Tidal stimulation of the formation of the outer planets

点击翻译按钮获取中文摘要

Planet formation is a key issue in current astronomy and astrophysics, and as such it is subject to ongoing debates. An increasing amount of observational data on extrasolar planetary systems repeatedly challenges theoretical models. While many details on the basic mechanisms of forming planetesimals from dust and protoplanets from planetesimals are still unclear, there is increasing evidence for fingerprints of a dense dynamical birth environment of planetary systems like ours. The discoveries of exoplanets on strongly eccentric and/or misaligned orbits suggest even more complex dynamics in forming planetary systems than previously thought. Even our Sun exhibits a modest misalignment of 7degree wrt. the ecliptic plane, and, besides the eight regular planets, our Solar Systems also hosts a variety of minor planets on distant and eccentric orbits (e.g. Sedna). Their origin poses a challenge to current planet formation theory. The project which I am herewith applying for focuses on an attempt to understand these peculiar features of our Solar System through a yet rarely attended scenario of tidal perturbations of protoplanetary discs and material exchange in gas-rich star-forming environments, which may have played an important role in the formation of the Edgeworth-Kuiper Belt. In particular, transient vortices caused by the tidal forces by passing stars in the birth cluster or by the inflow of gas from dense structures inside the star-forming region and the possibility of enhanced dust coagulation inside these vortices will be analysed. In addition, the consequences of repeated accretion due to disc perturbations on the Solar chemistry, particularly the observed Lithium depletion, will be studied. To my knowledge no other group is working on this environment-driven ansatz to explain the peculiar features of the Solar System.