Merged Red-Giant Stars

红巨星是最大、最亮的恒星，它制造出许多常见的化学元素，比如碳和氮。由于它们的巨大体积，而且大多数恒星都是双星系统，因此很可能与伴星星星发生相互作用。这一过程通过共同的包层演化进行，形成了热核新星等奇异的双星现象，类超新星和中子星以及黑洞双星合并形成最近探测到的引力波。不幸的是，共同包络演化是所有恒星演化阶段中最不确定的。众所周知，对恒星的结构和性质进行定量预测是不可靠的。这个项目将扭转这个问题。许多双星系统无法在共同的包络演化中幸存下来：相反，它们合并形成单一的、奇特的巨星，红散兵？这些巨星的详细模型将被构建，以预测恒星的结构，旋转和化学，然后与最新的观测结果进行比较，以了解神秘但非常重要的普通恒星。

Red giants are the biggest and brightest stars, and make many common chemical elements, like carbon and nitrogen.Because of their great size, and because most stars are in binary systems, interaction with a companion star is very likely.This proceeds through common-envelope evolution and forms exotic binary phenomena like thermonuclear novae, type-Iasupernovae and neutron-star and black-hole binaries which merge to make the recently-detected gravitational waves.Unfortunately, common-envelope evolution is the most uncertain of all stellar-evolution phases. Quantitative predictions ofrates and properties of stars that survive it are notoriously unreliable. This project will reverse the problem. Many binarysystems do not survive common-envelope evolution: instead they merge to form single, peculiar giants, the ?redstragglers?. Detailed models of these giants will be constructed to predict stellar-structure, rotation and chemistry, andthen be compared to the latest observations to understand the mysterious, but hugely important, common-envelopemergers.