Abstract
Among warm giant stars, rapid mass loss sets in along a well-defined velocity dividing line (VDL) in the HR diagram. Hot coronae also disappear close to the VDL: hence, thermal pressure cannot drive the observed rapid mass loss in these stars. The VDL may be associated with magnetic fields changing from closed to open. Such a change was predicted (Mullan, 1978), and is consistent with the lack of X-rays from late-type giants. To refine this prediction, we derive a magnetic transition locus (MTL) based on Pneuman’s (1968) work on helmet streamer stability. The MTL agrees well with the empirical VDL. We propose that the change from closed to open fields not only makes rapid mass loss possible, but also contributes to energizing the mass loss in the form of discrete “bubbles”.
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© 1981 D. Reidel Publishing Company
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Mullan, D.J. (1981). Mass Loss from Warm Giants: Magnetic Effects. In: Iben, I., Renzini, A. (eds) Physical Processes in Red Giants. Astrophysics and Space Science Library, vol 88. Springer, Dordrecht. https://doi.org/10.1007/978-94-009-8492-9_39
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DOI: https://doi.org/10.1007/978-94-009-8492-9_39
Publisher Name: Springer, Dordrecht
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