We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Insights on the dynamical history of the Fomalhaut system.
- Authors
Faramaz, V.; Beust, H.; Augereau, J.-C.; Kalas, P.; Graham, J. R.
- Abstract
Context. The eccentric shape of the debris disk observed around the star Fomalhaut was first attributed to Fom b, a companion detected near the belt inner edge, but new constraints on its orbit revealed that it is belt-crossing, highly eccentric (e ~ 0.6-0.9), and can hardly account for the shape of the belt. The best scenario to explain this paradox is that there is another massive body in this system, Fomc, which drives the debris disk shape. The resulting planetary system is highly unstable, which hints at a dynamical scenario involving a recent scattering of Fom b on its current orbit, potentially with the putative Fom c. Aims. Our goal is to give insights on the probability for Fomb to have been set on its highly eccentric orbit by a close encounter with the putative Fom c. We aim to study in particular the part played by mean-motion resonances with Fom c, which could have brought Fom b sufficiently close to Fomc for it to be scattered on its current orbit, but also delay this scattering event. Methods. We assumed that Fomc is much more massive than Fom b, that is, Fom b behaves as a massless test particle compared to Fomc. This allowed us to use N-body numerical simulations and to study the influence of a fixed orbit Fom c on a population of massless test particles, that is, to study the generation of Fomb-like orbits by direct scattering events or via mean-motion resonance processes. We assumed that Fomb originated from an orbit inner to that of the putative Fomc. Results. We found that the generation of orbits similar to that of Fom b, either in terms of dimensions or orientation, is a robust process involving a scattering event and a further secular evolution of inner material with an eccentric massive body such as the putative Fom c. We found in particular that mean-motion resonances can delay scattering events, and thus the production of Fom b-like orbits, on timescales comparable to the age of the system, thus explaining the witnessing of an unstable configuration. Conclusions. We conclude that Fom b probably originated from an inner resonance with a Neptune-Saturn mass Fom c, and was set on its current orbit by a scattering event with Fomc. Since Fomb could not have formed from material in resonance, our scenario also hints at former migration processes in this planetary system.
- Subjects
CIRCUMSTELLAR matter; CELESTIAL mechanics; PLANETARY orbits; MASS (Physics); HUBBLE Space Telescope (Spacecraft)
- Publication
Astronomy & Astrophysics / Astronomie et Astrophysique, 2015, Vol 573, p1
- ISSN
0004-6361
- Publication type
Article
- DOI
10.1051/0004-6361/201424691