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Solar System Research - Finding and studying possible collisions of asteroids approaching the Earth requires a significant amount of computation. This paper describes the R0 program created to... 相似文献
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P. Maltby 《Solar physics》1972,26(1):76-82
Observations of the penumbral intensity of sunspots in 13 wavelength regions are presented. In 4 wavelength regions 54 sunspots are measured. In the other wavelength regions the number of sunspots considered ranges from 3–19.The penumbral intensity alters with position within the spot. This intensity variation is found to be comparable with the change in intensity from one spot to another. The penumbral intensity is found to be independent of spot size in the sample considered.The penumbra model of Kjeldseth Moe and Maltby (1969) with = 0.055 is supported by the measurements. 相似文献
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Magnetars are the neutron stars with the highest magnetic fields up to 1015–1016 G. It has been proposed that they are also responsible for a variety of extra-galactic phenomena, ranging from giant flares in nearby galaxies to fast radio bursts. Utilizing a relativistic mean field model and a variable magnetic field configuration, we investigate the effects of strong magnetic fields on the equation of state and anisotropy of pressure of magnetars. It is found that the mass and radius of low-mass magnetars are weakly enhanced under the action of the strong magnetic field, and the anisotropy of pressure can be ignored. Unlike other previous investigations, the magnetic field is unable to violate the mass limit of the neutron stars. 相似文献
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Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF31, were discovered, librating about the L5 Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ7, to be a Trojan, associated with the L4 Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND43) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW15 and 2000 TG2, within the resonant region capable of undergoing what we designate “circulation transition”, in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion. 相似文献
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In the text-books of astronomy, sections generally related to the Moon deal with the orbital elements of the Earth-Moon system such asa, e, i, ,
and the time of perigee passage. While the MEAN of the first of the three elements do not vary, mean longitude of the ascending node-mean longitude of the lunar perigee and the time of perigee passage undergoes secular as well as periodic changes due predominantly to the action of the Sun's gravitational attraction. While to a certain degree, explanations related to the calculation of the lunar orbit parameters are given, not a single graphical representation of these short- or long-periodic changes are presented. We allow the number of data related to these periodic changes must cover a large span of time; and if regression of the line of nodes or advances of the line of apses are to be graphically seen, data covering 18.61 and 8.85 yr, respectively, are needed. In this work we particularly aim at the graphical representation of the periodic changes of the line of nodes. 相似文献
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R. A. Vardanian 《Astrophysics》1995,38(4):394-395
Published in Astrofizika, Vol. 38, No. 4, pp. 700–702, October–December, 1995. 相似文献
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《Chinese Astronomy and Astrophysics》1982,6(3):233-242
We solve by an appropriate method the difficulty of near-commensurability, , in the motion of Hyperion (Saturn VII) and give a first-order solution of its motion. Our result explains two interesting observed features, the regression of the apsidal line and the exclusive occurrence of apocentre C conjunction of SVII and SVI. 相似文献
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T. P. Kiseleva S. M. Chanturiya T. A. Vasil’eva O. A. Kalinichenko 《Solar System Research》2012,46(5):387-389
The sets of photographic observations of the Galilean satellites of Jupiter taken at the Abastumani Astrophysical Observatory of the Academy of Sciences of Georgia are analyzed here. Positional observations of the system of Jupiter were made in the period from 1985 to 1994 with the use of the double Zeiss astrograph in order to determine the exact coordinates of Jupiter and its satellites. The accurate positions of the satellites and Jupiter itself, as well as their stellar (equatorial) coordinates relative to the stars of the currently available catalogs and the relative ??satellite ?? satellite?? coordinates were obtained from the observations. From the comparison of the observation results with the modern theories of motion of satellites, the accuracy in determining the positions of the satellites and Jupiter was analyzed. The results of observations are presented in the Pulkovo database of observations of Solar System bodies that is accessible to users at http://www.puldb.ru. 相似文献
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A hypothesis is proposed for the mechanism of superrotation of the atmosphere of Venus involving the following processes. Winds near the planet's surface, making up part of the Hadley cell, flow past the surface relief and excite internal atmospheric gravity waves. While moving upward, these waves become unstable and collapse generating turbulent eddies. Some portion of the energy of these eddies is transferred to a two-dimensional flow, which is maintained also at the expense of instability of large-scale motions. In this flow, the inverse energy cascade (transition from smaller eddies to larger eddies), or negative viscosity, appears as a key element of this mechanism. Large-scale quasi-two-dimensional turbulent eddies transfer their energy to Rossby planetary waves which, in turn, transmit it to a zonal flow. Based on this hypothesis and the existing experimental data, the time period over which superrotation is established, as well as the vertical and horizontal eddy viscosity coefficients, is estimated. In parallel, arguments in favor of the proposed hypothesis are obtained. 相似文献
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M. A. Vashkov’yak 《Solar System Research》2016,50(6):390-401
The problem of the secular perturbations of the orbit of a test satellite with a negligible mass caused by the joint influence of the oblateness of the central planet and the attraction by its most massive (or main) satellites and the Sun is considered. In contrast to the previous studies of this problem, an analytical expression for the full averaged perturbing function has been derived for an arbitrary orbital inclination of the test satellite. A numerical method has been used to solve the evolution system at arbitrary values of the constant parameters and initial elements. The behavior of some set of orbits in the region of an approximately equal influence of the perturbing factors under consideration has been studied for the satellite system of Uranus on time scales of the order of tens of thousands of years. The key role of the Lidov–Kozai effect for a qualitative explanation of the absence of small bodies in nearly circular equatorial orbits with semimajor axes exceeding ~1.8 million km has been revealed. 相似文献
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The study of the motion of interstellar clouds by direct dynamical methods is hindered by the lack of a complete set of initial
conditions of the motion. The hypothesis of the circular motion of interstellar matter of various composition is tested on
the basis of the catalog of Brand and Blitz. A modification of the method proposed by Edmondson and Hoerner, which was successfully
used for a statistical investigation of the shapes of the orbits of globular clusters, is used. It is established that interstellar
clouds move in nearly circular orbits with small deviations, so that data on the spiral structure of the Galaxy obtained by
radio-astronomical methods should be considered as close to reality.
Translated from Astrofizika, Vol. 43, No. 2, pp. 239–246, April-June, 2000. 相似文献
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Time scales of the transition from contact binary systems of the W UMa type to single stars of the blue straggler type are estimated. A model of one-way mass transfer from the primary component to the companion inside a common envelope (Eggen et al.) and a model of a contact binary lying on the zero-age main sequence with a companion that is losing mass (F. van't Veer) are used to calculate these scales. The merging times of components were calculated for 304 contact systems of the W UMa type from the Catalog of Approximate Photometric and Absolute Elements of Eclipsing Variable Stars on a scale of loss of mass and orbital angular momentum due to magnetic braking, under the assumption of synchronization of the axial rotation and orbital revolution. On the basis of the resulting statistics, the characteristic merging scales are 0.4-0.6 and 0.5-0.7 Gyr, respectively, for the above two models. The results of a comparison with the work of other authors are discussed. 相似文献
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