An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

An act or instance of emigrating; a body of emigrants; emigrants collectively.

Verbal noun of → emigrate.

1) The process or act of migrating; a migratory movement.
2) For an astronomical body, the process or act of changing its place over considerably large distances under the effect of certain physical forces. See, for example, → orbital migration; → Type I migration; → Type II migration.
3) Chem.: A movement or change of position of atoms within a molecule (Dictionary.com).

→ migrate; → -tion. Kuc "the act of moving from a dwelling, a place to another, decamping, migration."

Theoretical prediction according to which a → giant planet, formed in the outer regions of a → protoplanetary disk, could migrate inward by losing → energy and → angular momentum as the result of → gravitational interactions with the remnants of the disk. This orbital migration could explain the presence of giant gaseous Jupiter-like planets (→ hot Jupiters) very close to their host stars.

→ orbital; → migration.

The process whereby a → disk star changes its → galactocentric distance. Radial migration involves → angular momentum transfer, resulting from → resonances created by transient → density waves such as → bars or → spiral arms in → galactic disks. According to → galactic dynamics models, → churning is the main cause of radial migration. Radial migration of stars plays an important role in shaping the properties of galactic disks.

→ radial; → migration.

An → orbital migration of low-mass → planets in which no gap is created in the → protoplanetary disk. According to planetary models, beyond a critical core mass for the forming planet, a gap in the protoplanetary disk is created. The critical mass depends on the mass and → metallicity of the disk and therefore it does not have a singular value, but has been shown to be between about 10-30 Earth masses. Compare with → Type II migration.

→ type; → migration.

The → orbital migration of forming → planets that → accrete enough disk material to exceed the critical mass. This type migrates in a gap created in the → protoplanetary disk. Compare with → Type I migration.

→ type; → migration.