摘要:

AbstractImplications from the available information on the supernova SN 1987 A are discussed for the supernova models. We derive an upper bound of 10–25 eV for the neutrino rest mas

ISSN:0004-6337    

DOI:10.1002/asna.2113080602

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113080604

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe model of forced precession of a star gravitationally influenced by a companion is tested for a small group of stars having time‐scales of magnetic changes in the order of some years up to some decades. Results show that the observed secular periods cannot be reduced to a common time‐scale of regular precession. The main difficulty is the evident discrepancy between the oblateness of the stars required by the model and that attainable from rotational or magnetic flattening. Only the observed behaviour of the star 52 Her could be interpreted as a precessional mot

ISSN:0004-6337    

DOI:10.1002/asna.2113080605

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113080606

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe distribution of mass ratios for a sample of common proper motion (CPM) binaries is determined and compared with that of 798 visual binaries (VB's) studied earlier, in hopes of answering the question: Can the member stars of these systems have been drawn at random from the normal initial mass function for single stars? The observed distributions peak strongly towardq= 1·0 for both kinds of systems, but less strongly for the CPM's than for the VB's. Due allowance having been made for assorted observational selection effects, it seems quite probable that the CPM's represent the observed part of a population drawn at random from the normal IMF, while the VB's are much more difficult to interpret that way and could, perhaps, result from a formation mechanism that somewhat favors systems with roughly equal components

ISSN:0004-6337    

DOI:10.1002/asna.2113080607

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113080608

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe idea that the Titius‐Bode law reflects an unstable mode of a self‐gravitationl instability in very thin Keplerian disks makes a careful discussion of the Poisson equation especially necessary. Due to the planetary distances in the solar system (δr/r ⋍ 0·5) the well‐known short‐wave approximation is not appropriate for definite asertions. We will here use a simple series expansion of the relation between the radial and vertical wave numbers of the disturbances which is additionally valid for medium‐scale and non‐zonal modes. The numerical solution of the dispersion relation reveals an extra unstable branch for wave‐lengths of rings and spirals two orders of magnitudes larger than those already known. Though we are not yet able to consider modes long enough for application to the planetary system, we feel the existence of the medium‐wave instability (δr/r ⋍ 0·1) to be a serious challenge for a better

ISSN:0004-6337    

DOI:10.1002/asna.2113080609

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractIn the solar system satellite systems of Jupiter, Saturn and Uranus are typical ones. The distribution of the semi‐major axis of satellite orbits in each system may be expressed by an empirical formula corresponding to the Titius‐Bode law. We found that it can be written as an=B′ ·Bn, whereB′ andBare constants. Values ofB′ andBdepend on formation conditions of each system.Satellites should be formed in the gas‐satellitesimal disk around a planet and by aggregation of satellitesimals. The gas is the major component in the disk and its damping effect must play an important role in the process of aggregation of satellitesimals. It may be proved that radial small perturbation in the disk can cause the gravitational instability and the formation of gaseous rings with increased density, where satellitesimals can easy aggregat int

ISSN:0004-6337    

DOI:10.1002/asna.2113080610

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractThe point discussed is the importance of investigation of the systematic errors of Δδxand Δμxtypes and their effects on stellar positions as obtained from visual and photographic observationsGegenstand des Artikels ist die Untersuchung der systematischen Fehler Δδxund Δμxund ihrer Einflüsse auf die Sternpositionen, erhalten aus visuellen und photographischen Beoba

ISSN:0004-6337    

DOI:10.1002/asna.2113080611

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY

摘要:

AbstractTo overcome a possible magnitude equation the Tautenburg Schmidt plates of the Lohrmann programme were taken with a long 20‐minute exposure (System A) and a short 20‐second exposure (System C) displaced about 0·5 minute of arc in declination from the long exposure. The distance between the two images in dependence on the magnitude of a star and its position on the plate was analysed. The transformation of coordinates from system C to A can be performed by using first order polynomials. No higher order terms were found to be necessary. The coefficients of the polynomials can not be assumed as constant for all plates but must be computed from least squares solutions involving a sufficient number of stars on each plate. For three of four plates investigated significant orthogonal linear terms were dete

ISSN:0004-6337    

DOI:10.1002/asna.2113080612

出版商:WILEY‐VCH Verlag    

年代:1987

数据来源: WILEY