Earth-Life Science Institute | Tokyo Institute of Technology | 2019 Jun 26
Scientists use sophisticated computer simulations and observations of Trans-Neptunian Objects to understand the formation of the solar system.
Using sophisticated computer simulations and observations, a team led by researchers from the Earth-Life Science Institute (ELSI) at Tokyo Institute of Technology has shown how the so-called trans-Neptunian Objects (or TNOs) may have formed. TNOs, which include the dwarf planet Pluto, are a group of icy and rocky small bodies--smaller than planets but larger than comets--that orbit the Solar System beyond the planet Neptune. TNOs likely formed at the same time as the Solar System, and understanding their origin could provide important clues as to how the entire Solar System originated.
Largest TNOs with 1000 km in diameter and their satellite(s). The masses of the
satellite(s) range from 1/10 to 1/1000 of the corresponding TNOs. For comparison,
Earth and Moon are also shown. Credit: NASA/APL/SwRI/ESA/STScI
Like many solar system bodies, including the Earth, TNOs often have their own satellites, which likely formed early on from collisions among the building blocks of the Solar System. Understanding the origin of TNOs along with their satellites may help understand the origin and early evolution of the entire Solar System. The properties of TNOs and their satellites--for example, their orbital properties, composition and rotation rates--provide a number of clues for understanding their formation. These properties may reflect their formation and collisional history, which in turn may be related to how the orbits of the giant planets Jupiter, Saturn, Neptune, and Uranus changed over time since the Solar System formed. ...
The Tokyo Tech study found that the size and orbit of the satellite systems of large TNOs are best explained if they formed from impacts of molten progenitors. They also found that TNOs which are big enough can retain internal heat and remain molten for a span of only a few million years; especially if their internal heat source is short-lived radioactive isotopes such as Aluminum-26, which has also been implicated in the internal heating of the parent bodies of meteorites. Since these progenitors would need to have a high short-lived radionuclide content in order to be molten, these results suggest that TNO-satellite systems formed before the outward migration of the outer planets, including Neptune, or in the first ~ 700 million years of Solar System history. ...
Early Formation of Moons Around Large Trans-Neptunian Objects via Giant Impacts ~ Sota Arakawa, Ryuki Hyodo, Hidenori Genda
- Nature Astronomy (online 24 Jun 2019) DOI: 10.1038/s41550-019-0797-9