Article Description

The final stage of rocky planet formation involves giant impacts between planet-sized bodies. For planets in regions around where Mercury, Venus, Earth, and Mars are in our solar system, it has previously been shown that such collisions, while epic, are still of sufficiently low velocity to allow for mergers to dominate over fragmentation and thus for planets to be able to form. In this paper, we show analytically that, depending on the exact value of some parameters, this may or may not be the case for regions very close to stars (much closer than Mercury is to the Sun), though the values we think are correct show that planet formation is possible. We then report results from over 100 N-body simulations that show planet formation via giant impacts is still possible all the way down to the Roche radius, where tidal forces are so strong that planet formation is not possible anyway.