: The diversity of planetary system architectures: contrasting theory with observations

MIGUEL, Y.; GUILERA, O. M.; BRUNINI, A.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2011 vol. 417 p. 314 - 332

0035-8711

In order to explain the observed diversity of planetary system architectures and relate thisprimordial diversity to the initial properties of the discs where they were born, we develop asemi-analytical model for computing planetary system formation. The model is based on thecore instability model for the gas accretion of the embryos and the oligarchic growth regimefor the accretion of the solid cores. Two regimes of planetary migration are also included.Withthis model, we consider different initial conditions based on recent results of protoplanetarydisc observations to generate a variety of planetary systems. These systems are analysedstatistically, exploring the importance of several factors that define the planetary system birthenvironment. We explore the relevance of the mass and size of the disc, metallicity, mass ofthe central star and time-scale of gaseous disc dissipation in defining the architecture of theplanetary system.We also test different values of some key parameters of our model to find outwhich factors best reproduce the diverse sample of observed planetary systems. We assumedifferent migration rates and initial disc profiles, in the context of a surface density profilemotivated by similarity solutions. According to this, and based on recent protoplanetary discobservational data, we predict which systems are the most common in the solar neighbourhood.We intend to unveil whether our Solar system is a rarity or whether more planetary systemslike our own are expected to be found in the near future. We also analyse which is the morefavourable environment for the formation of habitable planets. Our results show that planetarysystems with only terrestrial planets are the most common, being the only planetary systemsformed when considering low-metallicity discs, which also represent the best environment forthe development of rocky, potentially habitable planets. We also found that planetary systemslike our own are not rare in the solar neighbourhood, its formation being favoured in massivediscs where there is not a large accumulation of solids in the inner region of the disc. Regardingthe planetary systems that harbour hot and warm Jupiter planets, we found that these systemsare born in very massive, metal-rich discs. Also a fast migration rate is required in order toform these systems. According to our results, most of the hot and warm Jupiter systems arecomposed of only one giant planet, which is also shown by the current observational data.