X-ray observations of PSR B1259−63 near the 2007 periastron passage

PSR B1259−63 is a 48-ms radio pulsar in a highly eccentric 3.4-yr orbit with a Be star SS 2883. Unpulsed γ-ray, X-ray and radio emission components are observed from the binary system. It is likely that the collision of the pulsar wind with the anisotropic wind of the Be star plays a crucial role in the generation of the observed non-thermal emission. The 2007 periastron passage was observed in unprecedented details with Suzaku , Swift , XMM–Newton and Chandra missions. We present here the results of this campaign and compare them with previous observations. With these data we are able, for the first time, to study the details of the spectral evolution of the source over a 2-month period of the passage of the pulsar close to the Be star. New data confirm the pre-periastron spectral hardening, with the photon index reaching a value smaller than 1.5, observed during a local flux minimum. If the observed X-ray emission is due to the inverse Compton (IC) losses of the 10-MeV electrons, then such a hard spectrum can be a result of Coulomb losses, or can be related to the existence of the low-energy cut-off in the electron spectrum. Alternatively, if the X-ray emission is a synchrotron emission of very high-energy electrons, the observed hard spectrum can be explained if the high-energy electrons are cooled by IC emission in Klein–Nishina regime. Unfortunately, the lack of simultaneous data in the TeV energy band prevents us from making a definite conclusion on the nature of the observed spectral hardening and, therefore, on the origin of the X-ray emission.     

Correlations between OH,NaD and OI 5577 Å emissions in the airglow

Simultaneous measurements of the night airglow OI 5577 Å and OH (8,3) band have been carried out at Cachoeira Paulista (23°S, 45°W), Brazil since 1976. Cross correlation analyses between the nocturnal variations of these emissions and also with the OH rotational temperature (ROT) for various time shifts are presented. It is found that OH (8,3) is well correlated with ROT but with a time lag of about 1 h. The variations of OI 5577 Å lead OH (8,3) by about 2–3 h and ROT covaries with 5577 Å with a time lag less than 1 h. For the sake of comparison, OI 5577 Å, OH and NaD data from a number of IQSY stations have been analysed. It is noted that (1) OI 5577 Å leads OH by about 2 h at mid-latitude stations and (2) OH is well correlated with Na 5893 Å with a time lag of less than 1 h. The presence of the phase lagged correlation patterns between OH/5577 Å, OH/ROT and OH/NaD indicates vertical propagation of a wavelike perturbation of the upper atmosphere.     

Status of butyltin pollution along the coasts of western Japan in 2001, 11 years after partial restrictions on the usage of tributyltin

Restrictions on the use of tributyltin (TBT) in aquaculture and on boats in coastal regions, except for ocean-going vessels, have been in place in Japan since 1990 due to the strong toxic effects of TBT on marine organisms. However, TBT pollution along the Japanese coasts has been reported after this legislation was enacted. In order to elucidate the present status of contamination by butyltin (BT) compounds, we measured the levels of BTs [monobutyltin (MBT), dibutyltin (DBT) and TBT] in seawater and Caprella spp. samples obtained from the western part of Seto Inland Sea, Uwa Sea and Uranouchi Bay in western Japan during March to September, 2001. Butyltins were detected in more than 90% of the seawater samples (n = 59), with average concentrations of 8.2 ± 9.2 (SD) ng MBT L⁻¹, 3.3 ± 3.0 ng DBT L⁻¹ and 9.0 ± 7.0 ng TBT L⁻¹. Among 41 stations situated on coastal lines, a sufficient number of Caprella organisms for chemical analysis could be collected from only 16 stations. The butyltin concentrations in seawater and Caprella samples from Uwa Sea and Uranouchi Bay, in which the dominant industry in both waters is aquaculture, showed significantly higher than or no significant differences from those samples from the western part of Seto Inland Sea, a major heavy-industry area in Japan. As the TBT concentration in seawater increased, the number of Caprella organisms collected decreased. The mean TBT concentration among the seawater samples was above the estimated lowest observable effect concentration (LOEC) that reduces the survival rate of Caprella danilevskii. Thus, the present study indicates that TBT is still a potential ecological hazard to the survival of marine invertebrates inhabiting coasts along western Japan, even 11 years after the partial ban on TBT usage was implemented.     

Rare earth elements and Opal/CaCO<Subscript>3</Subscript> ratio of sinking particles observed with a time-series sediment trap at the mouth of Tokyo Bay

A time-series sediment trap was deployed from December 1994 to February 2002 at the mouth of Tokyo Bay (35°03′ N, 139°40′ E; water depth, 850 m). Sinking particles were obtained with a time interval of one week at a depth of approximately 100 m above the sea floor. Observed total mass fluxes varied from 3.3 to 226.7 g/m²/day with an average of 28.0 g/m²/day. Concentrations of rare earth elements, Al, Ca and Si in particulate materials were measured. The combustible fraction at 450°C is assumed to be equivalent to the organic matter content. Contents of biogenic materials, namely organic matter, opal and calcium carbonate, were about 30% and the content of lithogenic material was about 70%. Using La/Yb ratios of particles from the sediment trap and Tama-gawa River and surface sediment of Tokyo Bay, it was estimated that about 50% of the lithogenic particles collected in the sediment trap at the mouth of Tokyo Bay originated from resuspended surface sediment in Tokyo Bay. An increasing trend of Opal/CaCO₃ ratio in the sinking particles was found in the spring season. It is suggested that the relative increase of diatoms is due to the decreasing dissolved inorganic nitrogen input into Tokyo Bay.     

Further studies of trace elements in C3 chondrites

Five carbonaceous chondrites (Renazzo C2V, Allende C3V, Omans C3O, Warrenton C3O, and Orgueil Cl) were analyzed by radiochemical neutron activation analysis for Ag, Au, Bi, Br, Cd, Cs. Ge, In, Ir, Ni, Os, Pd, Rb, Re, Sb, Se, Te, Tl, U and Zn. These data, together with earlier measurements on seven additional C3 s, are interpreted in the light of pétrographie studies by MCSWEEN (1977a, b) and revised condensation temperatures (WAI and Wasson, 1977). Elements condensing between ~ 700 and 420 K (Se, Zn, S, Te, Br, In, Bi, Tl) are systematically more depleted than those condensing between 1000 and 900 K (Ge, Ag, Rb), by factors of 1.3 to 2, and the depletion correlates inversely with matrix content and directly with degree of metamorphism. The most plausible explanation appears to be a gas-dust fractionation during condensation, by settling of dust to the median plane of the nebula. In this model, gas/dust ratios relative to the cosmic ratio ranged from 0.7 at 1000 K to 0.5 at 700 K for those C3O s that accreted first (Ornans, Warrenton) and from 1.3 to 0.6 for the last (Kainsaz). There appears to have been no further gas/dust fractionation below 700 K.Abundances of Sb, Au and Cd follow earlier trends. Depletion of Sb and Au correlates with abundance of Fe-poor olivine and seems to reflect greater volatilization upon more prolonged or intense heating during chondrule formation. The 50–100-fold depletion of Cd in C3Os compared to C3Vs suggests condensation in a region where enough Fe was present to buffer the H₂S pressure.     

A numerical study on the formation and variation of a clockwise-circulation during winter in the Yellow Sea

In the Yellow Sea, the north-westerly wind dominates in winter and the existence of horizontal clockwise circulation has been suggested (Yanagi and Takahashi, 1993). The formation and variation mechanisms of this clockwise circulation is investigated using the wind forced numerical model which has a simplified basin configuration of the Yellow Sea. The model results show that two vortices (an anticlockwise vortex off Chinese coast and a clockwise vortex off Korean coast) are generated by the uniform north-westerly wind. Both vortices propagate along the shelf slope as the first mode shelf waves. An anti-clockwise vortex can not grow because it does not balance to the wind forcing. On the other hand, a clockwise vortex can grow and it reaches to the equilibrium condition at the northern part of the Yellow Sea, because this circulation can balance to the wind forcing. The time scale to become into the equilibrium condition is about 2 days. From this fact, it is ascertained that a clockwise circulation in the basin is generated periodically according to the variable wind forcing with 4 days period. The steady part of the current field exists with the fluctuating one which is induced by the periodical north-westerly wind.     

Water demand and supply in large cities in Japan

After WW II, water demand in Japan for municipal and industrial use has increased drastically in those large cities and industrial regions with rapid urbanization and high economic growth. This was true especially in the decades of 1950 and 1960.Water shortage continues to be serious in some large cities in summer months. The author attempts to explain the reasons for this water shortage by explaining the relation between population growth and water demand in large cities. To meet these water shortages, there has been active development of water resources including construction of dams and saline barriers in large river basins and modernization of the water use system to increase its efficiency and re-use capacity for sewage treatment etc.At the same time, water resources development projects have been encountering various environmental problems as well as increased local protest in the 1970s. The author discusses the present dimensions of these problems and also presents several ideas regarding water resources planning for the future.     

Does sedimentary organic delta 13C record variations in quaternary ocean [CO2(aq)]?

Ocean surface water [CO2(aq)] variations based on glacial/interglacial changes in sediment delta 13Corg are shown to compare favorably with reconstructions based on ice core [CO2]. In particular, an approximate 80 microatmospheres increase in atmospheric pCO2 during the last glacial-interglacial transition is calculated to correspond to a 3-4 micromolar increase in ocean surface water [CO2(aq)] at atmospheric equilibrium. A widespread marine delta 13Corg decrease of 1-2% accompanied this event and was not preceded by an equivalent isotopic change in surface water total dissolved inorganic carbon. These observations support the hypothesis that [CO2(aq)] influences photosynthetic isotope fractionation between marine inorganic and organic carbon pools, and therefore that plankton/sediment delta 13Corg may serve as a proxy for surface water [CO2(aq)].