Porous structure is common in asteroids and satellites of outer planets. In order to study the relation between structure of the small bodies and their thermal and collisional evolution, we prepared porous sintered targets and performed impact disruption experiments.In our previous study with low impact velocity, we found that the impact strength is higher for the targets with similar porosity but with higher compressive strength (Setoh et al. 2006). In addition, the impact strength of our targets was much lower than a previous result of high velocity impact disruption of sintered glass beads target. We carried out high velocity impact experiments by using two-stage light gas gun at ISAS. Our new result on the largest fragment mass was closer to the previous one performed with high impact velocity. We will also discuss on the impact strength defined by fragment mass distribution.

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We performed impact disruption experiments onto pumice targets using two-stage light-gas gun in order to understand the impact disruption process of porous small bodies and to provide reference data for numerical simulations. Projectiles were nylon spheres of 7 mm in diameter and glass spheres of 3.2 mm in diameter. The target porosity was 72 %. The impact velocity was from 1.5 to 4.5 km/s. We showed that the degree of fragmentation increased with the energy density input into the pumice target and also showed that the fragmentation degree was different between the shots with different projectiles. We will measure the physical properties of the pumice target and will compare the experimental results with relevant numerical simulations.

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Most of the Antarctic micrometeorites (80%) contain hydrous silicate (Engrand and Murette, 1998). However, hydrated meteorites are only about 3% of that falls onto the earth. On the other hand, 30-40% of asteroids contain the hydrated mineral. In order to explain the difference of such relative existence level of hydrated minerals, we performed impact experiments onto hydrous and porous targets and to examine effects of dehydration of hydrated minerals in the dust formation by high velocity impact.

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Silica aerogel has been used as a suitable capture medium for solid microparticles with hypervelocity. The authors have been conducting experiments for evaluation of thermal alteration of particles captured by silica aerogel and energy partition. In this study, formation of penetration tracks in aerogel was observed and recorded by a high-speed camera. Excavation process of a single track, so-called a "carrot track" made by a 500 micron-Al₂O₃ grain was observed. At first a thin track grew in the direction of penetration and then it started to swell into a "carrot". Assuming that brighter part represents higher temperature/pressure area, shock wave dissipation in aerogel can be recognized. Combining this and our previous results, this study aims at finding empirical facts constraining energy partition.

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The seismic networks are quite sensitive for micro ground vibration, then those networks could detect not only seismic wave generated by earthquakes, but also ground oscillation generated by coupling of meteor shockwave with the ground near a station. Last years, we analyses this kind of ground motion data recorded by seismic network, as meteor shockwave signals. For example, we estimate some grate fireball's aerial path from arrival times of shockwaves, and we estimate sizes and ablation history of some great fireball and a meteorite fall from amplitude of ground motion induced by shockwave. However, the present meteoroid size estimation method from seismic records has a weak point. The weak point due to difficulty of overpressure estimation from ground motion amplitude. To flee from this problem, we have to measure the shockwave overpressure. We work to develop infrasound observation system for meteor shockwave monitoring. The system must have following capabilities. 1) Flat response with at least 0.1 to 20 Hz. 2) At least 0.001 Pa resolution (+/- 0 to 20 Pa range). In this talk, we will report the development of meteor shockwave monitoring system and future observation plans.

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Just after the appearance of meteors within an altitude range from 90 km up to120 km, faint luminescence can be usually observed as short-duration meteor trains, followed by persistent meteor trains in case of extremely bright parent meteors. In a recent study of trajectory analyses of the Leonids storm in 2001(Shigeno et al., 2003), considerable examples of short-duration train movies are found in their precise double-station video observations.

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On the night of January 15 2006, Stardust Reentry Capsule observing campaing was carried out using imagers and spectrographs onboad NASA's airbone DC-8. In order to understand physical processes occuring in natural meteors and meteorites, we performed spectroscopy using an intensified high-definition TV observation with a reflection grating 500 grooves/mm in the wavelength between 300 and 650 nm. The capsule, 0.8 m in diameter, entered the atmosphere by the speed of 12.9 km/s, which was the fastest artificial objects in our history.

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Carbonaceous chondrites are known to contain a few wt. % organic matter whose majority consists of macromolecular organic compounds (e.g. Botta and Bada, 2002; Sephton, 2002). Minerals are suggested to have catalytic effects for the production and alteration processes of these organic materials (e.g. Wing and Bada, 1992; Kerridge, 1999). We conducted mapping measurements of Tagish Lake meteorite grains by Fourier Transform Infrared Micro-Spectroscopy (micro-FTIR) and Scanning Electron Microscopy and Energy Dispersion X-ray Spectrometry (SEM-EDS) for studying the distribution of minerals and organic matter. Tagish Lake was powdered and pressed between two pieces of Al discs to make the sample flat. The mapping area is 590 x 950 microns for micro-FTIR (Jasco IMV-4000 + FTIR-6200; resolution 12.5 microns) and SEM-EDS (JEOL JSM-5510LV + JED-2300). By the micro-FTIR mapping, heterogeneous distribution of aliphatic C-H and organic C-O was observed, and aliphatic C-H was distributed with phyllosilicate O-H. SEM-EDS elemental analysis revealed that aliphatic C-H rich portions were Mg rich and Fe, S poor. These results indicate that aliphatic C-H is coexisting with Mg-rich phyllosilicates.

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Some Antarctic Micrometeorites (AMMs) were studied non-destructively by infrared (IR) microspectroscopy for characterizing organic and hydrous components in these particles. Their IR spectra showed absorption peaks of OH (molecular water) at 3400 cm−1, aliphatic carbonaceous components at 2960 cm−1 for CH3 and 2925 and 2860 cm−1 for CH2. By using peak height ratios of CH3/CH2 (2960 cm−1/2925 cm−1) and OH/CH2 (3400 cm−1/2925 cm−1), aliphatic and hydrous component characters of AMMs can be quantitatively investigated. The CH3/CH2 and OH/CH2 ratios of AMMs are ranging 0.6-0.9 and 1-3, respectively. These ratios of AMMs are smaller than those of carbonaceous chondrites. In order to study effects of heating, an AMM was heated in-situ under the IR microscope in atmosphere at temperatures from room temperature (RT) to 600˚C. The peak height ratio of CH3/CH2 remained mostly unchanged from RT to 210˚C and increased from 210˚C to 300˚C. The OH/CH2 ratio decreased from RT to 210˚C and then increased greatly from 210˚C to 300˚C. Effects of aqueous altaeration on micrometeorites are now being studied by hydrothermal experiments on simulated mineral-organic compounds.

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Chemical compositions in 39 of individual Antarctic Micro Meteorites (AMM) have been analyzed by instrumental neutron activation analysis (INAA). From analytical result, 26 grains of AMM have been classified into the E, H, L and LL chondrite groups based on the total Fe contents.

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Cosmic dusts are classified into interplanetary dust particles (IDPs) and micrometeorites (MMs) depending on the sampling site. MMs similar to anhydrous IDPs and those with extremely rich in carbon (ultra carbon-rich micrometeorites: UCMMs) have been found from Antarctica, and they are considered as cometary origin as well as anhydrous IDPs. Lately, such MMs have been discovered from snow, which should have less hydrous alteration than in ice. These MMs are larger than IDPs and should have important information on the early stage of the solar system.In this study, 3-D structures of 39 MMs recovered from Antarctic snow were studied nondestructively using X-ray microtomography. The samples were imaged at beamline BL20XU and BL47XU in SPring-8 at 10keV. The effective spatial resolution was about 0.5 micrometers. 3-D binery images of the samples were obtained from the CT images, and their volumes and porosities were calculated. The samples were also observed by SEM, and analyzed by EDS and SR-based XRD. Distributions of mineral phases were also estimated from the linear attenuation coefficients of the CT images by considering the XRD results. By comparing these data, the MM samples were classified. For future work, a detailed study using TEM will be carried out after choosing typical samples.

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The shapes of interplanetary dust particles (IDPs) have been studied based on infrared astronomy observations and/or computer simulations. Using fractal dimension as a parameter of the shapes, the relationship between the shapes and the aggregation processes during the early stage of planetary accretion has been studied. We conducted X-ray computed microtomography (CT) on micrometeorites, collected from Antarctic ice and snow to perform three-dimensional (3-D) multifractal analyses and to estimate their shapes quantitatively. The X-ray CT measurements for forty-nine micrometeorites were performed at BL47XU and BL20XU in SPring-8. Using synchrotron radiation (SR) as an X-ray source, we obtained quantitative CT images with the effective spatial resolution of about 0.5 micrometers.Multifractal analyses enable us to estimate spatial distributions of physical quantities as their singularity spectrum f(a) of a measure where the singularity strength is a. We performed multifractal analyses based on structure functions on binary 3-D images of micrometeorites. We could not obtain multifractal spectrum with any physical meanings. This result suggests that the micrometeorites analyzed have no multifractal nature or their shapes have some singular points on the present multifractal analyses.

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Chondrules suggest that there were some flash heating events to form chondrules in the early solar nebula. Shock wave heating model is considered to be one of the most plausible models for chondrule formation.
In the shock-wave heating model, dust particles are heated by the gas frictional heating. So it is easily expected that the dust particle start to melt from its surface to inside. Additionally, due to the ram pressure of the fast gas flow, the liquid part is considered to strip off from the solid part (Kadono and Arakawa 2005, Kato et al.2006)
In order to examine the thermal evolution and the dynamics of the dust particle, we are developing a numerical code that can solve hydrodynamics inside the dust particle containing solid, liquid, and gaseous phases simultaneously. Here, we report the current status of the development and the future plan of our research.

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We have examined if the shock-wave heating chondrule formation model forms compound chondrules. Especially, we focus on the formation process of compound chondrules by collisions. In the shock wave heating process, stripping off of liquid surface from partially molten dust particles, and the break up of totally molten particles can happen due to the gas dynamical pressure. The stripped off droplets and the fragments of the break up, which are called "secondary particles" here, are expected to have rather small relative velocity each other, that is needed to form compound chon-drules by collisions. Estimating the velocity of those particles based on a simple assumption that the maximum flow velocity in the liquid part of the molten particle determines the maximum velocity, we have found that the velocity is small enough for almost all the shock waves that can heat and melt the dust particles to form chondrules. Thus, it seems possible that collisions among secondary-secondary and primary-secondary dust particles would form compound chondrules.

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Although chondrules formed under levitated environment in space, most of the previous reproduction experiments have been carried out under non-levitated environment. Therefore, we carried out new reproduction experiments on chondrule formation by using a gas jet levitator. The experimental results show that nucleation of the levitated melts is very difficult and most chondrule melts turned to be glass by cooling. Because chondrule melts had to nucleate and crystallize in some way, we examined a hypothesis that the chondrule melts contacted with cosmic dusts and crystallized. To investigate the seeding effect, um-size silicate dust particles were accreted to the supercooled levitated melt and the results showed that the nucleation rate of the melts was promoted by collision with silicate particles and the melts crystallized in spite of at a narrow temperature range. And similar textures observed in pyroxene chondrules could be reproduced from very large supercooled enstatite melt (500-860 K).

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Infrared features seen for cometary dust (i.e. 10 micron silicate feature and blackbody continuum) are studied based on the light scattering of fractal aggregates. The shape model of dust is the aggregate composed of mixtures of silicate and carbon materials. The light scattering calculation of fractal aggregates is based on the cluster T-matrix method (Mackowski and Mishchenko,1996) improved by the Grouping and Adding Method (Okada et al, under review) to treat a larger number of monomers.

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For monitoring of urban atmospheric particles, simultaneous measurements of aerosols and suspended particulate matter (SPM) have been undertaken at Kinki University Campus, Higashi–Osaka, Japan, since 2004. The relationship between PM2.5 concentrations and aerosol properties obtained from radiometry using a multi-spectral photometer located as a NASA/AERONET station is examined in this work. It is found a linear correlation between aerosol optical thickness and PM2.5 concentrations for both ordinary days and days with dust events. This fact indicates that aerosol characteristics can be estimated from SPM data, and vice versa. Combining radiometric aerosol information with surface-level particulate mass measurements is useful in studying air quality and aerosol properties.It is of interest to mention that the largest dust event recorded among our long-term observations was detected during the spring of 2006.

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This work intends to make a model for bidirectional polarization distribution functions (BPDF) based on space-borne polarimetric data. It has been shown a parameter (named beta0) of modeled BPDF should be taken into account with place, especially over the desert.

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Planetary surfaces are usually covered with regolith, which is far from ideal for detailed X-ray fluorescence (XRF) analysis because its powdery rough surface affects XRF intensities. Kuwada et al. (1997) pointed out this phenomenon could cause a serious error in determining rock-types, particularly observed at large phase angles. Therefore, we performed laboratory experiments and model calculations to investigate particle size effects in planetary XRF spectrometry.

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We carried out deformation experiments of ice-silica glass beads mixtures systematically to study the effects of silica particles on the flow law. In this study, we examine the silica glass beads sizes, contents, and sample preparation methods. In the case of small glass beads mixtures, the silica content was strongly related to the flow law. In the case of big glass beads mixtures, the flow law was approximately consistent with the flow law of pure ice even if the content or the preparation method were changed at the strain rate less than 10^-4s^-1. Finally, we compared our results with the previous studies such as Hooke et al. (1972) and Durham et al. (1992). As a result, it is found that our results were consistent with their results qualitatively.

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Photolysis and hydrogenation of molecules on dust surfaces are important processes of molecular evolution in molecular clouds. We studied these processes expermentally for CO molecule and found that both reactions strongly depend on the temperature or the structure of ice mantle. The efficiency of photolysis and hydrogenation in the CO evolution for various temperatures and structures will be shown.

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Extreme deuterium fractionation of interstellar methanol has been observed in molecular clouds. Since methanol (CH3OH) is formed efficiently by grain-surface reactions: CO->H2CO->CH3OH, it is reasonable to consider that deuterated methanol is also produced by surface reactions involving deuterium atom. Indeed, we showed experimentally that d-methanol is produced efficiently by H-D substitution reaction in methanol: CH3OH->CH2DOH->CHD2OH->CD3OH. In our poster, we report the reaction rate and detail process of the H-D substitution reactions.

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At the main asteroid belt and Kuiper-belt region, it is commonly occurred that small bodies is disrupted into fragments by mutual collision and re-accumulated by its self-gravity. The tensile strength of these bodies is often neglected, however, they may gain the strength according to the growth of the mutual contact points (necks).Under low temperature, the growth process of the neck is mainly controlled by surface diffusion and evaporative condensation. In this study, we calculate the thermal condition in these bodies, and consider the growing process of the neck, which depends on the temperature. We try to find out effects of the distance from the sun and size of these objects.

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Sticking of dust aggregates is a crucial process in the formation ofplanetesimals. In the relevant temperature conditions, dust grains arethe mixture of silicates and organics. I performed an impact experimentusing the mixture of glass beads and silicon oil to determine thedependence of stickiness on the size of the glass beads. It was foundthat the stickiness of the mixture with 0.9 micron sized glass beads islarger than that with 100 micron one. This is probably due to thesmoothness of the surface of the mixture.

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According to the theoretical and analytical studies on the formation of planetary system and the formation of meorites, there should be variations in the formation time of planetesimals, causing variations in the thermal evolution afterward.In this study, we carried out the numerical model on the thermal evolution of small planets with the size from a few km to a few hundred-km for various formation time.Our model contains effects of: (1) heating by short lived radio nuclides, (2) low thermal conductivity of porous media, (3) sintering induced by pressure and temperature, and (4) silicate-metal separation due to permeable flow of molten metal through silicate grains.Our numerical results show that there are obvious conditions to be satisfied to form a metallic core, which seems consistent with the formation condition of iron meteorites derived from the textural feature of iron meteorites.

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We have investigated the evolution of the structure of the Oort cloud and the distribution of "new comets" from the Oort cloud due to the galactic tide. Oort cloud comets are believed to be planetesimals, which are scattered by planets. We considered the effect of the vertical component of the tidal force from the galactic disk on the structure of the Oort cloud. Due to the galactic tide, the eccentricity and inclination of some planetesimals conversely oscillate a great deal. This is an effective mechanism to form the Oort cloud and to bring back comets in the Oort cloud to the planetary region as new comets. We examined the effect by applying the analytical solutions to the orbital evolution of planetesimals.We found that due to the galactic tide, planetesimals with the semimajor axes >~1,000 AU raise the perihelion distances outside the planetary region in 4.5 Gyr. We also found that the galactic tide alone can not realize the isotropic distribution of inclination of the Oort cloud comets and the new comets, which is expected from the observation of long period comets.

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The spacial and size distributions of the small solar system bodies are important to investigate the processes of the solar system formation. They orbit near the Earth, so that they appear to move in the celestial sphere. Usually, more than three images are used to detect moving objects, but we detect them with two images because we can also make use of the data by other observations than surveys for small bodies. And we have originally developed the automatic detection program to analyze the data rapidly. This time, we have analyzed the r'-band data by Suprime-Cam on the Subaru telescope over the 1.9 square-degree field. The limiting magnitude was 24.4 mag. We detected 287 moving objects, and the slope of the cumulative size distribution obtained by them agreed with past researches.

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Fast Rotating Asteroids (FRAs) which are rotating faster than 2.2 hours or less exist in the group of Near Earth Asteroids (NEAs). Since NEAs originate from MBAs, some of MBAs could be FRAs. However, FRAs have not been discovered in the group of Main-Belt Asteorids (MBAs). It would be because of difficulty of the detection of MBAs less than 1 km in diameter , such dominate in the NEAs population. So, we used the large telescope, 8.2m Subaru telescope, and detected many small MBAs such as having apparent magnitude of 17-25 mag and then examined their lightcurves for searching FRAs in MBAs. As a result, we found the possibility that the MBAs of 20 percent or more are FRAs.

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Since 2002 November we have begun a campaign of lightcurve observation of the asteroids belonging to the Karin family which is as young as only 5.8 Myr old. Though our entire project is still on the way, multi-color observations in visible and near-infrared wavelength of the largest member of the family, (832) Karin, have suggested us the potential existence of a very interesting color variation on this asteroid's surface. The asteroid might have both an old, mature surface that probably had been a part of a parent body of the Karin family, as well as a new, fresh surface that the collisional event created. At the opposition of 2003 September, we observed a reddened and old surface on this asteroid, while in 2003 September we could not observeit. In this poster we report our latest result by a three-color near-infrared photometry of this asteroid that weperformed in 2006 February.

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The linear polarimetric measurements are given by the measurements of the Stokes parameters Q and U. In the existing polarimeter, the Q and U parameters are not measured at one exposure. It leads to uncertainties of the resultant accuracy because of the tracking error of the telescope and changes in atmospheric conditions. Therefore, to enhance the polarimetric accuracy and observational efficiency, we are constructing an imaging polarimeter which can measure the Stokes parameter Q and U, simultaneously. The polarimeter employs an unpolarized beam splitter and two Wollaston prisms, allowing the simultaneous acquisition of the four polarized images without moving parts.
The test-observations of the polarimeter have been made in January 2006, mounted on the Cassegrain focus of the 60cm telescope at Nishiharima Astronomical Observatory, Hyogo, Japan. By using the observational value of the unpolrized standard stars, we have estimated the instrumental polarization of 0.81% for the polarimeter and telescope system. The accuracy of the measurements is +/- 0.12%. Moreover the calibrated polarization of the polarized standard stars coincides with the value in literature within 0.2%.

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The Atacama Large Millimeter Array (ALMA) is an international astronomy project that consists of a system of radio telescopes in an array formation, located at the Atacama desert in northern Chile.The telescopes are capable of detecting sub-millimeter and millimeter wavelengths. The design specification of ALMA demand a much higher calibration accuracy than achieved by the conventional techniques used at the existing millimeter arrays, which is typically no better than 10 %. Absolute flux calibration for ALMA requires standard astronomical objects whose fluxes are known to 5 % accuracy. In order to achieve 5% accuracy calibra-tions, we propose to adopt Uranus and Ceres as primary calibrators.Any comments and collaboration requests by not only astronomers and but planetary scientists are welcome.

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We report the result of a prototype photometric search for transiting extrasolar planet using the 105cm Kiso Schmidt Telescope. Out of about 9000 stars monitored around l=40 degree, b=16 degree, we find that more than 400 show photometric precisicon better than 1%. Thus, the Kiso Schmidt Telescope has the photometric stability and accuracy necessary for a transiting extrasolar planet survey. Moreover, a new schmidt camera is scheduled to be operated in the Kiso Observatory in 2008. Since the field of view of the new schmidt camara is approximately 2 degree * 1.5 degree, we would be able to monitori more stars. We discuss the detection pro bability of transiting extrasolar planets on the case of using the new schmidt camera.

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A transit of an extrasolar planet is a phenomenon that an extrasolar planet cut across in front of its parent star. The detections of the phenomenon tell about the planet such as its mass and density. However, to date there are only 12 transiting extrasolar planets detected while over 200 planets have been detected by the Doppler method. We set up a 30cm telescope in Kobe University to detect the transit. Making the photometric observations, we monitor the lumi-nosity changes of stars, the changes in radial velocities of which have been seen in the N2K consortium (Fischer et al. 2005) which is the hot-Jupiter survey project with the Doppler method. In this lecture, we report the result of our transit observation.

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We have observed the extrasolar planets by transit method. The method is to observe light intensity when a planet is crossing in front of the star. However, the errors of light intensity were large, so that we could not find the information of extraplanets such as orbital parameters. In the paper, we clarify the reason of large error and report the new method to reduce the error.

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We report the calculation of spectra for various extrasolar Earth-like planets to search for them, which characterize their temperatures and atmospheres for evidence of habitability and life.

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We started a survey project for planets around G type giants at Okayama astrophysical observatory by using High Precision Dispersion Spectroscopy (HIDES) in 2001, and now continued. And we have found some objects have a radial velocity change like have planets. It is important that we know chemical abundances of parent stars to understand how planets are formed, but those of G type giants have not been studied so many times. Therefore, we also get high precision spectroscopy data to study chemical abundance in this project. We determined atmosphere parameters of some decades of G type giants including stars may have planets and describe about those.

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We tried to detecting Post T Tauri stars(PTTSs) by Lindroos objects.Lindroos objects are binary of about a hundred million years age.The primaries are heavy and already reach to main sequence,but more than half of the secondary has about solar mass and they are thought to PTTSs.By using the position of stars in the images of 2MASS and POSS,proper motion of stars near primary were decided.(The precision is 0".5-0".8/20yr.) As a result,we discovered two Lindroos cluster's candidates that they has same proper motion with its primary.

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We obtained a high resolution (about 0".1=14AU) near-infrared image of UY Aur using Coronagraphic Imager with Adaptive Optics (CIAO) on the Subaru Telescope. UY Aur is a classical T Tauri binary system in the Taurus-Auriga star forming region. The H-band magnitude of the secondary (UY Aur B) varies about 1.5 mag in a decade while that of the primary (UY Aur A) is stable. We detected the UY Aur circumbinary disk with a clumpy structure and a gap between the UY Aur binary and the disk. The lower limit of the clump mass is calculated to be about 6 Earth mass, assuming that the clump is bright due to the scattering light of the UY Aur binary.

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Many classical T Tauri stars have proto-planetary disks. However since such structures are very faint, observations with high spatial resolution and huge dynamic range are required. We have carried out near-infrared coronagraphic observations of DO Tau and detected very faint structure at 160 AU from the central star. With its morphology, we consider it as a proto-planetary disk.

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