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- Volume 80 - Année 2011
- A proper description of clumping in hot star winds: the key to obtaining reliable mass-loss rates?
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A proper description of clumping in hot star winds: the key to obtaining reliable mass-loss rates?
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Annexes
Abstract
Small-scale inhomogeneities, or ‘clumping’, in the winds of hot, massive stars are conventionally included in spectral analyses by assuming optically thin clumps. To reconcile investigations of different diagnostics using this microclumping technique, very low mass-loss rates must be invoked for O stars. Recently it has been suggested that by using the microclumping approximation one may actually drastically underestimate the mass-loss rates. Here we demonstrate this, present a new, improved description of clumpy winds, and show how corresponding models, in a combined UV and optical analysis, can alleviate discrepancies between previously derived rates and those predicted by the line-driven wind theory. Furthermore, we show that the structures obtained in time-dependent, radiation-hydrodynamic simulations of the intrinsic line-driven instability of such winds, which are the basis to our current understanding of clumping, in their present-day form seem unable to provide a fully self-consistent, simultaneous fit to both UV and optical lines. The reasons for this are discussed.
Pour citer cet article
A propos de : Jon O. Sundqvist
Universitätssternwarte München, Scheinerstr. 1, 81679 München, Germany
A propos de : Joachim Puls
Universitätssternwarte München, Scheinerstr. 1, 81679 München, Germany
A propos de : Achim Feldmeier
Institut für Physik und Astronomie, Karl-Liebknecht-Strasse 24/25, 14476 Potsdam-Golm, Germany
A propos de : Stanley P. Owocki
University of Delaware, Bartol Research Institute, Newark, DE 19716, USA