EDP Sciences
Free access
Volume 404, Number 3, June IV 2003
Page(s) 789 - 807
Section Cosmology
DOI http://dx.doi.org/10.1051/0004-6361:20030515

A&A 404, 789-807 (2003)
DOI: 10.1051/0004-6361:20030515

Three-component modeling of C-rich AGB star winds

II. The effects of drift in long-period variables
C. Sandin and S. Höfner

Department of Astronomy and Space Physics, Uppsala University, Box 515, 751 20 Uppsala, Sweden
(Received 18 December 2002 / Accepted 1 April 2003 )

We present three-component wind models for carbon-rich pulsating AGB stars. In particular we study the effects of drift in models of long-period variables, meaning that the dust is allowed to move relative to the gas (drift models). In addition we investigate the importance of the degree of variability of the wind structures. The wind model contains separate conservation laws for each of the three components of gas, dust and the radiation field. We use two different representations for the gas opacity, resulting in models with different gas densities in the wind. The effects which we investigate here are important for the understanding of the wind mechanism and mass loss of AGB stars. This study is hereby a necessary step towards more reliable interpretations of observations. We find that the effects of drift generally are significant. They cannot be predicted from models calculated without drift. Moreover, the non-drift models showing the lowest mass loss rates, outflow velocities, and the smallest variability in the degree of condensation do not form drift model winds. The wind formation in drift models is, except for a few cases, generally less efficient and the mass loss consequently lower than in the corresponding non-drift models. The effects of drift are generally larger in the more realistic models using that representation of the gas opacity which results in lower densities. The outflow properties of these models are also - for all cases we have studied - sensitive to the period of the stellar pulsations. A check of the mass loss rates against a (recent) fit formula shows systematically lower values, in particular in the more realistic models with a low density. The fit is in its current form inapplicable to the new models presented here.

Key words: hydrodynamics -- radiative transfer -- stars: AGB and post-AGB -- stars: mass-loss -- stars: variables: general

Offprint request: C. Sandin, Christer.Sandin@astro.uu.se

© ESO 2003

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access.

An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

  • If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
  • You can define your own OpenURL resolver with your EDPS Account.
    In this case your choice will be given priority over that of your library.
  • You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.