Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 62 for “"Stellar Evolution"”.
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Observational studies of key stages in stellar evolution
… into three poorly-understood, but key stages in stellar evolution. Stars undergoing the post T Tauri phase - which lies between the well-studied T Tauri stage of disc accretion and the arrival onto the Main Sequence - are difficult to identify and thus little-investigated. Knowledge of the …
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Constraining Stellar Evolution in Young Open Clusters with NGTS
Understanding stellar evolution is fundamental to astronomy, yet there remain significant gaps in our knowledge. Scientific progress requires testing our best explanations against observation, and open clusters act as key test sites for theories of stellar evolution. Observations of young open …
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Comprehensive analyses of massive binaries and implications on stellar evolution
Via their powerful radiation, stellar winds, and supernova explosions, massive stars (Mini & 8 M☉) bear a tremendous impact on galactic evolution. It became clear in recent decades that the majority of massive stars reside in binary systems. This thesis sets as a goal to quantify the impact of …
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Probing Late Stages of Stellar Evolution with Gaia-selected Planetary Nebulae
… of nebula magnitudes is related to the evolution of planetary nebula central stars across different masses. Distances and photometry from Gaia allow the brightness of the nebula and the evolution of the central star to be related directly in unprecedented detail.
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A Photometric Study of the Eclipsing Binary V574 Lyrae
… stars provide unparalleled insight into stellar evolution and eclipsing binary variables are particularly excellent laboratories for determining stellar physical parameters and behavior. These parameters, when taken with those of other stars, can be used to evaluate current theories on …
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Monte-Carlo simulations of globular cluster dynamics
… of theoretical calculations for the dynamical evolution of dense globular star clusters. Our new study was motivated in part by the wealth of new data made available from the latest optical, radio, and X-ray observations of globular clusters by various satellites and ground-based observatories, …
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Search and characterization of pulsars in southern globular clusters: new methodologies and results from an S-band survey
… enables tests of fundamental physics, studies of stellar evolution, and probes of the interstellar medium and Galactic structure. Globular clusters are particularly rich environments for pulsar studies. These dense stellar systems promote frequent dynamical interactions, leading to the formation …
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Testing stellar models with observations from AGB and post-AGB stars
… However, theoretical studies of the evolution of red-giants are inhibited by uncertainties in important processes such as mass loss, convective mixing, and grain formation in stellar winds. From an observational point of view it is difficult to determine stellar parameters such as the …
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Testing stellar models with observations from AGB and post-AGB stars
… However, theoretical studies of the evolution of red-giants are inhibited by uncertainties in important processes such as mass loss, convective mixing, and grain formation in stellar winds. From an observational point of view it is difficult to determine stellar parameters such as the …
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The Evolution of Planetary Nebula Nuclei
The evolution of planetary nebula nuclei (PNNs) is examined with the aid of the most recent available stellar evolution calculations and new observations of these objects. Their expected distribution in the log L-log T plane is calculated based upon the stellar evolutionary models of Paczynski, …
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Accreting Compact Objects in Technicolor: Multiwavelength Characterization of High Mass X-ray Binaries in the Local Group
… or black hole) that accretes mass from a massive stellar companion. HMXBs are highly observable due to their bright X-ray luminosities, making them an observational window into the complex process of massive binary stellar evolution. In this thesis I present work I have completed over the past six …
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Rotation and magnetism in massive stars
Rotation has a number of important effects on the evolution of stars. Apart from structural changes because of the centrifugal force, turbulent mixing and meridional circulation can dramatically affect a star's chemical evolution. This leads to changes in the surface temperature and luminosity as …
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The galactic population of binaries containing neutron stars
… is a theoretical investigation of the formation, evolution, and ultimate fate of low-, intermediate-, and high-mass X-ray binaries (L/I/HMXBs). The primary theoretical tool used throughout is binary population synthesis. Results of these calculations are used to account for the numbers and …
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Rare Stellar Populations in the Magellanic Clouds: Identification of Super-Asymptotic Giant Branch Star and Yellow Supergiant Binary Candidates
… of massive stars in rare or elusive phases of stellar evolution---thereby demonstrating the power of large surveys and systematic observation campaigns to constrain models of massive star evolution. First, I investigate the true nature of the peculiar star HV2112. Previous studies have …
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Spectroscopy of white dwarf stars observed by HETDEX.
… excellent benchmarks for testing theories of stellar evolution. For the purposes of numerical modelling, they can be treated as simple objects composed of two structures that can be treated independently: a thin photosphere and a degenerate core. Large-scale surveys, such as the Sloan Digital …
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Last Call for Life: Habitability of Terrestrial Planets Orbiting Red Giants and White Dwarfs
… the habitable zone, evolves as well. While stellar properties are relatively stable on the main sequence, post-main sequence evolution of a star involves significant changes in stellar temperature and radius, which is reflected in the changing irradiation at a specific orbital distance when …
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Fokker-Planck models and globular cluster evolution
Numerical models for globular cluster evolution using the orbit-averaged Fokker-Planck equation are compared with observations of the globular clusters M71 and NGC 6397. The first set of models studied includes a mass spectrum, a tidal boundary and allows for a central energy source from the …
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Open clusters and HII regions of our Galaxy
… are essential laboratories for understanding stellar evolution, as they allow constraints to be placed on stellar ages and luminosities. As distance indicators they are also important tracers of star formation in the Milky Way. One such cluster is Trumpler 27 that we identified for detailed …
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Chromospheric activity and lithium abundance in the NGC2516 and NGC3766 open clusters
… is very important for our understanding of stellar evolution and atmospheres, since all cluster members have almost the same age and chemical composition and this allows to infer their properties more easily than individual stars. In this work two open clusters have been considered, NGC2516 …
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