Chemical spots on the surface of the strongly magnetic Herbig Ae star HD 101412     

S. P. Jrvinen  S. Hubrig  M. Schller  I. Ilyin  T. A. Carroll  H. Korhonen 《Astronomische Nachrichten》2016,337(3):329-338

Due to the knowledge of the rotation period and the presence of a rather strong surface magnetic field, the sharp‐lined young Herbig Ae star HD 101412 with a rotation period of 42 d has become one of the most well‐studied targets among the Herbig Ae stars. High‐resolution HARPS polarimetric spectra of HD 101412 were recently obtained on seven different epochs. Our study of the spectral variability over the part of the rotation cycle covered by HARPS observations reveals that the line profiles of the elements Mg, Si, Ca, Ti, Cr, Mn, Fe, and Sr are clearly variable while He exhibits variability that is opposite to the behaviour of the other elements studied. Since classical Ap stars usually show a relationship between the magnetic field geometry and the distribution of element spots, we used in our magnetic field measurements different line samples belonging to the three elements with the most numerous spectral lines, Ti, Cr, and Fe. Over the time interval covered by the available spectra, the longitudinal magnetic field changes sign from negative to positive polarity. The distribution of field values obtained using Ti, Cr, and Fe lines is, however, completely different compared to the magnetic field values determined in previous low‐resolution FORS 2 measurements, where hydrogen Balmer lines are the main contributors to the magnetic field measurements, indicating the presence of concentration of the studied iron‐peak elements in the region of the magnetic equator. Further, we discuss the potential role of contamination by the surrounding warm circumstellar matter in the appearance of Zeeman features obtained using Ti lines. (© 2016 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)  相似文献   

Lattice-preferred orientations of late-Variscan granitoids derived from neutron diffraction data: implications for magma emplacement mechanisms     

Axel Müller  Bernd Leiss  Klaus Ullemeyer  Karel Breiter 《International Journal of Earth Sciences》2011,100(7):1515-1532

The lattice-preferred orientation (LPOs) of two late-Variscan granitoids, the Meissen monzonite and the Podlesí dyke granite, were determined from high-resolution time-of-flight neutron diffraction patterns gained at the diffractometer SKAT in Dubna, Russia. The results demonstrate that the method is suitable for the LPO analysis of polyphase, relatively coarse-grained (0.1–6 mm) rocks. The Meissen monzonite has a prominent shape-preferred orientation (SPO) of the non-equidimensional minerals feldspar, mica and amphibole, whereas SPO of the Podlesí granite is unapparent at the hand-specimen scale. The neutron diffraction data revealed distinct LPOs in both granitoids. The LPO of the non-equidimensional minerals feldspar, mica and amphibole developed mainly during magmatic flow. In the case of the Meissen monzonite, the magmatic flow was superimposed by regional shear tectonics, which, however, had no significant effect on the LPOs. In both samples, quartz shows a weak but distinct LPO, which is atypical for plastic deformation and different in the syn-kinematic Meissen monzonite and the post-kinematic Podlesí granite. We suggest that, first of all, the quartz LPO of the Meissen monzonite is the result of oriented growth in an anisotropic stress field. The quartz LPO of the Podlesí granite, which more or less resembles a deformational LPO in the flattening field of the local strain field, developed during magmatic flow, whereby the rhombohedral faces of the quartz crystals adhered to the (010) faces of aligned albite and to the (001) faces of zinnwaldite. Due to shape anisotropy of their attachments, the quartz crystals were passively aligned by magmatic flow. Thus, magmatic flow and oriented crystal growth are the major LPO-forming processes in both granitoids. For the Meissen monzonite, the solid-state flow was too weak to cause significant crystallographic re-orientation of the minerals aligned by magmatic flow. Finally, the significance of our results for the evaluation of the regional tectonic environment during magma emplacement is discussed. The discussion on the regional implications of the more methodologically oriented results provides the basis for future, more regionally aimed studies in view of the fabric characteristics of such plutons and their developing mechanisms.  相似文献   

Mendigite,Mn2Mn2MnCa(Si3O9)2, a new mineral species of the bustamite group from the Eifel volcanic region,Germany     

N. V. Chukanov  S. M. Aksenov  R. K. Rastsvetaeva  K. V. Van  D. I. Belakovskiy  I. V. Pekov  V. V. Gurzhiy  W. Schüller  B. Ternes 《Geology of Ore Deposits》2015,57(8):721-731

A new mineral, mendigite (IMA no. 2014-007), isostructural with bustamite, has been found in the In den Dellen pumice quarry near Mendig, Laacher Lake area, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. Associated minerals are sanidine, nosean, rhodonite, tephroite, magnetite, and a pyrochlore-group mineral. Mendigite occurs as clusters of long-prismatic crystals (up to 0.1 × 0.2 × 2.5 mm in size) in cavities within sanidinite. The color is dark brown with a brown streak. Perfect cleavage is parallel to (001). D _calc = 3.56 g/cm³. The IR spectrum shows the absence of H₂O and OH groups. Mendigite is biaxial (–), α = 1.722 (calc), β = 1.782(5), γ = 1.796(5), 2V _meas = 50(10)°. The chemical composition (electron microprobe, mean of 4 point analyses, the Mn²⁺/Mn³⁺ ratio determined from structural data and charge-balance constraints) is as follows (wt %): 0.36 MgO, 10.78 CaO, 37.47 MnO, 2.91 Mn₂O₃, 4.42 Fe₂O₃, 1.08 Al₂O₃, 43.80 SiO₂, total 100.82. The empirical formula is Mn_2.00(Mn_1.33Ca_0.67) (Mn_0.50 ²⁺ Mn_0.28 ³⁺ Fe_0.15 ³⁺ Mg_0.07)(Ca_0.80 (Mn_0.20 ²⁺)(Si_5.57 Fe_0.27 ³⁺ Al_0.16O₁₈). The idealized formula is Mn₂Mn₂MnCa(Si₃O₉)₂. The crystal structure has been refined for a single crystal. Mendigite is triclinic, space group \(P\bar 1\); the unit-cell parameters are a = 7.0993(4), b = 7.6370(5), c = 7.7037(4) Å, α = 79.58(1)°, β = 62.62(1)°, γ = 76.47(1)°; V = 359.29(4) ų, Z = 1. The strongest reflections on the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 3.72 (32) (020), 3.40 (20) (002, 021), 3.199 (25) (012), 3.000 (26), (\(01\bar 2\), \(1\bar 20\)), 2.885 (100) (221, \(2\bar 11\), \(1\bar 21\)), 2.691 (21) (222, \(2\bar 10\)), 2.397 (21) (\(02\bar 2\), \(21\bar 1\), 203, 031), 1.774 (37) (412, \(3\bar 21\)). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4420/1.  相似文献   

西藏甲玛铜多金属矿区成矿斑岩的岩浆混合作用:石英及长石斑晶新证据   总被引：6，自引：3，他引：3  

彭惠娟  汪雄武  Müller Axel  秦志鹏  侯林  周云 《矿床地质》2011,30(2):249-265

西藏甲玛矿区斑岩内石英和长石斑晶的阴极发光(CL)特征及元素含量变化有效记录了岩浆演化、混合及补给事件.石英斑晶的显微生长结构表明,原始岩浆经历过2次铁镁质岩浆混合作用.根据石英斑晶中Ti含量的变化可知,在2次溶蚀前后,石英结晶温度分别增高了约110℃和80℃.此外,斜长石斑晶的反环带及其Ba、Sr、Fe等元素的浓度梯...  相似文献   

Behavior of Gd-DTPA in simulated bank filtration     

Peter Möller  Andrea KnappePeter Dulski  Asaf Pekdeger 《Applied Geochemistry》2011,26(1):140-149

The behavior of Gd-DTPA during bank filtration was simulated in a 30 m column filled with Pleistocene sand and flushed by surface water from a lakeside in Berlin, Germany. The surface water is about a 1:1 mixture of river water and effluents from a sewage treatment plant. Throughout 34 days this water was continuously spiked with Gd-DTPA at a level of 60 μg/L. The broad plateau of the Gd-DTPA pulse declined by 15.4% within 34 days by transmetallation. Nine percentage of the total decline is caused by Y and rare earth elements; the remaining part is attributed to Cu²⁺ which is the most influential metal in surface water. All other metals also contributing to transmetallation are combined with Cu to Cu equivalents because only the rate constant of transmetallation of Cu²⁺ is known. The analytical results of the column effluents prove the pseudo-first-order kinetics of transmetallation based on reversible sorption of metals by pools in the column sediment and disprove biodegradation at noticeable levels. The mass ratio of water to tracer is <10¹⁰.  相似文献   

Erratum: Oxidation and emission of methane in a monomictic lake (Rotsee,Switzerland)     

C. J. Schubert  F. S. Lucas  E. Durisch-Kaiser  R. Stierli  T. Diem  O. Scheidegger  F. Vazquez  B. Müller 《Aquatic Sciences - Research Across Boundaries》2011,73(1):183-183

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A study to discriminate local,urban and regional source contributions to the particulate matter concentrations in the city of Dresden,Germany     

T. Gnauk  K. Müller  E. Brüggemann  W. Birmili  K. Weinhold  D. van Pinxteren  G. Löschau  G. Spindler  H. Herrmann 《Journal of Atmospheric Chemistry》2011,68(3):199-231

The fractions of local traffic (LT), urban background (UBG) and regional background (RBG) of the particle pollution at a traffic-influenced kerbside in Dresden, Germany, were determined by measurements of size-segregated mass concentration, chemical composition and particle size distributions in a network of five measurement stations partly existing and partly set up for this study. Besides the kerbside station, one urban background site and three rural sites were included in the study. Using data from these different sites, the LT, UBG, and RBG contributions were calculated, following the approach of Lenschow et al. (2001). At the kerbside site, 19% of the total number concentration (Dp_St = 10–600 nm) could be attributed to the RBG, 15% to the UBG, and 66% to the LT immediately nearby. Particle mass concentrations up to Dp_aer = 420 nm RBG amounts to 68%, UBG to 21%, and LT only to 11%. Highest mass concentrations were observed at all stations in autumn and winter during easterly inflow directions. The local traffic fraction of PM₁₀ mass at the kerbside station was found to be 30% for westerly inflow, but only 7% for southeasterly inflow due to the dominating transport fraction from up to 80% of the particle mass at this inflow direction. Size-resolved investigation showed the main fractions in both the particle size ranges of Dp_aer = 0.42 to 1.2 and 0.14 to 0.42 μm at all stations. The main components sulphate, ammonium and total carbon showed higher concentrations at south-eastern/eastern inflow in autumn at all stations, while nitrate at the kerbside and urban background site was higher during westerly inflow in winter. The chemical composition at the regional background site at westerly inflow (12% nitrate, 8% sulphate, 11% total carbon) was significantly different from that at easterly inflow (3% nitrate, 15% sulphate, 22% total carbon). The prevailing part of the ionic mass was always found in the fine particle range of Dp_aer = 0.14 to 1.2 μm at all stations. For all inflow directions highest total carbon concentrations were observed at the kerbside station, especially in the ultra-fine size range of Dp_aer = 0.05 to 0.14 μm with up to 30% of the whole carbon. PAH concentrations were always higher at south-eastern/eastern inflow especially during wintertime. Trace metal components and silicon were found mainly in the coarse mode fraction at the kerbside resulting from abrasion or resuspension.  相似文献   

Development of an improved empirical model for slant delays in the troposphere (GPT2w)   总被引：7，自引：0，他引：7  

Johannes Böhm  Gregor Möller  Michael Schindelegger  Gregory Pain  Robert Weber 《GPS Solutions》2015,19(3):433-441

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An assessment of a multi-model ensemble of decadal climate predictions     

A. Bellucci  R. Haarsma  S. Gualdi  P. J. Athanasiadis  M. Caian  C. Cassou  E. Fernandez  A. Germe  J. Jungclaus  J. Kröger  D. Matei  W. Müller  H. Pohlmann  D. Salas y Melia  E. Sanchez  D. Smith  L. Terray  K. Wyser  S. Yang 《Climate Dynamics》2015,44(9-10):2787-2806

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The prediction of surface temperature in the new seasonal prediction system based on the MPI-ESM coupled climate model     

J. Baehr  K. Fröhlich  M. Botzet  D. I. V. Domeisen  L. Kornblueh  D. Notz  R. Piontek  H. Pohlmann  S. Tietsche  W. A. Müller 《Climate Dynamics》2015,44(9-10):2723-2735

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