标题： 密近热亚矮星-白矮星双星的最终命运：涉及氦/碳/氧白矮星的合并以及以碳/氧为主包层的异常巨大恒星的形成 显示英文标题

标题： The final fates of close hot subdwarf - white dwarf binaries: mergers involving He/C/O white dwarfs and the formation of unusual giant stars with C/O-dominated envelopes

摘要： 最近，发现了一类由热次矮星和白矮星组成的洛希瓣充满的双星系统，其周期小于一小时。 目前，热次矮星处于壳层氦燃烧阶段，并将其剩余的薄氢包层部分转移给白矮星伴星。 随着热次矮星的演化继续，预计它将脱离，留下一个低质量的碳氧核心白矮星次级星，且具有厚厚的氦层。 然后，在$\sim 10$百万年的时标上，引力波辐射将再次使系统重新接触。 如果质量转移不稳定并且导致合并，但未触发灾难性的热核爆炸，那么将形成一个以碳氧为主包层的残骸，但其中仍富含氦，足以支持类似鹿豹座R型壳层燃烧阶段。 我们展示了这一阶段的演化计算，并讨论了其对残骸白矮星冷却的潜在影响。 显示英文摘要

摘要： Recently, a class of Roche-lobe-filling binary systems consisting of hot subdwarf stars and white dwarfs with sub-hour periods has been discovered. At present, the hot subdwarf is in a shell He burning phase and is transferring some of its remaining thin H envelope to its white dwarf companion. As the evolution of the hot subdwarf continues, it is expected to detach, leaving behind a low mass C/O core white dwarf secondary with a thick He layer. Then, on a timescale of $\sim 10$ Myr, gravitational wave radiation will again bring the systems into contact. If the mass transfer is unstable and results in a merger and a catastrophic thermonuclear explosion is not triggered, it creates a remnant with a C/O-dominated envelope, but one still rich enough in He to support an R Corona Borealis-like shell burning phase. We present evolutionary calculations of this phase and discuss its potential impact on the cooling of the remnant white dwarf.