John Silva, a graduate teaching assistant in the Department of Physics and Astronomy, has received an Iowa Space Grant Consortium (ISGC) Graduate Fellowship for a project that will measure precise and accurate ages for millions of nearby subgiant stars, enabling a robust reconstruction of the Milky Way’s star formation and chemical evolution.

This ISGC program is designed to support outstanding graduate students pursuing NASA-aligned research opportunities in Science, Technology, Engineering, and Math (STEM) disciplines. Program goals include alignment with the NASA Mission Directorates, encouragement of qualified individuals to continue in a space science or aerospace-related field, support of research infrastructure at our member institutions, and retention of U.S. graduates. 

Working with Assistant Professor David Nataf, Silva's project is entitled "Accurate, Precise, and Self-consistent Ages & Metallicities for 400,000 Solar Neighborhood Subgiants." Subgiant stars are ideal targets because they have exhausted their hydrogen cores, and layers with heavy elements have not yet started to mix. Thus, their luminosity (brightness) is highly dependent on mass and the original chemical makeup (metallicity).  

The proposed research project will construct an extensive catalog using measurements from the Gaia telescope, cross-matched with other surveys of infrared, visible, and ultraviolet light. Using these types of data in tandem has been shown to yield age-metallicity estimates with high precision, and this method will minimize false matches between surveys and reduce uncertainties. Ultimately, the revised catalog will be used to investigate and map how these stars are distributed throughout the Galaxy. This will allow the research team to work backwards, gaining insight into how the Milky Way evolved to produce the stars we see presently.