Resolving the Milky Way's Global Star Formation History

University Of Utah, Salt Lake City UT

Investigators

Abstract

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.