Field Binary OB Stars: Multifaceted Diagnostics of Star Formation

最大质量的恒星对于理解恒星如何形成以及它们在整个生命过程中如何影响其宿主星系至关重要，特别是在它们不可避免的爆炸结束时。 我们通常认为高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，而是在明显的孤立状态下发现的（称为“场”星）。 该项目将量化大质量场星的性质，并确定从星团中喷出的恒星与孤立形成的恒星对场的相对贡献。这些发现将为星星形成理论设定关键的观测约束，这些理论与理解我们所在星系内的环境（包括行星形成）广泛相关。 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纳入可以在本科天文学入门课程中使用的简单活动。PI参与了几项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伙伴关系。该研究小组将利用密歇根/麦哲伦光纤系统（M2 FS）对小麦哲伦星云中的OB星星群体进行光谱监测调查，这是一种多目标中阶梯光谱仪。 其目标是：（1）识别场星星双星，获得其轨道参数的分布，包括周期、质量比和偏心率。2)准确确定失控弹射机构的径向速度分布和约束模型。限制逃逸星与原位形成的恒星对场的相对贡献。(3)确定在原地形成的场星是否真的是慢转星。(4)通过二元性和v sin i确定Oe/Be星星属性的任何趋势，同时还提供高质量的巴耳末辐射监测。

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.