Chemical Abundances of Relic Red Giant Stars for Galactic Archeology

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How did galaxies such as our own Milky Way Galaxy form? What is the origin of all the chemical elements in the periodic table heavier than Helium? My students and I will carry out research in Galactic archeology to pursue these two important problems in fundamental origins. We will create computer models of the outer visible layers (the atmospheres) of very old red giant stars that are relics from the era in which our Milky Way Galaxy formed. This will allow us to computationally model the spectrum of the light emitted by these stars, including the ultraviolet (UV), visible, and the infrared (IR) bands of the spectrum. Our modelling treats the way that gas particles absorb light and give rise to star’s emitted spectrum more realistically than does rival modelling, and it has been shown that this allows us to simulate red giant stars’ spectra with significantly greater accuracy. Comparison of our simulated spectra to the observed spectra from international ground- and space-based observatories, in many of which Canada is a partner, will allow us to determine the chemical composition and other properties of old red giant stars, and this information is crucial to determining how the Galaxy formed and evolved. Our proposal is timely, because many on-going or soon-to-begin large scale observational surveys of unprecedented scope will obtain spectra of hundreds of thousands of stars over the next few years, and the potential of the data can only be realized if they are interpreted with realistic computational modelling. Within Canada, we are uniquely capable of providing state-of-the-art modelling to interpret data for the stellar component of the surveys being proposed as part of the feasibility study for the Next Generation Canada-France-Hawaii (ngCFHT) telescope. We will apply a related method to the collective light emitted by more remote groups of stars, such as the dwarf galaxies that orbit the Milky Way, and large star clusters that are found within other nearby larger galaxies such the Andromeda galaxy, to determine the properties and composition of those objects, too. My research students will acquire critical experience related to cognate areas such as terrestrial atmospheric and solar physics, and training in methods and skills of high performance technical computing in a modern data centre environment.