On the evolutionary time scale of the accreting component in massive close binaries     

C. Doom  J. P. De Grève 《Astrophysics and Space Science》1981,80(2):369-395

The remaining core hydrogen burning lifetime after mass exchange is computed for the mass gaining component in massive close binary systems. Results are obtained for various modes of mass accretion, for a wide range of initial masses and mass ratios, and for different values of mass loss from the system. The effect of mass loss by stellar wind is included. By use of general properties of massive close binary evolution, the position in time of four events is determined: the end of core hydrogen burning of the primary and the secondary, and the occurrence of the supernova of the primary and the secondary. It is found that the two supernova event occur rather close in time, compared to the Main Sequence time scales of the components.This research is supported by the National Foundation of Collective Fundamental Research of Belgium (FKFO) under No. 2.9009.79.  相似文献   

Progress report on the UMP-programme 1963–1965     

Aloís Zátopek 《Studia Geophysica et Geodaetica》1966,10(1):106-106

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Sector structure of the interplanetary magnetic field and anisotropy of 50–1000 GV cosmic rays     

G. Erdős  J. Kóta 《Astrophysics and Space Science》1980,67(1):45-59

It is demonstrated that, at high rigidities (50 GV and beyond), all the main features of cosmic-ray anisotropy of solar origin can be explained in terms of regular particle motion —without diffusion being involved — in the large-scale interplanetary magnetic field (IMF). A simple model of the IMF is adopted with a corotating warped neutral sheet separating the regions of alternative polarities; the warped shape is indispensable for obtaining any form of anisotropy. Energy losses occurring along various computed trajectories are calculated to give the sidereal, solar and antisidereal intensity waves. The reliability of the variations obtained are checked by changing the parameters of the IMF model. Both the sense and amplitude of the polarity-dependent sidereal vector are compatible with those established experimentally. Also reproduced are the predictions of corotation in addition to the 3-hour phase of the semi-diurnal wave. The corotation is found to be near perfect at 50 GV, while it reduces at 100 GV. The model presented accounts for the change of solar daily vector that was observed in 1969.  相似文献   

Influence of injection conditions on field tracer experiments   总被引：2，自引：0，他引：2  

Brouyère S  Carabin G  Dassargues A 《Ground water》2005,43(3):389-400

Calibration of ground water transport models is often performed using results of field tracer experiments. However, little attention is usually paid to the influence, on resulting breakthrough curves, of injection conditions and well-aquifer interactions, more particularly of the influence of the possible trapping of the tracer in the injection wellbore. Recently, a new mathematical and numerical approach has been developed to model injection conditions and well-aquifer interactions in a very accurate way. Using an analytical solution derived from this model, a detailed analysis is made of the evolution of the tracer input function in the aquifer. By varying injection conditions from one simulation to another, synthetic breakthrough curves are generated with the SUFT3D ground water flow and transport finite-element simulator. These tests show clearly that the shape of the breakthrough curves can be dramatically affected by injection conditions. Using generated breakthrough curves as "actual" field results, a calibration of hydrodispersive parameters is performed, neglecting the influence of injection conditions. This shows that neglecting the influence of actual injection conditions can lead to (1) errors on fitted parameters and (2) misleading identification of the active transport processes. Conclusions and guidelines are drawn in terms of proposed methodologies for better controlling the tracer injection in the field, in order to minimize risk of misinterpretation of results.  相似文献   

Melt inclusions in scoria and associated mantle xenoliths of Puy Beaunit Volcano,Chaîne des Puys,Massif Central,France   总被引：1，自引：1，他引：0  

Séverine?JannotEmail author  Pierre?Schiano  Pierre?Boivin 《Contributions to Mineralogy and Petrology》2005,149(5):600-612

In order to characterize the composition of the parental melts of intracontinental alkali-basalts, we have undertaken a study of melt and fluid inclusions in olivine crystals in basaltic scoria and associated upper mantle nodules from Puy Beaunit, a volcano from the Chaîne des Puys volcanic province of the French Massif Central (West-European Rift system). Certain melt inclusions were experimentally homogenised by heating-stage experiments and analysed to obtain major- and trace-element compositions. In basaltic scoria, olivine-hosted melt inclusions occur as primary isolated inclusions formed during growth of the host phase. Some melt inclusions contain both glass and daughter minerals that formed during closed-system crystallisation of the inclusion and consist mainly of clinopyroxene, plagioclase and rhönite crystals. Experimentally rehomogenised and naturally quenched, glassy inclusions have alkali-basalt compositions (with SiO₂ content as low as 42 wt%, MgO>6 wt%, Na₂O+K₂O>5 wt%, Cl~1,000–3,000 ppm and S~400–2,000 ppm), which are consistent with those expected for the parental magmas of the Chaîne des Puys magmatic suites. Their trace-element signature is characterized by high concentration(s) of LILE and high LREE/HREE ratios, implying an enriched source likely to have incorporated small amounts of recycled sediments. In olivine porphyroclasts of the spinel peridotite nodules, silicate melt inclusions are secondary in nature and form trails along fracture planes. They are generally associated with secondary CO₂ fluid inclusions containing coexisting vapour and liquid phases in the same trail. This observation and the existence of multiphase inclusions consisting of silicate glass and CO₂-rich fluid suggest the former existence of a CO₂-rich silicate melt phase. Unheated glass inclusions have silicic major-element compositions, with normative nepheline and olivine components, ~58 wt% SiO₂, ~9 wt% total alkali oxides, <3 wt% FeO and MgO. They also have high chlorine levels (>3,000 ppm) but their sulphur concentrations are low (<200 ppm). Comparison with experimental isobaric trends for peridotite indicates that they represent high-pressure (~1.0 GPa) trapped aliquots of near-solidus partial melts of spinel peridotite. Following this hypothesis, their silica-rich compositions would reflect the effect of alkali oxides on the silica activity coefficient of the melt during the melting process. Indeed, the silica activity coefficient decreases with addition of alkalis around 1.0 GPa. For mantle melts coexisting with an olivine-orthopyroxene-bearing mineral assemblage buffering SiO₂ activity, this decrease is therefore compensated by an increase in the SiO₂ content of the melt. Because of their high viscosity and the low permeability of their matrix, these near-solidus peridotite melts show limited ability to segregate and migrate, which can explain the absence of a chemical relationship between the olivine-hosted melt inclusions in the nodules and in basaltic scoria.  相似文献   

NO<Subscript>3</Subscript> Vertical Profile Measurements from Remote Sensing Balloon-Borne Spectrometers and Comparison with Model Calculations     

Jean-Baptiste?RenardEmail author  Martyn?P.?Chipperfield  Gwena?l?Berthet  Fabienne?Goffinont-Taupin  Claude?Robert  Michel?Chartier  Howard?Roscoe  Wuhu?Feng  Emmanuel?Rivière  Michel?Pirre 《Journal of Atmospheric Chemistry》2005,51(1):65-78

Eleven vertical profiles of stratospheric NO₃ have been obtained since 1992 using the AMON and SALOMON balloon-borne UV-visible spectrometers. The measurements are compared to the SLIMCAT 3D model and calculations based on the steady-state hypothesis for NO₃. The calculations cannot reproduce some parts of the profiles which exhibit strong concentration fluctuations over few kilometres, as a consequence of the dependence of NO₃ on local temperature variations. A statistical use of the data allows us to estimate the influence of the temperature dependence of the absorption cross-section on the data analysis, and the validity of the recommended reaction rates available in the literature. Discrepancies exist between the model based on recommended kinetics and observations at warmer temperatures. Nevertheless, the analysis is biased by local temperature inhomogeneities, and only a low-resolution vertical shape of the NO₃ profiles can be retrieved.  相似文献   

IRAS F02044+0957: An interacting system     

V. H. Chavushyan  O. V. Verkhodanov  J. R. Valdés  R. Mújica  S. A. Trushkin 《Astrophysics》2005,48(1):89-98

A list of 750 objects has been compiled using the Astrophysical CATalogs Support System (CATS) database, by cross-identifying sources in the IRAS catalogues and the catalogue of the Texas survey at 365 MHz. We have carried out a search for optical counterparts of those objects, where the difference in positions between the two catalogues and the APM is less than 3. One of these sources, IRAS F02044+0957, was observed with the RATAN-600 radio telescope at four frequencies in April 1999. Optical spectroscopy of the components of the system was made with the 2.1-m telescope of the Guillermo Haro Observatory. The radio and optical spectra, the NVSS radio map and the optical and infrared images allow us to conclude that the steep spectrum (=–0-94 ± 0-02) radio source IRAS F02044+0957 is a pair of interacting galaxies, a LINER and a HII galaxy, at z=0.093.Published in Astrofizika, Vol. 48, No. 1, pp. 113–124 (February 2005).  相似文献   

Net primary production and decomposition of salt marshes of the Ebre delta (Catalonia,Spain)     

Antoni?CurcóEmail author  Carles?Ibà?ez  John?W.?Day  Narcís?Prat 《Estuaries and Coasts》2002,25(3):309-324

Net primary production was measured in three characteristic salt marshes of the Ebre delta: anArthrocnemum macrostachyum salt marsh,A. macrostachyum-Sarcocornia fruticosa mixed salt marsh andS. fruticosa salt marsh. Above-ground and belowground biomass were harvested every 3 mo for 1 yr. Surface litter was also collected from each plot. Aboveground biomass was estimated from an indirect non-destructive method, based on the relationship between standing biomass and height of the vegetation. Decomposition of aboveground and belowground components was studied by the disappearance of plant material from litter bags in theS. fruticosa plot. Net primary production (aboveground and belowground) was calculated using the Smalley method. Standing biomass, litter, and primary production increased as soil salinity decreased. The annual average total aboveground plus belowground biomass was 872 g m⁻² in theA. macrostachyum marsh, 1,198 g m⁻² in theA. macrostachyum-S. fruticosa mixed marsh, and 3,766 g m⁻² in theS. fruticosa biomass (aboveground plus belowground) was 226, 445, and 1,094 g m⁻², respectively. Total aboveground plus below-ground net primary production was 240, 1,172, and 1,531 g m⁻² yr⁻¹. There was an exponential loss of weight during decomposition. Woody stems and roots, the most recalcitrant material, had 70% and 83% of the original material remaining after one year. Only 20–22% of leafy stem weight remained after one year. When results from the Mediterranean are compared to other salt marshes dominated by shrubbyChenopodiaceae in Mediterranean-type climates, a number of similarities emerge. There are similar zonation patterns, with elevation and maximum aboveground biomass and primary production occurring in the middle marsh. This is probably because of stress produced by waterlogging in the low marsh and by hypersalinity in the upper marsh.  相似文献   

Low-Degree Low-Order Solar p Modes As Seen By GOLF On board SOHO     

GarcÍa  R.A.  Régulo  C.  Turck-Chièze  S.  Bertello  L.  Kosovichev  A.G.  Brun  A.S.  Couvidat  S.  Henney  C.J.  Lazrek  M.  Ulrich  R.K.  Varadi  F. 《Solar physics》2001,200(1-2):361-379

Data recovered from the GOLF experiment on board the ESA/NASA SOHO spacecraft have been used to analyze the low-order low-degree solar velocity acoustic-mode spectrum below =1.5 mHz (i.e., 1n9,l2). Various techniques (periodogram, RLAvCS, homomorphic-deconvolution and RLSCSA) have been used and compared to avoid possible biases due to a given analysis method. In this work, the acoustic resonance modes sensitive to the solar central region are studied. Comparing results from the different analysis techniques, 10 modes below 1.5 mHz have been identified.  相似文献   

On multifractality of high-latitude geomagnetic fluctuations     

Z. Vörös 《Annales Geophysicae》2000,18(10):1273-1282

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