Markarian 313: An intermediate object between a seyfert and a starburst galaxy

An ultraviolet-excess galaxy Markarian 313 (NGC 7465), which consists of a multiple system with NGC 7463 and NGC 7464, is studied using the low- and high-resolution optical spectrum. Emission lines of H, H, [NII], and [OIII] have conspicuous blueward asymmetrical wings or blue slanted profiles in the spectrum of the nuclear region of the galaxy. The width of these emission lines is as broad as 600 km s^–1 at the zero-intensity level, and the velocity difference between the narrow and broad components is estimated at around 80 km s^–1 from the two-component Gaussian profile fitting. This fact could be an evidence of a large-scale dynamical motion in or surrounding the nuclear region of the galaxy, implying that it bears an intermediate characteristic between a Seyfert and a starburst galaxy.     

Intrusion of Kuroshio water onto the continental shelf of the East China Sea

As a fundamental study to evaluate the contribution of the Kuroshio to primary production in the East China Sea (ECS), we investigated the seasonal pattern of the intrusion from the Kuroshio onto the continental shelf of the ECS and the behavior of the intruded Kuroshio water, using the RIAM Ocean Model (RIAMOM). The total intruded volume transport across the 200m isobath line was evaluated as 2.74 Sv in winter and 2.47 Sv in summer, while the intruded transport below 80m was estimated to be 1.32 Sv in winter and 1.64 Sv in summer. Passive tracer experiments revealed that the main intrusion from the Kuroshio to the shelf area of the ECS, shallower than 80m, takes place through the lower layer northeast of Taiwan in summer, with a volume transport of 0.19 Sv. Comparative studies show several components affecting the intrusion of the Kuroshio across the 200 m isobath line. The Kuroshio water intruded less onto the shelf compared with a case without consideration of tide-induced bottom friction, especially northeast of Taiwan. The variations of the transport from the Taiwan Strait and the east of Taiwan have considerable effects on the intrusion of the Kuroshio onto the shelf.     

High-Nb hawaiite–mugearite and high-Mg calc-alkaline lavas from northeastern Iran: Oligo-Miocene melts from modified mantle wedge

Tertiary volcanic rocks in northwestern Firoozeh, Iran (the Meshkan triangular structural unit), constitute vast outcrops (up to 250 km²) of high-Mg basaltic andesites to dacites that are associated with high-Nb hawaiites and mugearites. Whole-rock ⁴⁰Ar/³⁹Ar ages show a restricted range of 24.1 ± 0.4–22.9 ± 0.5 Ma for the volcanic rocks. The initial ratios of ⁸⁷Sr/⁸⁶Sr and ¹⁴³Nd/¹⁴⁴Nd vary from 0.703800 to 0.704256 and 0.512681 to 0.512877, respectively, in the high-Mg basaltic andesites–dacites. High-Th contents (up to 11 ppm) and Sr/Y values (27–100) and the isotopic composition of the subalkaline high-Mg basaltic andesites–dacites indicate derivation from a mantle modified by slab and sediment partial melts. Evidence such as reverse zoning and resorbed textures and high Ni and Cr contents in the evolved samples indicate that magma mixing with mafic melts and concurrent fractional crystallization lead to the compositional evolution of this series. The high-Nb hawaiites and mugearites, by contrast, have a sodic alkaline affinity and are silica undersaturated; they are also enriched in Nb (up to 47 ppm) and a wide range of incompatible trace elements, including LILE, LREE, and HFSE. Geochemistry and Sr–Nd isotopic compositions of the high-Nb hawaiites and mugearites suggest derivation from a mantle source affected by lower degrees of slab melts. Post-orogenic slab break-off is suggested to have prompted the asthenospheric upwelling that triggered partial melting in mantle metasomatized by slab-derived melts.     

Active spreading and hydrothermalism in North Fiji Basin (SW Pacific). Results of Japanese French Cruise Kaiyo 87

The aim of the Japanese-French Kaiyo 87 cruise was the study of the spreading axis in the North Fiji Basin (SW Pacific). A Seabeam and geophysical survey allowed us to define the detailed structure of the active NS spreading axis between 16° and 22° S and its relationships with the left lateral motion of the North Fiji Fracture Zone. Between 21° S and 18°10′ S, the spreading axis trends NS. From 18°10 S to 16°40 S the orientation of the spreading axis changes from NS to 015°. North of 16°40′ S the spreading axis trends 160°. These two 015° and 160° branches converge with the left lateral North Fiji fracture zone around 16°40′ S to define an RRFZ triple junction. Water sampling, dredging and photo TV deep towing give new information concerning the hydrothermal activity along the spreading axis. The discovery of hydrothermal deposits associated with living communities confirms this activity.     

Cluster analysis on the bulk elemental compositions of Antarctic stony meteorites

Remote sensing observations by recent successful missions to small bodies have revealed the difficulty in classifying the materials which cover their surfaces into a conventional classification of meteorites. Although reflectance spectroscopy is a powerful tool for this purpose, it is influenced by many factors, such as space weathering, lighting conditions, and surface physical conditions (e.g., particle size and style of mixing). Thus, complementary information, such as elemental compositions, which can be obtained by X‐ray fluorescence (XRF) and gamma‐ray spectrometers (GRS), have been considered very important. However, classifying planetary materials solely based on elemental compositions has not been investigated extensively. In this study, we perform principal component and cluster analyses on 12 major and minor elements of the bulk compositions of 500 meteorites reported in the National Institute of Polar Research (NIPR), Japan database. Our unique approach, which includes using hierarchical cluster analysis, indicates that meteorites can be classified into about 10 groups purely by their bulk elemental compositions. We suggest that Si, Fe, Mg, Ca, and Na are the optimal set of elements, as this set has been used successfully to classify meteorites of the NIPR database with more than 94% accuracy. Principal components analysis indicates that elemental compositions of meteorites form eight clusters in the three‐dimensional space of the components. The three major principal components (PC1, PC2, and PC3) are interpreted as (1) degree of differentiations of the source body (i.e., primitive versus differentiated), (2) degree of thermal effects, and (3) degree of chemical fractionation, respectively.     

A new, automatic hydrothermal fluid sampler using a shape-memory alloy

A new hydrothermal fluid sampler has been developed to provide more maneuverability in underwater operation. The sampler characteristically employs a shape-memory alloy, which senses high temperature and actuates the suction mechanism. A shape-memory alloy is also used to switch the intake valve of the sampler, the intention being to avoid missampling when the inlet is in low temperature water. Prototype samplers were designed to collect the fluids hotter than 80°C. Test sampling was performed at hydrothermal vents (1372–1374 m deep) in the submarine volcano, Suiyo Seamount, Izu-Bonin Arc, northwestern Pacific. Observed fluid temperature was between 138 and 298°C, while the ambient seawater temperature was 3.1°C. Each prototype collected about 100 ml fluid as designed. The magnesium concentration in the samples indicated a seawater content of 47.5–90.8%, which indicates the entrainment of ambient seawater. Microscopic observatinn revealed the occurrence of microorganisms in the sample fluids at a population density of 10⁵ to 10⁶ cells ml⁻¹, which is 2–3 orders of magnitude higher than those in seawater at that depth. The use of the newly developed fluid sampler will greatly facilitate the collection of vent-associated microorganisms, which are of potential biological and biotechnological interest.     

Physical characteristics of Hayabusa target Asteroid 25143 Itokawa

In March 2001, the Hayabusa spacecraft target, Asteroid 25143 Itokawa, made its final close approach to Earth prior to the spacecraft's launch. We carried out an extensive observing campaign from January to September 2001 to better characterize this near-Earth asteroid. Global physical properties of the surface of Itokawa were characterized by analyzing its photometric properties and behavior. Results included here capitalize on analysis of broadband photometric observations taken with a number of telescopes, instruments, and observers. We employed a Hapke model to estimate the surface roughness, single particle scattering albedo, single particle scattering characteristics, phase integral, and geometric and bond albedo. We find that this asteroid has a higher geometric albedo than average main belt S-class asteroids; this is consistent with results from other observers. The broadband colors of Itokawa further support evidence that this is an atypical S-class asteroid. Broadband colors show spectral characteristics more typically found on large-diameter main-belt asteroids believed to be space-weathered, suggesting the surface of this small diameter, near-Earth asteroid could likewise be space-weathered.     

ANALYSIS OF Cu, Cd, Co AND Ni IN SURFACE WATER OF THE KUROSHIO AREA IN THE EAST CHINA SEA

Study of 1986 and 1987 heavy metal distribution in surface water of the Kuroshio area in the East China Sea showed regional and slight seasonal variations in distribution and concentration . Heavy metal levels in Taiwan Strait, the sea area north of Taiwan and the continental shelf are higher than those in the main axis of the Kuroshio . Dissolved Cu in summer and winter decreases with the increase of salinity , but dissolved Cd has no obvious change with salinity .     

Motion of iron sulfide inclusions inside a shock‐melted chondrule

Abstract— We calculated the trajectories of molten spheres of iron sulfide inclusions inside a melted chondrule during the nebular shock wave heating. Our calculations included the effects of high‐velocity internal flow in the melted chondrule and apparent gravitational force caused by the drag force of nebular gas flow. The calculated results show that large iron sulfide inclusions, which have radii 0.23 times larger than those of the parent chondrules, must reach the surface of the melted chondrule within a short period of time (<<1 s). This effect will provide us with very important information about chondrule formation by nebular shock wave heating.     

The development of Fe-nodules surrounding biological material mediated by microorganisms

Takashikozo is a phenomenon of Quaternary sediments in Japan. They are cylindrical Fe-oxyhydroxide nodules that form as plaques round plant roots, where Fe is preferentially concentrated to develop a solid wall. Structural features suggest that after the roots have decayed, the central space where the roots were situated acts as a flow path for oxidized water. Analysis of microbial 16S rDNA extracted from the nodules identified iron-oxidizing bacteria encrusted round the roots where they are the likely initiators of nodule formation. Direct microscopic observation revealed an accumulation of Fe-oxyhydroxides that fill the pore spaces and is also likely to be linked with the encrusting microbial colonies. Geological history and nanofossil evidence suggest that these Fe-nodules may have been buried at a depth of up to several tens of meters for at least 10⁵ years in reducing Quaternary sediments. Thus Fe-oxyhydroxide nodules that have formed in a geological environment at the interfaces between water and rock by microbial mediation can persist under reducing conditions. If this is the case, the phenomenon is significant as an analogue of post-closure conditions in radioactive waste repositories, since it could influence nuclide migration.