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Radiative amplification of sound waves in the winds of O and B starsThe velocity perturbation associated with an outwardly propagating sound wave in a radiation-driven stellar wind gives rise to a periodic Doppler shifting of absorption lines formed in the flow. A linearized theory applicable to optically thin waves is used to show that the resulting fluctuation in the absorption-line force can cause the wave amplitude to grow. Detailed calculations of the acceleration due to a large number of lines indicate that significant amplification can occur throughout the high-velocity portion of winds in which the dominant force-producing lines have appreciable optical depths. In the particular case of the wind of Zeta Pup (O4f), it is found that the e-folding distance for wave growth is considerably shorter than the scale lengths over which the physical properties of the flow vary. A qualitative estimate of the rate at which mechanical energy due to nonlinear waves can be dissipated suggests that this mechanism may be important in heating the supersonic portion of winds of early-type stars.
Document ID
19790061083
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Macgregor, K. B.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Hartmann, L.
(Harvard-Smithsonian Center for Astrophysics Cambridge, MA, United States)
Raymond, J. C.
(Harvard-Smithsonian Center for Astrophysics Cambridge, Mass., United States)
Date Acquired
August 9, 2013
Publication Date
July 15, 1979
Publication Information
Publication: Astrophysical Journal
Subject Category
Astrophysics
Accession Number
79A45096
Funding Number(s)
CONTRACT_GRANT: NSG-5229
Distribution Limits
Public
Copyright
Other

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