The hunt for Planet 9 continues

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The hunt for the hypothetical Planet 9 in the outer solar system continues, with several recent research papers providing new evidence and insights:

New Evidence from Neptune-Crossing Objects

A new study by Konstantin Batygin and colleagues, accepted for publication in The Astrophysical Journal Letters, analyzes the orbits of long-period, nearly planar, Neptune-crossing objects in the outer solar system. Their computer simulations, accounting for the gravitational influence of the known planets, galactic tides, and passing stars, show that the observed orbital properties of these objects align closely with predictions of models that include Planet 9. This provides some of the strongest statistical evidence yet for Planet 9's existence.

Narrowing Down the Search Area

A recent analysis using data from the Pan-STARRS1 survey has ruled out the existence of a Planet 9 with the predicted characteristics in a large portion of the hypothesized search area. Combined with previous analyses of data from the Zwicky Transient Facility and Dark Energy Survey, this result eliminates about 78% of the proposed orbital parameter space for Planet 9. The remaining regions to search are largely near the galactic plane where the high density of stars makes detection more difficult.

Indirect Detection through Potential Satellites

Another novel approach proposed by Man Ho Chan suggests looking for potential satellites of Planet 9. Tidal heating effects could make these satellites detectable in the infrared by telescopes like ALMA, even if Planet 9 itself remains elusive.

Ongoing Observational Efforts

The upcoming Vera Rubin Observatory is expected to greatly aid the search when it begins operations. Its ability to survey large areas of the sky to great depth should allow a more comprehensive assessment of whether Planet 9 exists. While the evidence for Planet 9 has grown, it remains a hypothetical world until it can be directly observed. Astronomers will continue scanning the outer solar system in hopes of finally spotting this elusive giant planet in the years to come. The possibility of making such a momentous discovery continues to motivate this exciting astronomical detective work.
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