摘要:

AbstractThe possibility of the formation of polycyclic hydrocarbon molecules in the atmospheres of very cool stars and in the gases ejected by supernovae and Seyfert galaxies is analyzed. Donn has suggested that such molecules may be Platt particles. It is found out that these can only be originated in some of those sources if their original carbon abundance is very high in relation to the one usually attributed to our Galaxy.

ISSN:0004-6337    

DOI:10.1002/asna.19712930112

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe observed 10 μm emission is interpreted as due to Si‐O‐stretching vibrations of the SiO4‐tetrahedrons of circumstellar silicate

ISSN:0004-6337    

DOI:10.1002/asna.19712930113

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractFrom an examination of the catalogue of early‐type stars by Neckel it follows that O stars generally have a mean circumstellar extinctionAV = 0.89 ± 0.55 mag. On the basis of this result the consequences of the hypothesis are considered that all interstellar dust was formed in circumstellar regions in the process of star formation. If dust formation occurs in dense clouds with radii of about 0.1 pc in the neighbourhood of massive hot stars the observed relative abundances of Ca and Na in the interstellar gas can be explain

ISSN:0004-6337    

DOI:10.1002/asna.19712930114

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractObservational indications which point out that the formation of dust particles in the circumstellar space usually accompanies the formation of most stars are discussed. An analytic treatment of circumstellar crushing processes leading to dust grains is presented. A necessary and sufficient condition for the escape of dust grains produced in circumstellar space by fragmentation is given, and dynamical effects on the grains are estimated.

ISSN:0004-6337    

DOI:10.1002/asna.19712930115

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractThe dynamical behaviour of dust particles during cloud collisions is calculated. It is shown that particles with a reciprocal specific cross section ⪆ 5 ⋅ 10−5g ⋅ cm−2at the end of a collision and all subsequent processes are gathered in a thin sheet in the inner parts of the new‐built cloud. Particles with a smaller value of this quantity are distributed more or less uniformly among the gas of the cloud as before th

ISSN:0004-6337    

DOI:10.1002/asna.19712930116

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

摘要:

AbstractFrom a discussion of catalogues of reflection nebulae based on the Palomar Observatory Sky Survey it is shown that a genetic relation exists between the nebulae and the illuminating stars.

ISSN:0004-6337    

DOI:10.1002/asna.19712930117

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.19712930118

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY

ISSN:0004-6337    

DOI:10.1002/asna.19712930101

出版商:WILEY‐VCH Verlag    

年代:1971

数据来源: WILEY