摘要:

AbstractWe discuss some properties of the initial data introduced in previous articles to study the past light cone initial value problem in cosmology. A parametrization of the conformal cone metric (the geometrical part of the initial data) is proposed which is closely related to astronomical observations of image distrotions of distant extragalactic objects. The quantities used here as initial data have simple transformation properties under a Lorentz rotation of the oberver.

ISSN:0004-6337    

DOI:10.1002/asna.2113060102

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractCan observational selection effects, tied with the existence of strong lines, explain the observed log (1 +z) periodicity of the quasar's histogram, as sometimes claimed? A first approach shows that one must distinguish radio from optical quasars. In the former case spectroscopic selection due to strong lines is investigated from the study of homogeneous samples. Then, the role played by pairs of strong lines in the redshift's determination is evaluated and it shows that teh spectroscopic selection cannot explain the observed periodicity of the radio quasar's histogram. The study of the complete sample confirms this conslusion.

ISSN:0004-6337    

DOI:10.1002/asna.2113060103

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060105

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractAssuming that the potential field on the plane of symmetry of a nearly axisymmetric galaxy is a polynomial of the fourth degree, we study the conditions of existence and stability of the main types of periodic orbits. We verify the theoretical results by numerical calculations.

ISSN:0004-6337    

DOI:10.1002/asna.2113060106

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractWe consider accretion onto a two–dimensional polytropic tube. In contrast to the standard papers we apply spatially uniform eddy viscosity (and eddy conductivity in part II resp.). In principle, the resulting rotation law is non–keplerian and proves to be rather flat. Wether the angular velocity increases or decreases inwadly depends on the strength of the torque exerted on the outer surface which is due to the inflow of angular momentum. Large (small) torque cause super–(sub–)rotation. The frictionally originated luminosity varies for various models. It lies one or two orders of magnitude below the total avialable accretion energy. For certain combinations of the Mach numbers the radial inflow profile possesses a soni

ISSN:0004-6337    

DOI:10.1002/asna.2113060107

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractIt is suggested that the effects of change in the celestial coordinates due to general precession be computed by solving numerically the differential equations for the instataneous rates of change in right ascension and declination. An approximate solution in closed from is given. Similar differential equations may be solved for the complete rotation matrix, requiring only the knowledge of the variations of the two functionmandnwith time. This suggests the existence of a relation between the classical precessional elementsz, ζ0and Θ, and this relation is derived. Some numerical examples are also presente

ISSN:0004-6337    

DOI:10.1002/asna.2113060108

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractA rotaing rigid body with elipsoidal cavity filled with magnetic fluid is considered as a pulsar model. Dynamical equations for the pulsar model are derived and investigated, certain integrable cases are indicated. Three–parameter sets of periodic solution integrable in terms of elliptic functions of the time variable are obtained. A formula is derived for the period of rotation and magneto–rotational oscillations of the pul

ISSN:0004-6337    

DOI:10.1002/asna.2113060109

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060112

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060113

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060101

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY