Origin of hot Super-Earths and the vortex-assisted mode of planet formation (NASA proposal number 16-XRP16_2-0063)

In spite of steady advances, planet formation remains, by and large, a mystery. Although a relatively consistent theory has been developed in the past two decades, its application to the observed distribution of exoplanets has not fared too well. In this proposal, we aim to solve one of the most vexing problems that arose from this comparison, which is the prediction of a dearth of planets of 5?15M? at close separation from the star. However, as shown by Ke- pler, these Hot Super-Earths are in fact the most common type of planet. The usual explanation for close-in planets, i.e., migration from outer orbits, fails to explain them because due to their large gravitational cross-section, Super-Earths capture a lot of solid material during their mi- gration, developing a large mass (>20-30M?) and subsequently capturing gas from the nebula. Here we aim to show that in situ formation is a promising mechanism to explain these Super- Earths. The in situ formation is possible because 1). the inner boundary between turbulent and laminar zones is at ? 0.1 AU, 2). Large-scale vortices are predicted in this transition, 3) Vortices should be excellent planet formation sites; 4) Pebble drift from the dead zone brings more planet building blocks to the vortex; and 5) The turbulent/laminar zone boundary is also a migration stopping point. We propose two sets of hydrodynamical simulations including embedded pebbles: one to decisively demonstrate the efficiency of vortex-assisted planet formation, and a second to test whether this planet formation mode leads to in situ growth of Super-Earths.