Exoplanets: The tip of the iceberg?

Abstract

As the number of large scale ground- and space-bound planet detection and imaging projects is growing, the need for theoretical guidance in order to optimize instrumental design is rapidly mounting. In an effort to provide this required framework, we present the results of Monte Carlo simulations of the formation of giant planets and compare them with the current population of exoplanets. Our models show that due to the severe current observational detection bias only a small percentage (3.6 %) of the potentially existing planets can be detected. Indeed, a large number of planetary embryos never grow enough to become giant planets giving raise to a large populations of bodies with masses smaller than ${\simeq} 5 M_{\hbox{\it \scriptsize jup}}$. In addition, this observational bias, coupled with the fact that systems enriched in heavy elements tend to form more massive planets, explains the currently observed correlation between stellar metallicity and likelihood to host planets. Finally, we show that the disk gas delivery rate during the late stages of formation actually determines the maximum planetary mass.