共查询到20条相似文献，搜索用时 20 毫秒
1.
Reflection effect phenomenon is studied on the formation of spectral lines in a close binary system when primary component has an extended atmosphere and the secondary component is a point source. Irradiation effect is calculated using one dimensional rod model and self radiation is calculated using continuum radiative transfer equation in spherically symmetric atmosphere. The total radiation is the sum of the radiation of the individual components and the mutually reflected light. Line profiles are also computed along the line of sight observer at infinity for irradiation, self radiation and total radiation and compared in order to study the reflection effect on spectral lines. It is found that the radiation field varies on the primary component when angle of incidence changes from the secondary component. The contour maps show that the radiative interaction makes the outer surface of the primary star warm when its companion illuminates the radiation. The effect of reflection on spectral lines is studied and noticed that the flux in the lines increases at all frequency points and the cores of the lines received more flux than the wings and equivalent width changes accordingly. 相似文献
2.
A. G. Emslie 《Astrophysics and Space Science》1980,71(2):363-370
We examine the linear growth of density perturbations in homogeneous isotropic (Friedmann) model universes, including the effect of a decoupled radiation pressure field in the modelling. Amplification factors for density perturbations in all models are derived numerically, and it is shown that the effect of radiation pressure is to decelerate the growth of such condensations, thus requiring larger inhomogeneities to be produced at radiation decoupling in order to produce protogalaxies. 相似文献
3.
A method of computing the diffuse reflection and transmission radiation by an inhomogeneous, plane-parallel planetary atmosphere with internal emission source is discussed by use of the adding method. If the atmosphere is simulated by a number of homogeneous sub-layers, the radiation diffusely reflected or transmitted by the atmosphere can be expressed in terms of the reflection and transmission matrices of the radiation of sub-layers. The diffusely transmitted radiation due to the internal emission source can be also easily computed in the same manner. These equations for the emergent radiation are in a quite general form and are applicable to radiative transfer in the atmosphere in the region from ultraviolet to infrared radiation. With this method, the tiresome treatment due to the polarity effect of radiation is overcome. 相似文献
4.
For the evaluation of the effect of the nonuniform surface albedo to the emergent radiation from the atmosphere, the emergent radiation from the atmosphere bounded by the two-halves of the Lambert surface with different albedos is computed. The principal plane is assumed to be perpendicular to the boundary of surfaces. The atmosphere is assumed to be homogeneous, which is composed of aerosol, molecules, and absorbent gases. Their optical thicknesses are 0.25, 0.23, and 0.02, respectively. The model aerosol is of the oceanic and water soluble types.In the computational procedure, the emergent radiation is approximated by the contributions due to the multiple scattering in the atmosphere, directly attenuated radiation, and radiation due to single scattering in the atmosphere which is reflected by the Lambert surface (up to 4 interactive radiative modes between atmosphere and surface). For quantitative analysis, results are compared with those of the atmosphere-uniform surface model, where the multiple scattering is considered. The numerical simulation exhibits the extraordinary effect near the surface boundary of different albedos. The effect decreases exponentially with the distance from the boundary. It is a function of the observational position, difference of surface albedos, optical thickness and aerosol type.The upward radiance would simply be evaluated using the present scattering approximation method if the atmosphere is in clear condition. Whereas in hazy condition, the effect of multiple scattering in the atmosphere should be considered more precisely, since the upward radiance exhibit a strong dependence on observational nadir angles due to multiple scattering in the atmosphere. Furthermore, it depends on the optical characteristics of aerosols. 相似文献
5.
It is shown that an outgoing null radiation field in the outer space of a Kerr-Newman black hole is darkened by the rotation
of the black hole. This rotational darkening is calculated for a spheroid emitting null radiation normally to its surface,
yielding the von Zeipel-like effectthat the equatorial region is darkened more strongly than the polar regions.This effect
is not confined to the case of black holes but is also observable for relativistically rotating fluid spheroids such as atmospheres
of pulsars or neutron stars. Moreover, application to Hawking radiation suggests that the black hole cannot be viewed as a
classical black body but that the Hawking radiationis a global geometric effect.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
6.
V. V. Zheleznyakov 《Astrophysics and Space Science》1971,13(1):87-99
A model of pulsars is discussed in which formation of a polar diagram of the radiation is influenced by the motion of the source around a neutron star with a velocity close to that of light. For a power-law frequency-spectrum of the radiation and isotropy of the diagram in a system of coordinates rotating with the source, the width of the observed pulse is shown to be independent of frequency.The proposed explanation of the second period characteristics of type CP 1919 pulsars is based on the effect of relativistic motion of the radiation source. The positions are established (relative to the axis of rotation of the star) of the local sources of radiation in the optical and in the radio ranges for the pulsar NP 0532. It is shown how the polarization characteristics of the optical radiation of this pulsar may be connected with the effects of relativistic orbiting of the source of radiation about the star. 相似文献
7.
介绍了一种新的建立太阳辐射压摄动模型的方法,即Ｖｏｋｒｏｕｈｌｉｃｋｙ等人提出的方法。该方法以辐射转移方程为基本数学工具,并运用相应的物理概念,通过对太阳辐射场强和辐射流量的计算来求出太阳辐射压摄动。此方法既适用于卫星处于地球半影区内和地球阴影之外的情形,也适用于地球反照辐射压的计算。还介绍了该方法的一些计算结果,并简单评述了其不足之处。 相似文献
8.
E. Landi Degl'innocenti 《Solar physics》1983,85(1):3-31
A unifying theoretical approach is presented to derive from the general principles of Quantum Electrodynamics both the radiative transfer equations for polarized radiation and the statistical equilibrium equations for an atomic system interacting with a polarized radiation field. The radiation field is described by means of Stokes parameters while the atomic system is described in terms of its density-matrix operator. The non-diagonal terms of the density matrix are fully accounted for so that this formalism can be suitably employed to describe a wide variety of physical phenomena like resonance scattering, the Hanle effect and the Zeeman effect, either in optically thin or optically thick atmospheres, together with all the possible intermediate situations.The general formulae derived in the first sections of the paper are subsequently particularized introducing the dipole approximation in the relevant matrix elements describing the interaction between the atomic system and the radiation field. The final equations assume a quite compact expression by the introduction of suitable spherical tensors connected with the components of the polarization unit vectors associated with each direction of the radiation field. The general expressions and the main properties of these tensors are discussed in the Appendix. 相似文献
9.
Badam Singh Kushvah 《Astrophysics and Space Science》2008,315(1-4):231-241
The existence of equilibrium points and the effect of radiation pressure have been discussed numerically. The problem is generalized by considering bigger primary as a source of radiation and small primary as an oblate spheroid. We have also discussed the Poynting-Robertson (P-R) effect which is caused due to radiation pressure. It is found that the collinear points L 1,L 2,L 3 deviate from the axis joining the two primaries, while the triangular points L 4,L 5 are not symmetrical due to radiation pressure. We have seen that L 1,L 2,L 3 are linearly unstable while L 4,L 5 are conditionally stable in the sense of Lyapunov when P-R effect is not considered. We have found that the effect of radiation pressure reduces the linear stability zones while P-R effect induces an instability in the sense of Lyapunov. 相似文献
10.
In this work, we describe an analysis of the internal solar radiation fields in Saturn's atmosphere. The aim of this paper is to study how the solar radiation flux in optical wavelengths (0.25-1.0 μm) is attenuated, primarily by the effect of the aerosols located close to the tropopause level, retrieving also the corresponding solar heating rates. We use a doubling-adding method and previous results on the vertical cloud and haze structure of Saturn's atmosphere. Our study shows that the maximum penetration level (∼250 mbar) for these wavelengths is substantially higher than previously expected because of the huge optical thickness of the tropospheric haze described in all vertical cloud structure models. We compare our results with previous estimates and parameterizations for seasonal climate models and propose a new approach for future models, with an intense and concentrated heating rate close to the top level of the tropospheric haze. Given that our spectral range accounts for about the 70% of the total solar flux, and using previous estimates for the penetration levels of infrared radiation in Saturn's atmosphere, we conclude solar radiation effect is negligible at levels below 600 mbar. This result is fundamental for understanding the role of solar radiation in the general atmospheric circulation of Saturn. 相似文献
11.
This paper investigates the motion of a test particle around the triangular equilibrium points under the effects of radiation pressure of the second primary and its Poynting–Robertson (P–R) effect when the first primary is an oblate spheroid. It is seen that triangular points are influenced by the presence of these parameters: radiation pressure from the secondary and the incidental P–R effect and the oblateness of the first primary. The linear stability of the problem is studied and applied to the binary system RXJ 0450.1-5856, the triangular points are unstable due to positive roots in the Lyapunov sense when P–R effect is considered as against their conditional stability in the absence of P–R drag effect. 相似文献
12.
R. M. Nugayev 《Astrophysics and Space Science》1983,91(1):53-62
The results of various calculations of the Casimir effect and of the effect of particle creation by accelerated mirrors are applied to the case of a collapse-formed black hole, which in consequence produces black-body radiation. Its temperature coincides exactly with Hawking's result. The difference between the vacuum expectation values of the energy-momentum tensors of scalar and electromagnetic fields near the horizon is found. Further investigation of expanding spheres in flat-space-time should disclose where the radiation is being created and what happens near the horizon. 相似文献
13.
Hamid M. K. Al-Naimiy 《Astrophysics and Space Science》1978,53(1):3-11
The radiation of a charge rotating in a circle with the constant velocity (in the external magnetic field) in the isotropic plasma with random inhomogeneities of the electron density has been considered. A general expression is obtained for the radiation intensity at thenth harmonic, which is a generalization of the known Shott formula. In the ultra-relativistic case the conditions are clarified under which the inhomogeneity effect on the form of the spectrum of radiation from a particle is essential. An asymptotic formula is derived for the spectral intensity in the region of sufficiently low frequencies. The mechanism of transient radiation in this case is shown to prevail over the synchrotron one. 相似文献
14.
A detailed derivation of the effect of solar radiation pressure on the orbit of a body about a primary orbiting the Sun is
given. The result is a set of secular equations that can be used for long-term predictions of changes in the orbit. Solar
radiation pressure is modeled as a Fourier series in the body’s rotation state, where the coefficients are based on the shape
and radiation properties of the body as parameters. In this work, the assumption is made that the body is in a synchronous
orbit about the primary and rotates at a constant rate. This model is used to write explicit variational equations of the
energy, eccentricity vector, and angular momentum vector for an orbiting body. Given that the effect of the solar radiation
pressure and the orbit are periodic functions, they are readily averaged over an orbit. Furthermore, the equations can be
averaged again over the orbit of the primary about the Sun to give secular equations for long-term prediction. This methodology
is applied to both circular and elliptical orbits, and the full equations for secular changes to the orbit in both cases are
presented. These results can be applied to natural systems, such as the binary asteroid system 1999 KW4, to predict their
evolution due to the Binary YORP effect, or to artificial Earth orbiting, nadir-pointing satellites to enable more precise
models for their orbital evolution. 相似文献
15.
R. Fabbri 《Astrophysics and Space Science》1981,77(2):529-537
We analyse in detail the spectral shape of the Sunyaev-Zel'dovich effect in the cosmic background radiation, taking into account the relativistic corrections for a hot electron gas. We calculate the displacement of the zero-signal frequency, which is especially informative in a new method for measuring the millimetric temperature of the background radiation; we also present a simple analytical expression, to be used to fit the experimental data in spectral measurements of the effect in very hot cluster gases. 相似文献
16.
《New Astronomy》2013
We investigate the effect of mass on the radiation of a relativistically rotating neutron star. The method of Haxton and Ruffini is used to find the radiation flux from a relativistically rotating neutron star. By extending the idea of a point charge orbiting a black hole, a pulsar is modeled by simulating a relativistically rotating magnetic dipole embedded within a neutron star. The resulting equations retain the mass of the neutron star, thereby introducing effects of general relativity on the radiation from the dipole. We present exact solutions to the modeling equation as well as plots of energy spectra at different rotational velocities and inclination angles. We also present plots of total energy versus mass and two tables containing a comparison of energy ratios. These demonstrate that, for realistic neutron star masses, the high speed enhancement of the radiation is always more than compensated by the frame dragging effect, leading to a net reduction of radiation from the star. It is found that the inclusion of mass not only reduced the special relativistic enhancement, but negates it entirely as the mass of the neutron star approaches the mass limit. 相似文献
17.
D.J. Scheeres 《Icarus》2007,188(2):430-450
A detailed derivation is given of the effect of solar radiation on the rotational dynamics of asteroids, commonly called the YORP effect. The current derivation goes beyond previous discussions published in the literature and provides a comprehensive secular dynamical analysis of the effect of solar radiation torques acting on a uniformly rotating body, and the evolution of its rotation state over time. Our predicted model has the global radiation properties of the asteroid as explicit parameters, and hence can be specified independent of these parameters. The resulting secular equations for the rotation rate and rotation pole are characterized by three parameters of the body's shape and explicitly includes the effect of thermal inertia on the evolution of these rotation state parameters. With this detailed model, in conjunction with estimated asteroid shapes and poles, we compute the expected YORP torques and dynamic response of several asteroids and the change in rotation rate for specific shapes as a function of obliquity. Finally, we define a convenient dimensionless parameter that is only a function of the body geometry and that can be used to characterize the effects of YORP. 相似文献
18.
K. E. papadakis 《Celestial Mechanics and Dynamical Astronomy》1998,72(4):235-244
The nonlinear stability zones of the triangular Lagrangian points are determined numerically and the effect of radiation of primaries is considered, in addition to the known effect of mass distribution, using the photogravitational restricted threebody problem model. It is found that radiation also has a considerable effect reducing the stability zones. In cases of resonances, these zones are reduced to negligible size for some parameter values within the linear stability regions. 相似文献
19.
The growth of weak MHD discontinuities have been studied in a radiation induced flow field at very high temperature. Growth and decay properties of weak MHD discontinuities have been discussed under the influences of time-dependent gasdynamic field, the radiation field and the magnetic field with finite electrical conductivity. The effects of thermal radiation and conduction of the global behaviour of weak MHD discontinuities have been studied under a quasi-equilibrium and quasi-isotropic hypothesis of the differential approximation to the radiative heat transfer equation. It is shown that the existence of the time-dependent radiation field gives rise to a radiation induced wave which has a negligibly small effect on the non-relativistic flow properties of the gasdynamic field. It is also shown that the radiation stresses resist the steepening tendency of a compressive weak wave and help in stabilizing it whereas the thermal conduction effects counteracts to destabilize it. It is found that under radiation effects the shock formation is either disallowed or delayed. The two cases of diverging waves and converging waves have been studied separately to answer a particular question as to when a shock discontinuity or a coustic will be formed or disallowed under curvature effects. 相似文献
20.
P. J. E. Peebles 《Astrophysics and Space Science》1971,10(2):280-290
The possible significance of a large cosmic sub-millimeter electromagnetic radiation background is considered. It is shown that in some scalar-tensor cosmological models such an effect could be primeval, that is, the result of processes occurring at an epoch earlier than we now can attempt to compute. The radiation background due to electron pair annihilation in a scalar-tensor model also is considered. It is shown that, while this effect could very substantially increase the far infrared background, it cannot make a spectrum that would be consistent with all the available tentative measurements.Research supported in part by the National Science Foundation. 相似文献