A hypothetical mystery planet that was supposed to be dependent on strange orbits in the outer Solar System had just dealt with one of the biggest hits yet.
According to a comprehensive study of distant objects, led by physicist Kevin Napier of the University of Michigan, Planet Nine may not exist – because the evidence does not exist. Instead, it is what astronomers have influenced by planetary gravity rather than selective bias in the observations.
The pre-printed paper has been uploaded to arXiv, and is awaiting peer review.
Planet Nine broke the scene in 2016, when astronauts Konstantin Batygin and Caltech-based Michael Brown published a paper The Astronomical Journal sets the scene for a planet not yet discovered in the outer spheres of the Solar System. The evidence, they said, lay in other objects far beyond Neptune’s orbit.
These objects are called Extreme Neptunian Extremes (ETNOs). They have large elliptical orbits, no closer to the Sun than Neptune’s orbit at 30 celestial units, and go beyond 150 celestial units.
Batygin and Brown discovered that perihelion has the same angle as these orbits, the point in the orbit closest to the Sun. They ran a series of symbols, and discovered that a large planet could gather orbits like this.
Planet Nine, according to the calculations, should be about five to 10 times the mass of the Earth, varying at a distance of somewhere between 400 and 800 celestial units.
Given that this hypothetical planet would be so far away, and because the skies are so large, it would not be easy to find. So the investigation has been ongoing.
Just as Planet Nine itself would be hard to find, however, so are ETNOs. These bodies are smaller than a planet, and therefore weaker. When they move away from the Sun, we have little chance of seeing them. And this is where some astronauts think there is a bias of selection.
“Because ETNOs follow highly elliptical orbits, and the brightness drops to 1 / r4, they are almost always found within a few decades of perihelion,” the researchers wrote in the paper aca.
“In addition, telescopic studies monitor a limited range of the skies, at certain times of the year, to a limited depth. These effects lead to a large selection bias.”
The difficulty of seeing ETNOs means that we did not find much. The first simulations run by Batygin and Brown were based on just six ETNOs, collected from a range of studies with unpublished selection activities; in other words, no electoral bias was clear.
Recent surveys have been cautious about their selection activities. And, while one study did not find enough ETNOs to create a complete statistical population, combining studies can lead scientists to a stronger conclusion. This is what Napier and his team did.
They took five items from the Outdoor Solar System Sources Survey (OSSOS) (previously uncovered evidence of collection), five items from the Dark Energy Survey, and four items found by astronauts Scott Sheppard, Chad Trujillo, and David Tholen, at who has led the study for Planet Nine.
Because the three studies had completely different objectives, so did they have different responsibilities. The challenge was to resolve these differences so that the items could be combined effectively in one large study. To do this, the team designed a survey simulator.
“In fact,” they wrote in their paper, “a survey simulator simulates traces of a population model of Solar System groups using point history, depth, and survey detection criteria. operation of a survey function for its given population, which allows us to account for bias, and thus to understand the real basic numbers. “
If the ETNO collection had been caused by a physical impact, it should have remained consistent with the larger sample of items analyzed by the Napier team. Instead, their results suggested that an ETNO sample was consistent with the uniform rotation of parent groups in space.
This does not mean, the researchers were careful to note, that Planet Nine does not exist. It just means that the life of the planet cannot be traced from ETNO data. There is insufficient information to justify or justify it.
Other lines of evidence point to its existence as well. For example, the strange orbits of objects outside the Kuiper Belt Solar System such as Sedna – although astronomers have proposed another explanation for that behavior.
It will be possible to analyze stronger regulation with a larger population of ETNOs and Kuiper Belt objects, which may mean waiting for items from a more powerful telescope, such as the proposed Vera Rubin Observatory which will begin activity sometime this year.
In the meantime, the strong search for the accessible planet leads to some truly amazing discoveries, including some dwarf planets that may be slipping out to the limits of outside the Solar System, and a handful of gas moors.
So, whether Planet Nine exists or not, the debate itself is remarkable for science – leading to discoveries that we may not have otherwise come across.
The study was published on the pre-printed website arXiv.org.