Trojan Earths

In a protoplanetary disk around a young star, it is believed that regions with higher gas densities tend to concentrate solid material. If these high gas density regions are sufficiently long-lived, the aggregates of solid material within them can gravitationally collapse to form planets. The presence of a gas giant planet like Jupiter can create such long-lived, high gas density regions; especially around the gas giant planet’s leading (L4) and trailing (L5) Lagrangian points. The high gas density regions around L4 and L5 tend to concentrate solid material in a process known as Lagrangian trapping. A paper by Lyra et al. (2008) show that Lagrangian trapping can lead to gravitational collapse of aggregated solid material and form objects with masses in the regime of terrestrial planets (~ 0.1 to 10 Earth masses).Figure 1: A contour plot showing the 5 Lagrangian points of the Sun-Earth system. The same layout of the 5 Lagrangian points also applies for the Sun-Jupiter system. The regions around the leading (L4) and trailing (L5) Lagrangian points are “islands of stability”.As a gas giant planet orbits around its infant star, it clears out a wide gap in the protoplanetary disk. The environment within the gap is depleted ...