Poster Abstracts

Name/Affiliation:  Samantha Lawler (University of Victoria)

Title:  The Disk and Planets of the Solar System Analogue tau Ceti

tau Ceti is a nearby, mature star very similar to our Sun, with a massive Kuiper belt analogue (Greaves et al. 2004) and possible multiplanet system (Tuomi et al. 2013) that makes its comparison to our Solar System very appropriate. We present infrared and submillimeter observations of the debris disk from the Herschel Space Observatory and the James Clerk Maxwell Telescope (JCMT). We find the best model of the disk is a wide annulus ranging from 5-55 AU, inclined from face-on by 30 degrees. Tuomi et al. (2013) report 5 possible super-Earths tightly nestled inside 1.4 AU and we model this planetary system and place dynamical constraints on the inner edge of the disk. We find that due to the low masses and fairly circular orbits of the planets, the disk could reach as close to the star as 1.5 AU, with some stable orbits even possible between the two outermost planets. The photometric modelling cannot rule out a disk inner edge as close to the star as 1 AU, though 5-10 AU produces a better fit to the data. Dynamical modelling shows that the 5 planet system is stable with the addition of a Saturn-mass planet on an orbit outside 5 AU, where the Tuomi et al. analysis was not as sensitive. Though higher-resolution observations are required to better determine the inner disk edge, these Herschel observations add credibility to the proposed planetary system, and provide weak evidence for at least one additional planet, increasing the similarity between the tau Ceti planet/disk system and our own Solar System.