Flight Center's Solar EUV Rocket
Telescope and Spectrograph (SERTS), and with the Yohkoh Soft X-Ray
Telescope (SXT) on 1993 August 17. SERTS provided spatially resolved
active region and quiet sun spectra in the 280 to 420 Angstroms
wavelength range, and images in the lines of He II 304 Angstroms,
Mg IX 368 Angstroms, Fe XV 284 Angstroms, and Fe XVI 335 Angstroms
and 360 Angstroms. The SERTS waveband is accessible to CDS, SUMER,
and EIT on SOHO. SXT provided images through multiple broadband
filters. The SERTS images in Fe XV (T=2 MK) and XVI (T=2.5 MK) exhibit
remarkable morphological similarity to the SXT images. Whereas the
Fe XV and XVI images outline the loop structures seen with SXT, the
cooler He II (T=0.1 MK) and Mg IX (T=1 MK) images seem to outline loop
footpoints. From the spatially resolved spectra, we obtained emission
line profiles for lines of Fe X (1 MK) through Fe XVI, and Mg IX and
Ni XVIII (3.2 MK) for each spatial position. Based upon the spatial
variations of the line intensities, the active region systematically
narrows as it is viewed with successively hotter lines. The active
region appears narrowest in the X-ray emission, which is consistent
with our understanding that Yohkoh is most sensitive to the hottest
plasma in its line of sight. EUV emission from Fe XVII (T=5 MK) is weak
but detectable in the active region core. The most intense, central
core straddles the magnetic neutral line. Temperature maps obtained
with SERTS image ratios and with SXT filter ratios are compared. Line
intensity ratios indicate that the active region temperature is greatest
in the central core, but that the density varies very little across the
region. Significant Doppler shifts are not detected in the EUV lines.
Title: A high-temperature component in coronal holes observed with
YOHKOH SXT
Authors: Hara, H.; Tsuneta, S.; Acton, L. W.; Bruner, M. E.; Lemen,
J. R.; Ogawara, Y.
Bibcode: 1996AdSpR..17d.231H
Altcode: 1996AdSpR..17..231H
Temperatures of coronal holes are estimated from several sets of soft
X-ray images taken through various broad-band filters with the Soft
X-ray Telescope (SXT) aboard Yohkoh. The effect of scattered X-rays from
bright regions surrounding a temperature determination area, especially
those from nearby active regions, is carefully removed with the point
spread function derived from the post-launch data. An isothermal
approximation is applied to thus corrected data. The temperatures of
coronal holes near the disk center are found to be 1.8 - 2.4 x 10^6
K, which is almost the same as those derived for quiet regions. The
emission measures in coronal holes are estimated to be 10^25.5-26.2
cm^-5, about ten times smaller than in quiet regions. We conclude that
temperatures in coronal holes do not differ from those in quiet regions,
and that the depression in soft X-ray intensity of coronal hole regions
results from a lower density by a factor of 3 than quiet regions. We
propose that the coronal hole component observed with the SXT is not
the same one which is observed with the Skylab EUV instrument. An
X-ray intensity from a coronal hole is independently confirmed by the
eclipse observation on 1993 November 13, and consistent with intensities
derived from the scattering correction.
Title: Discovery of a loop-top hard X-ray source in impulsive
solar flares
Authors: Masuda, S.; Kosugi, T.; Tsuneta, S.; Hara, H.
Bibcode: 1996AdSpR..17d..63M
Altcode: 1996AdSpR..17...63M
Observations of a solar flare on 13 January, 1992 (17:25 UT) with the
Hard X-ray Telescope (HXT; /1/) and the Soft X-ray Telescope (SXT;
/2/) aboard Yohkoh /3/ clearly show an impulsive hard X-ray source well
above a soft X-ray flaring loop. This source reveals that the primary
energy release, maybe the magnetic reconnection, occurs well above the
soft X-ray flaring loop. It is most plausible that this ``loop-top''
hard X-ray source represents the site where the downward plasma outflow,
ejected from a reconnection point located above the hard X-ray source,
collides with an underlying closed magnetic loop. This observation thus
shows for the first time where the high-energy electrons are energized.
Title: A Coronal Velocity Field around a Long-Duration Event: Search
for Reconnection Inflow
Authors: Hara, H.; Ichimoto, K.
Bibcode: 1996ASPC..111..183H
Altcode: 1997ASPC..111..183H
A coronal Doppler velocity field around an LDE-type solar flare at
the peak phase is presented from observations with a ground-based
coronagraph in a visible coronal emission line (Fe XIV 5303 Å). The
flare loop was in an edge-on configuration to the line-of-sight
direction. At the peak phase, the authors could not find any high-speed
flow around the flare loop, corresponding to the reconnection inflow
whose speed is 0.01 - 0.1 of the Alfvén speed. On the other hand,
high-velocity components exceeding 10 km s-1 and large line
broadening in the emission line were observed near the brightest part
of the flare loop in the decay phase.
Title: Structures and heating mechanisms of the solar corona
Authors: Hara, H.
Bibcode: 1996PhDT........62H
Altcode:
No abstract at ADS
Title: Loop-Top Hard X-ray Source in Solar Flares
Authors: Masuda, S.; Kosugi, T.; Shibata, K.; Hara, H.; Sakao, T.
Bibcode: 1996mpsa.conf..203M
Altcode: 1996IAUCo.153..203M
No abstract at ADS
Title: Spectroscopic observations in SOLAR-B.
Authors: Watanabe, T.; Hara, H.; Harada, T.
Bibcode: 1996uxsa.conf..219W
Altcode: 1996uxsa.coll..219W
An XUV spectroscopic imager is proposed on board SOLAR-B to link
the observations in the photosphere and the corona, and to observe
the velocity field in the transition region and lower corona. A 4,800
gr/mm concave grating is responsible for spectroscopic measurements. In
order to achieve high throughput of the instrument, the collecting
mirror and the grating are LSM coated. Restriction of the observing
wavelengths, which are, at the moment, 250 - 290 Å, reduces the
abberations and increases the efficiency of the spectrograph system,
which will enable, for the first time, high-cadence observations
in these wavelengths. Introduction of a spherical grating with
varied-spacings also help improving off-axis optical performances.
Title: Active Zones and Coronal Holes of the Sun and Their Cycle
Variation Magnetic Activity Cycle in the X-ray Coronal Structures
Authors: Hara, H.
Bibcode: 1996mpsa.conf..321H
Altcode: 1996IAUCo.153..321H
No abstract at ADS
Title: Hard X-Ray Sources and the Primary Energy-Release Site in
Solar Flares
Authors: Masuda, Satoshi; Kosugi, Takeo; Hara, Hirohisa; Sakao, Taro;
Shibata, Kazunari; Tsuneta, Saku
Bibcode: 1995PASJ...47..677M
Altcode:
Accurately coaligned hard and soft X-ray images, taken simultaneously
with the Hard X-ray Telescope (HXT) and the Soft X-ray Telescope
(SXT) aboard Yohkoh, of impulsive solar flares on 1992 January 13
(17:29 UT), 1992 October 4 (22:21 UT), and 1993 February 17 (10:35
UT), occurring near the limb, clearly reveal that, in addition to
double-footpoint sources, a hard X-ray source exists well above the
corresponding soft X-ray loop structure around the peak time of the
impulsive phase. This hard X-ray source shows an intensity variation
similar to double-footpoint sources and a spectrum that is relatively
hard compared with that of loop-top gradual source which appeared later
in the flare. We believe that this is the first clear evidence that
magnetic reconnection, which is responsible for the primary flare energy
release, is under progress above the soft X-ray flaring loop. Maybe
this ``loop-top'' hard X-ray source represents the reconnection site
itself or the site where the downward plasma stream, ejected from
the reconnection point far above the hard X-ray source, collides with
the underlying closed magnetic loop. The characteristics of this hard
X-ray source are quantitatively discussed in the schemes of thermal
(T >~ 10(8) K) and nonthermal interpretations of hard X-ray emission.
Title: Hot-Plasma Ejections Associated with Compact-Loop Solar Flares
Authors: Shibata, K.; Masuda, S.; Shimojo, M.; Hara, H.; Yokoyama,
T.; Tsuneta, S.; Kosugi, T.; Ogawara, Y.
Bibcode: 1995ApJ...451L..83S
Altcode:
Masuda et al. found a hard X-ray source well above a soft X-ray loop
in impulsive compact-loop flares near the limb. This indicates that
main energy release is going on above the soft X-ray loop, and suggests
magnetic reconnection occurring above the loop, similar to the classical
model for two ribbon flares. If the reconnection hypothesis is correct,
a hot plasma (or plasmoid) ejection is expected to be associated
with these flares. Using the images taken by the soft X-ray telescope
aboard Yohkoh, we searched for such plasma ejections in eight impulsive
compact-loop flares near the limb, which are selected in an unbiased
manner and include also the Masuda flare, 1992 January 13 flare. We
found that all these flares were associated with X-ray plasma ejections
high above the soft X-ray loop and the velocity of ejections is within
the range of 50--400 km s-1. This result gives further support for
magnetic reconnection hypothesis of these impulsive compact-loop flares.
Title: Coordinated Observation of the Solar Corona Using the Norikura
Coronagraph and the YOHKOH Soft X-Ray Telescope
Authors: Ichimoto, K.; Hara, H.; Takeda, A.; Kumagai, K.; Sakurai,
T.; Shimizu, T.; Hudson, H. S.
Bibcode: 1995ApJ...445..978I
Altcode:
Spectroscopic observations of coronal emission lines were carried
out at the Norikura Solar Observatory in cooperation with the soft
X-ray telescope on board the Yohkoh satellite to study the plasma
distributions at different temperatures. Intensity and velocity
distributions in Fe XIV wavelength 5303 (green), Fe X wavelength
6374 (red), and Ca XV wavelength 5694 (yellow) lines are compared
with the soft X-ray images. It is found that the soft X-ray images
closely resemble those of the yellow line that represents a rather
high temperature component of the corona. On the other hand the
low-temperature component seen in the green and the red lines shows
quite a different distribution from that of the high-temperature
component; the low-temperature component consists of many thin loops
or streaks, while the high-temperature component is more diffuse. We
find that the active elements of the cool component, i.e., complex
loop systems, rapid changes of small structures, and localized large
plasma motions, all tend to be cospatial with the hot component.
Title: Comparison of Synoptic Maps of Solar Soft X-Ray Features,
Photospheric Magnetic Fields, and Helium 1083 NM
Authors: Harvey, J.; Slater, G.; Nitta, N.; Shibata, K.; Tsuneta,
S.; Sakurai, T.; Hara, H.
Bibcode: 1994AAS...18512308H
Altcode: 1994BAAS...26Q1523H
We studied the wealth of structural features visible in Yohkoh/SXT
and NSO/KP synoptic maps of the Sun that cover Carrington rotations
1847 through 1879. In order to do this comparison, various methods to
reduce soft X-ray maps to simple structural elements were explored. In
the end, the best way of comparing the various data sets turned out to
be to filter the X-ray maps to emphasize high-spatial frequencies and
then to either simply blink the various images or to make colorized
composite maps that distinctively assign different colors to various
quantities. Among the results are: 1. Active regions exhibit normal or
"anemone" (fountain-like) X-ray loop structure tendency depending on
whether the surrounding large-scale unipolarity of the magnetic field
is small or large. 2. There is a systematic twist of the coronal loops
around magnetic concentrations in the southern hemisphere and vice-versa
in the north. The sense is the same as one would expect from the action
of differential rotation. 3. Dark lanes in the X-ray images are centered
over large-scale polarity patterns of one sign or the other. 4. The
X-ray loops at the boundaries between large-scale opposite polarity
patterns are frequently strongly sheared. The presence or absence of
a filament in these locations may be related in a complicated way to
the amount of shear. 5. At the resolution of the synoptic maps, the
footpoints of X-ray loops are almost always rooted in locally strong
magnetic concentrations and also in extra-dark 1083 nm elements.
Title: A loop-top hard X-ray source in a compact solar flare as
evidence for magnetic reconnection
Authors: Masuda, S.; Kosugi, T.; Hara, H.; Tsuneta, S.; Ogawara, Y.
Bibcode: 1994Natur.371..495M
Altcode:
SOLAR flares are thought to be the result of magnetic reconnection
— the merging of antiparallel magnetic fields and the consequent
release of magnetic energy. Flares are classified into two
types1: compact and two-ribbon. The two-ribbon flares,
which appear as slowly-developing, long-lived large loops, are
understood theoretically2-6 as arising from an eruption
of a solar prominence that pulls magnetic field lines upward into
the corona. As the field lines form an inverted Y-shaped structure
and relax, the reconnection of the field lines takes place. This view
has been supported by recent observations7-10. A different
mechanism seemed to be required, however, to produce the short-lived,
impulsive compact flares. Here we report observations made with the
Yohkoh11 Hard X-ray Telescope12 and Soft X-ray
Telescope13, which show a compact flare with a geometry
similar to that of a two-ribbon flare. We identify the reconnection
region as the site of particle acceleration, suggesting that the
basic physics of the reconnection process (which remains uncertain)
may be common to both types of flare.
Title: Temperatures of Coronal Holes Observed with the YOHKOH SXT
Authors: Hara, Hirohisa; Tsuneta, Saku; Acton, Loren W.; Bruner,
Marilyn E.; Lemen, James R.; Ogawara, Yoshiaki
Bibcode: 1994PASJ...46..493H
Altcode:
Temperatures of coronal holes have been estimated from several sets
of soft X-ray images taken through various broad-band filters with the
Soft X-ray Telescope (SXT) aboard Yohkoh. Since coronal holes are dark
areas, a detailed examination of the telescope point spread function,
which is slightly dependent on the X-ray wavelength, is of crucial
importance. The calibration is made using post-launch data, and the
effect of scattered X-rays from bright regions surrounding coronal
holes, especially those from nearby active regions, is carefully
removed. An isothermal approximation is applied to the thus-corrected
data. The temperatures of coronal holes near the disk center are found
to be 1.8--2.4 times 10(6) K, which is almost the same as those derived
for quiet regions not including active regions. The emission measures
in coronal holes are estimated to be 10(25.5--26.2) cm(-5) , about ten
times smaller than those of quiet regions. We conclude that temperatures
in coronal holes do not differ from those in quiet regions, and that
the depression in the soft X-ray intensity of coronal hole regions
results from a lower density by a factor of 3 than quiet regions.
Title: The X-ray Intensity Distribution of the Solar Corona and
its Variability
Authors: Hara, H.
Bibcode: 1994kofu.symp...57H
Altcode:
We report initial analysis of image brightness distributions
that concisely represent the spatial structure of the solar X-ray
corona. This research makes use of histograms of pixel brightnesses
obtained from whole-Sun images from the soft X-ray telescope
(SXT) aboard Yohkoh. We discover that the soft X-ray intensity
histogram essentially consists of a power-law distribution in bright
regions and another one in less bright regions. Active regions
show a power-law intensity distribution, whereas quiet regions have
non-power law distribution. The comparison of the histograms in the
active and less active phases shows that the integrated soft X-ray
variability is related to a variation of the total area and the
appearance/disappearance of bright component of active regions. The
overall shapes of the X-ray histograms are similar to those of
histograms of the photospheric magnetic fields given by Schrijver
and Harvey (1989), implying that a coronal brightness distribution is
related to a magnetic field distribution on the photosphere.
Title: Hard and Soft X-ray Observations of a Super-Hot Thermal Flare
of 6 February, 1992
Authors: Kosugi, T.; Sakao, T.; Masuda, S.; Hara, H.; Shimizu, T.;
Hudson, H. S.
Bibcode: 1994kofu.symp..127K
Altcode:
No abstract at ADS
Title: Spectroscopic Observations of Coronal Emission Lines and
their Relation to Soft X-ray Images
Authors: Ichimoto, K.; Kumagai, K.; Sakurai, T.; Hara, H.; Takeda,
A.; YOHKOH SXT Team
Bibcode: 1994kofu.symp..113I
Altcode:
Spectroscopic observations of coronal emission lines were carried out
to obtain the plasma distribution at different temperatures. Images
in FeXIV5303A(green), FeX6374A(red) and CaXV5694A(yellow) are compared
with the soft X-ray images taken with the Soft X-ray Telescope on board
Yohkoh. It is found that the distributions of green and red lines are
quit different from that of the soft X-rays, while the yellow line
shows quite similar distribution.
Title: Eclipses of the solar X-ray corona by Mercury and the Moon.
Authors: Hudson, H.; Freeland, S.; Lemen, J.; Kosugi, T.; Soma, M.;
Watanabe, T.; Hara, H.; Shimizu, T.
Bibcode: 1994BAAS...26..795H
Altcode:
No abstract at ADS
Title: Temperature of Coronal Holes Measured by YOHKOH SXT
Authors: Hara, H.; Tsuneta, S.; Acton, L. W.; Lemen, J. R.; Ogawara, Y.
Bibcode: 1994xspy.conf..217H
Altcode:
No abstract at ADS
Title: Temperature Structure of Active Regions Deduced from the
Helium-Like Sulphur Lines
Authors: Watanabe, T.; Hara, H.; Shimizu, T.; Hiei, E.; Mariska,
J. T.; Bentley, R. D.; Fludra, A.; Lang, J.; Phillips, K. J. H.;
Pike, C. D.; Bromage, B. J. I.
Bibcode: 1994xspy.conf...55W
Altcode:
No abstract at ADS
Title: Temperature and Density Structure of a Solar Flare Observed
by the YOHKOH SXT and HXT
Authors: McTiernan, J.; Kane, S.; Loran, J.; Lemen, J.; Acton, L.;
Hara, H.; Tsuneta, S.; Kosugi, T.
Bibcode: 1994xspy.conf..255M
Altcode:
No abstract at ADS
Title: Temperature and Density Structure of the 1991 November 2 Flare
Observed by the YOHKOH Soft X-Ray Telescope and Hard X-Ray Telescope
Authors: McTiernan, James M.; Kane, Sharad R.; Loran, Jon M.; Lemen,
James R.; Acton, Loren W.; Hara, Hirohisa; Tsuneta, Saku; Kosugi, Takeo
Bibcode: 1993ApJ...416L..91M
Altcode:
No abstract at ADS
Title: The Dynamics of Coronal Holes as Determined From X-ray Synoptic
Maps Derived From SXT Imagery
Authors: Slater, G. L.; Linford, G. A.; Strong, K. T.; Acton, L. W.;
Tsuneta, S.; Hara, H.; Takahashi, T.; Hiei, H.; Kubo, M.; Harvey,
K.; Bornmann, P.; McIntosh, P. S.; Sime, D.; Watari, S.
Bibcode: 1993BAAS...25.1179S
Altcode:
No abstract at ADS
Title: Classification of Active Regions Based on X-ray Images
1. Active Regions appearing in Coronal Holes
Authors: Nitta, N.; Shibata, K.; Hara, H.
Bibcode: 1993BAAS...25.1187N
Altcode:
No abstract at ADS
Title: Yohkoh-SXT Observations from the Spartan and Nixt Max91
Campaign
Authors: Morrison, M.; Bruner, M.; Freeland, S.; Lemen, J.; Linford,
G.; Nitta, N.; Slater, G.; Strong, K.; Hara, H.; Kano, R.; Shimizu,
T.; Tsuneta, S.; Hudson, H.; Ogawara, Y.; Kosugi, T.; Sakao, T.;
Watanabe, T.; Takeda, A.; Acton, L.
Bibcode: 1993BAAS...25.1213M
Altcode:
No abstract at ADS
Title: Observations of X-ray Jets Using YOHKOH Soft X-Ray Telescope
Authors: Shibata, K.; Ishido, Y.; Acton, L.; Strong, K.; Hirayama,
T.; Uchida, Y.; McAllister, A.; Matsumoto, R.; Tsuneta, S.; Shimizu,
T.; Hara, H.; Sakurai, T.; Ichimoto, K.; Nishino, Y.; Ogawara, Y.
Bibcode: 1993ASPC...46..343S
Altcode: 1993IAUCo.141..343S; 1993mvfs.conf..343S
No abstract at ADS
Title: Effective Geometrical Thickness and Electron Density of a
Flare of 1991 December 2 Observed with the Soft X-Ray Telescope of
YOHKOH and Coronagraph
Authors: Ichimoto, Kiyoshi; Hirayama, Tadashi; Yamaguchi, Asami;
Kumagai, Kazuyoshi; Tsuneta, Saku; Hara, Hirohisa; Acton, Loren W.;
Bruner, Marilyn E.
Bibcode: 1992PASJ...44L.117I
Altcode:
A very small geometrical thickness of 1000 km was found for an M3.7
flare of 1991 December 2, which occurred beyond the limb. While
the Yohkoh soft X-ray telescope gives the emission measure, a new
coronagraph which can observe continuum images at 6630- Angstroms gives
the electron column density originating from electron scattering of a
10(7) K flare plasma. The reasoning for the latter is because [Fe XIV]
5303 Angstroms images show a much different shape compared with X-ray
and the 6630- Angstroms continuum, and there was no Hα emission. From
these we obtained an electron density of 4times 10(10) cm(-3) and the
above-mentioned small length in the line of sight. Since the apparent
width of a flaring plasma both in soft X-ray and continuum images
measured parallel to the limb is ~ 4 times 10(4) km at a height of 7
times 10(4) km, the smallness of the effective length of 1000 km is
striking, and may have significant bearing on the energy conversion
of the flare. A brief discussion concerning the origin of the mass
and magnetic morphology is given.
Title: Observations of X-Ray Jets with the YOHKOH Soft X-Ray Telescope
Authors: Shibata, Kazunari; Ishido, Yoshinori; Acton, Loren W.; Strong,
Keith T.; Hirayama, Tadashi; Uchida, Yutaka; McAllister, Alan H.;
Matsumoto, Ryoji; Tsuneta, Saku; Shimizu, Toshifumi; Hara, Hirohisa;
Sakurai, Takashi; Ichimoto, Kiyoshi; Nishino, Yohei; Ogawara, Yoshiaki
Bibcode: 1992PASJ...44L.173S
Altcode:
Time series of Soft X-ray Telescope images have revealed many X-ray
jets in the solar corona. The typical size of a jet is 5 times 10(3)
--4 times 10(5) km, the translational velocity is 30--300 km s(-1) ,
and the corresponding kinetic energy is estimated to be 10(25) --10(28)
erg. Many of the jets are associated with flares in X-ray bright points,
emerging flux regions, or active regions. They sometimes occur several
times from the same X-ray feature. In some cases, a dark void appears
after ejection at the footpoint of the jet. The void seems to be
the result of a change in the topology of the X-ray emitting plasma,
perhaps due to magnetic reconnection. Some jets show a structure which
suggests a helical magnetic field configuration along the jet. One
of the jets associated with a flaring bright point was identified as
being an Hα surge. In this case, the X-ray bright point is situated
just on the Hα bright point at the footpoint of the surge. The top
of the surge is not bright in X-rays. We briefly discuss the origin
of these newly discovered X-ray jets.
Title: High-Temperature Plasmas in Active Regions Observed with the
Soft X-Ray Telescope aboard YOHKOH
Authors: Hara, Hirohisa; Tsuneta, Saku; Lemen, James R.; Acton,
Loren W.; McTiernan, James M.
Bibcode: 1992PASJ...44L.135H
Altcode:
High-temperature plasmas reaching 5--6times 10(6) K in solar
active regions have been found with the soft X-ray telescope aboard
Yohkoh. NOAA region 6919 was investigated in detail using five different
X-ray filters: The temperature of a bright loop in the active region
is 5.7times 10(6) K, with an emission measure of 5.0times 10(28)
cm(-5) ; in a fainter part of the region plasma, we find 5.0times
10(6) \ K and 4.0times 10(27) cm(-5) . This indicates that such
high-temperature plasmas exist in the active region, irrespective of
the brightness. Another observation of the quiet corona was conducted in
order to investigate the reliability of a temperature analysis with the
same filter pairs which show such high temperatures in active regions:
The inferred temperature was 2.7times 10(6) K, and the emission measure
1.3times 10(26) cm(-5) , which is consistent with the typical results
of Skylab. Therefore, the high-temperature plasmas in solar active
regions are considered to be real.
Title: Observation of a Solar Flare at the Limb with the YOHKOH Soft
X-Ray Telescope
Authors: Tsuneta, Saku; Hara, Hirohisa; Shimizu, Toshifumi; Acton,
Loren W.; Strong, Keith T.; Hudson, Hugh S.; Ogawara, Yoshiaki
Bibcode: 1992PASJ...44L..63T
Altcode:
A long-enduring soft X-ray flare at the solar limb was well observed
by the Soft X-ray Telescope aboard the Yohkoh spacecraft from its
pre-flare stage through the post-flare phase. A ``helmet streamer"
arch appears several hours prior to the flare, in association with a
continuous expansion and restructuring of the active-region magnetic
structure. This arch then starts to flare, and increases its height and
footpoint separation at v = 10--30 km s(-1) . The arch has a complex
temperature structure in the rising phase, whereas the outer arches
have systematically higher temperatures in the decay phase. Magnetic
reconnection in a neutral sheet at the loop top, created by pre-flare
magnetic restructuring, would explain this type of flare.
Title: Temperature Structure of Solar Flares Observed by the
YOHKOH SXT
Authors: McTiernan, J. M.; Kane, S. R.; Loran, J. M.; Lemen, J. R.;
Acton, L. W.; Hara, H.; Tsuneta, S.
Bibcode: 1992AAS...180.3002M
Altcode: 1992BAAS...24Q.775M
Hot plasmas from several solar flares have been observed by the Soft
X-ray Telescope (SXT) on board the Yohkoh satellite. For a sample of
flares observed by the SXT with a variety of X-ray filters, we have
calculated temperature and emission measures as functions of space and
time. Initial results from this analysis show the following: (1) The
flare plasmas range in temperarure from several million degrees K up to
greater than 20 million degrees K, depending on the individual event;
(2) The region with the higest temperature does not coincide with
the brightest region. For example, for the flare of 15 November 1991
(2238 UT) the temperature was typically 8-9 million degrees K on the
bright kernels, with temperatures of 15-25 million degrees K on the
edges of the bright regions. The average temperature for the flare was
approximately 10 million degrees K. A preliminary interpretation of
these observational results in terms of the temperature and density
structure inside a magnetic loop will be presented.
Title: NASDA's Space Operations and Data System II
Authors: Hara, H.; Yamada, S.; Igarashi, S.; Horiguchi, K.; Kuniyasu,
Y.; Kuroki, S.; Nishihata, S.; Oniyama, A.; Yambe, M.
Bibcode: 1992aiaa.confV....H
Altcode:
NASDA has begun the definition of its satellite tracking-and-control
Space Operations and Data System II, which will encompass the launching
of the COMETS telecommunications and broadcasting technology engineering
satellite in 1997. The satellites that are to transfer data with COMETS
via an intersatellite link encompass the next-generation earth-observing
satellite ADEOS, the Tropical Rainfall Measurement Satellite, the
Engineering Test Satellite II, and the Japanese Experiment Module
of Space Station Freedom. Detailed schematics for these systems'
interrelations are provided.