Browsing Astronomy by Title
Now showing items 28-47 of 63
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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 ($\lesssim$ $10^4$ $M_{\odot}$). ... -
Pulling Back the Veil: The Characterization and Habitability of Enshrouded Worlds
This dissertation explores global atmospheric haze and cloud layers and shows that they are not impenetrable barriers to information about the lower atmosphere and surface environment of planets. Uncovering techniques to ... -
Quasar Variability as seen by Large Optical Sky Surveys
Quasars are powered by accretion of hot gas onto a growing, supermassive black hole, at cosmological distances. Such an active galactic nucleus (AGN) in the heart of distant galaxies is a source of intense radiation spanning ... -
Resolved Stars' Insights into Galaxy Physics
The history of a galaxy is encoded in its individual stars, and resolved stellar populations in nearby galaxies provide a wealth of information about star formation history (SFH), its relation to the interstellar medium, ... -
Self-Interacting Dark Matter in Cosmological Simulations
Self-Interacting Dark Matter is a cosmologically consistent alternative theory to Cold Dark Matter that solves problems of the Cold Dark Matter model on small scales. Our N-body simulations demonstrate that Self-Interacting ... -
Sifting Through the Static: Exploring the Space Beyond Neptune with Digital Tracking
Trans-Neptunian Objects (TNOs) provide a window into the history of the Solar System, but they can be challenging to observe due to their distance from the Sun and relatively low brightness. Digital tracking helps address ... -
Simulating and Characterizing the Pale Blue Dot
(2013-02-25)The goal of this work is to develop and validate a comprehensive model of Earth's disk-integrated spectrum. Earth is our only example of a habitable planet, or a planet capable of maintaining liquid water on its surface. ... -
Simulating Multiphase Galactic Halos: The Impact of Cosmic Rays Through an Observational Lens
All galaxies evolve embedded in a vast gaseous halo --- the circumgalactic medium (CGM) --- that dwarfs the mass and spatial extent of the stars in the galactic disk. Recent ultraviolet (UV) absorption studies reveal that ... -
Small Samples No More: Probing the Evolution of Massive Stars
Evolved massive stars --- the post-main sequence descendants of stars with initial masses higher than roughly 8 solar masses --- are rare yet critically important objects. As residents of their host galaxies, they inject ... -
Spots and Flares: Stellar Activity in the Time Domain Era
Time domain photometric surveys for large numbers of stars have ushered in a new era of statistical studies of astrophysics. This new parameter space allows us to observe how stars behave and change on a human timescale, ... -
Star Cluster Formation Efficiency in the Andromeda Galaxy
This work revolutionizes the study of star clusters in the Local Group galaxy Andromeda (Messier 31) using high spatial resolution, multi-wavelength imaging from the Hubble Space Telescope obtained as part of the Panchromatic ... -
Star Formation in N-Body + SPH Simulations
(2014-02-24)The primary focus of my thesis work is to study star formation using a series of high resolution cosmological N-body Simulations. Specifically, I have studied the total stellar-to-halo mass ratio as a function of halo mass ... -
The Astrophysics of Active Galactic Nuclei Variability in Large Scale Spectroscopic Surveys
More than 50 years after the initial discovery of the extragalactic nature of quasi-stellar objects (quasars) by Schmidt (1963), studies of luminous active galactic nuclei (AGN) have revolutionized our understanding of ...