Influence of the r-mode instability on hypercritically accreting neutron stars     

Shin'ichirou Yoshida  Yoshiharu Eriguchi 《Monthly notices of the Royal Astronomical Society》2000,316(4):917-922

We have investigated the influence of the r-mode instability on hypercritically accreting neutron stars in close binary systems during their common envelope phases, based on the scenario proposed by Brown et al. On the one hand, neutron stars are heated by the accreted matter at the stellar surface, but on the other hand they are also cooled down by the neutrino radiation. At the same time, the accreted matter transports its angular momentum and mass to the star. We have studied the evolution of the stellar mass, temperature and rotational frequency.
The gravitational-wave-driven instability of the r-mode oscillation strongly suppresses spinning up of the star, the final rotational frequency of which is well below the mass-shedding limit, in fact typically as low as 10 per cent of that of the mass-shedding state. On a very short time-scale the rotational frequency tends to approach a certain constant value and saturates there, as long as the amount of accreted mass does not exceed a certain limit to collapse to a black hole. This implies that a similar mechanism of gravitational radiation to that in the so-called 'Wagoner star' may work in this process. The star is spun up by accretion until the angular momentum loss by gravitational radiation balances the accretion torque. The time-integrated dimensionless strain of the radiated gravitational wave may be large enough to be detectable by gravitational wave detectors such as LIGO II.  相似文献   

Tide-related Changes in mRNA Abundance of Aromatases and Estrogen Receptors in the Ovary and Brain of the Threespot Wrasse <Emphasis Type="Italic">Halichoeres trimaculatus</Emphasis>     

Dae-Ju Oh  Sung-Pyo Hur  Selma Bouchekioua  Yuki Takeuchi  Shingo Udagawa  Neelakanteswar Aluru  Yong-Ju Park  Ji-Gweon Park  Se-Jae Kim  Thomas W. Moon  Mathilakath M. Vijayan  Akihiro Takemura 《Ocean Science Journal》2018,53(2):239-249

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Erratum: Modelling peculiar velocities of dark matter haloes     

Takashi Hamana  Issha Kayo  Naoki Yoshida  Yasushi Suto  Y. P. Jing 《Monthly notices of the Royal Astronomical Society》2005,357(4):1407-1408

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Recent progress in the theory and application of symplectic integrators   总被引：1，自引：0，他引：1  

Haruo Yoshida 《Celestial Mechanics and Dynamical Astronomy》1993,56(1-2):27-43

In this paper various aspect of symplectic integrators are reviewed. Symplectic integrators are numerical integration methods for Hamiltonian systems which are designed to conserve the symplectic structure exactly as the original flow. There are explicit symplectic schemes for systems of the formH=T(p)+V(q), and implicit schemes for general Hamiltonian systems. As a general property, symplectic integrators conserve the energy quite well and therefore an artificial damping (excitation) caused by the accumulation of the local truncation error cannot occur. Symplectic integrators have been applied to the Kepler problem, the motion of minor bodies in the solar system and the long-term evolution of outer planets.  相似文献   

On a class of variational equations transformable to the Gauss hypergeometric equation     

Haruo Yoshida 《Celestial Mechanics and Dynamical Astronomy》1992,53(2):145-150

A new class of linear ordinary differential equations with periodic coefficients is found which can be transformed to the Gauss hypergeometric equation, and therefore the monodromy matrices are computable explicitly. These equations appear as the variational equations around a straight-line solution in Hamiltonian systems of the form H = T(p) + V(q), where T(p) and V(q) are homogeneous functions of p and q, respectively.  相似文献   

Radiative Shock Experiments At Luli     

M. Koenig  T. Vinci  A. Benuzzi-Mounaix  S. Lepape  N. Ozaki  S. Bouquet  L. Boireau  S. Leygnac  C. Michaut  C. Stehle  J. -P. Chièze  D. Batani  T. Hall  K. Tanaka  M. Yoshida 《Astrophysics and Space Science》2005,298(1-2):69-74

We present the set-up and the results of a supercritical radiative shock experiment performed with the LULI nanosecond laser facility. Using specific designed targets filled with xenon gaz at low pressure, the propagation of a strong shock with a radiative precursor is evidenced. The main measured quantities related to the shock (electronic density, propagation velocities, temperature, radial dimension) are presented and compared with various numerical simulations.  相似文献   

A polarimetric study of Asteroid 25143 Itokawa     

Alberto Cellino  Fumi Yoshida  Philippe Bendjoya  Masateru Ishiguro  Jun Saito 《Icarus》2005,179(2):297-303

The near-Earth Asteroid 25143 Itokawa, the target of the Japanese space mission Hayabusa, was observed in June, 2004 with the Torino photopolarimeter attached at the 2.15 m telescope of the El Leoncito Observatory (Argentina). The degree of linear polarization in five colors was measured over a wide range of phase angles, between 40° and 80°. The data obtained are sufficient to derive an estimate of the asteroid's albedo of 0.24±0.01, which is in good agreement with the S-type taxonomic classification of this object. The phase-polarization curve has been sampled in UBVRI colors, covering a wide range of phase angles that cannot be reached by Earth-based observations of Main Belt asteroids.  相似文献   

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

Hidekazu Yoshida  Koshi Yamamoto  Yuki Murakami  Nagayoshi Katsuta  Toru Hayashi  Takeshi Naganuma 《Environmental Geology》2008,55(6):1363-1374

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.  相似文献   

Geochemistry of Mesozoic intracontinental basalts from Yunnan, southern China: Implications for geochemical evolution of the subcontinental lithosphere   总被引：2，自引：0，他引：2  

Dr. S. Okamura  Dr. G. Y. Wu  Dr. C. H. Zhao  Dr. H. Kagami  Dr. T. Yoshida  Dr. Y. Kawano 《Mineralogy and Petrology》1997,60(1-2):81-98

Summary Southwestern Yunnan, comprising the Yangtze and Shan-Thai microcontinents and the Simao block, has successively undergone subduction of an oceanic plate, followed by a collision of the microcontinents and intracontinental rifting associated with basaltic volcanism during Late Paleozoic to Mesozoic.The Triassic Nanjian basalts, erupted on the Yangtze microcontinent, have more enriched isotopic ratios and higher LREE/HFSE and LREE/HREE ratios. This suggests the existence of an enriched subcontinental lithosphere under the Yangtze microcontinent which stabilized over long periods of the earth's history (> 2Ga).The Middle Jurassic Simao basalts have more depleted geochemical features and also have element enrichments characteristic of a subduction zone environment, although the basalts were erupted in an intracontinental graben. It may be inferred that the lithospheric mantle of the Simao block was modified by subduction processes during Latest Carboniferous to Late Triassic prior to the onset of the Middle Jurassic continental rifting. The lack of correlation between depletion of HFSE, Y and HREE, and relative enriched Nd isotopic ratios suggests that the source depletion of the Simao basalts is not an old feature and has been contemporaneous with the subduction-related enrichment through mantle metasomatism shortly before the basalts were produced.The Middle Jurassic Baoshan basalts which erupted during the continental rifting on the Shan-Thai microcontinent have an Sr-Nd isotopic composition similar to the bulk earth and higher concentrations of incompatible trace elements. These features suggest that the subcontinental lithosphere under the Shan-Thai microcontinent underwent mantle metasomatism just prior to eruption of the Baoshan basalt.

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Geochemie mesozoischer interkontinentaler Basalte aus Jünnan, Südchina: Hinweise auf die geochemische Entwicklung der subkontinentalen Lithosphäre

Zusammenfassung Südwestjünnan umfaßt den Jangtse und den Shan-Thai Mikrokontinent und den Simao Block. Das Gebiet wurde von aufeinander folgenden Subduktionsphasen einer ozeanischen Platte betroffen, auf die Kollision der Mikrokontinente und interkontinentales Rifting folgte. Dieses war mit basaltischem Vulkanismus während des späten Paläozoikums bis ins Mesozoikum assoziiert.Die triassischen Nanjian-Basalte, die auf dem Jangtse Mikrokontinent eruptierten, haben mehr angereicherte Isotopenverhältnisse und höhere LREE/HFSE und LREE/HREE Verhältnisse. Dieses weist auf eine angereicherte subkontinentale Lithosphäre unter dem Jangtse Mikrokontinent hin, die sich während langer Perioden der Erdgeschichte stabilisierte (>2Ga).Die mittel jurassischen Simao-Basalte haben eine mehr verarmte geochemische Signatur aber auch Elementanreicherungen, die für ein Subduktionszonen-Milieu charakteristisch sind, obwohl die Basalte in einem interkontinentalen Graben ausgetreten sind. Man kann daraus schließen, daß der lithosphärische Mantel des Simao-Blockes durch Subduktionsprozesse während des jüngsten Karbons bis in die späte Trias vor dem Beginn des mittel-jurassischen kontinentalen Riftings modifiziert worden war. Das Fehlen einer Korrelation zwischen der Anreicherung von HFSE, Y und HREE und relativ angereicherter Nd-Isotopenverhältnisse weist darauf hin, daß die Verarmung der Quelle der Simaobasalte nicht weit zurückreicht. Sie dürfte viel eher gleichaltrig mit der subduktions-bedingten Anreicherung durch Mantel-Metasomatose kurz vor der Entstehung der Basalte sein.Die mittel-jurassischen Baoshan-Basalte, die während des kontinentalen Riftings auf den Shan-Thai Mikrokontintent eruptierten, haben eine Sr-Nd-Isotopensignatur, die ähnlich der Gesamterde ist, jedoch höhere Konzentrationen inkompatibler Spurenelemente zeigt. All dies legt nahe, daß die subkontinentale Lithosphäre unter dem Shan-Thai-Mikrokontinent kurz vor der Eruption der Baoshan-Basalte von Mantel-Metasomatose betroffen worden ist.

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With 8 Figures

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Visiting Fellow, Geology Department, Australian National University, Australia  相似文献   

http://www.sciencedirect.com/science/article/pii/S1674987115000870     

Hisatoshi Sato  Miyuki Tahata  Yusuke Sawaki  Shigenori Maruyama  Naohiro Yoshida  Degan Shu  Jian Han  Yong Li  Tsuyoshi Komiya 《地学前缘(英文版)》2016,7(4):663-671

Cap Carbonates overlie the Marinoan Snowball Earth-related glacial diamictite,and possibly record the drastic surface environmental change and biological evolution after the Snowball Earth.We conducted on-land drilling from the Liantuo Formation,through the Nantuo,to the lower Doushantuo Formation in the Three Gorges area of South China to collect fresh,continuous samples in the Three Gorges area.We obtained high-resolution chemostratigraphies of δ~(13)C and δ~(18)O values of carbonates from the topmost part of the Nantuo Formation to the Cap Carbonate,in order to decode the detailed surface environmental change in the shallow marine setting.The δ~(13)C chemostratigraphy possesses some unique characteristics:(1) stable δ~(13)C values as a whole,but ubiquitous low δ~(13)C anomalies through the Cap Carbonate,(2) increase of the δ~(13)C values from-3 to +5‰ across the C2/C3 boundary,(3) no δ~(13)C anomaly between the C1 and C2 boundary,and(4) presence of an anomalous high δ~(13)C value(+2.3‰)and a faint positive correlation between δ~(13)C and δ~(18)O values in the C1 unit.Evidence of quite low δ~(13)C anomalies(with a nadir of-41‰),ubiquitous negative δ~(13)C anomalies through the Cap Carbonate,and a high δ~(13)C anomaly accompanied with a faint positive correlation between δ~(13)C and δ~(18)O values in the C1 unit supports decomposition and formation of methane hydrate during Cap Carbonate formation.The drastic increase of δ~(13)C values from the upper C2 to C3 units indicates enhancement of primary productivity and organic carbon burial,possibly due to high continental fluxes after the Snowball Earth event,evidenced by high Sr isotope values.The increase is restricted to the proximal side of the inner shelf in South China,and the timing of the increase of δ~(13)C values of carbonates is earlier at Three Gorges area than any other area,suggesting that the enhancement of primary productivity started in the proximal environment because of higher continental influxes.The increase in oxygen contents of seawater due to the enhanced primary productivity possibly resulted in the emergence of multicellular animals soon after Cap Carbonate deposition.  相似文献