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Mapping Debris Disks At Extreme Contrast: Near-Ir Polarimetric Differential Imaging With The Gemini Planet Imager., Juan Sebastian Bruzzone
Mapping Debris Disks At Extreme Contrast: Near-Ir Polarimetric Differential Imaging With The Gemini Planet Imager., Juan Sebastian Bruzzone
Electronic Thesis and Dissertation Repository
Debris disks are gas-poor evolved circumstellar disks that show decreased near- to mid- infrared thermal excess emission because of lack of material close to the star. Regarded as massive analogues to the Main Asteroid or Kuiper Belts in the Solar System, these often young dust-rich disks comprise second-generation dust created by disruptive collisions of planetesimals and the decay products of asteroids and comets. Of the dozen or so directly imaged planets to date many share a distinctive characteristic: they reside in stellar systems known to also possess circumstellar dust. High-angular resolution characterization of debris disks, whose morphology is thought to …
From Large-Scale Molecular Clouds To Filaments And Cores : Unveiling The Role Of The Magnetic Fields In Star Formation, Sayantan Auddy
From Large-Scale Molecular Clouds To Filaments And Cores : Unveiling The Role Of The Magnetic Fields In Star Formation, Sayantan Auddy
Electronic Thesis and Dissertation Repository
I present a comprehensive study of the role of strong magnetic fields in characterizing the structure of molecular clouds. We run three-dimensional turbulent non-ideal magnetohydrodynamic simulations (with ambipolar diffusion) to see the effect of magnetic fields on the evolution of the column density probability distribution function (PDF). Our results indicate a systematic dependence of the column density PDF of molecular clouds on magnetic field strength and turbulence, with observationally distinguishable outcomes between supercritical (gravity dominated) and subcritical (magnetic field dominated) initial conditions. We find that most cases develop a direct power-law PDF, and only the subcritical clouds with turbulence are …
High Resolution Spectroscopy Of The Hyades Giants, Antonio Martinez
High Resolution Spectroscopy Of The Hyades Giants, Antonio Martinez
Electronic Thesis and Dissertation Repository
The four K0IIIHyades red clump giants, γ , δ , ϵ , and θ 1Tauri, are ideal candidates for cool star research. They are easily observable at a distance of only 47 pc and one star, ϵ Tauri, is a suspected Maunder minimum star. These stars also provide a useful opportunity to investigate the nature of the photospheric velocity field, and assess the effectiveness of a range of spectroscopic tools including the merits of the microturbulence-macroturbulence approach to the study of cool star spectra. High resolution (λ /Δ λ ∼ 100,000) exposures, taken from January 2001 to October 2008 in …