자료유형  

 학위논문

Control Number  

0016935792

International Standard Book Number  

9798380596930

Dewey Decimal Classification Number  

520

Main Entry-Personal Name  

Johnson, James William.

Publication, Distribution, etc. (Imprint  

[S.l.] : The Ohio State University., 2023

Publication, Distribution, etc. (Imprint  

Ann Arbor : ProQuest Dissertations & Theses, 2023

Physical Description  

1 online resource(404 p.)

General Note  

Source: Dissertations Abstracts International, Volume: 85-04, Section: B.

General Note  

Advisor: Weinberg, David H.

Dissertation Note  

Thesis (Ph.D.)--The Ohio State University, 2023.

Restrictions on Access Note  

This item must not be sold to any third party vendors.

Summary, Etc.  

요약The chemical composition of the universe is constantly changing. With only hydrogen, helium, and trace amounts of lithium left over in the wake of the Big Bang, all heavier atomic nuclei in the universe were produced through the fusion of lighter nuclei inside stars. When a star dies, it disperses a considerable portion of this material back to its surroundings. As the sites of star formation in the universe, galaxies are like petri dishes of their own nuclear reactions, facilitating the formation of new stars and retaining the heavy nuclei they produce. By analyzing the chemical abundance structure of galaxies, we can deduce both their evolutionary histories and the stellar evolution processes which produced the stable elements on the periodic table.Thanks to the advent of large spectroscopic surveys, this field of galactic archaeology has recently ushered in a new age. The APOGEE survey alone has estimated abundances of at least 15 different elements in over 650,000 stars in the Galaxy. In this dissertation, I draw on galactic chemical evolution (GCE) models to shed light not only the processes shaping galaxy evolution, but also the mechanisms of nucleosynthesis in stars.Using a powerful and efficient GCE software developed as part of this work, I quantify the impact of sudden bursts in star formation in dwarf galaxies and develop methods with which to pin down the details of these events and the evolutionary timescales at play. Introducing elemental yields as free parameters, I demonstrate that this framework can deduce the evolutionary histories of galaxies and yields from stellar populations simultaneously. Applications of this methodology to disrupted dwarf galaxies in the Milky Way's stellar halo observed with the H3 survey provide results consistent with known trends of galaxy properties with stellar mass.To harness the constraining power of supernova surveys in GCE models, I investigate the origin of the observed high Type Ia supernova rates in dwarf galaxies. With both a lower metal content than their higher mass counterparts and more extended star formation histories, both of these effects are required to make sense of the results. The increased prevalence of close binary stars at low metallicities lends a natural explanation to the origin of the metallicity dependence of the rate. These results have strong implications for the enrichment histories of galaxies by directly increasing the rate of metal production at low abundances.Harnessing the power of APOGEE, I then assess which observed characteristics of the disk abundance structure in the Milky Way can be described by classic inside-out Galaxy growth and the radial migration of stars. This empirically motivated combination successfully reproduces many of the observed correlations between stellar age and chemical compositions. Its most interesting failure is its inability to explain the observed dichotomy in multi-element abundances across the disk. This result suggests that the Galaxy experienced a rather episodic star formation history.Using these models of the Milky Way as a prototype, I turn them toward similar external galaxies at low redshift. I further demonstrate the ability of the GCE framework to deduce elemental yields from stars by comparing simple parameterizations of nitrogen yields from stars against a compilation of measurements of the seemingly universal trend between gas-phase nitrogen and oxygen abundances. I find that the nitrogen yield relative to the oxygen yield must increase approximately linearly with the metal mass fraction with a constant floor at low metallicity, a result which is quite insensitive to variations in, e.g., the star formation history and efficiency of outflows from the disk. This result has strong implications for stellar evolution due to the sensitivity of nitrogen production to poorly understood processes in stars.Lastly, I quantify the evolution of the radial metallicity gradient in APOGEE by conditioning a large sample of stars on their ages. I find that a gradient closely resembling that of the youngest stars in the Galaxy was established ~9 Gyr ago. This result is best explained by GCE models invoking equilibrium abundances, whereby metal production is balanced by losses to, e.g., new star formation and outflows. This explanation contrasts with the traditional view that gradients are a consequence of inside-out Galaxy growth. The age independence of the stellar metallicity gradient and its interpretation as a consequence of equilibrium reframe the discourse surrounding abundance gradients in spiral galaxies.

Subject Added Entry-Topical Term  

Astronomy.

Subject Added Entry-Topical Term  

Astrophysics.

Subject Added Entry-Topical Term  

Planetology.

Index Term-Uncontrolled  

Galaxy evolution

Index Term-Uncontrolled  

Milky way

Index Term-Uncontrolled  

Dwarf galaxies

Index Term-Uncontrolled  

Supernovae

Added Entry-Corporate Name  

The Ohio State University Astronomy

Host Item Entry  

Dissertations Abstracts International. 85-04B.

Host Item Entry  

Dissertation Abstract International

Electronic Location and Access  

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Control Number  

joongbu:641852