Electron temperatures and densities of planetary nebulae determined from the nebular hydrogen recombination spectrum and temperature and density variations     

Y. Zhang  X.-W. Liu  R. Wesson  P. J. Storey  Y. Liu  I. J. Danziger 《Monthly notices of the Royal Astronomical Society》2004,351(3):935-955

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Coronal Fe ix line intensities and electron density diagnostics     

P.J. Storey  C.J. Zeippen 《Monthly notices of the Royal Astronomical Society》2001,324(1):L7-L10

The relative intensities of the most prominent extreme-ultraviolet lines of Fe  ix , seen in the outer atmospheres of the Sun and other stars, have been shown to be inconsistent with the best available atomic data. The density-sensitive Fe  ix λ 241.7/ λ 244.9 line intensity ratio, for example, yields electron densities in the solar corona that disagree with those obtained from ratios in other ions, particularly at higher densities. We show here that these differences can be largely removed by using newly calculated atomic data, in particular electron impact collision strengths that include pronounced resonance features, and by incorporating a measure of line excitation by collisional excitation and cascading.  相似文献   

OBSERVATIONS ON THE DEVELOPMENT OF A DIGITAL MAPPING SYSTEM     

P. Storey  † 《The Photogrammetric Record》1983,11(61):55-58

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Paleoproterozoic subduction-related metasomatic signatures in the lithospheric mantle beneath NE Brazil: inferences from trace element and Sr–Nd–Pb isotopic compositions of Neoproterozoic high-K igneous rocks     

Maria Helena Bezerra Maia de Hollanda  Mrcio Martins Pimentel  Emanuel Ferraz Jardim de S 《Journal of South American Earth Sciences》2003,15(8):885-900

Late Neoproterozoic (ca. 580 Ma), high-K, mafic-intermediate rocks represent voluminous bimodal magmatism in the Borborema Province, northeast Brazil. These rocks show the following chemical signatures that reflect derivation from a subduction-modified lithospheric mantle source: (1) enrichment in large ion lithophile elements (Rb, Ba, K, Th) and light rare-earth elements (REE) (La/Yb_CN=11–70), (2) pronounced negative Nb anomalies, and (3) radiogenic Sr (0.71202–0.7059) and unradiogenic Nd (_Nd from −9.3–−20.1) isotopic compositions. T_DM model ages suggest that modification of the lithospheric mantle source (metasomatised garnet lherzolite) may have occurred in the Paleoproterozoic during the Transamazonian/Eburnean tectonics that affected the region. Interaction with asthenospheric fluids is believed to have partially melted this enriched source in the Neoproterozoic, probably as a result of asthenosphere-derived fluid percolation in the Brasiliano/Pan-African shear zones that controlled the emplacement of these mafic-intermediate magmas. The involvement of this asthenospheric component is supported by the nonradiogenic Pb isotopic ratios (²⁰⁶Pb/²⁰⁴Pb=16–17.3, ²⁰⁷Pb/²⁰⁴Pb=15.1–15.6, ²⁰⁸Pb/²⁰⁴Pb=36–37.5), which contrast with the enriched Sr and Nd compositions and thereby suggest the decoupling of Rb–Sr, Sm–Nd, and U–Pb systems at the time of intrusion of the mafic-intermediate magmas in the crust.  相似文献   

Comment by Emanuel Mazor on Tóth,József, 1995, Hydraulic continuity in large sedimentary basins: Hydrogeology Journal,v. 3, no. 4, p. 4–16     

Emanuel Mazor 《Hydrogeology Journal》1996,4(3):98-102

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Influence of the initial water content and dry density on the soil–water retention curve and the shrinkage behavior of a compacted clay     

Emanuel Birle  Dirk Heyer  Norbert Vogt 《Acta Geotechnica》2008,3(3):191-200

The paper presents the results of an experimental study on the effects of the initial water content and dry density on the soil–water retention curve and the shrinkage behavior of a compacted Lias-clay. The initial conditions after compaction (initial water content and initial dry density) have been chosen on the basis of three Proctor tests of different compaction efforts. According to the eight chosen initial conditions clay samples have been compacted statically. The relation between total suction and water content was determined for the drying path starting from the initial conditions without previous saturation of the specimens. A chilled-mirror dew-point hygrometer was used for the suction measurements. For the investigation of the shrinkage behavior cylindrical specimens were dried to desired water contents step-by-step without previous saturation. The volume of the specimens was measured by means of a caliper. Based on the test results the influence of different initial conditions on the soil suction and the shrinkage behavior is analyzed. The soil–water retention curves obtained in terms of the gravimetric water content are independent of the initial dry density. At water contents above approximately 11–12.5% a strong influence of the compaction water content is observed. At smaller water contents, the soil–water retention curve is independent of the compaction water content. The results of the shrinkage tests show that the influence of the compaction dry density on the shrinkage behavior is negligible. Similar to the drying behavior of saturated samples a primary and a residual drying process could be distinguished. The primary drying process is strongly influenced by the initial water content. In contrast, the rate of the volume change of the residual drying process is unaffected by the initial water content.  相似文献   

10 μm imaging of the nucleus of NGC 1068: The bell tolls for parsec-scale tori?     

Murray Cameron  Reinhard Genzel  John W. V. Storey 《Experimental Astronomy》1994,3(1-4):61-64

The potential of mid-infrared imaging, at a resolution of 0.5 or better, as a powerful tool in unravelling the complex environments in the vicinity of active galactic nuclei is discussed in the light of new data on the Seyfert nucleus in NGC 1068. In particular, we examine the growing body of evidence that the extinction of the broad-line region in NGC 1068 has its origins in an extended molecular disk and is the result of obscuration at 100 pc from the AGN.  相似文献   

The WC10 central stars CPD−56° 8032 and He 2–113 –III. Wind electron temperatures and abundances     

Orsola De Marco  P. J. Storey  & M. J. Barlow 《Monthly notices of the Royal Astronomical Society》1998,297(4):999-1014

We present a direct spectroscopic measurement of the wind electron temperatures and a determination of the stellar wind abundances of the WC10 central stars of planetary nebulae CPD−56° 8032 and He 2–113, for which high-resolution (0.15-Å) UCLES echelle spectra have been obtained using the 3.9-m Anglo-Australian Telescope.
The intensities of dielectronic recombination lines, originating from autoionizing resonance states situated in the C²⁺+e⁻ continuum, are sensitive to the electron temperature through the populations of these states, which are close to their LTE values. The high-resolution spectra allow the intensities of fine-structure components of the dielectronic multiplets to be measured. New atomic data for the autoionization and radiative transition probabilities of the resonance states are presented, and used to derive wind electron temperatures in the two stars of 21 300 K for CPD−56°8032 and 16 400 K for He 2–113. One of the dielectronic lines is shown to have an autoionization width in agreement with the theoretical predictions. Wind abundances of carbon with respect to helium are determined from bound–bound recombination lines, and are found to be C/He=0.44 for CPD−56° 8032 and C/He=0.29 for He 2–113 (by number). The oxygen abundances are determined to be O/He=0.24 for CPD−56° 8032 and 0.26 for He 2–113.
The effect of optical depth on the temperature and abundance determinations is investigated by means of a Sobolev escape-probability model. We conclude that the optically thicker recombination lines can still be used for abundance determinations, provided that their upper levels are far from LTE.  相似文献   

Conference reports     

Bryan Storey 《Journal of African Earth Sciences》1998,26(4):527-537

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Hubble Space Telescope observations of magellanic cloud planetary nebulae: Stellar winds     

Emanuel Vassiliadis 《Astrophysics and Space Science》1996,238(1):67-70

Narrow-band [OIII] 500.7 nm images and ultraviolet spectrophotometry are obtained for 20 planetary nebulae (PNe) in the Magellanic Clouds using the Hubble Space Telescope (HST). Four objects show P Cygni-like features in the ultraviolet HST data, and/or broad emission complexes near the HeII 468.6 nm and CIV 580.6 nm lines in ground-based spectra. All objects are of excitation class four or lower, and all are compact and dense compared to other objects in the sample. The likelihood of detecting ultraviolet P Cygni-like profiles in future HST spectroscopy of other objects is discussed.  相似文献