清水 敏文

We use high-resolution observations of the Sun in Ca II H (3968 angstrom) from the Solar Optical Telescope on Hinode to show that there are at least two types of spicules that dominate the structure of the magnetic solar chromosphere. Both types are tied to the relentless magnetoconvective driving in the photosphere, but have very different dynamic properties. "Type-I" spicules are driven by shock waves that form when global oscillations and convective flows leak into the upper atmosphere along magnetic field lines on 3-7 minute timescales. "Type-II" spicules are much more dynamic: they form rapidly (in similar to 10 s), are very thin (<= 200 km wide), have lifetimes of 10-150 s (at any one height), and seem to be rapidly heated to (at least) transition region temperatures, sending material through the chromosphere at speeds of order 50-150 km s(-1). The properties of Type II spicules suggest a formation process that is a consequence of magnetic reconnection, typically in the vicinity of magnetic flux concentrations in plage and network. Both types of spicules are observed to carry Alfven waves with significant amplitudes of order 20 km s(-1).

We present one Hinode Spectropolarimeter (SP) magnetograrn of AR 10930 that produced several major flares. The inversion from Stokes profiles to magnetic field vectors was made using the standard Milne-Eddington code. We successfully applied the Uniform Shear Method for resolving the 180 degrees ambiguity to the magnetogram. The inversion gave very strong magnetic field strengths (near 4500 gauss) for a small portion of area in the umbra. Considering that the observed V-profile of 6301.5 angstrom was well-fitted as well as a direct estimation of the Zeeman splitting results in 4300-4600 gauss, we think that the field strengths should not be far from the actual value. A cross-comparison of the Hinode SP and SOHO MDI high resolution flux densities shows that the MDI flux density could be significantly underestimated by about a factor of two. In addition, it has a serious negative correlation (the so-called Zeeman saturation effect) with the Hinode SP flux density for umbral regions. Finally, we could successfully obtain a recalibrated MDI magnetogram that has been corrected for the Zeeman saturation effect using not only a pair of MDI intensity and magnetogram data simultaneously observed, but also the relationship from the cross-comparison between the Hinode SP and MDI flux densities.

We present initial results on the line-of-sight field calibration of the two kinds of Stokes I and V data taken by the Solar Optical Telescope on the satellite Hinode: spectral profiles of Stokes I and V parameters recorded on the Spectro-polarimeter (SP), and monochromatic images of the same parameters recorded on the Narrow-band Filter Imager (NFI). By applying the center-of-gravity method to the SP data of AR 10930 taken on 2006 December 11, we determined the line-of-sight field at every location in the active region. As a result, we found that the line-of-sight field strength ranges up to 2kG in plages, even without taking into account the filling factor, and up to 3.5 kG or higher values inside the umbra of the major sunspot. We calibrated the NFI data in reference to the field determined from the SP data. In regions outside the sunspots and the penumbral regions, we adopted a linear relation, B-parallel to = beta V/I, between the circular polarization, V/I, and the line-of-sight field strength, B-parallel to, and obtained beta = 23.5 kG in regions outside the sunspots, and beta = 12.0 kG in penumbral regions. In umbral regions of sunspots, a first-order polynomial was adopted to model the reversal of the polarization signal over the field strength.

A high resolution imaging observation of a sunspot umbra was made with the Hinode Solar Optical Telescope. Filtergrams at wavelengths of the blue and green continua were taken during three consecutive days. The umbra consisted of a dark core region, several diffuse components, and numerous umbral dots. We derived basic properties of umbral dots (UDs), especially their temperatures, lifetimes, proper motions, spatial distribution, and morphological evolution. The brightness of UDs is confirmed to depend on the brightness of their surrounding background. Several UDs show fission and fusion. Thanks to the stable condition of the space observation, we could for the first time follow the temporal behavior of these events. The derived properties of the internal structure of the umbra are discussed from the viewpoint of magnetoconvection in a strong magnetic field.

Here we present spectro-polarimetric measurements of several pores and the surrounding regions taken with the Solar Optical Telescope aboard Hinode at various viewing angles. We analyzed the Stokes V area asymmetry, and confirmed that it is depressed at the center of the pores, while it shows large positive values (a blue lobe larger than a red lobe) in the surrounding area; this is consistent with a previous report. In addition to this ring of positive asymmetry, we found regions of alternating positive and negative area asymmetries when weak V regions were observed near the solar limb. The positive asymmetry occurs on the disk-center side and the negative asymmetry on the limb side of the magnetic concentrations. These center-to-limb variations of the Stokes V area asymmetry can be interpreted as being a systematic inflow of plasma into the magnetic concentrations from their surroundings.

We present a method to study the penumbral fine structure using data obtained by the spectropolarimeter on board Hinode. For the first time, the penumbral filaments can be considered as being resolved in spectropolarimetric measurements. This enables us to use inversion codes with only one-component model atmospheres, and thus to assign the obtained stratifications of the plasma parameters directly to the penumbral fine structure. This approach was applied to the limb-side part of the penumbra in the active region NOAA 10923. Preliminary results show a clear dependence of the plasma parameters on the continuum intensity in the inner penumbra, i.e., a weaker and horizontal magnetic field along with an increased line-of-sight velocity are found in the low layers of the bright filaments. The results in the mid penumbra are ambiguous, and future analyses are necessary to unveil the magnetic field structure and other plasma parameters there.

Exploiting high-resolution observations made by the Solar Optical Telescope on board Hinode, we investigate the spatial distribution of the power spectral density of the oscillatory signal in and around the active region NOAA 10935. The G-band data show that in the umbra the oscillatory power is suppressed in all frequency ranges. On the other hand, in Ca II H intensity maps oscillations in the umbra, so-called umbral flashes, are clearly seen with the power peaking around 5.5 mHz. The Ca II H power distribution shows the enhanced elements with the spatial scale of the umbral flashes over most of the umbra, but there is a region with suppressed power at the center of the umbra. The origin and property of this node-like feature remain unexplained.

The Solar Optical Telescope (SOT) on-board Hinode successfully and continuously observed the formation process of a light bridge in a matured sunspot of the NOAA active region 10923 for several days with high spatial resolution. During its formation, many umbral dots were observed to be emerging from the leading edges of penumbral filaments, and rapidly intruding into the umbra. The precursor of the light bridge formation was also identified as a relatively slow inward motion of the umbral dots, which emerged not near the penumbra, but inside the umbra. The spectro-polarimeter on SOT provided physical conditions in the photosphere around the umbral dots and the light bridges. We found that the light bridges and the umbral dots had significantly weaker magnetic fields associated with upflows relative to the core of the umbra, which implies that there was hot gas with weak field strength penetrating from the subphotosphere to near the visible surface inside those structures. There needs to be a mechanism to drive the inward motion of the hot gas along the light bridges. We suggest that the emergence and the inward motion are triggered by a buoyant penumbral flux tube as well as subphotospheric flow crossing the sunspot.

The small-scale structure of the Evershed effect is being studied using data obtained by the Spectropolarimeter and the Broadband Filter Imager of the Solar Optical Telescope aboard Hinode. We find that the Evershed flow starts at the leading edge of inwardly migrating bright penumbral grains, and turns to nearly a horizontal flow preferentially in the dark lanes of the penumbra. A number of small elongated regions that have an upward motion of similar to 1 km s(-1) are found in the deep photosphere distributed over the penumbra. They are cospatial with bright grains and have relatively horizontal magnetic fields. A number of patches having a strong downward motion associated with the opposite magnetic polarity from the sunspot are also found in the mid and outer penumbra. They could be identified as foot points of the Evershed flow channels, though the identification of individual pairs is not straightforward. Our results provide strong support for some recent findings from ground-based high-resolution observations, and are in general agreement with the well-known picture of the uncombed structure of the penumbra, in which the penumbrae consist of rising flux tubes carrying nearly horizontal Evershed flows embedded in more vertical background magnetic fields.

Results from initial helioseismic observations by the Solar Optical Telescope on-board Hinode are reported. It has been demonstrated that intensity oscillation data from the Broadband Filter Imager can be used for various helioseismic analyses. The k-omega power spectra, as well as the corresponding time-distance cross-correlation function, which promise high-resolution time-distance analysis below the 6-Mm travelling distance, were obtained for G-band and Ca II-H data. Subsurface supergranular patterns were observed from our first time-distance analysis. The results show that the solar oscillation spectrum is extended to much higher frequencies and wavenumbers, and the time-distance diagram is extended to much shorter travel distances and times than were observed before, thus revealing great potential for high-resolution helioseismic observations from Hinode.

In this paper we propose an inversion strategy for the analysis of spectropolarimetric measurements taken by Hinode in the quiet Sun. The Spectro-Polarimeter of the Solar Optical Telescope aboard Hinode records the Stokes spectra of the Fe I line pair at 630.2 nm with unprecendented angular resolution, high spectral resolution, and high sensitivity. We discuss the need to consider a local stray-light contamination to account for the effects of telescope diffraction. The strategy is applied to observations of a wide quiet Sun area at disk center. Using these data we examine the influence of noise and initial guess models in the inversion results. Our analysis yields the distributions of magnetic field strengths and stray-light factors. They show that quiet Sun internetwork regions consist mainly of hG fields with stray-light contamination of about 0.8.

In the present work, we used optical and X-ray data from the Hinode satellite to study the response of the solar chromosphere and the corona to the emerging flux in the photosphere. In total, twelve emerging flux regions (EFRs) were selected to conduct this study. The average separation of the two polarities and the lifetime of these EFRs were 3 ''.2 and 40 min, respectively. All of these regions showed corresponding enhanced emission in the Ca II H line and soft X-rays with different filters, indicating that these small-scale and short-lived EFRs heat the chromosphere and the corona to some extent.

We present observations of magnetic fields of the very quiet Sun near disk center using the Spectro-Polarimeter of the Solar Optical Telescope aboard the Hinode satellite. These observations reveal for the first time the ubiquitous presence of horizontal magnetic fields in the internetwork regions. The horizontal fields are spatially distinct from the vertical fields, demonstrating that they are not arising mainly from buffeting of vertical flux tubes by the granular convection. The horizontal component has an average "apparent flux density" of 55 M x cm(-2) (assuming the horizontal field structures are spatially resolved), in contrast to the average apparent vertical flux density of 11 M x cm(-2). The vertical fields reside mainly in the intergranular lanes, whereas the horizontal fields occur mainly over the bright granules, with a preference to be near the outside edge of the bright granules. The large apparent imbalance of vertical and horizontal flux densities is discussed, and several scenarios are presented to explain this imbalance.

To understand the physical mechanisms for activity and heating in the solar atmosphere, the magnetic coupling from the photosphere to the corona is an important piece of information from the Hinode observations, and therefore precise positional alignment is required among the data acquired by different telescopes. The Hinode spacecraft and its onboard telescopes were developed to allow us to investigate magnetic coupling with co-alignment accuracy better than 1 ''. Using the Mercury transit observed on 2006 November 8 and co-alignment measurements regularly performed on a weekly basis, we have determined the information necessary for precise image co-alignment, and have confirmed that co-alignment better than 1 '' can be realized between Solar Optical Telescope (SOT) and X-Ray Telescope (XRT) with our baseline co-alignment method. This paper presents results from the calibration for precise co-alignment of CCD images from SOT and XRT.

Vector magnetic fields of moving magnetic features (MMFs) were well observed with the Solar Optical Telescope (SOT) aboard the Hinode satellite. We focused on the evolution of three MMFs with the SOT in this study. We found that an MMF having relatively vertical fields with the same polarity as the sunspot was detached from the penumbra around the granules appearing in the outer penumbra. This suggests that granular motions in the outer penumbra are responsible for disintegration of the sunspot. Two MMFs with polarity opposite to the sunspot are located around the outer edge of horizontal fields extending from the penumbra. This is evidence that the MMFs with polarity opposite to the sunspot are the prolongation of penumbral horizontal fields. Redshifts larger than the sonic velocity in the photosphere are detected for some of the MMFs with polarity opposite to the sunspot.

The Solar Optical Telescope (SOT) on board the Hinode satellite observed an X3.4 class flare on 2006 December 13. A typical two-ribbon structure was observed, not only in the chromospheric Ca II H line, but also in the G-band and Fe I 6302 angstrom line. The high-resolution, seeing-free images achieved by SOT revealed, for the first time, sub-arcsec fine structures of the "white light" flare. The G-band flare ribbons on sunspot umbrae showed a sharp leading edge, followed by a diffuse inside, as well as a previously known core-halo structure. The underlying structures, such as umbral dots, penumbral filaments, and granules, were visible in the flare ribbons. Assuming that the sharp leading edge was directly heated by a particle beam and the diffuse parts were heated by radiative back-warming, we estimated the depth of the diffuse flare emission using an intensity profile of the flare ribbon. We found that the depth of the diffuse emission was about 100 km or less from the height of the source of radiative back-wan-ning. The flare ribbons were also visible in the Stokes-V images of Fe 1 6302 A, as a transient polarity. reversal. This is probably related to a "magnetic transient" reported in the literature. The intensity increase in Stokes-I images indicates that the Fe I 6302 angstrom line was significantly deformed by the flare, which may cause such a magnetic transient.

We observed small-scale magnetic-flux emergence in a sunspot moat region by the Solar Optical Telescope (SOT) aboard the Hinode satellite. We analyzed filtergram images observed at wavelengths of Fe 6302 angstrom, G band, and Ca II H. In Stokes I images of Fe 6302 angstrom, emerging magnetic flux was recognized as dark lanes. In the G band, they showed to be their shapes almost the same as in Stokes I images. These magnetic fluxes appeared as dark filaments in Ca II H images. Stokes V images of Fe 6302 angstrom showed pairs of opposite polarities at footpoints of each filament. These magnetic concentrations were identified to correspond to bright points in G band/Ca II H images. From an analysis of time-sliced diagrams, we derived the following properties of emerging flux, which are consistent with those of previous studies: (1) Two footpoints separate each other at a speed of 4.2 km s(-1) during the initial phase of evolution, and decrease to about 1 km s(-1) 10 minutes later. (2) Ca II H filaments appear almost simultaneously with the formation of dark lanes in Stokes I in an observational cadence of 2 minutes. (3) The lifetime of the dark lanes in the Stokes I and G band is 8 minutes, while that of Ca filament is 12 minutes. An interesting phenomena was observed, that an emerging flux tube expanded laterally in the photosphere with a speed of 3.8 km s(-1). A discussion on the horizontal expansion of the flux tube is given with refernce to previous simulation studies.

We use Hinode/SOT Ca II H-line and blue continuum broadband observations to study the presence and power of high frequency acoustic waves at high spatial resolution. We find that there is no dominant power at small spatial scales; the integrated power using the full resolution of Hinode (0.'' 05 pixels, 0.'' 16 resolution) is larger than the power in the data degraded to 0.'' 15 pixels (TRACE pixel size) by only a factor of 1.2. At 20 mHz the ratio is 1.6. Combining this result with the estimates of the acoustic flux based on TRACE data of Fossum and Carlsson (2006, ApJ, 646, 579), we conclude that the total energy flux in acoustic waves of frequency 5-40 mHz entering the internetwork chromosphere of the quiet Sun is less than 800 W m(-2), inadequate to balance the radiative losses in a static chromosphere by a factor of five.

Continuous observations of the flare productive active region 10930 were successfully carried out with the Solar Optical Telescope aboard the Hinode spacecraft during 2006 December 6 to 19. We focused on the evolution of photospheric magnetic fields in this active region, and the magnetic field properties at the site of the X3.4 class flare, using a time series of vector field maps with high spatial resolution. The X3.4 class flare occurred on 2006 December 13 at the apparent collision site between the large, opposite polarity umbrae. Elongated magnetic structures with alternatingly positive and negative polarities resulting from flux emergence appeared one day before the flare in the. collision site penumbra. Subsequently, the polarity inversion line at the collision site became very complicated. The number of bright loops in Ca II H increased during the formation of these elongated magnetic structures. Flare ribbons and bright loops evolved along the polarity inversion line and one footpoint of the bright loop was located in a region having a large departure of the field azimuth angle with respect to its surroundings. SOT observations with high spatial resolution and high polarization precision revealed temporal change in the fine structure of magnetic fields at the flare site: some parts of the complicated polarity inversion line then disappeared, and in those regions the azimuth angle of the photospheric magnetic field changed by about 90 degrees, becoming more spatially uniform within the collision site.

We observed X-ray bright points (XBPs) in a quiet region of the Sun with the X-Ray Telescope (XRT) aboard the Hinode satellite on 2006 December 19. XRT's high-resolution X-ray images revealed many XBPs with complicated structure and evolving dramatically with time. Almost all of the dynamic eruptions in the quiet region were composed of XBPs, and they had either loop or multiloop shapes, as is observed in larger flares. Brightening XBPs had strong magnetic fields with opposite polarities near their footpoints. While we have found a possible example of associated magnetic cancellation, other XBPs brighten and fade without any associated movement of the photospheric magnetic field.

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 5 mHz wave power above regions of enhanced photospheric magnetic field in both chromospheric, transition region, and coronal emission.

We present spectropolarimetric measurements of dark-cored penumbral filaments taken with Hinode at a resolution of 0.3 ''. Our observations demonstrate that dark-cored filaments are more prominent in polarized light than in continuum intensity. Far from disk center, the Stokes profiles emerging from these structures are very asymmetric and show evidence for magnetic fields of different inclinations along the line of sight, together with strong Evershed flows of at least 6-7 km s(-1). In sunspots closer to disk center, dark-cored penumbral filaments exhibit regular Stokes profiles with little asymmetries due to the vanishing line-of-sight component of the horizontal Evershed flow. An inversion of the observed spectra indicates that the magnetic field is weaker and more inclined in the dark cores as compared with the surrounding bright structures. This is compatible with the idea that dark-cored filaments are the manifestation of flux tubes carrying hot Evershed flows.

We study the emergence of magnetic flux at very small spatial scales (less than 2") in the quiet-Sun internetwork. To this aim, a time series of spectropolarimetric maps was taken at disk center using the instrument SP/SOT on board Hinode. The LTE inversion of the full Stokes vector measured in the Fe I 6301 and 6302 lines allows us to retrieve the magnetic flux and topology in the region of study. In the example presented here, the magnetic flux emerges within a granular structure. The horizontal magnetic field appears prior to any significant amount of vertical field. As time goes on, the traces of the horizontal field disappear, while the vertical dipoles drift-carried by the plasma motions-toward the surrounding intergranular lanes. These events take place within typical granulation timescales.

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. © 2007 Springer Science+Business Media B.V.

Moving magnetic features (MMFs) are small photospheric magnetic elements moving outward in the zone ( moat region) surrounding mature sunspots. Vector magnetic fields and horizontal motion of the classical MMFs ( called isolated MMFs hereafter) are investigated using coordinated ASP and MDI observations. Their magnetic and velocity properties are compared to nearby magnetic features, including moat fields surrounding the isolated MMFs and penumbral uncombed structure. The moat fields are defined as nonisolated MMFs because they also move outward from sunspots. The nonisolated MMFs have nearly horizontal magnetic fields of both polarities. We find that the isolated MMFs located on the lines extrapolated from the horizontal component of the uncombed structure have magnetic fields similar to the nonisolated MMFs. This suggests that the MMFs with nearly horizontal fields are intersections of horizontal fields extended from the penumbra with the photospheric surface. We find clear evidence that the isolated MMFs located on the lines extrapolated from the vertical component of the uncombed structure have vertical field lines with polarity same as the sunspot. This correspondence shows that such MMFs are detached from the spine ( vertical) component of the penumbra. We estimate that the magnetic flux carried by the vertical MMFs is about 1-3 times larger than the flux loss of the sunspot. We suggest that the isolated vertical MMFs alone can transport sufficient magnetic flux and are responsible for the disappearance and disintegration of the sunspot.

The Focal Plane Package (FPP) of the Solar Optical Telescope (SOT) includes the first precision Spectro-Polarimeter (SP) for solar space observations. The FPP/SP will provide high precision measures of the vector magnetic field in the solar photosphere. Here we present some as-built performance specifications for the entire system of telescope + polarimeter. The FPPSP system represents significant gains in several aspects over existing spectro-polarimetric systems, notably, angular resolution, polarimetric accuracy, spectral purity, and most importantly, temporal continuity of stable, high angular resolution. In this short summary of the poster, a few of the performance characteristics of the SP are presented.

The solar observation satellite "SOLAR-B," which is being developed under the joint cooperation of JAXA and NAOJ with the U.S.A. (NASA) and the U.K. (PPARC), will be launched in summer 2006. SOLAR-B requires very high pointing stability for its three telescopes. In particular, the Solar Optical Telescope (SOT), which has the highest resolution and narrowest field of view among these telescopes, requires 0.06 [arcsec]_3σ of short-term (10[s]) stability to meet the observation demands. However, it is very difficult to achieve such levels of stability by only using the satellite attitude control system due to disturbance from the observation equipment. Therefore, we propose using the Correlation Tracker and tip-tilt Mirror package (CTM), which stabilizes the sun observation image. CTM consists of a correlation tracker and a piezo-based tip-tilt mirror with servo control electronics. This paper describes the mechanism and the control and determination methods of the control gain of CTM as well as the results of experiments conducted to clarify its capability.

The SOT (Solar Optical Telescope, e.g., Shimizu 2004) optical system consists of 50cm-aperture optical telescope (OTA) and focal plane instrument (FPP). The solar light into the telescope penetrates through many optical elements located in OTA and FPP before illuminating CCDs. Natural solar light was fed to the integrated SOT in sun tests for verifying various optical aspects including the confirmation of photon throughput. CCD exposures provide the number of photons accumulated in an exposure duration with a clean-room test condition. To estimate the absolute intensity of the solar light at the telescope entrance in the clean-room test condition, we developed a pinhole-PSD sensor for simultaneous monitoring the solar light outside the clean room and measured the transmission of light through two flat mirrors of the heliostat and clean-room entrance window glass as a function of wavelength. The PSD sensor was pre-calibrated with continuous monitoring the solar light in a day long under a clear constant sky condition, determining the earth atmospheric attenuation and the PSD output for the solar light on orbit. These throughput measurements have provided an estimate on photon throughput for the SOT flight model. The results confirm suitable number of photons without saturation for proper CCD exposures in flight.

We report the results of the examination about the relative alignment among the instruments on SOT. We employ a test data set obtained in the natural sun-light test in May 2005, which has had a grid pattern over the entire FOV. SOT has the filtergraph (FG) and the spectro-polarimeter (SP). The FG consists of six broadband filter imagers (BFI) and six narrowband filter imagers (NFI). We examined the displacements among the images taken with different filters to an accuracy of better than 0.1 pixel corresponding to 0.02". It is important to know relative displacements and plate scales of these instruments for accurate alignment of observational data. We note that the values measured in our work are relative and it is needed to decide the absolute values with another way.

This paper reports on our new findings from the International Time Program observations at the Canaries islands, Spain, in July 2005. We have found small-scale photospheric events with extremely red-shifted Stokes V signals in sunspot moat regions. A preliminary estimate of the physical conditions for an observed Stokes V profile indicates the presence of a downward motion with a supersonic speed in the order of 10 km/s. With the currently evaluated observational information, we interprete the supersonic flows as downward motion from magnetic reconnection occurring at the upper chromosphere or lower photosphere. With coordinated observations of the Solar-B onboard telescopes, Stokes measurements by the SOT spectro-polarimeter would give new information for further understanding the nature of these events with strongly red-shifted Stokes V, and for discussing the physical conditions involving in possible magnetic reconnections in the lower solar atmosphere.

We investigate vector magnetic fields of moving magnetic features (MMFs) around a mature sunspot with the Advanced Stokes Polarimeter and SOHO/MDI. In addition to the classical isolated MMFs identified by visually inspecting the time sequence of MDI magnetograms, we focus on any diffuse moving magnetic features that are not recognized as classical MMFs. This feature is called non-isolated MMFs. The non-isolated MMFs occupy most of the moat region surrounding the sunspot, and have nearly horizontal magnetic fields with both polarities. We find that the isolated MMFs located on the lines extrapolated from the horizontal component of the penumbral uncombed structure have magnetic fields similar to the non-isolated MMFs. This suggests that such MMFs are part of horizontal fields extended from the penumbra. The isolated MMFs located on the lines extrapolated from the vertical component of the uncombed structure have vertical fields with polarity same as the sunspot. Our observation shows that such MMFs are detached from the vertical component of the penumbra. Their flux transport rate is estimated to be 1-3 times larger than a flux loss rate of the sunspot. The isolated vertical MMFs alone can be responsible for decaying the sunspot.

The Narrowband Filter Instrument (NFI) of the Solar Optical Telescope onboard Solar-B provides 2D magnetograms/Dopplergrams with a. tunable Lyot filter (width similar to 0.1 angstrom) in 6 selected wavelength bands, and spatial sampling of 0."08/px. The Zeeman-effect sensitivity of NFI and the detection limits of weak magnetic fields are evaluated for 2 photospheric and 3 chromospheric lines. Magnetic-field retrievability from the NFI observables is studied. using synthetic Stokes profiles of Fe I 5250 angstrom. We find that, with optimized wavelength sampling at 4 positions, the inferred magnetic field is sufficiently accurate under the hypothesis of constant magnetic field and velocity along the LOS.

The tip-tilt mirror (TTM) system was developed for the extreme ultraviolet (XUV) Cassegrain telescope aboard the Institute of Space and Astronautical Science sounding rocket. The spatial resolution of the telescope is about 5 arcsec, whereas the rocket pointing is only controlled to be within ± 0. 5 deg of the target (sun) without additional stability control. To stabilize the XIV image within about 5 arcsec on the focal plane, the TTM system controls the tilt of the secondary mirror with two-axis fixed-coil magnetic actuators. The TTM system has a wide tilt angle and can drive the large secondary mirror at high frequency. The two position-sensitive detector-, one placed in the telescope and the other in the TTM mechanical structure, are used for closed-loop control of toe TTM. The closed-loop control system, which has command and telemetry, is executed by the flight software on the digital signal processor. The TTM has a launch-lock mechanism to protect against launch vibrations up to about 16G. The sounding rocket was launched from the Kagoshima Space Center on 31 January 1998. The TTM worked perfectly during the flight and achieved better than the expected 5-arcsec stability on the focal plane during CCD charge-coupled device exposures.

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 (similar to0.2arcsec) 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 phiw500mm. 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.

Extremely stable pointing of the telescope is required for images on the CCD cameras to accurately measure the nature of magnetic field on the sun. An image stabilization system is installed to the Solar Optical Telescope onboard SOLAR-B, which stabilizes images on the focal plane CCD detectors in the frequency range lower than about 20Hz. The system consists of a correlation tracker and a piezo-based tip-tilt mirror with servo control electronics. The correlation tracker is a high speed CCD camera with a correlation algorithm on the flight computer, producing a pointing error from series of solar granule images. Servo control electronics drives three piezo actuators in the tip-tilt mirror. A unique function in the servo control electronics can put sine wave form signals in the servo loop, allowing us to diagnose the transfer function of the servo loop even on orbit. The image stabilization system has been jointly developed by collaboration of National Astronomical Observatory of Japan/Mitsubishi Electronic Corp. and Lockheed Martin Advanced Technology Center Solar and Astrophysics Laboratory. Flight model was fabricated in summer 2003, and we measured the system performance of the flight model on a laboratory environment in September 2003, confirming that the servo stability within 0-20 Hz bandwidth is 0.001-0.002 arcsec rms level on the sun.

Collaborative observations of NOAA Active Region 9231 were carried out during 9 days in 2000 November using the Advanced Stokes Polarimeter (ASP), Yohkoh/SXT, TRACE, and SOHO/MDI, in order to record the evolution of the photospheric magnetic field and its related coronal response. During this period an emerging flux region (EFR) appeared in the photosphere near the well-developed leading sunspot of this region, and subsequently bright bundles of coronal loops formed between the main concentrations of opposite magnetic polarity. The structure of the photospheric field comprising the EFR is classified into three regions: (1) the main bipolar magnetic flux of the EFR (2) two small, rapidly emerging bipoles within the EFR and (3) the remainder of the EFR excluding the other two regions. Two small, rapidly emerging bipoles are observed within a few hours of their first appearance at the photosphere. Examination of the vector magnetic field, its filling factor, and Doppler motion within the EFR shows that the young emerging magnetic field is nearly horizontal, the intrinsic field strength is weaker than that of the surrounding magnetic field (∼500 G), and the weak field has a high filling factor (&gt 80%) and upward motion (&lt 1 km s-1). At both ends of the horizontal field structure we find that the magnetic field strength increases to about 1500 G and the filling factor drops to about 40% as the magnetic field becomes vertical in orientation during its first 12 hr. This field strength is typical of the field within the main bipolar magnetic flux, but the filling factor increases to 80% during the following 2 days. The process for organizing magnetic field configuration including convective collapse and flux concentration provides one possible explanation of the evolution of the field strength and the filling factor in the EFR. In addition, aymmetric surface distributions of magnetic field inclination were observed in the horizontal magnetic field area in the EFR. These asymmetric distributions were also observed in the small, young, emerging bipoles. This may mean that the magnetic field of the EFR is affected by the preexisting magnetic environment surrounding the EFR and that the emerging magnetic loops are deformed before or at the time they reach the photospheric level.

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 &gt 1 MK) temperature evolution of coronal loops. The detailed morphological comparison of an active region shows that hot loops seen in SXT (T &gt 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.

Magnetic properties and heat generation characteristics of a bio-compatible ceramic Mg1+xFe2-2xTixO4 system have been investigated as an implant material for the magnetic induction hyperthermia. Curie temperature (T-c) of the ceramic decreases with increasing x, and become T-c similar to 350 K at x = 0.35 and similar to 315 K at x = 0.38, which is suitable Curie temperature for implant material. The temperature of ceramic as a function of time under the high frequency alternating magnetic field is self-controlled at T-c. The surface temperature of a powder injection sphere cancer model, which was a mixture of the agar phantom and the ceramic powder implant, and the temperature distribution around the sphere set in the pure agar phantom matrix have been measured. The result is in good agreement with calculation using a finite element method (FEM). It was found that the temperature distribution inside of the sphere and the minimum quantity of Mg1+xFe2-2xTixO4 necessary for hyperthermia could be estimated by the FEM calculation. (C) 2003 Elsevier Ltd. All rights reserved.

Doppler velocities in the penumbra of a δ-configuration sunspot observed near the limb indicate flows that converge upon the line separating locally positive and negative polarity magnetic field (the polarity inversion line). These flows persist for many hours. Observations of this region with the Advanced Stokes Polarimeter (ASP) reveal a convex vector field geometry with magnetic lines of force arching upward from positive polarity, then downward to negative polarity. The straightforward interpretation of the combined Doppler velocity and vector field information leads to an untenable physical situation: were flows directed from both footpoints toward the tops of arched magnetic lines of ferce, mass would rapidly load the tops of the arches. However, there is no observational evidence of the dynamics that such a loading would require. To better understand this apparent contradiction, we perform two-component analyses of the observed Stokes spectral profiles in the vicinity of the polarity inversion line, in order to extract information about unresolved structure of the magnetic field and its associated flows. Fits to the observed profiles, obtained by use of two different inversion techniques, suggest strongly that, as in penumbrae of simple sunspots, the field geometry in the convergence zone is "fluted." However, unlike in simple sunspots, which have only an outward-directed Evershed flow in the more horizontal of the field components, at each spatial point our analysis reveals flows in the two components that are oppositely directed. We interpret these observations as indicative of an interleaved system of field lines in the vicinity of the polarity reversal, whereby the convergent streams are able to slip past one another and return downward into the solar interior.

By combining Yohkoh soft X-ray images with high-resolution magnetograms simultaneously obtained at La Palma, we studied photospheric magnetic signatures responsible for soft X-ray microflares (active-region transient brightenings). In order to have a reliable correspondence between the photosphere and the corona, we studied 16 pointlike transient brightenings with X-ray source size less than 10″ occurring during periods when the seeing was excellent at La Palma, although a lot of transient brightenings were in forms of multiple-or single-loop structures. In half of the studied events, small-scale emergences of magnetic flux loops are found in the vicinity of the transient brightenings. Six events of that half show that a small-scale flux emergence accompanies the X-ray brightening 5-30 minutes prior to its onset. In the other half of the studied events, no apparent evolutionary change of magnetic flux elements is found associated with the transient brightenings. Many of these events are found in rather strong magnetic fields, such as sunspots and pores, implying that small-scale changes of magnetic flux are obscured or suppressed by strong magnetic fields. The horizontal plasma flows derived from local cross-correlation tracking of granules in continuum images are suppressed at the feet of some X-ray transient brightenings.

Yohkoh has provided new observations of the X-ray corona for over 10 years and has made several advances in understanding magnetic origins of the heating and energy releases in the corona. We have, especially, learned much about weak transient activities, such as jets and transient brightenings (microflares) from Yohkoh observations and also from EUV observations by the SOHO and TRACE spacecraft. Some observations have been published, clearly showing a key role of magnetic flux just after newly emerging from below the surface. These observations can be explained by an emerging flux model. © 2002 Elsevier B.V. All rights reserved.

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 Angstrom above and 2 Angstrom below the Fe XIV 211 Angstrom (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 Angstrom (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.

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 211Å 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 (&gt 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 211Å line indicates a possible down-flow of 1.8 MK plasma near the footpoints of multiple cool loops. © 2000 COSPAR. Published by Elsevier Science Ltd.

We have developed narrow-bandpass MoSi/Si multilayer mirrors for a Japanese sounding-rocket program. A high spectral resolution λ/Δλ exceeding 40 was achieved by a two-mirror telescope with a multilayer coating. The single telescope had two bandpasses in the extreme-UV range for detecting a coronal high-velocity flow the wavelength at peak reflectance (hereafter peak wavelength) in one of the bandpasses was 210.2 å, situated on the blue side of the target’s Fe XIV 211.3-å coronal emission line, and the peak wavelength in the other was 213.3 å on the red side. A high uniformity in a peak wavelength of less than 1 å was achieved over a primary (secondary) mirror surface 158 (96) mm in diameter. The ratio of the reflectance for the Fe XIV line at 211 å to that for an intense He II line as a contaminant at 304 å in the telescope system became 2 × 105 owing to a wave trap consisting of a single Si layer on the MoSi/Si multilayer. The narrow-bandpass ( 5-å) telescope was launched on 31 January 1998 by sounding rocket S520CN-22, and images of the whole-Sun corona at Fe XIV 211 å were successfully obtained. © 1999 Optical Society of America.

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 approximate to 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 Angstrom 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.

We present an overview of an ongoing Japanese sounding rocket project with the Solar XUV Doppler Telescope (XDT) scheduled to be launched in January, 1998. The telescope employs a pair of high-wavelength-resolution multilayer mirrors and a back-thinned CCD. It is designed to observe the coronal velocity field of the whole Sun by measuring line-of-sight Doppler shifts of the Fe XIV 211 Angstrom line (1.8 MK). The detection limit is estimated to be about 60 km/s.

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 +1-0.5 degree around the target (Sun) without stability control. The 'ITM is utilized to stabilize the XUV image on the focal plane by tilting the secondary mirror with two-axes fixed-coil magnetic actuators. The actuator used here is robust, has wide tilt angle, and is able to drive the large secondary mirror (10cm dia., 300g) with high frequency, as compared with conventional Piezo-electric or moving-coil type actuators. The two position-sensitive detectors in the telescope optics and in the TFM mechanical structure form the normal and local closed-loop modes. The Tl'M has four gain 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 T1'M system as well as the high pointing accuracy once the tracking is established. The TFM has a launch-lock mechanism against the launch vibration of 160. 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.

We compare microwave total power spectral data from the Owens Valley Radio Observatory Solar Array with soft X-ray transient brightenings observed with the Yohkoh soft X-ray telescope. We find that the transient brightenings are clearly detected in microwaves in 12 of 34 events (35%), possibly detected in another 17 of 34 events (50%), and only five of 34 events (15%) had no apparent microwave counterpart. Comparing the radio and soft X-ray characteristics, we find that (1) the soft X-ray peak is delayed relative to the microwave peak in 16 of 20 events, (2) the microwave flux is correlated with the flux seen in soft X-rays, (3) when radio fluence is used instead of radio flux (24 events) the correlation increases substantially, (4) the microwave spectra in the range 1-18 GHz vary greatly from event to event, (5) the microwave spectra often peak in the range 5-10 GHz (13 of 16 events), and (6) the microwave spectra of some events show narrowband spectra with a steep low-frequency slope. We conclude that the emission from at least some events is the result of a nonthermal population of electrons, and that transient brightenings as a whole can therefore be identified as microflares, the lowenergy extension of the general flare energy distribution. Soft X-ray transient brightenings, and therefore microflares, cannot heat the corona. © 1997. The American Astronomical Society. All rights reserved.