Astronomy and Astrophysics – Astrophysics
Scientific paper
Nov 2008
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2008a%26a...491l...1h&link_type=abstract
Astronomy and Astrophysics, Volume 491, Issue 2, 2008, pp.L1-L4
Astronomy and Astrophysics
Astrophysics
38
Stars: Agb And Post-Agb, Stars: Mass-Loss, Stars: Atmospheres, Stars: Winds, Outflows, Circumstellar Matter, Dust, Extinction
Scientific paper
Context: In view of the recent problem regarding the dynamical modelling of winds of M-type AGB stars (insufficient radiation pressure on silicate grains), some of the basic assumptions of these models need to be re-evaluated critically. Aims: Accepting the conclusion that non-grey effects will force silicate grains to be virtually Fe-free, the viability of driving winds with micron-sized Fe-free silicates, instead of small particles, is examined. Methods: Using both simple estimates and detailed dynamical atmosphere and wind models, it is demonstrated that radiation pressure on Fe-free silicate grains is sufficient to drive outflows if the restriction to the small particle limit is relaxed, and prevailing thermodynamic conditions allow grains to grow to sizes in the micrometer range. Results: The predicted wind properties, such as mass loss rates and outflow velocities, are in good agreement with observations of M-type AGB stars. Due to a self-regulating feedback between dust condensation and wind acceleration, grain growth naturally comes to a halt at particle diameters of about 1~μm. Conclusions: The most efficient grain sizes to drive winds are in a rather narrow interval around 1~μm. These values are set by the wavelength range corresponding to the flux maximum in typical AGB stars, and are very similar to interstellar grains.
No associations
LandOfFree
Winds of M-type AGB stars driven by micron-sized grains does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Winds of M-type AGB stars driven by micron-sized grains, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Winds of M-type AGB stars driven by micron-sized grains will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1840462