Explorations of the Remnant Exoplanetary Debris Disks around White Dwarf Stars

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Dennihy, Erik
- Affiliation: College of Arts and Sciences, Department of Physics and Astronomy

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Always amenable to modern astrophysical needs, the compact degenerate remnants of stars like our Sun known as white dwarf stars have recently been put into service as exoplanetary laboratories. Their nominally pure hydrogen or helium atmospheres reveal pollution from the debris of crushed up exoplanets, and our understanding of the physics of their atmospheres provides a means to explore the chemical makeup of the rocky bodies they accrete. This thesis work will build on observations of the exoplanetary systems around white dwarf stars by providing new discoveries of such systems, including one that appears to have accreted the crust of an exo-earth analogue. We also pioneer a novel discovery technique which is capable of both revealing new systems and isolating the most interesting among them. Some of our new observations required a major upgrade to a facility class scientific instrument at the Southern Astrophysical Research Telescope in Chile, and we detail the design and implementation of this new upgrade which is now available to the entire US astronomical community. With this upgrade, we discovered a rapidly evolving white exoplanetary system which both challenges the existing theories of white dwarf exoplanetary system evolution and provides the only path forward to test such theories on a reasonable timeline. We conclude with a discussion of the impact these new observations and discovery tools have on the field, and the future directions they enable.

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