Connecting Dwarf Galaxies, Metal Poor Stars, and the Origins of the Elements

点击翻译按钮获取中文摘要

The surfaces of stars contain a fossil fingerprint of the chemical composition of their birth clouds, and metal-poor stars are particularly important as tracers of the formation and assembly history of the Galaxy. Moreover, metal-poor stars are important for understanding the origins of the elements given that few nucleosynthetic events would have contributed to their chemical compositions. In the upcoming decade of large high-resolution spectroscopic, photometric, and astrometric surveys, samples of metal-poor stars with interesting origins and dynamics will be discovered throughout the Milky Way. Higher precision analyses will reveal their detailed compositions, allowing us to break degeneracies in stellar and galaxy modeling, to explore their origins and better understand the formation of the elements. This research program builds on my expertise in stellar spectroscopy and my successful collaboration with the Pristine survey to find rare metal-poor stars, leading to two long term goals: (1) Finding and analyzing metal-poor stars throughout the Milky Way and dwarf galaxies - Studies of metal-poor stars in the Milky Way and nearby satellites have shown chemical abundance patterns that differ due to a range of (degenerate) galactic and stellar modeling assumptions. Larger statistical samples are required to break those degeneracies and map the metal-poor Milky Way. (2) Understanding the origins of heavy r-process elements - The origin of the elements remains one of the great unsolved problems in physics, although a major breakthrough came with the discovery of r-process nucleosynthesis in a neutron star merger, as an addition to a ubiquitous r-process site. A comparison of metal-poor stars that formed in a variety of environments is needed to constrain these nucleosynthetic pathways. This research program will use the Gemini Observatory GRACES and upcoming GHOST spectrographs for high resolution (R>50,000) spectra of metal-poor stars; GHOST is particularly necessary for spectra below 450 nm for r-process element spectral lines. This program will also use spectra of metal-poor stars (~3000 targets) from the upcoming WEAVE spectroscopic survey. Therefore, this is an exciting time for the discovery and analysis of a large number of metal poor stars, in a variety of galactic environments (Galactic bulge, plane, globular clusters, streams, and in dwarf galaxies). The impact of my research program will be a better understanding of the origin of the heavy elements and the assembly history of the metal-poor Galaxy, leading to improvements in galaxy and stellar modeling. This program provides training opportunities for HQP in observational and theoretical astrophysics, and unique opportunities to develop new data analysis methodologies (e.g., machine learning algorithms) and to be involved in instrumentation developments (e.g., science verification for GHOST), thereby preparing for future Canadian facilities (e.g., TMT, MSE, or equivalents).