Primeval Turbulence?

Some difficulties with the Primeval Turbulence picture for galaxy formation are considered. It is shown that the evolution of the matter turbulence one decoupled from the radiation depends very much on the assumed turbulence velocity. If the velocity is small the turbulence simply adds to the amplitude of the growing density perturbation mode, an effect almost indistinguishable from the equally ad hoc assumption of a somewhat larger initial density perturbation. If the turbulence velocity field were made large enough to provide the angular velocity of the Galaxy, or the nominal peculiar velocities of galaxies, the galaxies would have formed sooner than one would otherwise have speculated.Research supported in part by the National Science Foundation.     

The effects of diffuse solar radiation on the motion of an artificial satellite

Previous analyses of the orbits of spherical balloon satellites have attempted to satisfy residuals in observed perturbations in Keplerian elements, assumed to be caused by diffuse radiation pressure, by introducing small variations ins, the parameter representing the reflection characteristics of the satellite's surface. It is difficult to distinguish, however, between those perturbations caused by diffuse radiation and those caused by reflected radiation, as a result of the deformation of the assumed sphere. Following the derivation by Lucas of exact expressions for both incident and reflected radiation forces on a prolate spheroidal satellite, and the subsequent work of Aksnes pertaining to spherical satellites, the theory is extended to include the effects of diffuse radiation whilst at the same time qualifying the assumption that the radiation force acting along the Sun-satellite line can be taken as parallel to the Sun-Earth line.     

Reflection effect in close binaries. I. Distribution of radiation from a point source

The radiation field along an irradiated surface of a component in a binary system is calculated. The source of irradiation is assumed to be a point source. This is done primarily to understand easily how the incident radiation will get changed after it is being scattered by the atmosphere. It is noticed that the maximum radiation comes from intermediate points of the atmosphere, the reason being that here we have the combined radiation due to the star and incident radiation from the point source outside the star although both are diluted.     

Effect of continuum absorption on the polarization of resonance lines

Multiple resonance scattering of radiation in a spectrum line with absorption in the continuum is examined. It is assumed that the scattering atmosphere is semi-infinite and that there is no magnetic field or continuum emission at the frequencies of the spectrum line. The polarization characteristics of the emerging radiation are determined for unpolarized primary radiation sources distributed uniformly within an atmosphere in the case of a Voigt absorption profile. The calculations employ an iterative solution of the Ambartsumyan-Chandrasekhar matrix integral equation.     

Spherical mhd shock waves under the action of monochromatic radiation

Self-similar MHD shock waves have been studied under the action of monochromatic radiation into a non-uniform stellar atmosphere with a constant intensity on unit area. It has been assumed that the radiation flux moves through the gas. Variation of flow variables have heen shown in tables for two different cases.     

Polarized line formation by resonance scattering: Lorentz profile

Multiple resonance scattering of spectral line radiation is examined in atmospheres with uniformly distributed sources of unpolarized radiation. It is assumed that the profile of the absorption coefficient is lorentzian and that scattering involves complete frequency redistribution. The polarization characteristics of the emerging radiation are determined by iterative solution of a nonlinear Ambartsumyan-Chandrasekhar matrix integral equation. In particular, it is found that for pure scattering the maximum polarization at the limb of the disk is 5.421%. The polarization characteristics of the emerging radiation are compared for three different absorption profiles: Lorentz, Doppler, and rectangular (monochromatic radiation). __________ Translated from Astrofizika, Vol. 50, No. 2, pp. 199–217 (May 2007).     

A relaxation method for the computation of model stellar atmospheres

A general Monte Carlo relaxation method has been formulated for the computation of physically self-consistent model stellar atmospheres. The local physical state is obtained by solving simultaneously the equations of statistical equilibrium for the atomic and ionic level populations, the kinetic energy balance equation for the electron gas to obtain the electron temperature, and the equation of radiative transfer. Anisotropic Thomson scattering is included in the equation of transfer and radiation pressure effects are included in the hydrostatic equation. The constraints of hydrostatic and radiative equilibrium are enforced. Local thermodynamic equilibrium (L.T.E.) is assumed as a boundary condition deep in the atmosphere. Elsewhere in the atmosphere L.T.E. is not assumed.The statistical equilibrium equations are solved with no assumptions made concerning detailed balance for the bound-bound radiative processes. The source function is formulated in microscopic detail. All atomic processes contributing to the absorption and emission of radiation are included. The kinetic energy balance equation for the electron gas is formulated in detail. All atomic processes by which kinetic energy is gained and lost by the electron gas are included.The method has been applied to the computation of a model atmosphere for a pure hydrogen early-type star. An idealized model of the hydrogen atom with five bound levels and the continuum was adopted. The results of the trial calculation are discussed with reference to stability, accuracy, and convergence of the solution.Contribution No. 385 from the Kitt Peak National Observatory.Operated by the Association of Universities for Research in Astronomy, Inc., under contract with the National Science Foundation.     

Fluctuations of pulsar emission with sub-microsecond time-scales

A model of pulsar emission fluctuations down to sub-microsecond time-scales is presented. The model is consistent with the empirical amplitude modulated noise model. It is proposed that the time-scale of the shortest observed micropulses is determined by the coherence of single-particle curvature radiation.The National Radio Astronomy Observatory is operated by the Associated Universities, Inc., under contract with the National Science Foundation.     

Non-thermal primeval fireball?

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.     

Formation of spectral lines in a dynamically active stochastic and multicomponent atmosphere

This paper is devoted to a determination of the statistical mean quantities describing spectral line radiation of dynamically active stochastic and multicomponent atmospheres. The lines in LTE are considered so that the effects of multiple scattering can be neglected. Two types of problem are discussed. In the first it is assumed that the realization of one or another type of nonthermal motion depends on the type of structural element and in the other this type of dependence is absent, i.e., it is supposed that the assumed random values of the velocity are distributed according to a law that is common to all the components. Particular attention is paid to a determination of the relative mean square deviation of the intensity of the observed radiation. It appears that the distinctive feature of the relative mean square deviation of the radiation in a line formed in a dynamically active stochastic atmosphere is local “spikes” (maxima) in the wings of the line. The theoretical results in this paper are compared with spectral observations of quiescent solar prominences obtained in framework of the SOHO space mission. __________ Translated from Astrofizika, Vol. 50, No. 1, pp. 121–134 (February 2007).     

Gravitational radiation of a differentially rotating superfluid neutron star

The gravitational radiation of a neutron star with a weakly coupled superfluid component is considered. It is assumed that regions can exist in the star's core which rotate at substantially higher angular velocities than the observed angular velocities of pulsars. A star of this sort has a quadrupole moment on the order of the maximum value for the neutron star configurations that have been discussed, so it could be a powerful source of gravitational radiation for the planned Advanced LIGO detector. Translated from Astrofizika, Vol. 51, No. 4, pp. 647–652 (November 2008).     

Momentum and energy transfer between plasma,hydrogen, and radiation during the recombination era of the Universe

It is assumed that during the recombination era the Universe is a fluid consisting of plasma, neutral hydrogen, and radiation interacting via the processes of photo-recombination, photo-ionization, and Thomson scattering. The corresponding mass exchanges between plasma and hydrogen and both the momentum and energy transfer are calculated near the hydrodynamical equilibrium. A perturbation in the hydrodynamical quantities is introduced and the corresponding dynamical equations are obtained as well.     

On the Effect of Radiative Relaxation on the Flux of Mechanical-Wave Energy in the Solar Atmosphere

In estimating the flux of mechanical-wave energy in the solar photosphere from observations it is generally assumed that the energy is transported upwards at the group velocity. It is pointed out that because the associated fluctuations in temperature relax through exchange of radiation, meaning that there is some dissipation of wave energy, the energy velocity is not the group velocity. An expression for the energy velocity is deduced for the case of an underlying isothermal atmosphere. It seems likely that the energy velocity in the solar atmosphere is significantly lower than the group velocity except at high and very low frequencies.     

The photolysis of nitrous oxide in the far ultraviolet

The photolysis of nitrous oxide has been studied in a flow system using xenon resonance radiation at 1470 and 1295 Å and krypton resonance radiation at 1236 and 1165 Å. The average quantum yields with regard to decomposed nitrous oxide, nitrogen and higher oxides of nitrogen were found to be larger in the experiments using the longer wave lengths than in the experiments using the 1236 and 1165 Å radiation. The ratio of the quantum yield with respect to oxygen and nitrogen was found to be lower in the experiments with the resonance radiation of xenon than in the experiments with the resonance radiation of krypton.

From the data obtained, it can be assumed that at the xenon resonance radiation the initial absorption of a light quantum leads to the production of nitrogen molecules and oxygen atoms. At the shorter wave lengths, the initial absorption act probably proceeds in a dual manner. It is supposed that both the splitting of nitrous oxide into nitrogen molecules and oxygen atoms and into nitrogen atoms and nitric oxide occurs at this radiation.     

VLF input impedance of a loop antenna embedded in the magnetosphere

An analysis is made to calculate input impedance of a loop antenna for radiation of the VLF whistler mode in the magnetosphere. The magnetosphere is assumed to be represented by a cold, uniform and collisionless magnetoplasma medium. Assuming a uniform current distribution of a circular loop, oriented at an arbitrary angle with respect to the Earth's magnetic field line, several closed-form expressions for the loop impedance have been derived. It is found that the loop input reactance is in substantial agreement with the self-inductance of a loop in free space and that the radiation resistance for a small loop can be as large as ～10 ² Ω. It is also found that a second order quasi-static theory is quite valid for determining the input impedance for small loops radiating VLF whistlers in the magnetosphere.     

Theory of Accretion onto Neutron Stars

Hydrodynamically stationary, spherically symmetric accretion onto a neutron star is examined taking the reverse effect of radiation into account. It is assumed that the plasma flow is adiabatic and that radiation is generated in a thin surface layer of the neutron star, where incoming particles are slowed down. It is shown that for stationary accretion, neither a stop, nor a substantial slowing down of the accretion flux is possible for any physically allowed conditions far from the neutron star.     

Spin-down of millisecond pulsars owing to gravitational wave emission

The gravitational radiation from millisecond pulsars owing to glitches in their angular velocity is examined. It is assumed that the energy transferred from interior superfluid regions to the crust of a neutron star is converted into gravitational wave energy by damping oscillations of the matter in the star. The gravitational wave intensity and amplitude are calculated for fourteen millisecond pulsars. Gravitational radiation can explain the observed spin-down of millisecond pulsars and an estimate is given for the magnetic field at which the proposed mechanism predominates in the spin-down of these pulsars. __________ Translated from Astrofizika, Vol. 51, No. 3, pp. 479–486 (August 2008).     

Propagation of cylindrical shock waves under the action of monochromatic radiation

A model of cylindrical shock waves is investigated under the action of monochromatic radiation into non-uniform stellar interiors with a constant intensity on a unit area. We have assumed that the radiation flux moves through the gas.     

Simulation of atmospheric effects on the emergent radiation over a checkerboard type of terrain

To evalute the effect of the non-uniform surface on the radiation field, the upwelling radiation at the top of the atmosphere bounded by the checkerboard type of terrain is computed using the modified doubling method. The terrain is composed of the square Lambert surfaces with two different albedoes. The dimension of the each square is assumed to be 0.5–6 km. The radiance of the terrain is discussed with respect to the atmospheric effect. The observational site is located at altitude 30 km. The corresponding projected point on the ground is located at the center of a square. The solar and observational direction is located in the plane parallel to the checkerboard squares. The atmosphere is assumed to be homogeneous, which is composed of aerosol and molecules, where the model aerosol is of the oceanic or the water soluble types.Numerical simulation exhibits the extraordinary effect near the edge of each squares. The radiance of the terrain depends upon the difference of albedoes and size of squares. It increases with the increase of the dimension of the square. It decreases with the optical thickness. At large optical thickness, the variation of radiation with zenith direction depends upon the aerosol characteristics. It shows little dependence on the solar zenith angle if less than 20°.     

The effect of solar radiation pressure on the orbit of a cylindrical satellite

The effect of solar radiation pressure on the orbits of cylindrical satellites is considered. The cylinder is assumed to reflect radiation both specularly and diffusely. The resultant forces on a stationary cylindrical satellite are given. The evolution of the satellite's orbit is described for two particular modes of rotation. In both cases the satellites are assumed to be in circular Sun-synchronous orbits.