Planet formation scenarios in dense star-forming environments

Ingo Thies 7.4.

Abstract:

The formation of planetary systems like the Solar System is not an isolated process but is embedded in a highly dynamical star-forming environment like, e.g., the Orion Nebula Cluster or the Carina Nebula. In particular, close encounters between stars and protostellar or protoplanetary nebulae are likely to influence the outcome of planet formation, e.g. through disc truncation and induced turbulence. Tidal perturbations and accidental multiple accretion may have altered the structure and the inclination of the protoplanetary disc relative to the early Sun, possibly explaining the observed truncation at ~50 AU and the 7 degree tilt between the ecliptic plane and the Solar equator. I will show that the strong interactions of this kind, which are most likely in very dense stellar systems, may even turn a planetary system upside down, placing certain limits on the size and mass of the Sun's birth cluster. In addition, I will discuss disc fragmentation as a possible formation channel for massive planets and brown dwarfs.