The Realizability of the Double-Detonation Mechanism for Type Ia Supernovae

Ia型超新星（SN）在测量宇宙的加速膨胀中起着至关重要的作用，产生了宇宙中一半的重金属，并作为恒星流体动力学、核物理学、双星演化和许多其他天体物理学方面的试验台。然而，尽管它们的重要性和几十年的观测和理论研究，引起这些爆炸的恒星系统的详细性质仍然不确定。阿拉巴马大学塔斯卡卢萨分校的一个研究小组将使用基于计算机的数值模拟来研究Ia超新星爆炸最有希望的候选情景之一。这种情况被称为“双重爆炸”机制，它始于一颗高度致密的白矮星表面的爆炸性氦爆炸，这反过来又在该恒星的核心产生了碳燃烧的爆炸。这项研究将包括对研究生和本科生进行高性能计算和科学软件开发方面的培训。除了研究成果，这项工作还将制作面向普通观众的科学成果短视频，为小团体制作便携式天文馆程序，以及供高年级天文学课程的学生运行的恒星爆炸的简单模拟。理解双爆机制的障碍仍然存在，这项工作将有助于解决这些障碍。恒星氦壳中第一次点火的详细机制尚不清楚，这使人们对爆炸开始的这个关键阶段的稳健性产生了疑问。为了使这个场景成为超新星Ia的主要贡献者，点火过程不仅必须在微调下可行，而且必须健壮且几乎是通用的。其次，根据最近的模拟，很明显，爆炸恒星外层的详细结构和伴星的存在对于确定所产生的超新星是否与观测到的超新星相匹配至关重要。通过量身定制的模拟，这项工作将确定双星系统中真实的点火和表面层结构是否会导致真实的超新星。该项目由天文科学部和刺激竞争性研究的既定计划（EPSCoR）共同资助。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Type Ia supernovae (SN) play an essential role in measuring the accelerating expansion of the Universe, produce half of the Universe’s heavy metals, and serve as testbeds for stellar hydrodynamics, nuclear physics, binary stellar evolution, and many other aspects of astrophysics. However, despite their importance and several decades of observational and theoretical investigation, the detailed nature of the stellar systems that give rise to these explosions remains uncertain. A research team at the University of Alabama Tuscaloosa will use computer-based numerical simulations to investigate one of the most promising candidate scenarios for a SN Ia explosion. This scenario, called the “double-detonation” mechanism, starts with an explosive helium detonation on the surface of a highly compact white dwarf star, which in turn yields a carbon-burning detonation in the core of that star. The research will involve the training of graduate and undergraduate students in high performance computing and the development of scientific software. Along with research products, this work will produce short videos of scientific results intended for a general audience, a portable planetarium program for small groups, and simple simulations of stellar explosions that can be run by students in upper-division astronomy courses.Obstacles remain to understanding the double-detonation mechanism and this work will help resolve them. The detailed mechanism of the first ignition in the helium shell of the star is still unclear, calling into question the robustness of this critical stage of the beginning of the explosion. In order for this scenario to be viable as a major contributor to SNe Ia, the ignition process must not just be possible under fine-tuning, but robust and almost universal. Secondly, based on recent simulations, it is clear that the detailed structure of the outer layers of the exploding star and the presence of the companion star are critical to determining whether the resulting supernova matches those observed. Using tailored simulations, the work will determine whether a realistic ignition and surface layer structure placed in a binary star system leads to realistic supernovae. This project is jointly funded by the Division of Astronomical Sciences and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.