The conductive propagation of nuclear flames. II. Convectively bounded flames in C + O and O + Ne + Mg cores
The conductive propagation of nuclear flames. II. Convectively bounded flames in C + O and O + Ne + Mg cores
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DOI：
10.1086/173565
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发表时间：
1994
期刊：
影响因子：
--
通讯作者：
F. Timmes;S. Woosley;R. Taam
中科院分区：
文献类型：
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作者：
F. Timmes;S. Woosley;R. Taam
我们确定了火焰锋面的速度和许多其他物理性质，这些火焰锋面向内传播到由碳和氧(CO)和霓虹和氧(NEOMG)组成的简并和半生成的核心，当这种火焰被对流区域包围在它们的外部时。这种锋面的燃烧本身是不完整的，只燃烧了初始质量函数的一小部分。在恒星中建立了一个能量平衡的条件，在这个条件下，从对流区域发射的中微子的能量速率等于穿过燃烧前沿的未燃烧燃料的可用能量。燃烧锋本身的传播又受对流壳底部温度的限制，但不能大大超过绝热值。解决这两个条件之间的一致性可以为火焰提供一个独特的速度。一氧化碳白矮星的典型数值是每秒几百分之一厘米。NEOMG混合物中的火焰速度较慢。表格的形式可以很容易地在恒星演化代码中实现，并产生对流壳层进入内部的速率。将这些速度与恒星结构的局域方程相结合，我们找到了下面每个引力势的最小密度，结合恒星结构的局域方程，我们找到了每个引力势的最小密度，低于这个密度，火焰就不能传播，而必须死亡。尽管必须建立详细的恒星模型来最终解决一些问题，但我们的结果是，位于边缘的CO白矮星不会一直燃烧碳到其中心，除非白矮星的质量超过0.8个太阳质量。另一方面，在质量不超过1.0个太阳质量的白矮星中，单靠压缩很难点燃碳的燃烧。因此，在不断增加的CO矮星中燃烧的压缩点燃的壳层碳几乎肯定会一直传播到恒星的中心。简要讨论了中子星形成和Ia型超新星模型的意义。这也适用于质量在10-12个太阳质量范围内的大质量恒星，这些恒星点燃了霓虹灯燃烧的中心。
We 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.