摘要:

AbstractThe mutual interaction between galactic dark halos and visible matter are explored by modelling a galaxy as two homogeneous, concentric and coaxial spheroidal subsystems, one completely lying within the other. The tensor virial theorem in its extended appropriate form is used and a general method outlined, then an application to the Galaxy is done. The values of equatorial semiaxis and axis ratio of the bright subsystem, and of the velocity components of both subsystems, deduced from a number of known observational data, are used in the computations as input parameters. Discussing the results, special effort has been devoted to the mutual sensitivity of halo and disk parameters which we understand in a twofold manner: 1) numerical interdependence between the present parameters of the visible Galaxy and the ones of dark matter, and 2) dependence of the bright component evolution on the characteristics of the dark halo, in which the former was embedded since the beginning. At present, due to the smallness of dark matter inside the bright disk, the halo‐disk interaction is so weak that few informations can be obtained; consequently, the solutions for dark masses and their axis ratios vary in a large range. Nevertheless, if one demands a spherical and isotropic halo, then from ad= 90 kpc a dark massMd= 1.5 · 1012M⊙ results in agreement with other independent estimations. Probably this was not the situation in the past when the disk was bigger and contained more dark mass. The dependence onMd/Mband εd/εbwas likely affecting the star formation rate and in this way contributing to the present morphology of the Galaxy and other ga

ISSN:0004-6337    

DOI:10.1002/asna.2113120202

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractBy allowing the equation of state for matter to be of a decompressive nature we study the effect on entropy generation in a ten‐dimensional cosmological model. We study the three cases when bulk viscosity is constant, depends on the energy density, and lastly, on the square of the curvatur

ISSN:0004-6337    

DOI:10.1002/asna.2113120203

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113120204

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractWe consider the Newtonian limit of the theory based on the Lagrangian\documentclass{article}\pagestyle{empty}\begin{document}$ \ell = (R + \sum\limits_{k = 0}^p {a_k R\square ^k R)\sqrt { - g.} } $\end{document}. The gravitational potential of a point mass turns out to be a combination of Newtonian and Yukawa terms. For sixth‐order gravity (p= 1) the coefficients are calculated explicitly. For generalpone gets\documentclass{article}\pagestyle{empty}\begin{document}$ \phi = m/r(1 + \sum\limits_{t = 0}^p {c_i } \exp (‐ r/l_i))\;with\;\sum\limits_{t = 0}^p {c_i} \; = \;1/3 $\end{document}. Therefore, the potential is always unbounded near. The origi

ISSN:0004-6337    

DOI:10.1002/asna.2113120205

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113120206

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractFor the variable binary AM Her, which is the proto‐type of a subgroup of cataclysmic stars, revised parameters of the system and its components are give

ISSN:0004-6337    

DOI:10.1002/asna.2113120207

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113120208

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractNew measurements of the effective magnetic field of the supergiantvCep confirm the earlier finding of the temporary presence of a magnetic field larger than 1000 Gauss. The observations were obtained using photographic and photoelectric methods. Searching for periods yields as the best representation of theBeffvalues (related to 3 cycles) the period 4.7 years.

ISSN:0004-6337    

DOI:10.1002/asna.2113120209

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113120210

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY

摘要:

AbstractStarting from an exact definition of the tangential point on Schmidt plates the three azimuthal projections used in Schmidt plate astrometry are compared and plate‐tilt effects, which differ from those on astrographic plates, are discussed. It is shown that the azimuthal equidistant projection should be used preferably in Schmidt plate reduction. Practical recommendations are given to minimize the number of significant terms in the reduction mode

ISSN:0004-6337    

DOI:10.1002/asna.2113120211

出版商:WILEY‐VCH Verlag    

年代:1991

数据来源: WILEY