Nucleosynthesis in tidally disrupted white dwarfs

毫无疑问，黑洞有两类：潜伏在星系中心的超大质量黑洞和恒星质量的黑洞，这些黑洞可以通过与X射线双星系统中的正常恒星相互作用而被探测到。越来越多的证据表明，在一些球状星团中可能存在第三类所谓的中等质量黑洞。当恒星漂移通过星团时，一些恒星将不可避免地游荡到离黑洞足够近的地方，从而遭受潮汐干扰。IMBH不仅有可能扰乱太阳类型的恒星，还可能扰乱致密的白矮星，这些恒星将被更大质量的黑洞整体吞噬。我们最近开始调查白矮星的命运，这些白矮星接近黑洞的距离足够近，以至于被破坏和压缩到在某些情况下引发爆炸性核燃烧的程度。我们发现，如果白矮星穿透到潮汐半径足够深，那么热核点火是白矮星的自然结果。我们的模拟使用了一个与流体力学相耦合的最小核反应网络。它被量身定做，以准确地将正确的能量反馈复制到气流中，但它不能提供详细的同位素丰度。计算这种潮汐扰动的详细丰度及其与星团的混合是这项提案的重点。

Two classes of black holes are established beyond reasonable doubt: supermassive black holes that lurk in centres of galaxies and stellar-mass black holes that are detectable via their interaction with normal stars in X-ray binary systems. Suggestive evidence has accumulated that a third class of so-called intermediate mass black holes (IMBHs) may exist in some globular clusters. As stars drift through the cluster, some will inevitably wander sufficiently close to the hole that they suffer a tidal disruption. IMBHs have the potential to disrupt not only solar-type stars but also compact white dwarf stars which would be swallowed as a whole by more massive black holes. We have recently begun to investigate the fate of white dwarfs that approach the hole close enough to be disrupted and compressed to such an extent that explosive nuclear burning is triggered in some cases. We found that thermonuclear ignition is a natural outcome for white dwarfs provided that they penetrate deeply enough into the tidal radius. Our simulations used a minimal nuclear reaction network coupled to the hydrodynamics. It is tailored to accurately reproduce the correct energetic feedback onto the gas flow, but it cannot deliver detailed isotopic abundances. The calculation of the detailed abundances for such tidal disruptions and their mixing with the cluster are the focus of this proposal.