Book contents
- Frontmatter
- Contents
- Preface
- Conference Photograph
- Conference Participants
- Part one Stellar Evolution and Wind Theory
- Part two Wolf-Rayet Ring Nebulae
- Part three Supernovae
- Part four Asymptotic Giant Branch stars
- Mass loss from late type stars
- Kinematics and structure of circumstellar envelopes
- Circumstellar shells of Long–Period Variables
- Observation of circumstellar shells with the IRAM telescopes
- Part five Planetary Nebulae
- Part six Novae and Symbiotic Stars
- Poster Papers
- Author Index
- Object Index
Mass loss from late type stars
from Part four - Asymptotic Giant Branch stars
Published online by Cambridge University Press: 07 September 2010
- Frontmatter
- Contents
- Preface
- Conference Photograph
- Conference Participants
- Part one Stellar Evolution and Wind Theory
- Part two Wolf-Rayet Ring Nebulae
- Part three Supernovae
- Part four Asymptotic Giant Branch stars
- Mass loss from late type stars
- Kinematics and structure of circumstellar envelopes
- Circumstellar shells of Long–Period Variables
- Observation of circumstellar shells with the IRAM telescopes
- Part five Planetary Nebulae
- Part six Novae and Symbiotic Stars
- Poster Papers
- Author Index
- Object Index
Summary
Abstract
Physical processes involved in mass loss from late type stars are reviewed, including the formation of an extended atmosphere, chemical nucleation and growth of dust grains, and radiation pressure driven winds. Extensive numerical and analytical studies show that shock waves are a viable mechanism to lift material above the photosphere of AGB stars where radiation pressure on newly formed dust can drive a cool wind. Atmospheres of RGB stars are permeated by limited strength acoustic shock waves and the force associated with them drives an outflow once the radiative cooling timescale becomes long compared to the dynamical timescale. This leads in a rather natural way to Reimer's law. Non–radial pulsations are likely important for protoplanetary nebula formation. Stardust formation is a chemical process regulated by thermodynamic as well as kinetic effects. Detailed models for C-stardust formation, based upon the extensive chemical literature on sooting flames, suggest that nucleation takes place close to the stellar photosphere, while the main chemical growth occurs at much larger distances (≃ 2 – 3R•). Radiation pressure on dust coupled by friction to the gas determines the physical charateristics of AGB winds, but plays no role in RGB winds.
Introduction
Mass loss from late type stars is a ubiquitous phenomenon which has important ramifications for the further evolution of the star. Typically, the nuclear burning timescale of a giant is 10−7 M⊙/yr. For comparison, the mass loss rate on the Asymptotic Giant Branch (AGB) varies from 10−6 to a few times 10−4M⊙/yr.
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- Chapter
- Information
- Circumstellar Media in Late Stages of Stellar Evolution , pp. 232 - 245Publisher: Cambridge University PressPrint publication year: 1994
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