The Stability of Dust-driven winds from AGB stars

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Session 83 -- Circumstellar Gas and Dust
Display presentation, Wednesday, 11, 1995, 9:20am - 6:30pm

[83.06] The Stability of Dust-driven winds from AGB stars

N. Mastrodemos, M. Morris (UCLA)

We have numerically investigated the effects of dust in the detailed structure of winds from late-type pulsating variables. The coupling between dust and gas in the outflows from late-type giants has been shown to be unstable, in preliminary calculations that did not include the effects of finite pressure (Morris 1992). We have constructed time-dependent, two-fluid, dust-driven hydrodynamic wind models to investigate the effects of dust streaming in the presence of luminosity variations and density perturbations. A detailed thermal balance is accounted for by including dust-gas viscous heating and molecular cooling. On small scales, the wind appears inhomogeneous, with density shells that persist for many hundred stellar radii. However their growth is not rapid enough, compared to the expansion time of the envelope, to allow the development of instabilities. Resonances between the pulsation period and the growing modes give rise to larger structures that appear as standing waves. We are currently investigating the effects of multiple dust species, the degree of coupling to the gas and the resulting range of drift velocities. This research was supported by LLNL/IGPP and NSF grant AST 9218157 to UCLA.\\ \\ Morris, M. 1992, in ``Mass Loss on the AGB and Beyond'', ed: H.Schwarz\\ Goldreich, P., Scoville, N., 1976, ApJ, 205, 144\\ Justtanont, K., Skinner, C.J., Tielens, A.G.G.M., 1994, ApJ (submitted)\\

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