摘要:

AbstractWe consider a spherical‐smmetric perturbation in an initially homogeneous dust filled universe within the frame‐work of the Bondi‐Tolman solution. The decoupling of the perturbed region from the background evolution naturally leads to shell‐crossing in a certain outer environment, which describes energy relaxation. In the approximation of Newtonian gravity it can be analytically determined the behaviour of the outgoing front shell and different parameters of the shell‐crossing region. On the basis of the obtained results we give a possible explanation for the “large voids” in the observed galaxy

ISSN:0004-6337    

DOI:10.1002/asna.2113060602

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060604

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractThe data compiled for 34 very young massive compact infrared source (Becklin‐Neugebauer objects) in a separately published catalogue serve as the basis for an investigation of their general properties.First, the correlations of the strength of the ice and silicate bands at 3.1 μm and 10 μm, resp., with each other and with other parameters of the sources are investigated. In accordance with theoretical expectations the strengths of both bands are not well correlated with each other. The ratio τ10/τ3of their optical depths veries from 0.85 to 8 (and possibly up to 22). That implies for the number densities of the grains that (naked) silicate grains always are considerably more abundant than ice grains (grains with ice mantles). It follows from the discussion of the relationships between τ10, the temperature parameter of the sources, and their luminosity that relations between τ10and temperature and possibly between τ10and the luminosity exist.Stellar wind models for the ionized region around the embedded star are favoured after the analysis of the intensities of the hydrogen infrred emission lines and the radio continuum.The limited observational data do not yet allow a decision on a correlation between the silicate band depth and energy content and/or the velocity of the bipolar outflow detected in a number of sources.The BN objects are clearly more frequently associated with H2O masers than OH masers. The linear separations of the infrared peaks from the masers are compatible with models where the H2O masers are situated near the edges the gas‐dust shells of the

ISSN:0004-6337    

DOI:10.1002/asna.2113060605

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060606

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060607

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

摘要:

AbstractNew spectroscopic and photometric observations of the variable Ap star ET And carried out 1982 and 1983 confirm once again the existence of short‐time variations. For the radial velocity variations a period of 0.19771 days and for the light variations a period of 0.0989 days was found. Some spectrograms show a velocity progression of the Balmer lines. The gradient is of such a kind that the radial velocity values increase from the line Hγto H15. Different models for the interpreation of the velocity progression are discuss

ISSN:0004-6337    

DOI:10.1002/asna.2113060608

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060611

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060612

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060614

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.2113060616

出版商:WILEY‐VCH Verlag    

年代:1985

数据来源: WILEY