UBC Theses and Dissertations
Characterizing debris discs in the late stages of planet formation White, Jacob Aaron
Debris discs are systems of dynamically evolved byproducts of the planet formation process. They can be used to test various planet formation theories. In my thesis I use submm-cm observations to characterize the debris in HD 141569 and Fomalhaut, as well as to investigate how stellar emission can serve as a confounding parameter in disc studies. HD 141569 is a unique system hosting a large B9.5 star, a complex circumstellar disc of gas and dust, and two M dwarf companions. Using ALMA data, I inferred the total gas mass of the system and directly imaged the inner and outer edge of the gas disc. Using ALMA and VLA data, I placed constraints on the morphology, mass, and dynamical state of the inner and outer dust discs. I used the properties of the gas and dust to argue that the system may be more accurately characterized as a young debris disc as opposed to a transitional disc. Fomalhaut is a commonly studied nearby debris system. I used ALMA observations to place tight constraints on the morphology, mass, and grain size distribution of the outer debris ring. In addition, I used ALMA and IR data to cast doubt on the existence of an asteroid belt in the inner system. To separate the emission from discs and their host stars, high angular resolution observations are necessary. When the resolution is still not sufficient to spatially separate the two, an accurate model of the stellar emission is required. I am the PI on an observational campaign entitled Measuring the Emission from Stellar Atmospheres at Submillimeter/millimeter wavelengths (MESAS). This project seeks to observe stars with no known debris at wavelengths commonly used for studying discs, build a spectral profile of the sub-millimetre to centimetre emission, and use these profiles as templates for the stellar emission in unresolved debris features.
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