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The conductive propagation of nuclear flames. 2: Convectively bounded flames in C + O and O + Ne + Mg coresWe determine the speeds, and many other physical properties, of flame fronts that propagate inward into degenerate and semidegenerate cores of carbon and oxygen (CO) and neon and oxygen (NeOMg) white dwarfs when such flames are bounded on their exterior by a convective region. Combustion in such fronts, per se, is incomplete, with only a small part of the initial mass function burned. A condition of balanced power is set up in the star where the rate of energy emitted as neutrinos from the convective region equals the power available from the unburned fuel that crosses the burning front. The propagation of the burning front itself is in turn limited by the temperature at the base of the convective shell, while cannot greatly exceed the adiabatic value. Solving for consistency between these two conditions gives a unique speed for the flame. Typical values for CO white dwarfs are a few hundredths of a centimeter per second. Flames in NeOMg mixtures are slower. Tables are presented in a form that can easily be implemented in stellar evolution codes and yield the rate at which the convective shell advances into the interior. Combining these velocities with the local equations for stellar structure, we find a minimum density for each gravitational potential below with the local equations for stellar structure, we find a minimum density for each gravitational potential below which the flame cannot propagate, and must die. Although detailed stellar models will have to be constructed to reslove some issues conclusively, our results that a CO white dwarf inginted at its edge will not burn carbon all the way to its center unless the mass of the white dwarf exceeds 0.8 solar mass. On the other hand, it is difficult to ignite carbon burning by compression alone anywhere in a white dwarf whose mass does not exceed 1.0 solar mass. Thus, compressionally ignited shell carbon burning in an accerting CO dwarf almost certainly propagates all the way to the center of the star. Implications for neutron star formation, and Type Ia supernova models, are briefly discussed. These are also applicable to massive stars in the about 10-12 solar mass range which ignite neon burning off center.
Document ID
19950035622
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Timmes, F. X.
(Univ. of California at Santa Cruz, Santa Cruz, CA United States)
Woosley, S. E.
(Univ. of California at Santa Cruz, Santa Cruz, CA United States)
Taam, Ronald E.
(Northwestern Univ. Evanston, IL, United States)
Date Acquired
August 16, 2013
Publication Date
January 1, 1994
Publication Information
Publication: Astrophysical Journal, Part 1
Volume: 420
Issue: 1
ISSN: 0004-637X
Subject Category
Astrophysics
Accession Number
95A67221
Funding Number(s)
CONTRACT_GRANT: NAGW-1273
CONTRACT_GRANT: NSF AST-91-13150
CONTRACT_GRANT: NAGW-2525
Distribution Limits
Public
Copyright
Other

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