2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/6436According to current theories, tidal interactions between a disk and an embedded planet may lead to the rapid migration of the protoplanet on a timescale shorter than the disk lifetime or estimated planetary formation timescales. Therefore, planets can form only if there is a mechanism to hold at least some of the cores back on their way in. Once a giant planet has assembled, there also has to be a mechanism to prevent it from migrating down to the disk center. This paper reviews the different mechanisms that have been proposed to stop or slow down migration.8 pages, submitted for publication in 'Planetary Systems and Planets in Systems', eds. S. Udry, W. Benz and R. von Steiger (ISSI Space Sciences Series, 19, reprinted from Space Science Reviews - Kluwer)Astrophysicstext