Planetary Migration
Planetary migration is the inward or outward drift of a planet from its formation orbit due to disk torques, planet-planet scattering, or resonance capture. Migration is invoked to reconcile present-day orbits with formation locations implied by atmospheric composition — e.g., volatile-rich planets observed close to their stars must have migrated inward from beyond the water-ice-line.
The 2:1 mean motion resonance between toi-1130b (mini-Neptune) and its outer hot-Jupiter companion is a textbook architecture produced by convergent migration. Combined with toi-1130b’s high-mean-molecular-weight-atmosphere, it supports an ex-situ formation + inward migration history (src-jwst-toi-1130b-atmosphere-2026-05). The outer hot Jupiter likely “pebble-filtered” inner-disk solids, modulating what TOI-1130b accreted before migrating.
Interior–atmosphere decoupling (TOI-5205 b, 2026)
toi-5205-b — a Jupiter-sized GEMS giant around a 0.4 M☉ M dwarf — exhibits an atmospheric metallicity below its host star’s while interior models (ravit-helled, simon-muller, university-of-zurich) require the bulk planet to be ~100× more metal-rich. The team interprets this as heavy elements migrating inward within the planet during formation, with the interior and atmosphere subsequently ceasing to mix. This is a distinct migration-related signature from the standard inward-orbital-drift sense — migration within the planet rather than of the planet (src-sciencedaily-forbidden-exoplanet-atmosphere-2026-04).