In person: 370 Cahill -- Attendees joining in person must have a valid Caltech UID.
To Join via Zoom: https://caltech.zoom.us/j/89695722750
ABSTRACT: The planetary systems of white dwarfs (WDs) are fertile ground for insight into the physical properties and dynamical evolution of planetary systems more generally. Particularly intriguing is the small, but growing population of systems containing a white dwarf and a short-period giant planet (or low-mass brown dwarf). I will discuss current hypotheses regarding the dynamical histories of these systems, focusing mainly on the representative system WD1856+534 (and 'b'). In the first part of the talk, I will describe the circumstantial evidence that WD1856b survived high-eccentricity migration to its current orbit driven by gravitational interactions with stellar companions; I will also summarize the main uncertainties of this scenario. In the second part, I will turn to the problem of planetary engulfment during the red-giant stage, including the question of whether a giant planet can eject the stellar envelope and survive. I will present preliminary results from a study of planetary engulfment using 1D hydrodynamics in MESA. These include quantitative predictions for certain observable signatures of recent engulfment events and some possible insights on the mechanics of mass ejection during inspiral of a giant planet or brown dwarf.