共查询到20条相似文献，搜索用时 31 毫秒
1.
T. Padmanabhan 《Astrophysics and Space Science》1982,83(1-2):247-268
The definition of particle states in various accelerated frames is considered. It is shown that in any realistically accelerated system, quantum field theory can be formulated without any ambiguity. We further show that the definition of a particle based on Green's function techniques does not always agree with the definition based on explicit quantization. We analyse the standard accelerated detector results from this point of view and show that the uncertainty principle imposes a rigorous bound on these detection processes. 相似文献
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A possible link between EPR‐type quantum phenomena and astrophysical objects like black holes, under a new general definition of entanglement, is established. A new approach, involving backward time evolution and topology changes, is presented bringing to a definition of the system black hole‐worm hole‐white hole as an entangled system. 相似文献
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Milan Burša 《Earth, Moon, and Planets》1993,62(2):139-144
The exact definition of the tidal potential is given on the basis of the theory of the restricted three-body problem. There are no limitations as regards the perturbing terms in the gravitational fields of the tide forming bodies; andno a priori conditions are needed in the definition. 相似文献
5.
We propose a new formal definition of discovery for a Solar System object. It is based on an objective and mathematically
rigorous algorithm to assess when a set of observations is enough to constitute a discovery. When this definition is satisfied,
in almost all cases the orbit is defined well enough to establish the nature of the object discovered (Main Belt vs. Near
Earth Asteroid, Trans-Neptunian vs. long period comet). The frequency of occurrence of exceptions is estimated by a set of
numerical experiments.
The availability of a non-subjective definition of discovery allows some rules to be adopted for the assignment of discovery
credit with a minimum risk of dispute. Such rules should be fair, encourage good practice by the observers and acknowledge
the contribution of the orbit computers providing the identifications and the orbits, as well as the one of all the contributing
observers. 相似文献
6.
Priscilla A. Sousa Silva Maisa O. Terra 《Celestial Mechanics and Dynamical Astronomy》2012,113(4):453-478
This paper is devoted to verify the consistency of the algorithmic Weak Stability Boundary definition concerning the achievement of capture-escape detection, through examining the transitions produced by the implementation of this definition. Our main goal is to show that many types of spurious transitions concerning capture-escape behavior are found besides the expected transitions due to the separatrix role of the hyperbolic invariant manifolds of the central manifold of the collinear equilibria of the Planar Circular Restricted Three-Body Problem. We identify and characterize authentic and spurious transitions and discuss their spatial distribution along the boundary for sets of initial conditions with high eccentricity, showing the frequent occurrence of spurious transitions and of collisional trajectories. Also, we investigate smooth and fractal-like portions of the boundary. Finally, we propose an alternative stability boundary definition based on the effective detection of capture-escape transitions. 相似文献
7.
L. Achmad 《Solar physics》1992,138(2):411-414
A simple and reliable method has been established for the definition of the depth of formation of lines in a stellar atmosphere. It is based on the determination of the level of emission of the reemitted line radiation. The new definition, which is applied in this paper to the solar case, does not suffer from the ambiguities of previously derived expressions. We apply this method to two artificial weak Oxygen I lines as examples.on leave from Department of Astronomy, ITB, Ganesha 10, Bandung 40132, Indonesia 相似文献
8.
Remote sensing techniques and data may be subdivided into three principal types according to how they are used: (1) defining techniques help to define unit boundaries and extent; (2) characterizing techniques allow classification and characterization of physical features, lithology, or chemical composition; (3) supporting techniques provide additional useful information but are not fundamental to the definition or characterization of units. Defined units represent a fundamental subdivision of the rocks in a planetary crust and thus represent processes and sequences of events. The definition and characterization of units provides a framework for the interpretation of planetary processes and history. Detailed consideration of unit definition and characterization is presented using the mare deposits of the Imbrium basin as an example. This example provides guidelines for the utilization of remote sensing techniques in geologic mapping of the Moon and other planets. 相似文献
9.
On the Collision Nature of Two Coronal Mass Ejections: A Review 总被引：1，自引：0，他引：1
Observational and numerical studies have shown that the kinematic characteristics of two or more coronal mass ejections (CMEs) may change significantly after a CME collision. The collision of CMEs can have a different nature, i.e. inelastic, elastic, and superelastic processes, depending on their initial kinematic characteristics. In this article, we first review the existing definitions of collision types including Newton’s classical definition, the energy definition, Poisson’s definition, and Stronge’s definition, of which the first two were used in the studies of CME–CME collisions. Then, we review the recent research progresses on the nature of CME–CME collisions with the focus on which CME kinematic properties affect the collision nature. It is shown that observational analysis and numerical simulations can both yield an inelastic, perfectly inelastic, merging-like collision, or a high possibility of a superelastic collision. Meanwhile, previous studies based on a 3D collision picture suggested that a low approaching speed of two CMEs is favorable for a superelastic nature. Since CMEs are an expanding magnetized plasma structure, the CME collision process is quite complex, and we discuss this complexity. Moreover, the models used in both observational and numerical studies contain many limitations. All of the previous studies on collisions have not shown the separation of two colliding CMEs after a collision. Therefore the collision between CMEs cannot be considered as an ideal process in the context of a classical Newtonian definition. In addition, many factors are not considered in either observational analysis or numerical studies, e.g. CME-driven shocks and magnetic reconnections. Owing to the complexity of the CME collision process, a more detailed and in-depth observational analysis and simulation work are needed to fully understand the CME collision process. 相似文献
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VLBI标准接口是近年来在VLBI技术中诞生的一个新概念,它旨在解决多年来各VLBI数据传输系统不兼容的问题．该文阐述了VLBI数据传输系统的发展历史,包括传统的记录／回放系统和新兴的网络数据传输两方面的内容;说明了VLBI标准接口的作用和意义;并分别介绍了VLBI标准接口规范3方面的内容:VLBI标准接口件规范(VSI-H)、VLBI标准接口软件规范(VSI-S)和VLBI标准接口网络规范(VSI-E)． 相似文献
11.
D.‐E. Liebscher 《Astronomische Nachrichten》2007,328(6):586-587
The problem of interpretation of recession velocities reflects straightforwardly the curvature of space‐time. In a recent article it was claimed that this problem would show that the General Relativity Theory had to and would overrule the Special Relativity Theory (Davis & Lineweaver 2003; Lineweaver & Davis 2005). This must be corrected. It is shown that the simplistic definition of the recession velocity as change in distance on a space of constant cosmological time yields in fact a pseudo‐euclidean angle and that the simplest correct definition of the recession velocity fits perfectly with the SRT formula for the Doppler effect. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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P. Hagedorn 《Celestial Mechanics and Dynamical Astronomy》1975,11(1):59-73
The problem of the motion of a string attached to a satellite on a circular orbit, as treated by Singh and Demin, is reconsidered. In their paper they discuss problems of uniqueness and stability. In particular the radial equilibrium positions were found to be unstable in a certain sense. In the present paper it is shown that: (i) with the stability definition used by Singh and Demin the equilibrium of a string hanging in a uniform gravity field would also be unstable; (ii) a definition of stability more appropriate for continuous systems would establish the stability of the string both in orbit and in a uniform gravity field.The results reported in this note were obtained during a stay at Stanford University sponsored by the Volkswagen Foundation, Hannover, Germany. 相似文献
14.
L. K. Kristensen 《Astronomische Nachrichten》1987,308(2):135-138
The problem of a sharp definition of two photometric parameters for asteroids in the presence of empirical phase functions is discussed. In a rational magnitude system advantage should be taken of the nearly linear phase curve. 相似文献
15.
We have defined a new Hβ absorption index definition, Hβo , which has been optimized as an age indicator for old and intermediate age stellar populations. Rather than using stellar spectra, we employed for this purpose a library of stellar population spectral energy distributions of different ages and metallicities at moderately high resolution. Hβo provides us with improved abilities for lifting the age–metallicity degeneracy affecting the standard Hβ Lick index definition. The new index, which has also been optimized against photon noise and velocity dispersion, is fully characterized with wavelength shift, spectrum shape, dust extinction and [α/Fe] abundance ratio effects. Hβo requires spectra of similar qualities as those commonly used for measuring the standard Hβ Lick index definition. Aiming at illustrating the use and capabilities of Hβo as an age indicator we apply it to Milky Way globular clusters and to a well selected sample of early-type galaxies covering a wide range in mass. The results shown here are particularly useful for applying this index and understand the involved uncertainties. 相似文献
16.
Mitsugu Makita 《Solar physics》1977,51(1):43-49
The contribution function method used so far to define the effective depth for the formation of absorption lines is discussed and a new definition of the effective depth is proposed. The effective depth is the level where a thin slab having the equivalent optical thickness to the total line absorption is placed so as to give the observed line intensity. 相似文献
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Jacques Henrard 《Celestial Mechanics and Dynamical Astronomy》1979,19(4):337-355
A new solution for the Main Problem on Lunar Theory is given. This solution maintains the advantages of an analytical solution and should be more accurate than previous analytical or numerical solutions. It contains the effects of the mass ratios which are often neglected in the definition of the Main Problem. 相似文献
19.
Horst R. Beyer Kostas D. Kokkotas 《Monthly notices of the Royal Astronomical Society》1999,308(3):745-750
We present a mathematically rigorous proof that the r-mode spectrum of relativistic stars to the rotational lowest order has a continuous part. A rigorous definition of this spectrum is given in terms of the spectrum of a continuous linear operator. This study verifies earlier results by Kojima concerning the nature of the r-mode spectrum. 相似文献
20.
Gamal G. L. Nashed 《Astrophysics and Space Science》2010,330(2):367-372
We apply the energy-momentum tensor which is coordinate independent, of the gravitational field established in the Hamiltonian structure of the teleparallel equivalent of general relativity (TEGR), to an axially symmetric tetrad field to calculate energy, momentum and angular momentum. Also the definition of the gravitational energy is used to investigate the energy within the external event horizon of this tetrad. 相似文献