Stellar Duets in Theory and Observations. Common envelope, planetary nebulae and the origin of close binaries

这里要进行的工作集中在近双星演化的公共包络阶段，这是系统演化中的一个点，当伴星在演化的主星的包络内运行时。在这次事件中，螺旋伴星贡献了轨道能量的折射，解开并驱逐了包络，导致了一颗周期较短的双星。正是这种相互作用的工作原理决定了所有进化的近距离双星的性质，目前人们对这种相互作用知之甚少。这里假设，行星状星云中心恒星中的大部分(如果不是全部)是后共同包络双星，这与行星状星云是通过单星的自然演化而产生的正则观点相反。考虑到这一点，将开展三个项目，以探索共同包络阶段的物理、其对各种演化的近双星类型分布的影响，以及行星状星云的中心恒星最终确实是双星的可能性。首先，利用径向速度技术，将继续对中心恒星之间的双星进行初步(和提示性的)搜索，并将其扩展以确定行星状星云的二进制比例。其次，将对常见的包络相互作用进行简化模拟，以确定角动量损失作为一次质量和二次质量以及其他恒星和系统参数的函数。初始水动力模拟将使用拉格朗日光滑颗粒流体力学和欧拉自适应网格加密程序进行，并将选择最合适的方法来进行大部分研究。最后，这个模型的结果将被合并到人口合成代码中，通过复制第一个项目中建立的行星星云之间的二元性结果来测试结果。这项工作的结果将通过美国自然历史博物馆、地球和空间玫瑰中心以及海登天文馆的外展项目进行展示。常见的信封相互作用的可视化将被开发出来，在博物馆展示，并包括在科学简报中。将在博物馆晚间课程的背景下，开发并重复开设一门关于石碑革命的课程，重点是二进制。模拟结果和所有光谱数据将通过博物馆的数据档案馆提供给社区。

ABSTRACTThe work to be carried out here centers on the common envelope phase of the evolutionof close binaries, a point in the system's evolution when the companion orbits inside theenvelope of the evolved primary. During this event, the spiraling in companion donates afraction of its orbital energy to unbind and expel the envelope, resulting in a binary with ashorter period. It is the workings of this interaction, poorly understood at the moment,which dictate the properties of all evolved close binaries. Here it is postulated that themajority of, if not all, planetary nebulae central stars are post-common envelope binaries,which is contrary to the canonical view that planetary nebulae arise through the naturalevolution of single stars. With this in mind, three projects will be undertaken to explorethe physics of the common envelope phase, its effects of the distribution of variousevolved close binary types, and the possibility that the central stars of planetary nebulaetend to indeed be binaries. First, using radial velocity techniques, initial (and suggestive)searches for binarity among central stars will be continued and extended to determine theplanetary nebulae binary fraction. Second, common envelope interactions will benumerically modeled to determine the angular momentum loss as a function of primaryand secondary masses as well as other stellar and system parameters. The initialhydrodynamic modeling will be undertaken with both Lagrangian Smooth ParticleHydrodynamics and an Eulerian Adaptive Mesh Refinement codes and the best suitedapproach will be selected to carry out the bulk of the investigation. Finally, the results ofthis modeling will be incorporated into a population synthesis code to test the outcome byreproducing the results of binarity among planetary nebulae established in the firstproject.The results of this work will be featured in outreach programs through the AmericanMuseum of Natural History, the Rose Center for Earth and Space, and the HaydenPlanetarium. Visualizations of common envelope interactions will be developed fordisplay at the Museum and included in the Science Bulletins. A course on stellarevolution with emphasis on binarity will be developed and offered on repeat occasionswithin the context of the Museum's evening courses. The simulation outputs and allspectroscopic data will be made available to the community through the Museum's dataarchives.