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991.
María Lina Berríos-Salas Margarita Guzmán-Vega José Fernández-Labra Manlio Maldini-Sánchez 《Astrophysics and Space Science》1989,162(2):205-209
This work presents the light curves for rotating spotted stars generated by a computational code developed by us. This code is based in a model of the system and its analytical solution. The work also present an analysis of the photometric curve variations with the changes in the model's parameters.As a first result we have simulated a temporal evolution of the light curve when the photospheric spot varies its size and position and we reproduced some observational light curves of the II Peg star.Work supported by Dirección de Investigación, Universidad de La Serena, Chile. 相似文献
992.
J. Sánchez Almeida 《Solar physics》1992,137(1):1-14
Two formal solutions of the radiative transfer equation for polarized light have been proposed. One uses the Stokes parameters to describe the polarization, while the other uses the coherency matrix. It is shown in the present work that they are equivalent. Both can be used to compute response and contribution functions for the Stokes parameters and both require the solution of systems of differential equations with similar numbers of independent variables. New equations to solve the radiative transfer problem using the Stokes parameters formalism are presented. In addition, a computer code which synthesizes the Stokes profiles by means of these equations is described.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
993.
Bálint Érdi 《Celestial Mechanics and Dynamical Astronomy》1982,28(1-2):209-218
Szebehely's equation for the potential generating a prescribed family of orbits in two dimensions is generalized for three-dimensional orbits. A simultaneous system of first-order linear partial differential equations is derived for the determination of the potential in the three-dimensional case. Solutions of this system are found in several cases including Kepler's problem too.Paper presented at the 1981 Oberwolfach Conference on Mathematical Methods in Celestial Mechanics.This paper is dedicated to Professor Victor Szebehely on the occasion of his 60th birthday. 相似文献
994.
995.
M. Dolores García-Ramn Margarida Castaer Núria Centelles 《The Professional geographer》1988,40(3):307-315
An analysis of the presence of women geographers in Spanish universities indicates that women lecturers are a minority, especially in the top posts. The written contributions of women geographers in geographical journals published by geography departments, and in unpublished M.A. theses and doctoral dissertations are proportionally fewer than the corresponding percentage of staff members. 相似文献
996.
Repeat Ground Track Orbits of the Earth Tesseral Problem as Bifurcations of the Equatorial Family of Periodic Orbits 总被引:1,自引:0,他引:1
Martín Lara 《Celestial Mechanics and Dynamical Astronomy》2003,86(2):143-162
Orbits repeating their ground track on the surface of the earth are found to be members of periodic-orbit families (in a synodic frame) of the tesseral problem of the Earth artificial satellite. Families of repeat ground track orbits appear as vertical bifurcations of the equatorial family of periodic orbits, and they evolve from retrograde to direct motion throughout the 180 degrees of inclination. These bifurcations are always close to the resonances of the Earth's rotation rate and the mean motion of the orbiter. 相似文献
997.
For 181 PCA's recorded during the years 1956–1969 the association with flares is studied. Both the number of events which
cannot be associated with any flare on the visible hemisphere, as well as the longitude distribution of identified proton
flares, lead to the conclusion that 25–30% of PCA's are caused by flares behind the western solar limb. PCA's of this kind
are mostly small. During the investigated years no PCA > 13 dB and possibly no PCA > 8.5 dB were caused by flares behind the
limb, while hardly 60% of PCA's < l dB had their origin on the visible hemisphere.
While the sources of GLE's and of PCA's in general, are centered around 50°W which corresponds to the average curvature of
the magnetic field lines in interplanetary space, the strongest PCA's (> 8.5 dB) show an anomalous longitude distribution
centered around ∼ 20°W. It is suggested that this anomaly may be a consequence of the fact that in strong PCA events the kinetic
energy density of protons below 100 MeV becomes comparable to the magnetic energy density in space, thus leading to a ‘straightening’
of the magnetic field lines. 相似文献
998.
This study is part of an investigation of the possibility of using chemically peculiar (CP) stars to map local galactic structure.
Correct luminosities of these stars are therefore crucial. CP stars are generally regarded as main-sequence or near-main-sequence
objects. However, some CP stars have been classified as giants.
A selection of stars, classified in literature as CP giants, are compared to normal stars in the same effective temperature
interval and to ordinary ‘non giant’ CP stars. We find no clear confirmation of a higher luminosity for ‘CP giants’, than
for CP stars in general. In addition, CP characteristics seem to be individual properties not repeated in a component star
or other cluster members. 相似文献
999.
Pavel Voráček 《Astrophysics and Space Science》1989,155(2):341-343
An idea is put forward that the events considered in the non-locality phenomenon are co-local and simultaneous in the reference frame of information moving with the velocity of light. Then, the special relativity can explain many aspects of the issue. Furthermore, the impact of the idea is discussed in relation to problems of the Mach principle and those of the Planck era connected to the closeness or openess of our Universe. 相似文献
1000.
Described here is a preliminary and tentative application of a method for fine-classification of stars, selected for studies
of galactic structure. The present investigation is based on about 100 stars within the approximate spectral type range B6-A5,
for which both spectra andUBV photometry have been obtained.
The motivation of the project is the following: For the study of galactic fine-structure it is essential to use as many members
as possible of stellar agglomerations of various type for a statistical treatment of the material. A-type stars are fairly
numerous and reasonably bright, but if all chemically peculiar stars, fast rotators or multiple systems have to be omitted
there is generally too little left for a relevant investigation. Here we perform some experiments in order to find a method
for fine-classification of A stars, both normal and chemically peculiar, within the framework of the M K system.
In this connection it is desirable to reduce the present multitude of CP classifications to a manageable number. It is shown
here that, independenttly of the definition of the degree of peculiarity, there is no sharp borderline separating the CP stars
from the ‘normal’ ones.
Also it is found that spectral classification can on an average be performed with almost the same accuracy for CP stars as
for the ‘normal’ ones provided cases of extreme peculiarity are avoided.
Based on observations collected at European Southern Observatory, La Silla, Chile. 相似文献