Physics and Astronomy PhD Defense

Erik Dennihy

“Explorations of the Remnant Exoplanetary Debris Disks Around White Dwarf Stars”

Always amenable to modern astrophysical needs, white dwarf stars have recently been pressed into service of exoplanet studies as rocky exoplanetary abundance laboratories. Their nominally hydrogen atmospheres reveal the chemical abundances of recently-accreted exoplanetary debris, which sinks quickly from view if not actively replenished by a circumstellar accretion disk. I will present new methods for discovering and tracing the evolution of these post-main sequence planetary systems, including a major upgrade to the Goodman Spectrograph on the SOAR 4.1m telescope. Our observations and methods reveal new insights into the dynamical evolution of the accretion disks, which will help place further constraints on the exoplanetary abundances derived from the white dwarf atmospheres.