Field Binary OB Stars: Multifaceted Diagnostics of Star Formation

对于理解恒星是如何形成的，以及它们在整个生命过程中如何影响宿主星系，尤其是在它们不可避免的爆炸结束时，质量最大的恒星是至关重要的。我们通常期望大质量恒星与低质量恒星形成星团。然而，大约25%的大质量恒星不是在星团中发现的，而是在明显的孤立中发现的（被称为“场”星）。该项目将量化大质量星团的特性，并确定从星团中喷射出来的恒星与孤立形成的恒星对星团的相对贡献。这些发现将为恒星形成理论设定关键的观测约束，这与理解我们宿主星系内的环境，包括行星形成，有着广泛的关系。该项目将利用6.5米麦哲伦望远镜上的新仪器。该项目将涉及本科生和研究生。他们将把他们的数据集整合到简单的活动中，这些活动可以用于本科天文学入门课程。PI参与了一些课程创新和推广活动，包括与UM特别收藏图书馆，历史悠久的UM底特律天文台和UM自然历史博物馆的合作关系。这些活动促进了在本科生和公众中更广泛的科学教育，并建立了校园内的协同联系。该团队将使用密歇根/麦哲伦光纤系统（M2FS），一种多目标梯级光谱仪，对小麦哲伦云中OB星群进行光谱监测调查。他们的目标是：(1)识别野星双星，获得轨道参数的分布，包括周期、质量比和偏心率。2)准确确定失控弹射机构径向速度分布和约束模型。约束逃逸恒星与原地形成的恒星对磁场的相对贡献。(3)确定原位形成的场星是否确实是慢速旋转星。(4)利用二值性和vsini识别Oe/Be星性质的任何趋势，同时提供对Balmer发射的高质量监测。

The most massive stars are of vital interest to understanding how stars are formed, and how they affect their host galaxy throughout their life, especially in their inevitable explosive end. We normally expect high-mass stars to form in clusters with lower-mass stars. However, about 25% of high-mass stars are found not in clusters but in apparent isolation (known as "field" stars). This project will quantify the properties of massive field stars and determine the relative contributions to the field of stars that were ejected from clusters vs those formed in isolation. These findings will set critical observational constraints on theories of star formation, which are broadly relevant to understanding our environment within our host galaxy, including planet formation. The project will exploit new instrumentation on the 6.5-m Magellan telescope. The project will involve both undergraduate and graduate students. They will incorporate their data sets into simple activities that can be utilized in undergraduate introductory astronomy courses. The PI is involved in several curricular innovation and outreach activities, including partnerships with the UM Special Collections Library, the historic UM Detroit Observatory, and UM Museum of Natural History. These promote broader science education among undergraduates and the public, and build synergistic ties on campus.The team will carry out a spectroscopic monitoring survey of the field OB star population in the Small Magellanic Cloud using the Michigan/Magellan Fiber System (M2FS), a multi-object, echelle spectrometer. Their goals are to (1) Identify field star binaries and obtain the distributions of orbital parameters, including period, mass ratio, and eccentricity. 2) Accurately determine the radial velocity distribution and constrain models of runaway ejection mechanisms. Constrain the relative contribution to the field of runaways vs stars that formed in situ. (3) Determine whether field stars that formed in situ are indeed slow rotators. (4) Identify any trends in Oe/Be star properties with binarity and v sin i while also providing high-quality monitoring of the Balmer emission.