The "strongest statistical evidence yet" that there is a planet of this type orbiting at the edges of the Solar System may have been found. This is what astronomer Konstantin Bogytin, from the California Institute of Technology (Caltech), told The Independent.

Scientists say they have found evidence of an unknown planet in our solar system
New findings represent the ‘strongest statistical evidence yet’ that Planet 9 exists, researcher says
The IndependentAndrew Griffin

According to the researcher, to reach this conclusion, the team analyzed the movement of Trans-Neptunian Objects (TNOs), i.e. celestial bodies of various sizes beyond Neptune's orbit, which include dwarf planets such as Pluto and Eris.

The team focused on TNOs that were overlooked due to their unstable movements, caused by Neptune's gravity. This instability makes their paths more difficult to interpret, but the researchers were happy to accept the challenge.

The data was then entered into simulations and combined with known forces from other planets, passing stars and the galactic tide coming from the Milky Way - the push and pull of the galaxy itself. Two sets of simulations were run: one which assumed that Planet Nine was where astronomers think it might be, and another which simply assumed that Planet Nine doesn't exist.

"Taking into account observational biases, our results reveal that the orbital architecture of this group of objects aligns closely with the predictions of the inclusive P9 model," wrote the researchers, quoted by Science Alert.

‘Strongest Statistical Evidence Yet’ For Planet Nine Has Been Found, Scientist Says
The hunt for the elusive Planet Nine goes on, and new research claims to have the “strongest statistical evidence yet” that there is such a planet orbiting somewhere around the far edges of the Solar System.
ScienceAlertDavid Nield

However, the researchers admit that we are still a long way from obtaining conclusive proof that Planet Nine exists.

Previous attempts to detect it by analyzing its hypothetical effects on the rest of the Solar System have been insufficient. Nevertheless, as more powerful telescopes appear, this question has an increasing chance of being resolved.

Based on the team's calculations, a planet matching the expected characteristics of Planet Nine would be relatively small, with a mass only five times that of Earth and a distance around 500 times greater than our distance from the Sun.

The scientific article has been accepted for publication in the Astrophysical Journal Letters and can be consulted on arXiv .

Generation of Low-Inclination, Neptune-Crossing TNOs by Planet Nine
The solar system’s distant reaches exhibit a wealth of anomalous dynamical structure, hinting at the presence of a yet-undetected, massive trans-Neptunian body - Planet 9. Previous analyses have shown how orbital evolution induced by this object can explain the origins of a broad assortment of exotic orbits, ranging from those characterized by high perihelia to those with extreme inclinations. In this work, we shift the focus toward a more conventional class of TNOs, and consider the observed census of long-period, nearly planar, Neptune-crossing objects as a hitherto-unexplored probe of the Planet 9 hypothesis. To this end, we carry out comprehensive $N-$body simulations that self-consistently model gravitational perturbations from all giant planets, the Galactic tide, as well as passing stars, stemming from initial conditions that account for the primordial giant planet migration and sun’s early evolution within a star cluster. Accounting for observational biases, our results reveal that the orbital architecture of this group of objects aligns closely with the predictions of the P9-inclusive model. In stark contrast, the P9-free scenario is statistically rejected at a $\sim5\,σ$ confidence-level. Accordingly, this work introduces a new line of evidence supporting the existence of Planet 9 and further delineates a series of observational predictions poised for near-term resolution.
arXiv.orgKonstantin Batygin