Resolving the Milky Way's Global Star Formation History

研究人员试图更好地了解我们的银河系何时何地形成了千亿颗恒星。当恒星形成和燃烧核燃料时，这段历史被记录在气体和附近恒星的化学组成中。科学家可以利用这些化学变化来追踪不同类型的恒星是如何在不同的时间形成的。阅读这段恒星生命史需要敏锐的观察和详细的模型。研究人员将根据我们银河系中数十万颗恒星的年龄和化学信息建立模型。他们还将寻找气体流入银河系的影响，以及恒星自形成以来在微波辐射内部运动的影响。这些测量将帮助我们理解婴儿MW是如何成长为我们今天看到的巨大螺旋星系的。此外，该项目将解决犹他州难民社区成员的科学素养问题。研究人员将与这些社区的高中生合作，为高空气球设计实验。这些活动将教授计算技能和解决问题，学生们将为未来的团队设计工具包，以建造和发射他们自己的气球。直到最近，我们对MW丰富历史的测量在很大程度上仅限于太阳附近；但现在，大规模的恒星调查使前所未有的化学测量，甚至年龄测量成为可能，在银河系半径范围内的大量恒星。这些测量揭示了复杂的、依赖于位置的年龄和丰度模式，需要新的模型来重现和解释。年龄、恒星金属丰度和阿尔法元素增强的分布构成了化学演化模型所面临的最严格的观测约束。研究人员将使用阿帕奇点天文台星系演化实验(APOEE)的化学测量数据。测量数据是这项工作的理想数据，因为数据是均匀的，而且数据集覆盖了整个银河系半径范围。然而，许多远地点恒星，特别是内银河系的恒星，还没有可靠的年龄测量。研究人员将计算这些发光巨星的第一个年龄，以完成对该圆盘恒星历史的大规模建模所需的一组高质量观测。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The investigators seek to better understand where and when our Milky Way (MW) Galaxy formed its hundred billion stars. As stars form and burn their nuclear fuel, this history is recorded in the chemical makeup of the gas and stars near them. Scientists can use those chemical changes to trace how different types of stars formed at different times. Reading this stellar life history requires sensitive observations and detailed models. The researchers will fit models to age and chemical information for hundreds of thousands of stars in our galaxy. They will also look for the effects of gas flowing into the Galaxy, and of stars moving around inside the MW since they formed. These measurements will help us understand how the infant MW grew into the massive spiral galaxy we see today. In addition, the project will address scientific literacy among members of Utah’s refugee communities. The researchers will work with high-school students from these communities to design experiments for high-altitude balloons. These activities will teach computing skills and problem solving, and students will design kits for future groups to build and launch their own balloons.Until recently, our measurements of the MW’s enrichment history were largely limited to the solar neighborhood; but now, massive stellar surveys are enabling unprecedented chemical — and even age — measurements for enormous numbers of stars at a wide range of Galactic radius. These measurements reveal complex, position-dependent patterns of age and abundance that require new modeling to reproduce and interpret. The distributions of age, stellar metallicity, and alpha-element enhancement comprise the most stringent observational constraints ever confronted by chemical evolution models. The investigators will use chemical measurements from the Apache Point Observatory Galactic Evolution Experiment (APOGEE). The survey data are ideal for this work because the data are homogeneous, and the dataset spans the full range of Galactic radius. However, many of APOGEE’s stars, especially in the inner Galaxy, do not yet have reliable age measurements. The investigators will compute the first ages for these luminous giant stars in order to complete the set of high-quality observations required for large-scale modeling of the disk’s stellar history.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.