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posted by mrpg on Wednesday May 30 2018, @01:45AM   Printer-friendly
from the far-away-systems dept.

How we discovered 840 minor planets beyond Neptune – and what they can tell us

The new discoveries were made as part of a five year project called the Outer Solar System Origins Survey (OSSOS). The observations, conducted in 2013-2017, used the imaging camera of one of the world's major telescopes – the Canada-France-Hawaii Telescope on Maunakea in Hawaii. The survey looked for faint, slow-moving points of light within eight big patches of sky near the plane of the planets and away from the dense star fields of the Milky Way.

With 840 discoveries made at distances between six and 83 astronomical units (au) – one such unit is the distance between the sun and the Earth – the survey gives us a very good overview of the many sorts of orbits these "trans-Neptunian objects" have.

[...] We found 313 resonant trans-Neptunian objects, with the survey showing that they exist as far out as an incredible 130au – and are far more abundant than previously thought. Among these discoveries is the dwarf planet 2015 RR245, which is about half the size of Britain. It may have hopped onto its current orbit at 82au after an encounter with Neptune hundreds of millions of years ago. It was once among the 90,000 scattered objects of smaller size that we estimate currently exist.

The survey searched 155.3 square degrees of sky.

OSSOS. VII. 800+ Trans-Neptunian Objects—The Complete Data Release (open, DOI: 10.3847/1538-4365/aab77a) (DX)

The OSSOS discoveries include nine TNOs with q [perihelion] > 30 au and a [semimajor axis] > 150 au, eight of which have q > 38 au. [...] There has been recent interest in the apparent angular clustering of the MPC-listed TNOs with a > 150 au orbits, which some have hypothesized as evidence for a massive distant planet (Trujillo & Sheppard 2014; Batygin & Brown 2016). [...] Formation mechanisms for this distant population are not yet clear, and it remains an area of active investigation (e.g., Lawler et al. 2016; Nesvorny et al. 2017). However, all of the extreme TNO discoveries of OSSOS are consistent with a formation by random diffusion in semimajor axis due to weak kicks at perihelion by Neptune from orbits with semimajor axes in the inner fringe of the Oort cloud, as proposed in Bannister et al. (2017).


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  • (Score: 0) by Anonymous Coward on Wednesday May 30 2018, @11:37AM

    by Anonymous Coward on Wednesday May 30 2018, @11:37AM (#686222)
    Eris [wikipedia.org] is more massive than Pluto. There could potentially be still bigger TNOs out there.