Velocity of longitudinal waves in eclogite and ultrabasic rocks under pressures to 4 kilobars     

E. I. Bajuk  M. P. Volarovich  Karel Klíma  Zdeněk Pros  Jiří Vaněk 《Studia Geophysica et Geodaetica》1967,11(3):271-280

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Determination of the character of oriented potash feldspar overgrowth on plagioclase crystals in igneous rocks     

Ing. D. Němec 《Contributions to Mineralogy and Petrology》1967,16(2):149-155

A metod for determining the kind of potash feldspar overgrowths on plagioelase in igneous rocks is described and applied to different rocks types. The character of these overgrowths in volcanic and hypabyssal rocks seems to differ from that encountered in plutonic rocks.  相似文献   

Differences between Mean Sea Levels for the Pacific,Atlantic and Indian Oceans From Topex/Poseidon Altimetry     

Burša  Milan  Kouba  Jan  Müller  Achim  Raděj  Karel  True  Scott A.  Vatrt  Viliam  Vojtíšková  Marie 《Studia Geophysica et Geodaetica》1999,43(1):1-6

Geopotential values W of the mean equipotential surfaces representing the mean ocean topography were computed on the basis of four years (1993 - 1996) TOPEX/POSEIDON altimeter data: W = 62 636 854.10m ² s ^–2 for the Pacific (P), W = 62 636 858.20m ² s ^–2 for the Atlantic (A), W = 62 636 856.28m ²s^–2 for the Indian (I) Oceans. The corresponding mean separations between the ocean levels were obtained as follows: A – P = – 42 cm, I– P = – 22 cm, I – A = 20 cm, the rms errors came out at about 0.3 cm. No sea surface topography model was used in the solution.  相似文献   

Daily relative sunspot numbers 1749–1848: reconstruction of missing observations     

Letfus  V. 《Solar physics》1999,184(1):201-211

A great part of missing daily relative sunspot numbers in the time interval 1749–1848 was reconstructed by nonlinear two-step method of interpolation. In the first step gaps of missing observations not longer than five days were directly interpolated. In the second step data were sorted to so-called Bartels scheme, i.e., to rows of the length of 27 days subsequently ranged in a matrix. In this step the missing value at any position was interpolated from the data at the same position of preceding and following rows. The interpolation was limited to sequences of no more than four missing data. The procedure enables to interpolate long gaps and simultaneously to respect the 27-day variation of solar activity. Monthly and annual means of relative sunspot numbers are presented. The differences between monthly and annual means of the primary observations and of the data completed by interpolation fluctuate around zero. The amplitude of fluctuations depends inversely on the frequency of observations. Most conspicuous are the deviations in the time interval 1776–1795 where the frequency of observations is very low or almost zero. The average dispersion of monthly differences is ±11.5 R and that of annual differences is ±7.8 R. The two-step method of interpolation was tested on the series of daily data in the time interval 1918–1948. The sequence of missing daily data in the years 1818–1848 represents a masking function. This function was applied to the continuous data series in the time interval 1918–1948 and then the modified series was reconstructed. The differences between the monthly and annual means of primary and reconstructed data are small with fluctuations around zero and with dispersion for monthly differences ±2.7 R a for annual differences ±0.6 R. Corresponding dispersions of the data differences for monthly means in the time interval 1818–1848 are ±4.3 R and ±1.1 R for annual means. The small dispersion values and small differences among them give evidence about the applicability and the effectiveness of the nonlinear two-step method of interpolation and also about high credibility of relative sunspot numbers after reconstruction.  相似文献   

Sydney Chapman (1888–1970)     

Zdeněk Kopal 《Astrophysics and Space Science》1970,8(2):147-148

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Note on tidal evolution of the Earth-Moon system     

Zdeněk Kopal 《Earth, Moon, and Planets》1980,22(1):129-130

The need is pointed out of a re-discussion of the past tidal evolution of the Earth-Moon system as a boundary-value problem on the time-scale indicated by radiometric dating of lunar soils returned by successive space missions from different localities on the Moon's surface.Paper presented at the European Workshop on Planetary Sciences, organised by the Laboratorio di Astrofisica Spaziale di Frascati, and held between April 23–27, 1979, at the Accademia Nazionale del Lincei in Rome, Italy.  相似文献   

In memorial     

Zdeněk Kopal  L. M. Ozernoy 《Astrophysics and Space Science》1976,40(2):240-242

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Tidal evolution in close binary systems     

Zdeněk Kopal 《Astrophysics and Space Science》1972,17(1):161-185

The aim of the present paper will be to give a mathematical outline of the theory of tidal evolution in close binary systems of secularly constant total momentum — an evolution activated by viscous friction of dynamical tides raised by the two components on each other. The first section contains a general outline of the problem; and in Section 2 we shall establish the basic expressions for the energy and momenta of close binaries consisting of components of arbitrary internal structure. In Section 3 we shall investigate the maximum and minimum values of the energy (kinetic and potential) which such systems can attain for given amount of total momentum; while in Section 4 we shall compare these results with the actual facts encountered in binaries with components whose internal structure (and, therefore, rotational momenta) are known to us from evidence furnished by the observed rates of apsidal advance.The results show that all such systems — be these of detached or semi-detached type — disclose that more than 99% of their total momenta are stored in the orbital momentum. The sum of the rotational momenta of the constituent components amounts to less than a percent of the total — a situation characteristic of a state close to the minimum energy for given total momentum. This appears, moreover, to be true not only of the systems with both components on the Main Sequence, but also of those possessing evolved components in contact with their Roche limits.Under such conditions, a synchronism between rotation and revolution (characteristic of both extreme states of maximum and minimum energy) is not only possible, but appears to have been actually approached — if not attained — in the majority of cases. In other words, it would appear that — in at least a large majority of known cases — the existing close binaries have already attained orbits of maximum distension consistent with their momenta; and tidal evolution alone can no longer increase the present separations of the components to any appreciable extent.The virtual absence, in the sky, of binary systems intermediate between the stages of maximum and minimum energy for given momentum leads us to conjecture that the process of dynamical evolution activated by viscous tides may enroll on a time-scale which is relatively short in comparison with their total age — even for systems like Y Cygni or AG Persei, whose total age can scarcely exceed 10⁷ yr. A secular increase of the semi-major axes of relative orbits is dynamically coupled with a corresponding variation in the velocity of axial rotation of both components through the tidal lag arising from the viscosity of stellar material. The differential equations of so coupled a system are given in Section 5; but their solution still constitutes a task for the future.The Lunar Science Institute Contribution No. 90. The Lunar Science Institute is operated by the Universities Space Research Association under Contract No. NSR 09-051-001 with the National Aeronautics and Space Administration.  相似文献   

Computation of the elements of eclipsing binary systems in the frequency-domain     

Zdeněk Kopal 《Astrophysics and Space Science》1982,81(1-2):123-177

The aim of the present paper will be to translate the essential parts of the theory of Fourier analysis of the light changes of eclipsing variables into more practical terms; and describe procedures (illustrated by numerical examples) which should enable their users to obtain the desired results with maximum accuracy and minimum loss of information by processes which can be fully automated.In order to unfold in steps how this can be done, the scope of the present paper-the first of two-will be restricted to an exposition of the analysis of light changes caused by eclipses of spherical stars; while between minima due to this cause the light of the system should remain sensibly constant. An extension of our analysis to incorporate photometric effects arising from mutual distortion of the components of close eclipsing systems between minima as well as within eclipses is being postponed for the second communication.In developing this subject we shall single out for the user's attention only those parts of the whole theory which are of direct relevance to practical work. Their justification can be largely found in sources already published; and new developments essential for our work, not yet made public, will be relegated to several Appendices at the end of the text, in order not to render its text too discursive and deflect the reader's attention from the main theme of its narrative.After a brief outline of the subject given in Section 1, Section 2 will introduce the reader to practical aspects of the Fourier analysis of the light curves; and Section 3 will be devoted to its use to determine the numerical values of the momentsA _2m of the light curves which constitute the cornerstones for all subsequent work. Section 4 will describe an algebraization of the process of determination of the elements for the case of total (annular) eclipses; while Section 5 will do the same for partial eclipses. The concluding Section 6 will be devoted to an error analysis of our problem, and to an outline of the way by which the errors of the individual observations will compound to the uncertainty of the final results. Lastly, Appendices 1–5 concluding the paper will contain additional details of some aspects of our work, or proofs of new processes made use of to obtain our results, whose earlier inclusion would have made the main text too discursive.  相似文献   

Moments of inertia of the lunar globe,and their bearing on chemical differentiation of its outer layers     

Zdeněk Kopal 《Earth, Moon, and Planets》1972,4(1-2):28-34

It is pointed out that the observed moments of inertia of the Moon, disclosed by its librations, are influenced mainly by the distribution of mass in the outer zone in which the lithostatic pressure is less than 10 kb (i.e., in the outer shell not more than 200 km deep); and a conspicuous departure of such moments from those expected in hydrostatic equilibrium disclosed that these layers could never have been fluid. In the same way, the actual shape of the lunar surface cannot represent a solidified surface of a fluid, petrified at any distance from the Earth.The shape of the Moon, and differences of its moments of inertia must reflect the way in which the initial process of cold accretion fell short of producing a globe with strictly spherically-symmetrical stratification of material; and has nothing to do with tides - present or fossil. Such melting or lava flows as may have occurred at the Moon's surface from time to time must have remained localized, and without much effect on the dynamical properties of the Moon. A global ocean of molten magma some 200 km in depth (postulated sometimes to provide a reservoir in which the differentiation of elements exhibited by surface rocks could have taken place) at any time in the past is incompatible with the dynamical evidence on the motion of the Moon about its center of gravity.Bellcomm, Inc., 955 L'Enfant Plaza North, S.W. Washington, D.C. 20024, U.S.A.  相似文献