Subaru Seminars

A new frontier in planetary studies is coming into maturity through the information provided by remote sensing of planetary systems by (i)interplanetary probes, (ii) near-earth spacecraft and (iii) ground-based observations of thermal emission. This talk will focus primarily on studies of planetary atmospheres, where these data supply a vertical dimension to measurements of horizonal measurements of clouds properties and cloud-tracked winds, as well as an assessment of planetary chemistry. A specific example will be shown in detail which serve as a "case study". A. In Jupiter, 3 earth-sized vortices which were stable for over 60 years merged in a two-step process in 1998 and 2000. The resulting oval remained white in color and stable but unexpectedly changed color in 2005 from white to red - as red as Jupiter's Great Red Spot. Our campaign to understand what changed physically in the vortex involved measurements of the field of temperatures, ammonia distribution and clouds using (1) high-resolution images of the vortex made before the color change with the COMICS mid-infrared facility on the Subaru telescope in May, 2005, (2) the mid-infrared VISIR camera/spectrometer on ESO's Very Large Telescope, made almost simultaneously with Hubble Space Telescope ACS images, and (3), the NASA Infrared telescope with the mid-infrared MIRSI instrument and the refurbished near-infrared facility camera NSFCam2. We are use these data to characterize the extent to which changes in storm strength (vorticity, postive vertical motion) influence (i) the depth from which colored cloud particles may have been "dredged up" from depth or (ii) the altitude to which particles may have been lofted and subject to high-energy UV radiation which caused a color change, as alternative explanations for the phenomenon. Clues to this will provide clues to the chemistry of Jupiter's cloud system and its well-known colors in general. Other examples will be shown relevant to Cassini observations of Saturn and Spitzer observations of Uranus and Neptune.

With Subaru, and other facilities, we are now probing the significantly large volume of the Universe at high redshift to witness or approach to the rather (hopefully) complete view of the history of the galaxy-scale structure formation. In this talk, we present our recent new results of the wide-field optical/infrared imaging and spectroscopic survey for galaxies at z=3.1 in/around SSA22 area.
Suprime Cam narrow-band image over the 1.5 sq. deg, or ~ 200Mpc (comoving) at the largest side, tells us the whole environments and the significance of the large-scale high-density region of the star-forming galaxies, compared with the similary deep narrow-band imaging in the general control fields. It was turned out that the highest density 'peak' with ~20Mpc scale (~1 SCam FOV!) has the overdensity of ~4 at z=3.1.
We also spectroscopically mapped a part of these structures with FOCAS, DEIMOS (Keck), and VIMOS (VLT) to understand the 3D density distribution of LyAlpha emitters as well as to investigate various spectroscopic properties (e.g., line width) of the very interesting targets such as extended Lyman Alpha Blobs, which are the candidates of massive galaxies in their forming phase, as well as a new class of interesting objects, the Very Large LyA Equivalent-Width Galaxies.
As the region has been mapped with the infrared facilities/projects such as Spitzer, WFCAM (UKIRT/UKIDSS), MOIRCS, I also briefly touch with the infrared view of this region.

The many of the work has been made in collabolation with Yuichi Matsuda (Kyoto) , Tomoki Hayashino (Tohoku), and colleagues in the projects.

Related Previous Papers;
Matsuda, Yamada et al. 2004, AJ, 128, 569
Matsuda, Yamada et al. 2005, ApJ, 634, L125
Matsuda, Yamada, et al. 2006, ApJ, 640, L123

Polycyclic aromatic hydrocarbons(PAHs) are thought to be the carriers of the unidentified infrared (UIR) bands, which have been observed in various astrophysical environments including HII regions, Reflection Nebulae, Planetary Nebulae, diffuse ISM, and external galaxies even at the distance of z=2.8. Their ubiquitous presence suggests that the diagnostic use of the UIR features is quite useful to probe the interstellar environment even in a distant galaxy. In the first half of my talk, I am planing to show you our recent result on the mid-infrared spectroscopy of non-isolated Herbig Ae/Be object MWC1080 using Subaru/COMICS and discuss the ionization of PAHs around the central B0 star traced by the UIR 11.0um/11.2um ratio. In the last half, I would like to introduce our recent results on the mid-infrared observation of super star clusters in two blue compact dwarf galaxies, Henize 2-10 and IIZw40 using Subaru/COMICS. I especially focus on the properties of PAHs to understand their evolution in such an active and young starburst environment. Through these attempts, we aim to demonstrate the formation, evolution, and destruction process of PAHs andto make the uqbiquitous PAH features as the valid measure of the physical quantities such as the interstellar radiation strength, the electron density, etc.

According to the current understanding, the presence of a considerable amount of dust in elliptical galaxies is quite common. Studies with ISO and Spitzer suggest even the presence of PAHs emission features in the SED of several elliptical galaxies. Hot ionized gas filling the interstellar space of elliptical galaxies, however, is expected to easily destroy such very small particles through sputtering by plasma ions. In this talk, I present the results of mid-IR spectroscopic observations of X-ray-emitting nearby dusty elliptical galaxies with the Spitzer Infrared Spectrograph (IRS). We have succeeded in detection of the PAH emission from the elliptical galaxies. The observed spectra seem to be quite unusual; the PAH features at 6.2, 7.7, and 8.6 um are very faint in contrast to prominent emission features at 11.3 and/or 12.7 um, which may reflect peculiar physical conditions of the ISM. The detection of the PAHs provides strong constraints on the evolution scenarios of the ISM of elliptical galaxies.

A brand new and powerful NIR spectrograph for the Subaru Telescope ( MOIRCS : Multi-Object InfraRed Camera and Spectrograph ) has just opened to the public from this September. Unique exchange mechanism for cooled multi-slit masks enables us to conduct low-resolution multi-object spectroscopy (MOS) in the NIR wavelength range up to K-band for more than 50 objects simultaneously. I will introduce the system of the MOS part of MOIRCS and observation technique.

In the cores of X-ray-luminous clusters of galaxies, estimated radiative gas cooling times are often significantly shorter than the Hubble time, suggesting the possibility that these clusters sustain a flow of cooling gas accreting onto the brightest cluster galaxy (BCG) at the cluster center (i.e., a cluster cooling flow). I will present the results from our Spitzer cluster program, showing that the BCGs located in clusters with an extremely short gas cooling time (< 1 Gyr) are IR-luminous, which is consistent with the idea that a cluster cooling flow is triggering the infrared activity in these BCGs. Judged from the Spitzer/IRS spectrum taken for one such IR-luminous BCG, the source of the infrared luminosity is star formation (e.g., strong PAH emission). Furthermore, the spectrum shows abnormally strong pure-rotational molecular hydrogen (H2) emission lines (likely shock-excited) with a corresponding warm H2 gas mass of 10^{10} Msun, the largest known to date. Together, these results indicate that the BCGs in strongly cooling cluster cores are unusually active, and suggest that their IR properties are intimately connected to the intracluster gas cooling process.
I will also describe briefly another on-going Spitzer cluster project to study gravitationally lensed high-redshift galaxies.

Dust grains are important material of planets and they change their distributions and properties in circumstellar disks during planetary system formation. Since many kinds of dust grains have distinguishing features in the mid-infrared (MIR) wavelengths, MIR observations are powerful for understanding disk evolution from the viewpoint of dust. We are making MIR observations using COMICS on Subaru to reveal dust distribution and evolution in circumstellar disks through planet formation. Our methods are (1) spectroscopy to study mineralogical evolution of dust, (2) high resolution imaging to study disk structures, and (3) spectroscopy with high spatial resolution to study dust distribution within the disks. We will present our recent results. Our presentation will include overall introduction of our results and detailed presentation for selected topics: dust distribution around beta Pic and protoplanetary disks, and a resolved outer disk around HD142527.

Recent observations have revealed that the mass of a supermassive black hole (SMBH) tightly correlates with that of a galactic bulge. In addition, the downsizing of galaxies and active galactic nuclei (AGNs) have been suggested. These indicate SMBH growth is closely related to the evolution of bulges. However, little has been clear regarding the physical link between the SMBH growth and bulge evolution. In my talk, attention is focused on the extraction of angular momentum from accretion matter onto SMBHs via radiation drag exerted in a stellar bulge. Based on this mechanism, we introduce a bulge-SMBH co-evolution, and then a way to verify the SMBH growth via radiation drag with Atacama Large Millimeter Array. Finally, I will discuss the origin of AGN downsizing briefly.

Solar-B is a satellite scheduled to be launched in September 2006. It is intended to observe the Sun to provide information about the coronal heating mechanism. An EUV Imaging Spectrometer (EIS) will be mounted in Solar-B and it will record EUV spectra in the wavelength ranges 170 - 210A and 250 - 290A. In these wavelength ranges we expect to measure various kinds of Fe ions (Fe IX to Fe XXIV) which exist from the Solar transition region to the corona. In order to make a non equilibrium model for these iron spectra in the Sun, we study EUV spectra from the Large Helical Device (LHD) in our Institute. Fe ion emission from LHD is also found to be in non-equilibrium. We measured Fe ion spectra from LHD and have identified spectra from Fe VIII to Fe XXIV. The first results from LHD in this wavelength region will be presented.

We are promoting to study the origin of inter-planetary dust particle by visible and infrared observations. We have been conducting the observation runs with WIZARD, which is a dedicated instrument developed for visible observation of the zodiacal light, ground-based telescopes (CFHT, UH88 and Kiso 1m) for the survey of cometary dust trails, and IRAC on board SST for thermal emission part of the dust trails. Studies of the inter-planetary dust particle is now very important to understand evolution and dissipation of dust disks around a star, since a dozen of extra-zodiacal dust disks are within our samples. We will introduce the property of the zodiacal dust as well as the particle in the dust trails based on our recent results.

SNe Ia are very important for the cosmological studies, but they are not perfect "standard candle". They have considerable intrinsic dispersion in their light curves (c.f. Phillips et al.1993). In addition, host galaxy dust extinction and peculiarity of SNe Ia give uncertainty in apparent brightness. Recently, we can use many samples of nearby SNe Ia to find out how we should reduce the intrinsic dispersion and how we should make corrections of uncertainty (c.f. Takanashi, 2005, master thesis; Takanashi et al., 2006, in prep.; Altavilla et al., 2004; Reindl et al., 2005). It is also interesting why SNe Ia have intrinsic dispersion and why there are peculiar ones. Some ideas are proposed for the cause of dispersion (e.g. Umeda et al., 1999), but the question is still unsettled. We have developed a "multi-band Stretch method", and investigated about 122 nearby (z < 0.11) SNe Ia samples. I will report what we found with the method.

I also report about the SDSS-II Supernova Survey, which is a 3 years project started from 2005 to 2007. This survey will obtain over 200 high-quality type Ia supernova light curves in the redshift range 0.05 < z < 0.35. We observed SNe detected by SDSS-II SN Survey with UH88 and Subaru(Yasuda et al.) last year. I will present the tentative report of the observations.

The current understanding of galaxy formation is that it proceeds in a 'bottom up' way, with the formation of small clumps of gas and stars that merge hierarchically until giant galaxies are built up. The baryonic gas loses the thermal energy by radiative cooling and falls towards the centres of the new galaxies, while supernovae blow gas out. Any realistic model therefore requires a proper treatment of these processes, but hitherto this has been far from satisfactory. Here I report an ultra-high-resolution simulation that follows evolution from the earliest stages of galaxy formation through the period of dynamical relaxation. The bubble structures of gas revealed in our simulation(< 10^8 years) resemble closely the high-redshift Lyman alpha emitters. After 10^9 years these bodies are dominated by stellar continuum radiation and look like the Lyman break galaxies known as the high-redshift star-forming galaxies at which point the abundance of heavy elements appears to be solar. After 1.10^10 years, these galaxies resemble present-day ellipticals.

We present our recent studies of galactic chemodynamics with our original galactic chemo-dynamical evolution code, GCD+ (Kawata & Gibson 2003). First, we demonstrate that the self-regulated AGN heating is crucial to explain the multi-wavelength properties of observed elliptical galaxies (Kawata & Gibson 2005, MNRAS, 358, 16). Next, a thick disk formation senario suggested by our numerical simulations (Brook et al. 2004, ApJ, 612, 894) is explained. Finally, we introduce our dwarf speroidal galaxy formation study (Kawata et al. astro-ph/0509402).

We started our science communication program in last October. The program consists of 3 types of classes: lecture style classes, exercise (hands-on) style classes, and practical training classes. Today I introduce our practical training classes.

While the evolution of dark matter structure in the standard Lambda- CDM cosmology is reasonably well understood, the evolution of the baryon component is less certain because of the complexity of physical processes such as star formation and feedback. We simulate cosmic chemical evolution with a N-body SPH code in which we include star formation, supernova and hypernova feedback, and chemical enrichment. For assumptions which produce plausible results in idealised collapse models of individual galaxies, the cosmic star formation rate shows a peak at z~4, and ~10% of baryon turn to stars. Stars in present-day massive galaxies formed in smaller galaxies at high redshifts, giving an old stellar age consistent with observations. Galactic winds blow effectively from less massive galaxies and eject heavy elements into the intergalactic medium, of which process produces the mass-metallicity relation of galaxies. Metal-enrichment history depends on the environment, and is consistent with the observed abundances of Lyman break galaxies, of damped Lyman-alpha systems, and of the intergalactic medium. I would like to discuss what kind of observations are required to investigate the formation and evolution of galaxies with numerical simulations.

We observed ammonia at a wavelength of 1.3 cm (23-24 GHz) in nearby galaxies with radiotelescopes (mainly with the Nobeyama 45m). Ammonia is a good probe of temperature and also molecular abundances in galaxies. Based on our ammonia observations and other works already published, the molecular abundance in a famous starburst galaxy M 82 was found to be peculiar among nearby galaxies regarding the formation mechanisms of molecules: a reason for this is discussed. Then, we present our recent results of ammonia observations toward a prototypical ultraluminous infrared galaxy, Arp 220, where quite wide absorption lines (total velocity width of about 1800 km/s) were detected (PASJ, 57, L29 (2005)). The present results clearly indicate the existence of extremely high-velocity motion in the central compact region of Arp 220.

The UKIRT Infrared Deep Sky Survey (UKIDSS) is a seven year programme to produce a legacy IR sky atlas, using UKIRT's new Wide Field Camera (WFCAM). It covers many thousand square degrees overall, but is actually a portfolio of five inter-related surveys ranging from shallow (K~19) through deep (K~21) to ultra deep (K~23) surveys, at both high and low galactic latitudes. As well as producing a multi-purpose resource of long lasting value, UKIDSS specifically aims to find the most distant known quasars and the nearest substellar objects; to determine the stellar mass function and its dependence on environment; to determine the epoch of spheroid formation; and to map the Galactic Plane. UKIDSS data are being uniformly processed and made publicly available through a fully queryable web system - the WFCAM Science Archive (WSA). UKIDSS began operations in May 2005, and will issue an early data release on January 31st 2006. I will summarise performance and prospects so far, and illustrate the use of the WSA.

HiCIAO is a new high contrast instrument for the Subaru telescope to be used with a combination of the new 188 actuator adaptive optics (AO). It can be regarded as a successor of the current coronagraph CIAO and 36-actuator AO. HiCIAO is a near-infrared camera equipped with sophisticated coronagraph and several simultaneous differential imaging modes, which will greatly enhance the contrast capability compared with the current instrument. The development consists of NAOJ/Mitaka, Subaru, and University of Hawaii. The design of this instrument is now in progress and we plan to have a two-half-day PDR sometime in September. The site will be at the Subaru Hilo office in Hawaii. The aim of the PDR is to establish the science and design of the Subaru/HiCIAO, and I would like to ask you to attend this meeting, hoping to have your advice and recommendation for this new instrument from either/both scientific or technical point of view as experts in this science/techniques. Since the basic fund for this instrument has been already secured via a Japanese MEXT fund, this may not be a main issue in the PDR. In a short word, I would like to ask your opinions/advices if our instrument design is suitable for a high contrast science under some given fund.

We have developed a multimode optical spectrograph, the Kyoto tridimensional spectrograph II (Kyoto 3DII). This has four observational modes: Fabry-Perot imager, lenslet-type integral field spectrograph (IFS), long-slit spectrograph, and filter-imaging modes. We have succeeded in its test observations on the University of Hawaii 88-inch Telescope as well as on the Subaru Telescope. The Kyoto 3DII is so far the only spectrograph with Fabry-Perot and/or IFS modes that is mounted on Subaru. The pixel/lenslet well samples image sizes obtained by Subaru so that we can take advantage of its good image quality and large aperture. Some results from successful test observations are shown. Although it is not a common user instrument, we have been carrying out some collaborative research programs with non-members.

A new optical design concept of telescopes to provide an aberration-free, wide field, unvignetted flat focal plane is described. The system employs three aspheric mirrors to remove aberrations, and provides a semi-circular field of view with minimum vignetting. The third mirror reimages the intermediate image made by the first two-mirror system with a magnification factor on the order of unity. The present system contrasts with the Korsch system where the magnification factor of the third mirror is usually much larger than unity. Two separate optical trains can be deployed to cover the entire circular field, if necessary.

The AAO has now been collaborating with Subaru for several years to develop the multi-fibre feed system, Echidna, for FMOS. The current status of the project will be outlined.
Measurements over the past few years have justified confidence we in Australia have felt for many years that the best Antarctic sites will provide remarkable opportunities for astronomy. In particular, seeing measurements at Dome C have indicated median seeing diameters about half those obtained on Mauna Kea. Some details of these results and a discussion of general Antarctic properties will be presented.

Using an absorption line from the metastable (J,K)=(3,3) level of H3+ together with other lines of H3+ and CO observed along several sightlines, we have discovered a vast amount of high temperature (T ~ 250 K) and low density (n ~ 100 cm-3) gas with a large velocity dispersion in the Centeral Molecular Zone (CMZ) of the Galaxy, i.e., within 200 pc of the center. Approximately three-fourths of the H3+ along the line of sight to the brightest source we observed, the Quintuplet object GCS 3-2, is inferred to be in the CMZ, with the remaining H3+ located in intervening spiral arms. About half of the gas in the CMZ has velocities near ~-100 km s-1 indicating that it is associated with the 180 pc radius Expanding Molecular Ring which approximately forms the boundary of the CMZ. The other half, with velocities of ~-50 km s-1 and ~0 km s-1, is probably closer to the center. CO is not very abundant in these clouds. Hot and diffuse gas in which the (3,3) level is populated was not observed toward several dense clouds and diffuse clouds in the Galactic disk where large column densities of colder H3+ have been reported previously. Thus the newly discovered environment appears to be unique to the CMZ. The large observed H3+ column densities in the CMZ suggests an ionization rate an order of magnitude higher than in the diffuse interstellar medium in the Galactic disk. Our finding that the H3+ in the CMZ is almost entirely in diffuse clouds indicates that the reported volume filling (f>=0.1) for n>= 10E4 cm-3 clouds in the CMZ is an overestimate by at least an order of magnitude.

Cataclysmic variables are close binaries with a white dwarf primary and a low-mass main-sequence companion that transfers mass onto the white dwarf through Roche-lobe overflow. In the case that the magnetic field of the WD is weak enough, the gas accreted onto the WD forms an accretion disk.
Two methods are used to reconstruct the structure of the disk. One is the eclipse mapping, a reconstruction technique using an eclipse of the high inclination binary systems. We can reconstruct two-dimensional (2D) brightness distribution from one-dimensional eclipse light curves based on the maximum entropy. Another useful method is the Doppler tomography, an imaging technique to map the line emissivity in 2D velocity space. This method, however, provides no definite information in position space. In other words, we need to assume a model relating the position space to the velocity place if we want to convert the velocities measured in a Doppler map to positions.
I will present a new method, by combining the above two methods, to map the velocity fields in position space over the disk plane. In this method, we need a set of high time-, and wavelenth-resolved spectra over an orbit of an eclipsed binary. The emission-line profiles are devided into dozens of sections with a constant wavelength interval. For each section, an eclipse light curve is constructed. We make an eclipse map using the eclipse mapping for each of calculated light curves with different wavelengths. Then we can get a map of the velocity fields.

Adaptive Optics System is now a key component of large ground-based telescopes regarding high resolution imaging. The Subaru AO team is currently building a new generation AO System that should have its first light in March 2006. Ultimately, a Laser Guide Star system will be added (first light: March 2007). I will first review the characteristics and performances of this system. Then I will focus on one of its key component: a Deformable Mirror made of 188 control elements, the largest bimorph mirror ever built. We will go through its mechanical behavior and see some limitations caused by its dynamic response that lead to my work on a damping system for the DM188.

We'll present some results from our on-going distant cluster project with Subaru called PISCES (Panoramic Imaging and Spectroscopy of Cluster Evolution with Subaru). The uniqueness of this project is its wide-field coverage; 34'x27' or 10-15~Mpc on a side, reaching well beyond the virial radii of clusters. We will address the following two key issues: (1) Truncation of star formation and transition of galaxy morphologies along large-scale structures. (2) Mass dependence of galaxy evolution, referred to as ``down-sizing".

The tool of spectropolarimetry applied to supernovae has shown that core collapse supernovae are strongly asymmetric and that Type Ia supernovae are less so, but still systematically asymmetric. These studies have led to new insights into the explosion mechanisms of both core-collapse and thermonuclear supernovae. The explosion of core-collapse supernovae is intrinsically 3-dimensional and there are strong evidences that the explosion is affected by the rotation of the progenitor star. Polarimetry studies of SN Ia may give long sought clues to the binary nature of Type Ia supernovae. The outer most layers of some SNIa are found to be consistent with being from turbulent burning, but with iron confined into lower velocity regions. These observations support the popular delayed-detonation models but also provide clues for further improvement of explosion models. These understandings of SNIa provide new insights into the origin of the observed scatter in the properties of Type Ia. They may help in making SN Ia even more precise tools of cosmology.

Astronomy is at the forefront for data conservation and distribution, and also for information networking, availability of observatory archives, and collaboration between archive providers, data centers and journals. The current astronomy information network already allows scientists to surf from observations to results published in journals, and includes value-added information services. The next step is integration of the massive, heterogeneous, distributed available information, including very large surveys, modelling results, etc.

Many VO projects around the world have started, and they have formed the International Virtual Observatory Alliance (IVOA). One main collaborative activity of this international effort is the definition of the interoperability standards required to go further in integrating heterogeneous, distributed information.

We have been developing Japanese Virtual Observatory (JVO), as a member of the IVOA, to integrate astronomical databases taken by both ground-based and satellite-based telescopes operated by the NAOJ and the JAXA/ISAS. JVO prototype has already been interconnected with the VOs in the US and Europe since last December.

I will present technical details and achievements of the JVO prototype.

I will present clustering properties of galaxies at z=3-6 in the 1 deg^2 sky of the Subaru/XMM-Newton Deep Field (SXDF). We have obtained about 20,000 Lyman Break Galaxies (LBGs) at z=3.5-6.2 and 1,000 Lyman alpha Emitters (LAEs) at z~3.1,3.7, and 5.7. Taking advantage of the largest and widest high-z galaxy samples ever obtained, we have investigated the distribution of high-z galaxies. The angular correlation functions of LBGs show a significant excess of clustering in a small angular scale, which is the evidence for the multiple occupation of LBGs in a single dark halo with a mass of ~10^12 Mo. The distribution of LAEs show filamentary large-scale structures with 10-40 Mpc scale voids. We have identified a very dense region of LAEs (4.8 sigma level) at z=5.7 in the southern area of the SXDF. Our spectroscopic follow-up observations revealed two concentrations made of 6 LAEs at z=5.69 and 4 LAEs at z=5.67, respectively, distributed in a 1-Mpc sphere. These concentrations have about 130 times higher star-formation rate density than the field. These concentrations may be proto-clusters just beginning to form. I will discuss the formation of clusters and large-scale structures based on these results.

Using the Subaru telescope, we recently discovered HE 1327-2326, a subgiant or dwarf with [Fe/H] = -5.4. It is only the second star with an extremly low metallicity of [Fe/H] < -5.0. We present our abundance analysis of this very peculiar object (non-detection of Li and high Sr abundance) together with models which try to explain the observed abundance pattern. The discovery paper is accepted for publication in 'Nature'. Note to the organizers: This result will be published in Nature soon (which has a press embargo of this result) we wish to ask for careful treatment of the abstract concerning its access to the general media.

The mass assembly history of elliptical galaxies is now a key issue in addressing the question of whether there is a crisis in the dark matter driven picture of galaxy formation. Should we be surprised by the claimed high abundance of massive, red-and-dead galaxies at redshift two in the light of contrary predictions from semi-analytic models where large ellipticals supposedly form late from recent mergers? I will describe a comprehensive dynamical study of nearly 200 distant field ellipticals in the northern GOODS field which shows the plot thickens. There is now convincing evidence that massive systems are generally older than their lower mass equivalents, in marked contrast to simple hierarchical growth. The implications of this and related recent evidence for `downsizing' in galactic assembly will be discussed.

The Crab Nebula in the optical bands shows a filamentary structure of supernova ejecta, while in the X-ray band it is dominated by a synchrotron cloud energized by the central Crab pulsar. In this talk, I will review recent progresses in X-ray studies of the Crab "Pulsar Wind" Nebula with the Chandra X-ray Observatory. We have revealed that most components of the Crab Nebula are temporally variable in their shapes with different time scales, and the X-ray spectrum varies across the nebula. I will discuss these results with our interpretations. At last, I will also present our observational result of Titan transit of the Crab Nebula.

Evidence will be reviewed regarding the age of the Galaxy's thick disk, and new observations of the behavior of metallicity vs. kinematics, and elemental abundances relative to iron for a sample of thin disk and thick disk stars will be presented. In combination with other larger surveys, it appears that the thick disk has experienced a very different chemical evolution than the thin disk, and that it may well have arisen from an independent galaxy's merger with the Milky Way. There are even signs of an enhanced star formation rate in the old thin disk following the merger. An exploration of elemental abundance patterns of the outer Galactic disk will also be explored. It appears that, contrary to model expectations, the radial metallicity gradient in the outer disk disappears beyond a Galactocentric distance of about 12 kpc. The light elements Mg, Si, Ca, and Ti, and the heavy element Eu, are enhanced relative to iron, suggesting dominance of Type II supernovae and a vigorous star formation rate, which also suggests mergers of low-metallicity material has contributed to the growth of the Galactic disk.

We report the discovery of a probable large scale structure composed of many galaxy clumps around the known twin clusters at z=1.26 and z=1.27 in the Lynx region. Our analysis is based on deep, panoramic, and multi-colour imaging (26.4'x24.1') in VRi'z'-bands with the Suprime-Cam on the 8.2m Subaru telescope. This unique, deep and wide-field imaging data-set allows us for the first time to map out the galaxy distribution in the highest redshift supercluster known. We apply a photometric redshift technique to extract plausible cluster members at z~1.27 down to i'=26.15 (5sigma) corresponding to ~M*+2.5 at this redshift. From the 2-D distribution of these photometrically selected galaxies, we newly identify seven candidates of galaxy groups or clusters where the surface density of red galaxies is significantly high (>5sigma), in addition to the two known clusters. These candidates show clear red colour-magnitude sequences consistent with a passive evolution model, which suggests the existence of additional high density regions around the Lynx superclusters.

We will present the scientific activities of our Laboratory of Astrophysics in the University of Nice France and expose some possible collaborations. Then we will emphasis the research activities concerning the small bodies in the solar system with the participation of the observatory of Torino in Italy.