Trans-Neptunian binary formation and evolution

BRUNINI, A.

The Trans-Neptunian Solar System

eLSEVIER

Lugar: New York; Año: 2020; p. 225 - 247

We will review the physical mechanisms involved in the dynamical evo-lution of Trans Neptunian Binaries (TNB). They include: gravitationalencounters with massive objects, the impulse transferred in the collisionswith objects of the background population of Trans Neptunian Objects,Kozai oscillations of the binary mutual orbit induced by the Sun and bythe planets, tidal friction on both the primary and the secondary compo-nent of the binary and perturbations due to the non sphericity of them.Then, we will show that, acting together, all these effects seem to explainmost of the orbital characteristics of the known binary systems. Giventhe number of surviving binaries after 4.5 Gy of dynamical evolution andthe binary fraction observed today, it is plausible to suggests that allthe planetesimals in the outer solar system should have born as bina-ries or multiple systems. TNB belonging to the Centaur population haveshort dynamical life times. In the frame of the present understandingabout binary evolution in the outer solar system, binary Jupiter FamilyComets would be found mainly in the form of contact binaries. If a pop-ulation of binary systems survived to the instability phase of the OuterSolar System as Neptune Trojans, we would have at present a consider-able fraction of them already in the Trojan Clouds. The observationalevidence does not rule out this possibility. As the dynamical evolutionof TNB involves strong diffusive mechanisms that could erase much oftheir primordial orbital structure, it would be necessary to accumulatemore observational data and the computation of mutual orbits, to imposedefinitive constraints to the proposed formation mechanisms.