Solar rotation velocity as determined from sunspot drawings of J. Hevelius in the 17th century     

Claudia Abarbanell  Hubertus Wöhl 《Solar physics》1981,70(1):197-203

Using two original copies of Hevelius' Selenographia and reducing spot positions with two different methods, we found that the solar angular rotation velocity at the beginning of the Maunder minimum was about the same as today. The gradient of the differential rotation was slightly steeper than given in modern reductions, but not significantly different. These findings are in contradiction to those published by Eddy et al. (1976).  相似文献   

The dependence of the frequency spectra of the interplanetary magnetic-field fluctuations on the direction of the mean field     

Jörn E. Kunstmann 《Earth, Moon, and Planets》1978,18(1):91-104

The frequency spectra of the interplanetary magnetic field fluctuations are the projection of their wavenumber spectra onto one dimension. Only the frequency spectra can be measured by spacecrafts. It is studied how their measured size depends on the direction of the mean fieldB ₀, which structures the symmetry of the fluctuations relative to the solar wind system. It is specialized for the slab model, Alfvén waves, magneto-acoustic waves and the isotropic case. For the slab model the frequency spectra are proportional to , whereq is the spectral index and the angle betweenB ₀ and the radial direction. For the diffusion coefficientK _TT the relation holds.  相似文献   

Noble gases in the Allende and Abee meteorites and a gas-rich mineral fraction: investigation by stepwise heating     

B. Srinivasan  Roy S. Lewis  Edward Anders 《Geochimica et cosmochimica acta》1978,42(2):183-198

Noble gases in three meteoritic samples were examined by stepwise heating, in an attempt to relate peaks in the outgassing curves to specific minerals: NeKrXe in Allende (C3V) and an Allende residue insoluble in HF-HCl, and Xe in Abee (E4). In Allende, chromite and carbon contain most of the trapped Ne (²⁰Ne/²²Ne ≈ 8.7) and anomalous Xe enriched in light and heavy isotopes, and release it at ~850°C (bulk meteorite) or 1000°C (residue). Mineral Q, containing most of the trapped Ar, Kr, Xe as well as some Ne (²⁰Ne/²²Ne ≈ 10.4), releases its gases mainly between 1200 and 1600°C, well above the release temperatures of organic polymers (300–500°) or amorphous carbon (800–1000°). The high noble-gas release temperature, ready solubility in oxidizing acids, and correlation with acid-soluble Fe and Cr all point to an inorganic rather than carbonaceous nature of Q.All the radiogenic ¹²⁹Xe is contained in HCl, HF-soluble minerals, and is distributed as follows over the peaks in the release curve: Attend 1000° (75%), 1300° (25%); Abee (data of Hohenberg and Reynolds, 1969) ~850° (15%), 1100° (60%), 1300° (25%). No conclusive identifications of host phases can yet be given; possible candidates are troilite and silicates for Allende, and djerfisherite, troilite and silicates for Abee.Mineral Q strongly absorbs air xenon, and releases some of it only at 800–1000°C. Dilution by air Xe from Q and other minerals may explain why temperature fractions from bulk meteorites often contain less ^124–130Xe for a given enrichment in heavy isotopes than does xenon from etched chromitecarbon samples, although chromite-carbon is the source of the anomalous xenon in either case. Air xenon contamination thus is an important source of error in the derivation of fission xenon spectra.  相似文献   

Differential rotation and giant cell circulation of solar Ca+-network     

E. H. Schröter  H. Wöhl 《Solar physics》1976,49(1):19-32

We report new results obtained from high precision computer controlled tracings of ca. 400 bright Ca⁺-mottles made during summer 1975 in continuation of our 1974 program (Schröter and Wöhl, 1975). In particular, we looked in 1975 for the existence of a giant circulation pattern in the equatorial zone. We find for the differential rotation: = 13.93 – 2.90 sin² B (deg/day, sidereal) when combining the new measurements with those obtained in 1974. Observations from 26th April until June 19th give strong evidence that at that time four giant circulation cells, crossing the solar equator, (i.e. a nonaxisymmetric velocity field pattern with respect to the solar equator) did exist. This yields two more rapid and two slower rotating sectors with v = ±80 m s^–1. These giant cells transport angular momentum towards the equator.  相似文献   

Fraktionierung der spurenelemente bei der kristallisation: Hans-Eberhard Usdowski. Springer-Verlag,Berlin, 1975, 104 S., 42 Abb., DM 29,80     

Heinrich M. Köster 《Chemical Geology》1976,18(4):327

  相似文献   

Transport and emplacement of crater and basin deposits     

Verne R. Oberbeck  Robert H. Morrison  Friedrich Hörz 《Earth, Moon, and Planets》1975,13(1-3):9-26

Material is ejected from impact craters in ballastic trajectories; it impacts first near the crater rim and then at progressively greater ranges. Ejecta from craters smaller than approximately 1 km is laid predominantly on top of the surrounding surface. With increasing crater size, however, more and more surrounding surface will be penetrated by secondary cratering action and these preexisting materials will be mixed with primary crater ejecta. Ejecta from large craters and especially basin forming events not only excavate preexisting, local materials, but also are capable of moving large amounts of material away from the crater. Thus mixing and lateral transport give rise to continuous deposits that contain materials from within and outside the primary crater. As a consequence ejecta of basins and large highland craters have eroded and mixed highland materials throughout geologic time and deposited them in depressions inside and between older crater structures.Because lunar mare surfaces contain few large craters, the mare regolith is built up by successive layers of predominantly primary ejecta. In contrast, the lunar highlands are dominated by the effects of large scale craters formed early in lunar history. These effects lead to thick fragmental deposits which are a mixture of primary crater material and local components. These deposits may also properly be named regolith though the term has been traditionally applied only to the relatively thin fine grained surficial deposit on mare and highland terranes generated during the past few billion year. We believe that the surficial highland regolith - generated over long periods of time - rests on massive fragmental units that have been produced during the early lunar history.  相似文献   

Acid leaching of ash and coal: Time dependence and trace element occurrences     

Mehtap Paul  Meryem Seferinoğlu  Gul Asiye Ayçık  Åke Sandström  Michael L. Smith  Jan Paul 《International Journal of Mineral Processing》2006

The leaching of coal and coal/asphaltite/wood-ashes in sulfuric acid (pH 1.0, 25 °C, S/L, 1:10) was studied as a function of time; acid consumption and extracted metal concentrations are presented. Whole coals consumed acid rapidly during the first few minutes, followed by slow acid consumption. Wood-, lignite-, and asphaltite-ashes consumed acid in two stages, the rapid phase extending < 30 min and the slow phase extended up to 10 days. The rapid phase was dominated by the dissolution of Ca, K and Mg ions for wood-ash, by Ca, Al and Mg ions for lignite-ash and Ca and Mg ions for asphaltite-ash. The sulfur concentration in solution and the concentrations of Ca, Fe, K, Mg, Na, P, Al and Mn in the aqueous phase verified the neutralizing capacity of the untreated ashes as well as the formation of insoluble sulfates in the residues. The slow phase kinetics differed for different fuels and exhibited leaching of several abundant elements—Fe, Al, K, Na and Mn. Trace elements (Ba, Cd, Co, Cr, Cu, Mo, Ni, Pb, Th, U, V, Zn) sometimes required up to 32 h for maximal extraction from ashes. Suggestions are presented regarding the chemical nature of trace elements in the untreated coals and ashes and suitable residence times for economical industrial processes. We think it possible to combine bacteriological oxidation of sulfidic concentrates of acid leaching from ash of various qualities or even whole coals.  相似文献   

Comparison of soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters     

Christine E. Geibe  Rolf Danielsson  Patrick A.W. van Hees  Ulla S. Lundstrm 《Applied Geochemistry》2006,21(12):2096-2111

The choice of sampling method for soil solution is of great importance. In this paper soil solution chemistry sampled by centrifugation, two types of suction lysimeters and zero-tension lysimeters have been studied with the purpose of investigating systematic differences between them. The samples were taken at 4 depths from an acidified forest soil as well as from adjacent lime and ash treated soils. A centrifugation drainage method was compared with two types of suction lysimeters (‘Rhizon’ and ‘Prenart’) and zero-tension lysimeters. About half of the 27 variables measured showed a significant difference between the sampling methods used. Typically the centrifuged samples had lower pH (4.0 vs. 4.4), Ca (21 μM vs. 30 μM) and Mg (25 μM vs. 34 μM) concentrations and higher Cl (330 μM vs. 230 μM) and DOC (4.4 mM vs. 3.2 mM) concentrations than the Rhizon lysimeters. Also the other lysimeters showed significant differences compared to the centrifuged samples for about half the number of analytes. Centrifuged samples had higher concentrations of all analytes except NO₃ and PO₄ compared to zero-tension lysimeters and also for all analytes except NO₃ and Al compared to Prenart lysimeters. Among the environmental factors considered depth showed an influence to some extent, while sampling occasion had a great significant impact on the difference between the centrifugation method and the Rhizon lysimeters. Factors like individual pits or soil treatment did not show any influence on the difference between the methods.  相似文献   

Évolution de l'onde semi-diurne M2 de la marée à Brest de 1846 à 2005     

Nicolas Pouvreau  Belén Martin Miguez  Bernard Simon  Guy Wöppelmann 《Comptes Rendus Geoscience》2006,338(11):802-808

The work of searching, recovering and quality control of ancient sea-level measurements at Brest is presented. This work enables us to complete a study carried out by Cartwright in 1972, which showed a decrease in the tidal M2 semi-diurnal amplitude of 1% per century. After including these ancient data, as well as the last four decades of observations in the analysis, our results show an increase of the amplitude of M2 after 1960 and a decrease before 1880, suggesting a long-period oscillation rather than a steady secular trend. To cite this article: N. Pouvreau et al., C. R. Geoscience 338 (2006).  相似文献   

Obituary for Dr. Wolfgang Engel     

Philip E. LaMoreaux  Gunter Dörhöfer  Jörg Matschullat 《Environmental Geology》2006,50(4):459-459

  相似文献