The orbital architecture and debris disks of the HR 8799 planetary system.
GOZDZIEWSKI K. and MIGASZEWSKI C.
Abstract (from CDS):
The HR 8799 planetary system with four ≃10 mJup planets in wide orbits up to ≃70 au and orbital periods up to 500 yr has been detected with direct imaging. Its intriguing orbital architecture is not yet fully resolved due to time-limited astrometry covering only ≃20 yr. Earlier, we constructed a heuristic model of the system based on rapid, convergent migration of the planets. Here we develop a better-structured and CPU-efficient variant of this model. With the updated approach, we reanalyzed the self-consistent, homogeneous astrometric data set in Konopacky et al. The best-fitting configuration agrees with our earlier findings. The HR 8799 planets are likely involved in a dynamically robust Laplace 8e:4d:2c:1b resonance chain. Hypothetical planets with masses below the current detection limit of 0.1-3 mJup within the observed inner or beyond the outer orbit, respectively, do not influence the long-term stability of the system. We predict the positions of such nondetected objects. The long-term stable orbital model of the observed planets helps to simulate the dynamical structure of debris disks in the system. A CPU-efficient fast indicator technique makes it possible to reveal their complex, resonant shape in 106 particles scale. We examine the inner edge of the outer disk detected between 90 and 145 au. We also reconstruct the outer disk, assuming that it has been influenced by the convergent migration of the planets. A complex shape of the disk strongly depends on various dynamical factors, like orbits and masses of nondetected planets. It may be highly noncircular, and its models are yet nonunique regarding both observational constraints and its origin.