摘要:

AbstractThe spectroscopic measured redshifts of 863 clusters of galaxies have been compiled from literature.

ISSN:0004-6337    

DOI:10.1002/asna.2113070202

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113070203

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractWe have determined the positions of 65 compact extragalactic objects with magnitudes between 16mand 21m.7. The mean error of one position is about 0″.3 in α cos δ and in δ. Some hitherto unpublished redshifts are also li

ISSN:0004-6337    

DOI:10.1002/asna.2113070204

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe paper supplements an earlier one on the mean‐field approach to spherical kinematic dynamo models (Rädler1980a) by results of numerical investigations.A number of dynamo models working on the basis of the α2‐mechanism are considered. Cases of pure α2‐mechanism are studied, which includes only the simplest form of α‐effect and no other induction effect, as well as cases with several additional effects due to fluctuating or mean motions. By the pure α2‐mechanism axisymmetric and non‐axisymmetric fields, can be excited and maintained with nearly equal ease. Part of the additional induction effects, however, clearly favour axisymmetric fields, and others non‐axisymmetric fields. The non‐axisymmetric fields are waves which travel in azimuthal direction, eastward or westward, depending on the models.For special dynamo models the transition from α2to αω‐mechanism and properties of the latter are investigated. The results support the presumption that the αω‐mechanism is able to maintain only axisymmetric but never non‐axisymmetric fields. Conditions for the occurrence of non‐oscillatory or oscillatory fields are discussed, and again the influence of additional induction effects is studied.There are further presented a model with βω‐mechanism maintaining an axisymmetric non‐oscillatory field, and models with two kinds of δω‐mechanisms allowing axisymmetric non‐oscillatory and oscillatory fields.Some ideas concerning dynamo models for the Earth, the Sun and magnetic stars are discussed.It seems possible to construct dynamo models for the Earth, on the basis of the α2‐mechanism which explain not only the presence of a magnetic field with a strong dipole part but also the inclination of the dipole axis against the axis of rotation, the occurrence of higher multipoles and the westward drift of the non‐axisymmetric parts. Models with αω, βω or δω‐mechanism, which have to be considered in the case of a strong differential rotation inside the core, provide an explanation at first only of the axisymmetric parts of the field, and the non‐axisymmetric parts have then to be interpreted, for example, as MAC‐waves.As far as dynamo models for the Sun are concerned, in addition to the possibility of an αω‐mechanism also that of a βω or δω‐mechanism is discussed, which, however, does not look not very promising. In the models developed so far, which work with the αω‐mechanism, only a few of the induction effects of fluctuating motions have been included; it seems necessary to investigate also influences of other effects. The sectorial structure of the solar magnetic field can hardly be understood in terms of the traditional mean‐field concept.The magnetic stars possess fields which strongly deviate from symmetry with respect to the axis of rotation. The occurrence of such fields seems understandable only if there is no noticeable differential rotation. T

ISSN:0004-6337    

DOI:10.1002/asna.2113070205

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113070206

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractThe evolution of a large‐scale magnetic field is considered in the non‐linear dynamo situation in discs with α‐effect due to non‐mirrorsymmetric turbulence and with strong differential rotation. The maximal value of the field strength is estimated by using an idealized dependence of the α‐coefficient on the field strength. It is assumed that α is a positive constant if the field strength is below, and equal to zero if the field strength is above a certain critical value. On natural assumptions it can be concluded that the maximal value of the field strength exceeds that critical value by about one

ISSN:0004-6337    

DOI:10.1002/asna.2113070207

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractA very important property of very young and massive stars (BN objects) is their intensive mass loss. We describe the main methods to derive the mass loss rates. Available observations are used to characterize the ionized stellar winds and the CO flows. The results are confronted with theories describing the anisotropic mass loss.

ISSN:0004-6337    

DOI:10.1002/asna.2113070208

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113070210

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

摘要:

AbstractVon FIEDLERund SCHIMMING(1983) wurde bewiesen, daß die von TREDERvorgeschlagenen Gravitationsfeldgleichungen 4. Ordnung mit einer Linearkombination des Bachtensors und des Einsteintensors auf der linken Seite statische, zentralsymmetrische Lösungen besitzen, welche in einer Umgebung des Symmetriezentrums analytisch und nicht flach sind. Die zunrchst nur in einer kleinen Umgebung vonr= o gesicherten Existenz dieser Lösungen (rRadius) läßt sich nun mit Hilfe des abstrakten Satzes über inverse Funktionen auf Intervalle o ≦r≦ α mit beliebig groß vorgegebenemαausdehnen. Ferner wird gezeigt, daß die Schwarzschildmetriken in einem gewissen Sinn die einzigen umr= +∞ analytischen, asymptotisch flachen, statischen, zentralsymmetrischen Lösungen obiger

ISSN:0004-6337    

DOI:10.1002/asna.2113070211

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113070212

出版商:WILEY‐VCH Verlag    

年代:1986

数据来源: WILEY