The physical structure of a nuclear flame is a basic ingredient of the theory of Type Ia supernovae (SNe Ia). Assuming an exponential density reduction with several characteristic times, we have followed the evolution of a planar nuclear flame in an expanding background from an initial density of 6.6 × 107 g cm-3 down to 2 × 106 g cm-3. The total amount of synthesized intermediate-mass elements (IMEs), from silicon to calcium, was monitored during the calculation. We have used the computed mass fractions, XIME, of these elements to estimate the total amount of IMEs synthesized during the deflagration of a massive white dwarf. Using XIME and adopting the usual hypothesis that the relevant flame speed is actually the turbulent speed on the integral length scale, we have built a simple geometrical approach to model the region where IMEs are thought to be produced. It turns out that a healthy production of IMEs involves the combination of not-too-short expansion times, τc ≥ 0.2 s, and high turbulent intensities. According to our results, it could be difficult to produce much more than 0.2 M☉ of intermediate-mass elements within the standard deflagrative paradigm. The calculations also suggest that the mass of the IMEs scales with the mass of the Fe-peak elements, making it difficult to reconcile energetic explosions with low ejected nickel masses, as in the well-observed supernova SN 1991bg or in SN 1998de. Thus, a large production of Si-peak elements, especially in combination with a low or moderate production of iron, could be better addressed either by the delayed detonation route in standard Chandrasekhar-mass models or, perhaps, by the off-center helium detonation in the sub-Chandrasekhar-mass scenario.
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机译：核火焰的物理结构是Ia型超新星（SNe Ia）理论的基本组成部分。假设指数密度随着几个特征时间而降低，我们就在不断扩大的背景下追踪了平面核火焰从最初的6.6×107 g cm-3降至2×106 g cm-3的演变。在计算过程中，监控了从硅到钙的合成中间质量元素（IME）的总量。我们已经使用这些元素的计算质量分数XIME来估计大规模白矮星爆燃期间合成的IME总量。使用XIME并采用通常的假设，即相关火焰速度实际上是整数长度范围内的湍流速度，我们建立了一种简单的几何方法来对认为产生IME的区域进行建模。事实证明，IME的健康生产涉及膨胀时间不短，τc≥0.2 s和高湍流强度的组合。根据我们的结果，可能很难在标准爆燃范式中产生超过0.2M☉的中间质量元素。这些计算还表明，IME的质量与铁峰元素的质量成比例，这使得难以与低射出的镍质量相协调的高能爆炸，例如在观测良好的超新星SN 1991bg或SN 1998de中。因此，可以通过标准Chandrasekhar-mass模型中的延迟爆轰路线，或者通过偏心氦爆轰来更好地解决大量Si峰元素的产生，尤其是与铁的中低等结合的问题。在次钱德拉塞卡（Chandrasekhar-mass）情景中。
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