In early 2016, astronomers at Caltech announced evidence for another large planet in the outer solar system. They – and most professional astronomers – call it Planet 9 far and unknown in the world (although some call it Planet X, as a tribute to those who are still annoyed at the IAU's 2006 decision to reduce Pluto to the status of a dwarf planet). Evidence for Planet 9 is always indirect. It originated from the strange orbit of small objects in the outer solar system. Since 2016, astronomers have been searching for Planet 9 (or Planet X) in the outer solar system, but, so far, they have not found it. Now another group of astronomers say the strange orbits of outer solar systems can be explained without Planet 9.
In other words, there might be no reason to assume Planet 9 exists.
What's going on here? Nothing more than a science process. However, science is primarily a process and the search for truth.
Researchers at the University of Cambridge and the American University of Beirut have proposed alternative explanations for the Planet 9 2016 hypothesis. They agree with observations that show some small external objects – called trans-Neptune objects or TNOs, moving more than 30 times the distance of the Earth from the sun – has a harmonious orbit. But this new work shows the combined gravitational power of many small and distant objects – not a single large Planet 9 – that can create that strange orbit. According to their statement, the team:
… propose a dish made of small ice objects with a combined mass of 10 times the Earth. When combined with a simplified model of the solar system, the hypothetical gravitational forces that are hypothesized can explain unusual orbital architecture that is shown by several objects outside the reach of the solar system.
New results are reported in peer-reviewed Astronomy Journal.
In general, the trans-Neptune object – or TNO – surrounds the sun on a nearly circular path oriented in all directions. However, these astronomers say:
Since 2003, around 30 TNOs in highly elliptical orbits have been seen: they stand out from the rest of TNO by sharing, on average, the same spatial orientation …
The Planet 9 hypothesis shows that to take into account the unusual orbit of TNO, there must be another planet … & # 39; grazing & # 39; TNO in the same direction through the combined effects of gravity and gravity from other solar systems.
Antranik Sefilian from Cambridge University explained how they arrived at an alternative perspective:
We want to see if there might be other causes, which are less dramatic and perhaps more natural, for the unusual orbits we see in some TNOs. We think, rather than leaving the 9th planet, and then worrying about its unusual formation and orbit, why not just explain the gravity of the small objects that make up the disk outside Neptune's orbit and see what happens to us?
Sefilian is a former student of Jihad Touma from the American University of Beirut. Together, they created a new computer model to explain unusual orbits without Planet 9. Sefilian said:
If you remove Planet 9 from the model and instead allow many small objects scattered over a large area, collective tourist objects among those objects can easily explain the eccentric orbit that we see in some TNOs.
This previous attempt to do the same work failed, said the astronomers, because in the previous model the total body mass outside Neptune only increased by about one tenth of the Earth's mass. It is too small to take into account the odd orbit of some TNOs. So that TNO has observed orbit – without the need for Planet 9 – the model proposed by Sefilian and Touma requires a combined mass of the outer solar system of several to 10 times the mass of the Earth. Sefilian explains why he and Touma think it's fair to explore the possibility that the masses might be out there. He says:
When observing others [solar] systems, we often study disks that surround the parent star to infer the properties of planets in orbit around them. The problem is that when you look at disks from within the system, it's almost impossible to see everything at once. Although we don't have direct observation evidence for the disk, we also don't have it for Planet 9, which is why we are investigating other possibilities.
Maybe both of those things are true – maybe there are big discs and the 9th planet. With the discovery of every new TNO, we gather more evidence that can help explain their behavior.
The bottom line: New work shows the combined gravitational power of many small, distant objects in the outer solar system – not a single large Planet 9 – might have created strange orbits of some outer solar system. In other words, there might be no reason for the existence of Planet 9.
Source: Pasture in Own Gravity Disks from Trans-Neptune Objects
Through Cambridge University
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