At least one quarter of all white dwarfs are actively accreting debris from planetesimals or planetary fragments. The prototype system G29-38 was discovered at the IRTF in 1987. Yet despite the intervening decades and a complete paradigm shift in the explanation from interstellar material to exoplanetary debris, there remain fundamental questions. The common assumption now is that the dust debris is in a circumstellar disk, yet if so the geometry and vertical optical depth are observationally degenerate. Optically thin and thick cases vary in disk mass — and hence parent body mass — by orders of magnitude. The parent body masses have far-reaching implications for planetary system architecture and long-term dynamics. We report on our work to break this degeneracy and even to test whether the dust is in a disk at all or some other geometrical distribution based on the fact that the prototype system contains a well-studied, pulsating star. Using MORIS and SpeX at the NASA 3-meter Infrared Telescope Facility, we simultaneously monitored the optical stellar pulsations and the ensuing infrared dust response. These observations can distinguish among a range of dust configurations, based on the observed infrared response to the known geometry of the optical pulsations.
AAS/Division for Extreme Solar Systems Abstracts
- Pub Date:
- August 2019