In a his new first-author paper (now on arXiv), UW–Madison undergraduate alumni Devansh Mathur investigates what happens to small planetary embryos interior to a forming hot Jupiter. Using hundreds of N-body simulations, he showed that if enough solid material is pushed inward during short-range migration, both the giant planet and smaller interior companion planets could grow in place.
With a second set of simulations, he found that the fate of these embryos depends strongly on the giant planet’s semi-major axis. When the hot Jupiter is close to the star, its gravity stirs the inner disk, driving frequent collisions that merge embryos into Earth-sized planets. Farther out, embryos experience fewer interactions and remain smaller, with little mass loss overall. Most material stays bound (reshaped, not removed) showing how compact inner companions can form alongside hot Jupiters.
This work has now been accepted for publication in the Publications of the Astronomical Society of the Pacific (PASP). Congratulations, Devansh, on your first paper!