If Planet Nine is there, a large, mysterious planet lurking in the dark corners of the solar system may not be where we thought it might be.
According to astronomers looking for the hypothetical object, the new information taken into account could mean that its orbit is significantly more elliptical than recently predicted.
The hypothetical planet Nine made a big comeback in 2016 when astronomers Konstantin Batigin and Michael Brown of Caltech published an article in The Astronomical Journal. In it, they present their argument for a still undiscovered planet in the outer current of the solar system. According to them, the evidence is hidden in other objects far beyond the orbit of Neptune.
These objects are called Extreme Trans-Neptunian Objects (ETNO). They have huge elliptical orbits that never pass closer to the Sun than Neptune̵
Batygin and Brown found that these orbits had the same angle in the perihelion, the point in their orbit that was closest to the Sun. Astronomers have conducted a series of simulations and found that the gravitational influence of a large planet can group orbits in this way.
Since this paper fell away, the theory has become very controversial, with many astronomers considering the existence of Planet Nine unlikely, but so far we have no hard evidence in one way or another. The most convincing way to settle the debate is if we find the slippery slope – and a new update from Batygin and Brown can help us try to do that.
Their new document was adopted in Astrophysical Journal Letters, and is available on the arXiv prepress server.
The initial discovery of a possible Planet Nine in 2016 was based on only six ETNOs – these sites are ultimately very small and very difficult to detect. Over time, more ETNOs have been discovered – we know about 19 today – which means we now have more data to analyze to calculate the planet’s characteristics.
In 2019, astronomers reviewed the available information and concluded that they had received several things a little incorrect. According to the revision, the mass of the planet was only five times the mass of the Earth, not the 10 that they originally calculated, and its eccentricity – how elliptical – was lower.
And now they have updated these calculations again.
“But,” they wrote in a blog post, Find Planet Nine, “the question we asked ourselves during the height of the pandemic is different: is there a lack of basic physics in our simulations?” Through our continuous and continuous study of the model, we found that the answer to this question is yes. “
According to their simulations, any object moving more than 10,000 astronomical units from the Sun is lost in space. What they didn’t take into account was that the Sun was not born in isolation, but probably in a large, highly populated star-forming cloud with other baby stars.
Under these conditions, the baby’s solar system would almost certainly form an inner section of the Oort cloud, the shell of ice bodies surrounding the solar system, between about 2,000 and 100,000 astronomical units of the Sun. The formation of giant planets such as Saturn and Jupiter would throw debris out into interstellar space; but the gravitational perturbations of the passing stars would push them back to the gravitational influence of the Sun, so that they would eventually form the inner Oort cloud.
We tend to think of the Oort cloud as something just hanging around, not really doing anything, but when Batigin and Brown did a whole bunch of new simulations, taking this physics into account, they found that objects in the inner region of the Oort Cloud could to move a little.
“But Planet Nine is changing that picture on a qualitative level,” the researchers said.
“Due to the long-term gravitational pull of Planet Nine’s orbit, the inner objects of the Oort Cloud evolve over billions of years, slowly being re-injected into the outer solar system. So what happens to them? We simulated this process, taking into account interference from canonical giant planets, Planet Nine, passing stars, and the galactic tide, and have found that these re-injected inner objects of the Oort Cloud can easily be mixed with counting distant objects in the Kuiper Belt and even show orbital grouping. “
This means that some of the extreme trans-Neptune objects we found could actually originate from the Oort cloud, which is really great. However, team simulations also showed that the grouping of Oort Cloud objects would be weaker than that of objects coming from the Kuiper Belt closer.
This suggests that a more eccentric orbit for Planet Nine would explain the data better than the orbit found in the 2019 researchers’ article.
We will not know exactly how eccentric this orbit could be until more research can be done on the grouped objects to determine which one originates from the inner Oort cloud; but there is a limit to how eccentric the orbit can become before it is no longer consistent with our observations of the outer solar system.
Because the hypothetical planet is so far away and so dark, our chances of spotting it are really low, so this information can be used to refine patterns and stop us from looking for it where it may not be – hopefully lead to the discovery of this elusive beast.
Even if we never found it, the discoveries it led to were great. A whole bunch of new Jovian moons and ultra-distant potential dwarf planets are not for sneezing.
Batygin and Brown’s new document was adopted in Astrophysical Journal Letters, and is available on arXiv.