Kane notes that moons near the edge of the Hill radius may be subject to resonant removal during planetary migration, leading to a Hill reduction factor roughly estimated as 1/3 for typical systems and 1/4 for the TRAPPIST-1 system; thus moons are not expected for the planets where R H / R R {\displaystyle R_{H}/R_{R}} is less than four.
Kane sinala que as lúas próximas ó bordo do radio de Hill poden estar suxeitas a eliminación da resonancia durante a migración planetaria, o que supón un factor de redución de preto de aproximadamente 1/3 para os sistemas típicos e 1/4 para o sistema TRAPPIST-1; polo tanto, non se esperan lúas para os planetas onde R H / R R {\displaystyle R_{H}/R_{R}} sexa inferior a catro.