Browsing by Subject "Galactic bulge"

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    Ancient stars and the inner galaxy as tracers of the Milky Way's early evolution
    (2023-06-12) Lucey, Madeline Reinke; Hawkins, Keith A.; Boylan-Kolchin, Mike; Bromm, Volker; Dinerstein, Harriet; Jofré, Paula; Sneden, Chris
    The oldest stars in our Galaxy contain crucial information about its formation and the early Universe. Simulations predict that the oldest stars are likely to be located in the central regions of galaxies. Furthermore, nucleosynthetic predictions for the first stars indicate large yields of carbon, suggesting that the oldest stars may be Carbon-Enhanced Metal-Poor (CEMP) stars. Studying the chemo-dynamical properties of metal-poor inner Galaxy stars and CEMP stars can illuminate their origins and, in turn, inform our models of first star formation and galaxy evolution. In this dissertation, I complete a three-part survey entitled Chemical Origins of Metal-poor Bulge Stars (COMBS). COMBS I and COMBS III focused on the chemical abundance analysis of ~600 metal-poor stars using VLT/FLAMES spectra, while COMBS II focused on the dynamics of these stars. These studies show evidence that the population that enriched the old metal-poor inner Galaxy stars had a more top-heavy IMF than the typical Milky Way population. Furthermore, my results indicate that secular disk evolution may be more important in early galaxy evolution than previously thought. However, the COMBS survey did not detect any CEMP stars in the inner Galaxy. To investigate this further, I used machine learning to identify an all-sky sample of millions of CEMP stars using Gaia DR3. In addition, my dissertation puts new constraints on the length and pattern speed of the Milky Way's bar by developing a novel orbit integration method which, in turn, improves the precision and accuracy of inner Galaxy dynamical analysis. In total, my dissertation brings new insights into the formation of the Galaxy, especially the bulge, and provided constraints on the formation of the first stars through the chemo-dynamics of ancient stars.