Merging White Dwarfs, Thermonuclear Supernovae, Other Transients

合并白矮星、热核超新星和其他超新星两颗白矮星的合并可以导致壮观的瞬变--热核超新星或吸积导致中子星坍塌--或者形成奇怪的物体--例如R CRB氦巨星。我们最近意识到，由碳和氧组成的两颗白矮星的合并很可能会产生最多的热核超新星，而且与目前的模式相反，这很可能发生，无论它们的总质量是否超过了可能的最大质量，钱德拉塞卡尔质量。我的建议是发展这一新的研究方向，希望回答以下几组问题：是什么触发了热核超新星？从观测来看，我们能区分近钱德拉塞卡天体的高密度点火，还是次钱德拉塞卡天体的高温点火吗？它是发生在与另一颗白矮星的快速合并中，还是发生在同伴的缓慢吸积过程中？白矮星合并的结果是什么？通过模拟，并购残余物有哪些特性？当剩余的圆盘堆积和自旋演化时会发生什么？一些核弹会引爆核逃逸者吗？随之而来的可能是爆炸吗？这会产生热核超新星吗？人们还可以期待什么其他的瞬变？自然界中发生了什么类型的瞬变？理论预测的大量不同的瞬变真的发生了吗？有没有我们没能想象到的？对于超新星，我们能看到恒星爆发的冲击波吗？看到喷出物与伴星、盘或其环境相互作用？

MERGING WHITE DWARFS, THERMONUCLEAR SUPERNOVAE, AND OTHER TRANSIENTSThe merger of two white dwarfs can lead to a spectacular transient -- a thermonuclear supernova or accretion induced collapse to a neutron star -- or the formation of strange objects -- such as the R CrB helium giant stars. We recently realized that mergers of two white dwarfs made of carbon and oxygen might well produce most thermonuclear supernovae, and that this would, contrary to the current paradigm, likely happen independently of whether or not their total mass exceeds the maximum possible, Chandrasekhar mass. My proposal is to develop this new research direction, hoping to answer the following sets of questions:What triggers thermonuclear supernovae? From observations, can we distinguish ignition due to high density in a near-Chandrasekhar object, or due to high temperature in a sub-Chandrasekhar one? Does it happen in a fast merger with another white dwarf, or during slow accretion from a companion?What are the outcomes of white-dwarf mergers? Using simulations, what properties do merger remnants have? What happens as remaining disks accrete and spins evolve? Will some ignite nuclear runaways? Might detonations follow? Would this produce thermonuclear supernovae? What other transients might one expect?What types of transients occur in Nature? Do the multitudes of different transients predicted by theory actually occur? Are there ones we failed to imagine? For supernovae, can we see the shock break out of the star? See ejecta interact with a companion, a disk, or its environment?