The gravity-darkening of highly distorted stars in close binary systems

From a quantitative analysis of the photometric ellipticity effect, values of the exponent of gravity-darkening have been empirically deduced for the components of sixteen W UMa systems with accurate cross-correlation spectroscopic mass ratios. In the analysis, the exponents for both components of a W UMa system are assumed to be the same. In view of the generally unstable nature of their light curves and the consequent difficulty to find an unique set of the fractional radii of both components, -values have been derived for various equipotential surfaces with boundary cases set at the inner and outer Roche lobes.The results indicate that if the fill-out factors are less than 0.5 (as is so for most of the actual cases), the deduced -values are all greater than Lucy's conventional value of 0.32. The empirical -values as a whole are found to increase with the mean effective temperature of the components and, furthermore, they show a tendency to decrease with increasing mass ratio, particularly for A-type systems. Thus, a W UMa system consisting of two components of quite different masses has a large empirical -value. These observational evidences indicate that the structure of the photosphere of contact components of W UMa systems is significantly different from that of normal Main-Sequence stars of similar spectral type and may provide a clue to solve puzzles of W UMa stars.     

Finite difference analog of the Coriolis force in papers by Endoh

A wrong finite difference form is used for the rotation of the Coriolis force in the vorticity equation with bottom topography in a series of papers byEndoh.     

Petrological model of the northern Izu–Bonin–Mariana arc crust: constraints from high-pressure measurements of elastic wave velocities of the Tanzawa plutonic rocks, central Japan

Ultrasonic compressional wave velocities (Vp) and shear wave velocities (Vs) were measured with varying pressure up to 1.0 GPa in a temperature range from 25 to 400 °C for a suite of tonalitic–gabbroic rocks of the Miocene Tanzawa plutonic complex, central Japan, which has been interpreted as uplifted and exposed deep crust of the northern Izu–Bonin–Mariana (IBM) arc. The Vp values of the tonalitic–gabbroic rocks increase rapidly at low pressures from 0.1 to 0.4 GPa, and then become nearly constant at higher pressures above 0.4 GPa. The Vp values at 1.0 GPa and 25 °C are 6.3–6.6 km/s for tonalites (56.4–71.1 wt.% SiO₂), 6.8 km/s for a quartz gabbro (53.8 wt.% SiO₂), and 7.1–7.3 km/s for a hornblende gabbro (43.2–47.7 wt.% SiO₂). Combining the present data with the P wave velocity profile of the northern IBM arc, we infer that 6-km-thick tonalitic crust exists at mid-crustal depth (6.1–6.3 km/s Vp) overlying 2-km-thick hornblende gabbroic crust (6.8 km/s Vp). Our model shows large differences in acoustic impedance between the tonalite and hornblende gabbro layers, being consistent with the strong reflector observed at 12-km-depth in the IBM arc. The measured Vp of Tanzawa hornblende-bearing gabbroic rocks (7.1–7.3 km/s) is significantly lower than that Vp modeled for the lowermost crustal layer of the northern IBM arc (7.3–7.7 km/s at 15–22 km depth). We propose that the IBM arc consists of a thick tonalitic middle crust and a mafic lower crust.     

Subaqueous sand blow deposits induced by the 1995 Hyogo-ken Nanbu Earthquake, Japan

Abstract The 1995 Hyogo-ken Nanbu Earthquake (Mw 6.9) occurred in the region around Kobe City and Awaji Island in south-west Japan. Co-seismic liquefaction caused subsidence of the land and damage to sea wall caissons on the man-made Port Island at Kobe City. A zone 2–3 m wide behind the caissons of the northern wharf on the island subsided into the intertidal zone and a sandy deposit settled into this subsided zone. The depos-it consists of upward-fining sequences that are subdivided into three parts, in ascending order: graded coarse- to medium-grained sand, parallel-laminated fine- to very-fine-grained sand, and massive mud. Grain fabric analysis (employing the anisotropy of magnetic susceptibility method and microscopic measurement) of these sequences shows that there is a remarkable contrast in grain fabric between the lowest portion of the graded sand division and the laminated sand division. The former has a high q -value (magnetic lineation/foliation) and a unimodal orientation of elongate grains in the horizontal plane, but random orientation in the vertical plane. Conversely, the latter is characterized by a low q -value and a grain fabric in which the long axes of the grains have random orientations and are nearly parallel to the plane of deposition. This result shows that the main depositional processes changed from a combination of flow and allied processes to the force of gravity. As still water is essential for gravity to be the dominant factor in deposition, this deposit is regarded as subaqueous sand blow deposits. If this interpretation is correct, the grain fabric produced by gravity alone is a useful criterion for distinguishing between subaqueous sand blow deposits and other liquefaction-induced deposits.     

Kosa (yellow sand) components in precipitation collected at central Japan

In east Asia, acidic gases derived from fossil fuel combustion have increased in the pastdecades. On the other hand, the Asian dust, also called Kosa (yellow sand) is transported follow-ing windstorms from arid lands in the Asian continent. Many researchers have been interested inthe reaction between acidic aerosols and Kosa aerosols as well as the long-range transport ofthese emissions. To investigate the characteristics of chemical components in precipitation on along-term basis over Japan, precipitation was sequentially collected from April 1984 to March 1997at Kanazawa located near the coast of the Sea of Japan. Precipitation samples were collected at 1mm intervals for the first 5 mm rainfall and all volume of rainwater after 6 mm for all precipitationevents with an automatic wet only precipitation collector. According to the analyses of precipitationincluding Kosa aerosols during Kosa periods, the reaction in the air between Kosa and acidiccomponents during the long-range transport was discussed.     

Intergrowth textures of diaplectic glass and crystal in shock-loaded P-anorthite

The intergrowth of diaplectic glass and primitive anorthite has been observed in fragments shocked to 300 kbar. The textures observed by electron microscopy are similar to those produced in shocked quartz crystals. The diffuseness of reflections, related to antiphase domains, show no noticeable change in comparison with unshocked specimens. These results indicate that no gradual change in original domain size occurs and that the transformation of primitive anorthite to diaplectic glass occurs abruptly.     

Distribution of titanium atoms in oxy-kaersutite

The distribution of Ti atoms in oxy-kaersutite has been studied by the neutron diffraction method. The cation distribution over the three octahedral sites determined by the x-ray method (Kitamura and Tokonami, 1971) is as follows; M1∶0.40MG+0.60 FE, M2∶0.75 MG+0.25 FE, M3∶0.50 MG+0.50 FE, where MG and FE represent (Mg+Al) and (Fe+Ti), respectively. The neutron diffraction study indicates that Ti atoms are enriched in the M1 site more than M2 and M3 sites as follows; M1∶0.40 MG+0.33 Fe+0.27 Ti, M2∶ 0.75 MG+0.23 Fe+0.02 Ti, M3∶0.50 MG+0.46 Fe+0.04 Ti. This distribution agrees with the result based on the Madelung energy of oxy-kaersutite by Whittaker (1972).     

Crystallization temperature of wyomingite from Leucite Hills

Wyomingite collected from Leucite Hills is composed mainly of leucite, diopside, phlogopite, and small amounts of apatite, calcite, magnetite and rare amphibole, and is characterized by very high content of potash. Thermal experiments at atmospheric pressure indicate that the liquidus phase is always diopside with liquidus temperature of 1320 °C, and solidus temperature is about 1000 °C. Various kinds of melt inclusions are abundant in all constituent minerals. They comprise mono-phase (glass only), two-phase (gas+glass), three-phase (gas+glass+one crystalline phase) and multi-phase (gas+glass+more than two crystalline phases) inclusions. Thermal experiments have been made on these inclusions in phlogopite, diopside, and leucite in order to estimate the temperature of crystallization by homogenizing these inclusions. The results show that the crystallization of wyomingite began with formation of phlogopite accompanied by diopside at 1270 °C. Although diopside ceased crystallization at 1220 °C recurrent crystallization of phlogopite was noticed between 1120 ° and 1040 °C. Leucite crystallized out abundantly between 1250 ° and 1150 °C. Complete solidification of wyomingite occurred at about 1000 °C.