Star formation & stellar evolution with binaries and interferometry

大多数恒星并不是孤立地诞生的，而是双星系统的一部分。一个大的悬而未决的问题是这样的双星是如何形成的，以及是什么导致了在它们的轨道特征中观察到的多样性。例如，一些双星在非常接近的轨道上，也可以相对于恒星自转轴倾斜。这些伴星不可能是在观测到的地点诞生的，但一定是在距离更远的地方形成的，后来被输送到了倾斜的、近距离的轨道上。该项目的目标是利用查拉望远镜阵列来解析双星，并研究数百个系统的轨道构型和基本参数。除了轨道外，我们的方法还允许我们测量这些系统中恒星的精确质量和年龄，以及轨道轴和恒星自转轴之间的对准。在这些研究中，我们将使用埃克塞特大学和密歇根大学合作建造的CHARA/MIRC-X仪器，以及VLTI/重力的补充观测。这些设备将相距数百米的望远镜发出的光结合在一起，从而能够以极高的精度进行测量。在这个博士项目中，陆毅将致力于从公共星表中选择最有希望的来源，验证所提出的方法，将数据与理论预测进行对峙，并发布第一批结果。他将加入我们日益壮大的、面向国际的干涉测量团队，并与埃克塞特理论专家和海外合作者合作。

Most stars are not born in isolation, but as part of binary star systems. One of the big open question concerns how such binaries form and what causes the diversity that is observed in their orbital characteristics. For instance, some binaries are on very close-in orbits that can also be tilted with respect to the stellar rotation axes. These companions cannot have been born at their observed location but must have formed at much wider separation and been transported onto their tilted, close-in orbits afterwards. The goal of this project is to use the CHARA telescope array in order to resolve binaries and to study the orbital configuration and fundamental parameters of hundreds of systems. Besides the orbits, our approach allows us also to measure precision masses & ages of the stars in these systems as well as the alignment between the orbital axis and the stellar rotation axes. The associated survey will provide fundamental new insights on the star formation process and also have a strong impact in the field of stellar evolution.For these studies we will use the CHARA/MIRC-X instrument that has been built as part of a collaboration between the University of Exeter and the University of Michigan, as well as complementary observations with VLTI/GRAVITY. These facilities combine the light from telescopes separated hundreds of meters apart, which enables measurements with extreme precision.In this PhD project, Yi Lu will work on selecting the most promising sources from public catalogues, validate the proposed method, confront the data with theory predictions, and publish first results. He will join our growing & internationally oriented interferometry team and collaborate with the Exeter theory experts and collaborators abroad.