Description: Mysterious Planet Nine
If the ninth planet is there, a huge and mysterious planet lurking on the dark edge of the solar system, then it may not be where we imagined it to be.
According to astronomers who study this hypothetical object, and with some new information, Planet Nine's orbit may be more elliptical than we thought.
Artist creation of Planet Nine (Nagual Design/TOM RUEN/ESO/Wikipedia Share)
In 2016, astronomers Konstantin Batygin and Michael Brown of the California Institute of Technology published a paper in the Journal of Astronomy where the hypothetical planet Nine appeared; in the paper, they elaborated on an undiscovered planet in the outer reaches of the solar system. They say the evidence exists in other objects far from Neptune's orbit.
These objects are known as extreme trans-Neptune objects; they have a large elliptical orbit that does not exceed Neptune, with perihelion being 30 astronomical units closest and aphelion points up to 150 astronomical units. Battigin and Brown found that these orbits have the same angle at perihelion(i.e., the point closest to the Sun in their orbit).
Astronomers conducted a series of simulations and found that if a large planet existed, its gravitational pull could cause the orbits of these objects to have such a clustering effect. Since the paper was published, this theory has become very controversial, because many astronomers have found that Planet Nine is unlikely to exist, but so far, we have no conclusive evidence to prove that it exists or does not exist. The most convincing way to resolve this controversy is to find this cunning object — and latest research from Battigin and Brown may help us accomplish this mission.
Their new paper has been accepted by the Astrophysical Journal Letters, and a preprint is available on the arXiv server.
Back in 2016, initial detection of a possible Planet Nine was based on only 6 ETNOs (extreme trans-Neptune objects), which, after all, were very small and very difficult to detect. Over time, more ETNO was discovered, and today we know 19 of them; this means that now we have more data to analyze and calculate the planet's characteristics.
In 2019, astronomers corrected existing information and found that their previous results were inaccurate. According to the corrected results, the planet has only five times the mass of Earth, not 10 times that they originally calculated, and its eccentricity — ellipticality — is lower.
Now they will update these calculations again.
"However," they wrote in an article on the Planet Nine blog, "what we ask ourselves at the most popular time of this theory is another question: Are basic physics concepts missing from our simulations?" Through our continuous exploration of the model, we found that the answer to this question is 'Yes'. ”
Their simulations assume that any object that leaves the sun for more than 10,000 astronomical units would get lost in space, they said. What they don't take into account is that the Sun wasn't born in isolation, it could have been born alongside other stars in a huge, crowded cloud of star-forming. In this case, the infant solar system will almost certainly form the inner part of the Oort cloud, which is the shell of ice that surrounds the solar system, about 2,000 to 100,000 AU from the sun. The formation of giant planets such as Saturn and Jupiter would throw debris outward into interstellar space; but the gravitational perturbations of passing stars would push them back into the gravitational influence of the Sun, eventually forming the inner Oort cloud.
We tend to think that the Oort cloud just wanders around space and actually does nothing, but when Battikin and Brown conduct a series of new simulations, taking these physical factors into account, they find that objects inside the Oort cloud may indeed move a little.
However, Planet Nine has changed this picture on a qualitative level," the researchers said.
"Due to the long-term gravitational pull of Planet Nine's orbit, the inner Oort cloud object evolved on billions of time scales, slowly reinjecting into the outer solar system. So what happens to them? We simulated this process, taking into account perturbations from classical giant planets, planet Nine, passing stars, and Galactic tides, and they found that these re-injected internal Oort cloud objects could easily mix with the census of distant Kuiper Belt objects and even exhibit orbital aggregation. "
This means that some of the extreme trans-Neptune objects we found may actually originate in the Ault Cloud, which is really cool. However, the team's simulations also showed that the aggregation of Oort cloud matter was weaker and closer to the reality than that of objects from the Kuiper Belt.
This suggests that Planet Nine's more elliptical orbits explain the data better than the orbits discovered in the researchers' 2019 paper.
Until more research is done on the aggregated objects to determine which of them originated in the inner Oort cloud, we cannot know for sure how much eccentricity the orbit may have; however, its degree of eccentricity is limited until the orbit is inconsistent with our observations of the outside of the solar system.
Because the hypothetical planet is so distant and dim, our chances of finding it are very low, so this information can be used to refine models and stop us from looking for it where it might not exist— hopefully to spot this elusive beast.
Although we never found it, the discoveries it brought were stunning. More new Jupiter moons and ultra-distant potential dwarf planets are not to be overlooked.
BY: MICHELLE STARR
FY: Dendi
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