Browsing Astronomy by Title
Now showing items 16-35 of 63
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The formation and evolution of the large magellanic cloud from selected clusters and star fields
(1998)We have obtained deep Hubble Space Telescope color-magnitude diagrams of fields centered on the six old LMC globular clusters NGC 1754, NGC 1835, WGC 1898, NGC 1916, NGC 2005, and NGC 2019. The data have been carefully ... -
From reionization until now: The history of the ionizing background
Ultraviolet light emitted by the first galaxies sparked the last major phase change of matter in the Universe. The bulk of gas in the Universe went from neutral to ionized, and as galaxies and quasars continued to replenish ... -
Galactic Gas Flows from Halo to Disk: Kinematics and Tomography in the Milky Way’s Low-Velocity Circumgalactic Medium
The evolution of galaxies is closely linked to the exchange of gas between their disk and the circumgalactic medium (CGM) – the massive, extended, diffuse halo of gas in which galaxies are embedded. Recent advances in ... -
A Ground-Based Search for Transit Timing Variations from the Apache Point Observatory
(2013-02-25)The following dissertation presents work done as part of a ground-based transit follow-up program designed to look for transit timing variations in well-known transiting systems called, the Apache Point Survey of Transit ... -
HI selected galaxies in the Sloan Digital Sky Survey
(2005)We present the results from a study of HI selected galaxies that fall within both the HI Parkes All Sky Survey (HIPASS) and the Sloan Digital Sky Survey (SDSS). By comparing the optical properties derived from the SDSS ... -
A hyperbolic tetrad approach to numerical relativity
(2003)An in-depth numerical study using 3 + 1 formulations of the Einstein equations for 1D colliding plane waves reveals factors which increase accuracy and stability: using "mixed" variables, hyperbolicity, satisfying the ... -
Inferring the Evolutionary Histories of Stars and Their Planets
Modern surveys like NASA’s Kepler mission have collected a wealth of data in the search for Earth-like exoplanets. This vast quantity of data has enabled novel statistical investigations of the physical processes that shape ... -
Karhunen-Loeve Analysis for Weak Gravitational Lensing
(2013-02-25)In the past decade, weak gravitational lensing has become an important tool in the study of the universe at the largest scale, giving insights into the distribution of dark matter, the expansion of the universe, and the ... -
Mapping the Circumgalactic Medium: Connecting Galaxies to their Environment
The work presented in this dissertation provides the groundwork for understanding key unresolved questions in the study of galaxy evolution: the circumgalactic medium (CGM) and the role of environment. I present a new ... -
The Milky Way in SDSS and in N-body Models
(2013-11-14)In this thesis, I present a comparison between recent Sloan Digital Sky Survey (SDSS) Galactic studies and N-body simulations to aid in the interpretation of observed structural features. I investigate the origin of the ... -
Modeling Supermassive Black Holes in Cosmological Simulations
My thesis work has focused on improving the implementation of supermassive black hole (SMBH) physics in cosmological hydrodynamic simulations. SMBHs are ubiquitous in mas- sive galaxies, as well as bulge-less galaxies and ... -
Modeling the Extragalactic Epoch of Reionization Foreground
The Epoch of Reionization represents a largely unexplored yet fundamental chapter of the early universe. During this period, spanning several hundred million years, the first stars and galaxies formed and the Hydrogen-dominated ... -
Observational Constraints on Models of Rapidly Evolving Luminous Stars
(2014-02-24)Resolved stellar populations in galaxies are excellent laboratories for testing our understanding of galaxy formation, integrated colors and luminosities, supernova progenitor masses, and energy input from stellar feedback. ... -
On The Evolution, Detection, and Characterization of Small Planets in the Habitable Zones of M Dwarfs
As the technology behind instrumentation in astronomy improves, so too does our ability to detect and characterize worlds outside our solar system. We are currently witnessing a revolution in exoplanet science: for the ... -
The optical counterparts of the luminous x-ray binary stars in globular clusters
(1998)Ten percent of our Galaxy's luminous (LX≳1036 ergs-1 ) X-ray point sources are located in globular clusters (GCs), but globular clusters contribute a much smaller fraction of normal stars to the Galaxy. X-ray bursts ... -
The Optical Variability of Quasars as Seen by SDSS
(2012-09-13)I provide a quantitative analysis of the database of 3.5 million photometric measurements for 80,000 spectroscopically confirmed quasars recently assembled by the Sloan Digital Sky Survey (SDSS). This database is an excellent ... -
Orbital Dynamics and Habitability of Exoplanets
With the discoveries of thousands of extra-solar planets, a handful of which are terrestrial in size and located within the ``habitable zone'' of their host stars, the discovery of another instance of life in the universe ... -
Physical conditions in giant extragalactic H II regions
(1984)Giant Extragalactic H II Regions (GEHRs) in nearby galaxies have been observed at both radio and optical wavelengths. Narrow band optical imaging, large and small aperture optical spectrophotometry, radio continuum imaging ... -
Planetesimal Accretion in the Solar System and Beyond: An Application to Systems of Tightly-Packed Inner Planets
Planetesimals are the smallest gravitationally bound objects to play a role in the planet formation process. In a bottom-up fashion, these bodies are thought to collide and grow to form protoplanets, which are roughly ... -
Properties of Stellar Clusters and their Relation to Molecular Gas in the Andromeda Galaxy
The apparent age and mass of a stellar cluster can be strongly affected by stochastic sampling of the stellar initial mass function, when inferred from the integrated color of low mass clusters ($\lesssim$ $10^4$ $M_{\odot}$). ...