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Stellar evolution at high mass with semiconvective mixing according to the Ledoux criterionThe effects of semiconvective mixing are investigated in evolutionary sequences of models for stars of 10, 15, and 30 solar masses with four different initial chemical compositions. The models are constructed using the Ledoux criterion for both the definition of convective instability and the state of convective neutrality assumed to be attained in regions with a gradient of mean molecular weight. It is shown that semiconvection is nonexistent at 10 solar masses, of minor importance at 15 solar masses, but covers most of the intermediate zone at 30 solar masses, developing into full convection if the initial hydrogen and metals abundances are high. The effects of low initial hydrogen and metals abundances are examined, and the critical importance is demonstrated of the depths of the semiconvective zone and the outer convective envelope in promoting a blue loop and determining the maximum effective temperature on the loop. The extent of the thermally stable stages of the blue-loop phase is determined.
Document ID
19750051594
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Stothers, R.
Chin, C.-W.
(NASA Goddard Institute for Space Studies New York, N.Y., United States)
Date Acquired
August 8, 2013
Publication Date
June 1, 1975
Publication Information
Publication: Astrophysical Journal
Volume: 198
Subject Category
Astrophysics
Accession Number
75A35666
Distribution Limits
Public
Copyright
Other

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