Astrophysics (index)about

tidal capture

(bodies entering orbit through dissipation of energy by tides)

Tidal capture refers to independent bodies entering orbit when passing close, by slowing down relative to each other through tidal forces between them. It affects only non-ridged bodies such as stars, or planets that have sizeable envelopes. It is an alternative to dynamic capture aka three-body capture, where gravity from a third body slows the relative motion of the two entering orbit. Tidal capture may be a significant means by which binary stars are formed (i.e., tidal-capture binaries) in volumes that have a very high density of stars, such as the central regions of globular clusters.

Both tidal or dynamic capture require a happenstance of bodies passing close, but dynamic capture should be far more rare since it requires the coincidence of a third body passing close as well. Likely more common is a swap, an interaction between a binary star and an additional star such that one of the binary pair ends up as a binary with the other star.


Referenced by:
binary star