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Mars-Sized Planetary Mass Object Could be Influencing Nearby Kuiper Belt Objects

posted by martyb on Monday June 26 2017, @12:06AM   
from the warp-and...weft? dept.

takyon writes:

Astronomers are inferring the existence of a "Planet Ten" (or actually the true "Planet Nine"?), a Mars-sized body in the Kuiper Belt, several times closer to the Sun than where the hypothetical Neptune-like Planet Nine is expected to be:

An unknown, unseen "planetary mass object" may lurk in the outer reaches of our solar system, according to new research on the orbits of minor planets to be published in the Astronomical Journal. This object would be different from — and much closer than — the so-called Planet Nine, a planet whose existence yet awaits confirmation.

In the paper, Kat Volk and Renu Malhotra of the University of Arizona's Lunar and Planetary Laboratory, or LPL, present compelling evidence of a yet-to-be-discovered planetary body with a mass somewhere between that of Mars and Earth. The mysterious mass, the authors show, has given away its presence — for now — only by controlling the orbital planes of a population of space rocks known as Kuiper Belt objects, or KBOs, in the icy outskirts of the solar system.

[...] According to the calculations, an object with the mass of Mars orbiting roughly 60 AU from the sun on an orbit tilted by about eight degrees (to the average plane of the known planets) has sufficient gravitational influence to warp the orbital plane of the distant KBOs within about 10 AU to either side.

Also at New Scientist.

The curiously warped mean plane of the Kuiper belt

We estimate this deviation from the expected mean plane to be statistically significant at the ∼97−99% confidence level. We discuss several possible explanations for this deviation, including the possibility that a relatively close-in (a≲100~au), unseen small planetary-mass object in the outer solar system is responsible for the warping.

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Original Submission

• Re:amusing perspective Re:amusing perspective (Score: 2) by stormwyrm on Monday June 26 2017, @01:04AM (1 child)

  by stormwyrm (717) on Monday June 26 2017, @01:04AM (#531046) Journal

  All science is provisional. [hermiene.net] The lack of disclaimers is something of a convention. If you're sure enough about something to several sigmas then you might as well say it with certainty. The exoplanet data is certain enough to that degree. A substantial planet though, even one on the scale of Uranus or Neptune somewhere in the Kuiper belt however is a lot harder to see. You'd think that something 10 times as far as Uranus and about the same size would be only be 100 times as faint, because brightness is inverse square. However, the hypothetical planet is not giving off its own light but reflecting sunlight, so the falloff is more like an inverse fourth power, which at that distance would make it incredibly dim. The only way you're going to be able to figure out that such a planet might exist is by having a look at the objects in its vicinity that you can see for anomalies in their orbits. It was how Neptune was first discovered, by anomalies in the orbit of Uranus. From there astronomers were able to guess at the likely orbit of the hypothetical planet and point their telescopes in the region of the sky thus indicated. In that way Urbain le Verrier was able to discover Neptune. The hypothesis of Planet Nine rests upon anomalous clusterings of orbits of certain known Kuiper belt objects. However, the most recent available data disfavours the existence of such a large planet [ossos-survey.org] of Uranus/Neptune scale in the Kuiper belt, though the existence of a smaller, Mars-sized body as hypothesised in TFA is not ruled out.

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• Re:amusing perspective (Score: 2) by takyon on Monday June 26 2017, @01:08AM

  by takyon (881) <takyonNO@SPAMsoylentnews.org> on Monday June 26 2017, @01:08AM (#531050) Journal

  However, the most recent available data disfavours the existence of such a large planet of Uranus/Neptune scale in the Kuiper belt

  That is disputed [sciencemag.org]:

  “I think it’s great work, and it’s exciting to keep finding these,” says Scott Sheppard, an astronomer at the Carnegie Institution for Science in Washington, D.C., who was among the first to suspect a large planet in the distant solar system. But he says three of the four new objects do have clustered orbits consistent with a Planet Nine. The fourth, an object called 2015 GT50, seems to skew the entire set of OSSOS worlds toward a random distribution. But that is not necessarily a knockout blow, he says. “We always expected that there would be some that don’t fit in.”

  The OSSOS team says any apparent clustering in their new objects is likely to be the result of bias in their survey. Weather patterns and a telescope’s location, for instance, determine what areas of the sky it can look at and when. It is also harder to see faint solar system objects in bright areas on the sky like the galactic center.

  Such biases make OSSOS more likely to find objects in regions that support the Planet Nine hypothesis, says OSSOS team member Michele Bannister, an astronomer at Queen’s University Belfast in the United Kingdom. When the team corrects for that effect, the apparent clustering vanishes. By contrast, the OSSOS team says, many details of the surveys behind the original six objects are unpublished, making it impossible to understand their biases.

  That argument does not impress Mike Brown, an astronomer at the California Institute of Technology (Caltech) in Pasadena, who along with Caltech colleague Konstantin Batygin catapulted Planet Nine into the mainstream with their bold claim. “Their main conclusion is that their observations are hopelessly biased, and it’s true,” he says. “But they then kind of make the leap of faith that everybody else’s must be biased, too.” For Brown, any biases in the hodgepodge of surveys that found the earlier objects should average out. That would make the clustering real—whether caused by Planet Nine or not.

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