Book ChapterDOI
The Physical and Chemical Structure of Circumstellar Envelopes
Alain Omont
- Vol. 117, pp 269-289
TLDR
The physical and chemical structure of massive circumstellar envelopes is reviewed in relation with infrared and millimeter observations, with a particular emphasis on the carbon-rich shell IRC+ 10216 as mentioned in this paper.Abstract:
The physical and chemical structure of massive circumstellar envelopes is reviewed in relation with infrared and millimeter observations, with a particular emphasis on the carbon-rich shell IRC+ 10216. The spatial distribution of the physical parameters (temperature, density, velocity field, mass-loss, ionization, etc.) and their relations are discussed. The different chemical processes responsible for the observed molecular abundances are examined: freezing-out of chemical equilibrium, radical and ion reactions, grain processes, photochemistry, etc.read more
Citations
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Book ChapterDOI
The Mechanism of Mass Loss from Pulsating Cool Stars
TL;DR: In this article, numerical modeling results are described and discussed for the dynamical structure and behavior of the atmospheres of long-period variable stars, such as the Mira variables, and mass loss is shown to result from rather complex interactions between pulsationinduced shocks, which greatly extend the atmosphere; time-dependent thermal relaxation, which is an important determinant of the atmosphere's thermal structure; and radiation pressure on dust grains, which transfer momentum to the gas and ultimately drive most of the mass loss.
Book ChapterDOI
Chemistry in Expanding Circumstellar Envelopes
TL;DR: In this article, the chemistry occurring in the expanding envelopes around cool, late-type stars is investigated. And although many different chemical processes help determine the overall chemical composition of such envelopes, the detailed composition, as evidenced by the many molecules detected at radio wavelengths, is best explained by a complex ion-molecule chemistry driven by ionisation caused by the ambient external ultraviolet radiation field and by cosmic-rays.
Book ChapterDOI
Polycarbon and hydrocarbon ions and molecules in space
TL;DR: In this article, the growth of polycarbon and hydrocarbon ions and molecules possible in interstellar clouds and circumstellar envelopes is viewed in terms of results of laboratory gas-phase measurements for selected ion/molecule reactions.
Book ChapterDOI
Chemistry of Circumstellar Shells
TL;DR: In this article, the chemistry of expanding envelopes around cool, late-type stars is discussed, and the properties of these objects relevant for their chemistry and the observed molecular abundances.
References
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BookDOI
Cool stars, stellar systems and the Sun
Sallie L. Baliunas,Lee Hartmann +1 more
TL;DR: In this paper, the authors focus on cool stars, stellar systems and the Sun, with a particular attention paid to binary stars and star clusters, star evolution, and star models.
Journal ArticleDOI
Reactions of modulated molecular beams with pyrolytic graphite. III. Hydrogen
M. Balooch,D. R. Olander +1 more
TL;DR: In this article, the reaction of hydrogen and pyrolytic graphite was studied by modulated molecular beam-mass spectrometric methods, and the data were analyzed in terms of a model in which methane is formed by sequential addition of H atoms to CHn (n=0,1,2,3) and acetylene is formed from surface combination of two CH groups.
Journal ArticleDOI
OH-IR stars. I. Physical properties of circumstellar envelopes
Peter Goldreich,Nick Scoville +1 more
TL;DR: In this paper, a theoretical model of the circumstellar envelope which surrounds a OH-IR star is developed and the predicted values of the gas temperature, T, and the OH abundance, n_(OH), depend upon the rate of mass loss from the central star, Ф.
Journal ArticleDOI
Models for the structure and origin of bipolar nebulae
TL;DR: The appearance of bipolar nebulae can most simply be explained in terms of an axisymmetric distribution of outflowing dust in which the dust is concentrated towards an equatorial plane and declines monotonically with latitude above that plane as discussed by the authors.