摘要:

Recent high resolution observations of powerful double radio sources have revealed both compact high brightness regions and extended low brightness regions, as well as complex polarization structure. This is consistent with the view that the sources have their energetic origins in the compact nuclei of galaxies and quasars and that energy must be supplied continuously during the source's active lifetime. Possible models involving either the formation of two antiparallel beams of hot plasma or the ejection of massive objects are discussed.

ISSN:0010-7514    

DOI:10.1080/05107517508228027

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

A spectral line emitted by an atom or molecule (throughout the article, spectral lines seen in emission ere described; however, the theory applies equally well to the absorption of radiation in plasmas) has a finite width and there are three distinct physical processes which contribute to this broadening. The energy levels between which the transition takes place have a natural width, which arises from the reaction of the radiation field on matter. This means that an atom has a finite time in any level before sponteneou decay takes place. Also the emitting atom may be moving in the line of sight, which produces an apparent change in the line frequency through the Doppler effect. Finally, broadening of the spectral line is caused by the interaction of the emitting atom with surrounding particles in the plasma. Thus a detailed analysis of line shapes can yield much information on the density, temperature and motion of plasmas, whether they are high density plasma created in the laboratory, or the lower density plasma of interest in astrophysics, such as the solar corona or the interstellar medium.

ISSN:0010-7514    

DOI:10.1080/05107517508228028

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

This article reviews the relevance of modern theories of polymerized matter based on structureless, flexible molecules to the understanding of basic experimental observations which are made on polymer solutions, rubbers, glasses and crystals. General phenomena such as the viscosities of polymer solutions and the origins of rubber elasticity are described satisfactorily by the theories. We await a suitable treatment of the glassy state. and the approach has only descriptive value when applied to crystalline polymer systems.

ISSN:0010-7514    

DOI:10.1080/05107517508228029

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

The theory of stellar evolution is reviewed in a simple fashion, with emphasis on topics for which some rethinking may be required. It is suggested that evolution of stars off the main sequence in the H-R diagram into the area occupied by the giants is caused, not by fuel exhaustion, but simply by instability following the ignition of thermonuclear energy release in the interior. The physics of a degenerate gas is discussed. It is pointed out that the equation of state remains the same as for a normal gas, but the pressure is exerted only by that fraction of the particles which occupy states withinkTof the Fermi level. Degeneracy of the electron gas causes a large reduction of opacity, leading to an increased rate of loss of energy. The higher luminosity is fist fed by gravitational potential energy released during a phase of rapid contraction. However, when the proton Fermi level reaches a certain threshold, thermonuclear processes take over. During intial contraction angular momentum is transferred from orbital motion to eddies. Two eddies, revolving about the centre of mass produce a binary star system. In the case when a number of eddies take up nearly all the orbital angular momentum further contraction into a single star occurs. Later this angular momentum appears to be transferred back into orbital motion of matter near the surface.

ISSN:0010-7514    

DOI:10.1080/05107517508228030

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

This article provides an introduction to the background theory required for the understanding of light scattering by solids and outlines experimental approaches. It is concerned primarily with the information which may be obtained about crystal excitations from inelastic light scattering. A general evaluation of the light scattering technique is presented and future prospects are discussed.

ISSN:0010-7514    

DOI:10.1080/05107517508228031

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

ISSN:0010-7514    

DOI:10.1080/05107517508228032

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor

摘要:

Electron Spin Resonance. By N. M. Atherton. (Ellis Horwood, 1973.) [Pp. 438.] £11.50. Scope: Treatise/textbook. Level: Specialist/postgraduate; undergraduate.

ISSN:0010-7514    

DOI:10.1080/05107517508228033

出版商:Taylor & Francis Group    

年代:1975

数据来源: Taylor