Results 1 - 10 of 2511
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[en] The modification of the equipotential surfaces of a binary system is studied when the radiation pressure of both components must be taken into account. For suitable values of the radiation parameters, new forms of mass transfer or mass loss may arise
[fr]On etudie la modification des surfaces equipotentielles dans un systeme binaire, lorsqu'il faut tenir compte des forces exercees par le rayonnement de chacune des deux composantes supposees tres lumineuses. De nouvelles formes de transfert de masse (ou de perte de masse) sont suggerees
[en] This short article describes an experiment that could be performed in science class to show that the photons which are massless particles, can even exert a force. This force can induce a very small displacement of the object on which it exerts. The experimental bench by making 2 laser beams interfere with each other, turns this displacement into an interference pattern. (A.C.)
[en] The measurement is reported of the velocity distribution in an atomic beam by means of atomic beam deflection under resonant light pressure. Both theoretical analysis and experimental results are given
[en] Theoretical and experimental investigations into the action of laser radiation pressure on atoms are reviewed. The paper describes briefly the history of the problem, presents the foundations of the theory of light pressure, describes and analyzes experimental work and discusses possible applications of light pressure to various fields of physics. In presenting the theory of light pressure primary attention is centered on the analysis of atomic motion in travelling and standing light waves. When discussing the possible applications of ligth pressure particular emphasis is placed upon the ways of realizing such principal ideas as radiative cooling, trapping and storing of atoms in laser fields. (orig.)
[en] The pressure due to the radiation from the Sun and neighboring protostars may have forced the coagulation into comets of the dust grains in the collapsing layers of the protosun at r = (1-5) x 103 AU. The grains were forced together by their self-shielding, which results in the radiation pressure due to photons coming from the direction of strong concentrations of dust being less than the pressure due to photons coming from a direction having a low concentration of dust. This causes the dust to drift toward regions of already strong dust concentration. The formation of comets under these conditions is consistent with the low rotation period of new comets and their extremely volatile chemical constituents
[en] In this paper, we discuss the problem of determination of light radiation pressure force upon an anisotropic surface. The optical parameters of such a surface are considered to have major and minor axes, so the model is called an orthotropic model. We derive the equations for force components from emission, absorption, and reflection, utilizing a modified Maxwell’s specular-diffuse model. The proposed model can be used to model a flat solar sail with wrinkles. By performing Bayesian analysis for example of a wrinkled surface, we show that there are cases in which an orthotropic model of the optical parameters of a surface may be more accurate than an isotropic model.
[en] We present a modification of a model of solar cycle evolution of the solar Lyα line profile, along with a sensitivity study of interstellar neutral hydrogen to uncertainties in radiation pressure level. The line profile model, originally developed by Kowalska-Leszczynska et al., is parameterized by the composite solar Lyα flux, which recently was revised. We present modified parameters of the previously developed model of solar radiation pressure for neutral hydrogen and deuterium atoms in the heliosphere. The mathematical function used in the model, as well as the fitting procedure, remain unchanged. We show selected effects of the model modification on interstellar neutral H properties in the heliosphere, and we discuss the sensitivity of these quantities to uncertainties in the calibration of the composite Lyα series.
[en] Radiation pressure acting on gas and dust causes H II regions to have central densities that are lower than the density near the ionized boundary. H II regions in static equilibrium comprise a family of similarity solutions with three parameters: β, γ, and the product Q0 nrms; β characterizes the stellar spectrum, γ characterizes the dust/gas ratio, Q0 is the stellar ionizing output (photons/s), and nrms is the rms density within the ionized region. Adopting standard values for β and γ, varying Q0 nrms generates a one-parameter family of density profiles, ranging from nearly uniform density (small Q0 nrms) to shell-like (large Q0 nrms). When Q0 nrms ∼> 1052 cm-3 s-1, dusty H II regions have conspicuous central cavities, even if no stellar wind is present. For given β, γ, and Q0 nrms, a fourth quantity, which can be Q0, determines the overall size and density of the H II region. Examples of density and emissivity profiles are given. We show how quantities of interest-such as the peak-to-central emission measure ratio, the rms-to-mean density ratio, the edge-to-rms density ratio, and the fraction of the ionizing photons absorbed by the gas-depend on β, γ, and Q0 nrms. For dusty H II regions, compression of the gas and dust into an ionized shell results in a substantial increase in the fraction of the stellar photons that actually ionize H (relative to a uniform-density H II region with the same dust/gas ratio and density n = nrms). We discuss the extent to which radial drift of dust grains in H II regions can alter the dust-to-gas ratio. The applicability of these solutions to real H II regions is discussed.
[en] A possibility of exciting steady convective motions in isotropic and anisotropic liquids under the action of a force produced by the radiation pressure of an acoustic wave with a spatially periodic transverse intensity distribution is considered theoretically and experimentally. Cells both with two rigid boundaries and with one free surface are studied. The fluxes lead to reorientation of the director of liquid crystal in the case of anisotropic liquid. As a result, it acquires a periodic distribution in the transverse plane. The phenomenon can be utilized for the imaging of acoustic fields with micro watt power