How planet-planet scattering can create high-inclination as well as long-period orbits
Abstract
Recent observations have revealed two new classes of planetary orbits. Rossiter-Mclaughlin (RM) measurements have revealed hot Jupiters in high-obliquity orbits. In addition, direct-imaging has discovered giant planets at large (~ 100 AU) separations via direct-imaging technique. Simple-minded disk-migration scenarios are inconsistent with the high-inclination (and even retrograde) orbits as seen in recent RM measurements. Furthermore, forming giant planets at large semi-major axis (a) may be challenging in the core-accretion paradigm. We perform many N-body simulations to explore the two above-mentioned orbital architectures. Planet-planet scattering in a multi-planet system can naturally excite orbital inclinations. Planets can also get scattered to large distances. Large-a planetary orbits created from planet-planet scattering are expected to have high eccentricities (e). Theoretical models predict that the observed long-period planets, such as Fomalhaut-b have moderate e ~ 0.3. Interestingly, these are also in systems with disks. We find that if a massive-enough outer disk is present, a scattered planet may be circularized at large a via dynamical friction from the disk and repeated scattering of the disk particles.
- Publication:
-
The Astrophysics of Planetary Systems: Formation, Structure, and Dynamical Evolution
- Pub Date:
- November 2011
- DOI:
- 10.1017/S1743921311020229
- arXiv:
- arXiv:1012.0584
- Bibcode:
- 2011IAUS..276..225C
- Keywords:
-
- scattering;
- methods: n-body simulations;
- methods: numerical;
- planetary systems;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- 5 Pages, 2 Figures, submitted to IAUS 276 conference proceedings