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Paper: Radiatively Driven Stellar Winds and Aspherical Mass Loss
Volume: 332, The Fate of the Most Massive Stars
Page: 169
Authors: Owocki, S.
Abstract: The high luminosity of massive stars can drive substantial mass loss, with significant consequences for their evolution and ultimate fate. A key general issue regards the relative importance of the cumulative loss in the comparitively moderate, line-driven stellar winds that persist through much of the star's evolution, versus briefer episodes of much stronger, continuum-driven mass loss associated with Luminous Blue Variable (LBV) phases, when the star may approach or exceed the Eddington limit. Building upon the standard CAK formalism for line-driven winds, the presentation here summarizes recent work on how the lateral structuring, or porosity, of a medium can moderate continuum driving, and lead to a much stronger mass loss that, as inferred for the giant eruption of eta Carina, approaches the "photon tiring" limit. A particular focus is the role of rapid (near-critical) stellar rotation in inducing an equatorial gravity darkening, with the associated polar brightening then driving both a higher polar mass flux and higher polar flow speed, a configuration that fits naturally with the inferred mass distribution and bipolar shape of the eta Carinae Homunculus nebula.
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