Key science questions

The following have been identified as key science questions for the Formation and Evolution of Planetary Systems theme:

• Circumstellar disk evolution and Planet formation
  • How are the temporal evolution of circumstellar disks and the formation of planets connected? What is the role of planet-disk interactions on the planetary system formation process?
  • Which roles do host mass and metallicity play?
  • What is the role of the star/planet formation environment (low-mass vs. high-mass star forming regions, clusters)?
  • Which are the conditions that decide about predominance the planet formation scenario: Core accretion vs. Gravitational instability?
  • Are there fundamental differences in the planet formation in single vs. binary/multiple systems?
  • What range of terrestrial planet compositions is produced through the processes of planet formation?

• Evolution of planetary systems
  • Are there common criteria for the long-term stability of planetary systems?
  • What is the "typical" planetary architecture, and what range is realized in nature?
  • How does planet migration affect the resulting planetary architectures?
  • What is the correlation of the presence of telluric planets with existence of superearths and gas giants?
  • Is there a correlation between the existence and location of planetesimal belts and the existence of planets?
  • Do exo-Oort’s clouds exist and what is their role in the planet formation/evolution process?
  • What are the properties of potentially existing free-floating Earth-mass objects?
  • Which are the major unique characteristica of the Solar System?

• Habitable Zone
  • Which parameters determine the region of the habitable zone in planetary systems? (Rem.: Is the term ``habitable zone’’ a good working term at all?: a) There are many parameters that play a role to provide liquid water. b) There are many further parameters — beyond the existence of liquid water — that obviously played a major role to make Earth habitable.)
  • Are giant outer planets a prerequisite for inner telluric planets with habitable zones?
  • How does the stellar habitable zone evolve in time?
  • Which are additional criteria which determine the habitability of planetary satellites?
  • Is it possible to identify / separate a galactic habitable zone (bulge, disk, halo, clusters)?
  • How might the formation history and subsequent dynamical evolution affect the potential for habitability? (e.g. outgasing, loss of atmosphere, internal energy and hence plate tectonics, impacts, orbital change, stability).