The origin of (47171) Lempo-like Kuiper belt triple systems during binary-binary interactions

BRUNINI, A. LOPEZ, C.

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2020 vol. 499 p. 4206 - 4212

0035-8711

The trans-Neptunian triple Lempo?Paha?Hiisi is composed of a tight inner binary with components of similar size and an outercompanion about half their size orbiting 10 times further away. Large trans-Neptunian objects like Pluto also have multiplesmall moons, but Lempo?s structure is unique in the Solar system, and the place and timing of its origin is still a subject ofdebate.We propose a new formation mechanism able to form a large number of systems like Lempo?Paha?Hiisi, which involvesbinary?binary close encounters in the primordial planetesimal disc at 30?40 au. Some of these systems were then implanted indifferent populations of the trans-Neptunian region during Neptune?s outward migration. Our results strongly support that the4:7 resonant multiple object Manw¨e?Thorondor was once a triple system similar to Lempo?Paha?Hiisi, but the orbit of the innerbinary evolved by tides, becoming a contact binary. As with Lempo?Paha?Hiisi, it should have originated in the planetesimal discbelow 30?40 au. Triple systems like Lempo?Paha?Hiisi or Manw¨e?Thorondor could not have formed in situ and the existenceof this kind of system is not expected in the cold classical Kuiper belt.