共查询到20条相似文献，搜索用时 15 毫秒
1.
Robert A. Greenkorn 《Solar physics》2012,280(1):205-221
A nonlinear analysis of the daily 10.7-cm radio flux values for each of Solar Cycles 19, 20, and 21 is used to determine if the results match those of the International Sunspot Numbers for each of these cycles. Fractals and chaos are described and a brief review of utilizing fractals and chaos is given. The origin of the 10.7-cm radio flux is discussed and a short review of recent work discussing its measurement and its relation to the international sunspot number and other proxies for solar activity cycles given. The parameters used to describe chaos for the 10.7-cm radio flux are discussed. The length of the data sets for either statistical analysis or nonlinear analysis of the 10.7-cm radio flux values is considered. These results indicate that the 10.7-cm radio flux values appear to be stochastic for Cycle 19 and chaotic for Cycles 20 and 21. The International Sunspot Numbers show similar behavior for these three cycles. A day-by-day comparison of the dimensionless 10.7-cm radio flux values and the dimensionless International Sunspot Numbers differences shows a linear trend. The results remain consistent in that the 10.7-cm radio flux values indicate, as did the International Sunspot Numbers, that there is a transition from stochastic behavior for Cycle 19 to chaotic behavior in Cycles 20 and 21. The day-by-day comparison of the 10.7-cm radio flux values and the International Sunspot Numbers emphasizes that the 10.7?cm radio flux values are responding to the magnetic field associated with the sunspots. 相似文献
2.
Radial integrals have been calculated under the one-electron hydrogenic model. Two different values of the effective charge parameter, one for the initial state and the other for the final state, are retained in these formulae. The model is able to reasonably reproduce the existing dipole oscillator strength values with little effort. The dipole oscillator strength values are given for many ions for the first time. 相似文献
3.
《Chinese Astronomy and Astrophysics》1984,8(1):54-62
The General Catalogue of Photoelectric Astrolabe Stars (GCPA) based on the Chinese photoelectric astrolabe system is described. It is a combined system of right ascension and declination synthesized from four primitive star catalogues' obtained with the photoelectric astrolabe. Four other primitive catalogues obtained with the Danjon astrolabe are reduced to the combined system and added to it. GCPA contains 1579 stars, 1541 Δα values and 1131 Δδ values. The overall average accuracy is ±3.3 ms in Δα, and ±0″.058 in Δδ; for the FK4 stars, the corresponding values are ±2.3 ms and ±0″.042. FK4 stars observed by two or more instruments gave 485 Δα values and 349 Δδ values, with external accuracies ±3.8 ms and ±0″.041. Corrections to the FK4 system as determined by GCPA are given and a comparison with the relevant catalogues is presented. 相似文献
4.
5.
P. S. Williams 《Astrophysics and Space Science》1988,143(2):349-358
Analytical solutions are constructed for the polytropen=1. An algorithm is devised to determine the numerical values of coefficients. These are compared with existing values determined from purely numerical schemes. The usefulness of the approach is discussed together with numerical strategies for this type of problem. 相似文献
6.
7.
The effect of rotation on unsteady free-convective started vertical plate is considered. It is assumed that the induced magnetic field is negligible compared to the applied magnetic field, which is fixed with the moving plate. Mathematical expressions for velocity and skin-friction are obtained by the Laplace transform technique. The profiles for velocity components are shown graphically with the effects of the rotation parameter, magnetic parameter and Grashof number. The numerical values of skin-friction components are given in tabalar form for different values of the parameters. 相似文献
8.
The Bethe approximation is used with measured and theoretical values of ionization cross sections and measured values of differential oscillator strengths to derive the initial energy spectrum of auroral secondary electrons. The differential flux of the auroral secondaries is then calculated, using the approximation of continuous energy loss. The calculations are applied to a particular aurora for which rocket data have been published. There is substantial disagreement between theoretical and measured electron spectra. The theoretical spectra show structure at energies less than 20 eV, associated primarily with vibrational and electronic excitation of molecular nitrogen. This structure is largely absent in the measured spectrum. Substantially more high energy electrons were measured than theory predicts. In addition, there are disagreements in the altitude profiles of the total number of non-thermal secondary electrons.
Calculated values of OI green line photon emission rates which result from excitation by secondary electrons and dissociative recombination of O2+ fall short of the measured values. The effect on the excitation rate of varying several parameters is investigated, and it is found that the results are particularly sensitive to competing inelastic processes in N2. 相似文献
9.
In this paper we review and interpret the values of upper-atmosphere rotation rate (zonal winds) obtained by analysing satellite orbits determined from observations. The history of the method is briefly reviewed, the basic principles are explained, objections to the method are answered, and three examples are given. Existing analyses of the atmospheric rotation rate A are critically reviewed, and, after rejecting some and revising others, we are left with 85 values. These are divided according to local time and season, to give the variation of A with height in nine situations—namely morning, evening and average local time, for summer, winter and average season. These observational results indicate that the value of Λ (in rev/day), averaged over both local time and season, increases from 1.0 at 125 km to 1.22 at 325 km and then decreases to 1.0 at 430 km and 0.82 at 600 km. The value of Λ is higher in the evening (18–24 h), with a maximum value (near 1.4) corresponding to a West-to-East wind of 150 m s?1 at heights near 300 km. The value of Λ is lower in the morning (06–12 h), with East-to-West winds of order 50 m s?1 at heights of 200–400 km. There is also a consistent seasonal variation, the values of Λ being on average 0.15 higher in winter and 0.1 lower in summer than the average seasonal value. No significant variation with solar activity is found, but there is a slight tendency for a greater rotation rate at lower latitudes for heights above 300 km. Unexpectedly, the values for the 1960s are found to be significantly higher than those for the 1970s. Finally, these observational values are compared with the theoretical global model of Fuller-Rowell and Rees: there is complete agreement on the trends, though there are some differences in the mean values. 相似文献
10.
Hong Zhang Cheng- Zhi ZhangDepartment of Astronomy Nanjing University Nanjing 《中国天文和天体物理学报》2004,4(5)
The relationship between the k2/Q of the Galilean satellites and the k2J/QJ of Jupiter is derived from energy and momentum considerations. Calculations suggest that the Galilean satellites can be divided into two classes according to their Q values: Io and Ganymede have values between 10 and 50, while Europa and Callisto have values ranging from 200 to 700. The tidal contributions of the Galilean satellites to Jupiter's rotation are estimated. The main deceleration of Jupiter, which is about 99.04% of the total, comes from Io. 相似文献
11.
The modification of Hill’s problem where the primary is radiating and the secondary is an oblate spheroid is considered. The evolution of the network of the basic families of planar periodic orbits for various values of the parameters of the problem is studied. For specific values of the parameters these families are determined accurately together with their stability properties. The stability of retrograde satellites in an appropriate space of initial conditions is also determined by means of surface of section portraits of the Poíncare map and higher order resonances are studied. Simple asymmetric periodic orbits of the problem are also determined. 相似文献
12.
Opacity limited fragmentation is considered for a spherically-collapsing isothermal molecular cloud in a low temperature range where molecular hydrogen and grains are the only cooling and opacity sources. The minimum Jeans mass of a fragment is calculated for different values of the parameters. The form of the initial mass function (IMF) is derived for low-mass protostellar fragments for different values of the parameters. They are discussed and compared with observations. A rough estimate of the cloud mass contained in the brown-dwarf regime is given. 相似文献
13.
The bulk chlorine concentrations and isotopic compositions of a suite of non‐carbonaceous (NC) and carbonaceous (CC) iron meteorites were measured using gas source mass spectrometry. The δ37Cl values of magmatic irons range from ?7.2 to 18.0‰ versus standard mean ocean chloride and are unrelated to their chlorine concentrations, which range from 0.3 to 161 ppm. Nonmagmatic IAB irons are comparatively Cl‐rich containing >161 ppm with δ37Cl values ranging from ?6.1 to ?3.2‰. The anomalously high and low δ37Cl values are inconsistent with a terrestrial source, and as Cl contents in magmatic irons are largely consistent with derivation from a chondrite‐like silicate complement, we suggest that Cl is indigenous to iron meteorites. Two NC irons, Cape York and Gibeon, have high cooling rates with anomalously high δ37Cl values of 13.4 and 18.0‰. We interpret these high isotopic compositions to result from Cl degassing during the disruption of their parent bodies, consistent with their low volatile contents (Ga, Ge, Ag). As no relevant mechanisms in iron meteorite parent bodies are expected to decrease δ37Cl values, whereas volatilization is known to increase δ37Cl values by the preferential loss of light isotopes, we interpret the low isotope values of <?5‰ and down to ?7.2‰ to most closely represent the primordial isotopic composition of Cl in the solar nebula. Similar conclusions have been derived from low δ37Cl values down to ?6, and ?3.8‰ measured in Martian and Vestan meteorites, respectively. These low δ37Cl values are in contrast to those of chondrites which average around 0‰ previously explained by the incorporation of isotopically heavy HCl clathrate into chondrite parent bodies. The poor retention of low δ37Cl values in many differentiated planetary materials suggest that extensive devolatilization occurred during planet formation, which can explain Earth's high δ37Cl value by the loss of approximately 60% of the initial Cl content. 相似文献
14.
Oxygen and nitrogen abundances for a selection of 113607 cold objects from the Sloan Digital Sky Survey (SDSS) spectra are
derived. Values of oxygen abundances 12 + log(O/H) are obtained using three parametric N calibrations, one of which is constructed
in this work. Values of nitrogen abundances 12 + log(N/H) are found with two N calibrations. The values of oxygen abundances
that are derived using three parametric N calibrations are consistent within 0.05 dex for the vast majority of the objects.
It is not improbable that there are systematic differences between the values of oxygen abundances which do not exceed 0.05
dex. The differences between the values of nitrogen abundances which are obtained using ON and NS calibrations reach 0.1 dex. We show that the vast majority of cold SDSS objects are in the same area of the diagram O/H—N/O
as cold H2 regions of nearby galaxies, for which the oxygen and nitrogen abundances are derived through the T
e
-method. This is indirect evidence that the values of oxygen and nitrogen abundances that are found with parametric N calibrations
are reliable. 相似文献
15.
V. A. Sarychev A. Guerman P. Paglione 《Celestial Mechanics and Dynamical Astronomy》2003,87(3):219-239
We consider the equilibria of a satellite in a circular orbit under the action of gravitational and constant torques. The number of equilibria depending on the parameters of the problem is found by the analysis of an algebraic equation of order 6. The domains with different numbers of equilibria are specified, and the equations of boundary curves are determined in function of values of the components of constant torque. Classification of different distributions of number of equilibria is made for arbitrary values of the parameters. 相似文献
16.
Andrej G. Sokolsky Akmal A. Vakhidov Nickolay N. Vasiliev 《Celestial Mechanics and Dynamical Astronomy》1995,63(3-4):357-374
The problem of computation of elliptic Hansen coefficients and their derivatives is considered for constructing a motion theory of an artificial Earth satellite with large eccentricity. An algorithm for analytical and numerical computation of these coefficients and their derivatives is described. The recurrence relations for derivatives of the first and second order and initial values for recurrences are obtained. As an example, numerical values of some elliptic Hansen coefficients are given for the orbit with eccentricityk=0.74. 相似文献
17.
A. Dinculescu 《Astrophysics and Space Science》2009,323(3):289-292
Based on the assumption that some apparent properties of the observable universe are accurate at a reasonable level of approximation, a tentative is made to independently derive the values of the baryon density parameter, the Hubble constant, the cosmic microwave background temperature and the helium mass fraction. The obtained values are in excellent agreement with those given by the most recent observational data. 相似文献
18.
W. M. Moslem 《Astrophysics and Space Science》2012,342(2):351-355
Properties of plasma expansion that propagates in an electron-positron-ion dense plasma are investigated. Suitable hydrodynamic equations for the ions and ultrarelativistic degenerate electrons and positrons are used. Using self-similar transformation, the basic set of nonlinear equations is solved numerically. Typical values of white dwarf stars are used to estimate the behavior of the ion number density and ion fluid velocity. The positive ions are found to initially slowly escape with high velocity when the ion-to-electron density ratio increases. For higher values of the electron number density, the self-similar solution validity domain decreases. The relevance of the results to white dwarf expansion and collapse is highlight. 相似文献
19.
G. Antonacopoulos 《Astrophysics and Space Science》1972,17(2):267-276
The secular terms of the planetary disturbing function are given, after elimination of short period terms by von Zeipel's
transformation.
The adequacy of this expansion up to terms of eighth order in the inclination and eccentricity is investigated by numerical
processes, as a function of the Keplerian elementsa, e andi. The eccentricityé of the outer planet, is taken equal to zero.
It is concluded that for values ofi which are not small the inclusion of additional terms in the expression for the disturbing function, results to drastic changes
in its values, while larger values ofe do not have an equaly large effect on the disturbing function. 相似文献
20.
The observation light curves of the main belt asteroid (469) Argentina, obtained on March 9–11 2002 and August 10–11 2004, are presented in this paper. The complex light curve of the (469) suggests that it may be in NPA rotation. Using the Fourier analysis method, some prominent spectrum values are derived individually for two subset data. Among these period values, periods of 13.00 and 8.74 h are regarded as basic components. Other derived period values can be combined linearly with these two basic period values. If the (469) is in a free-force precession mode, the motion mode will be LAM (largest-axis mode) according the ratio of precession and rotation periods. And the minimum of I
1/I
3 (ratio of the largest and smallest principal momentum of inertial) is 3.05. Assuming an external torque releasing by a satellite forces the (469) to precess, the mass of satellite roughly is the same order as the primary’s on condition that the precession and rotation periods are two basic values. At present, we cannot draw an unambiguous conclusion on (469)’s motion for sparse data, So the further observations are necessary for understanding the (469)’s tumbling motion farther. 相似文献