New data about two distant asteroids give a clue to the possible 'Planet Nine'

BTW, as to the "we have never seen this planet, or whatever it is". Back in Dec 2015 planetary scientists who were observing α Centauri using Atacama Large Millimeter/submillimeter Array (ALMA) noticed a fast moving object, in our solar system.

I am not sure if what they saw was planet X(9) or another object in the fringes of our solar system. But this paper was quickly withdrawn until they could gather more information.

Here is the nature article on it.

A super-Earth in our solar system? Not so fast.
Astronomers quietly submitted a research paper claiming they may have found a large planet on the far fringes of our solar system.
By Nathaniel Scharping | Published: Friday, December 11, 2015
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While examining the Alpha Centauri star system, the nearest to Earth, they noticed a fast-moving object crossing their field of view.

Its speed and brightness allowed them to rule out another star as the culprit, and based on wavelength readings obtained from ALMA, they believe it could be a Trans-Neptunian Object (TNO) orbiting the sun somewhere between 10 billion and 2 trillion miles from our home star. For comparison, Pluto is less than 4 billion miles away from the sun.

Although the finding is intriguing, the news has been met with a healthy dose of skepticism.

A New Member of the Solar System?

Stars typically emit too much light for astronomers to discern any objects in their immediate vicinity, but the ALMA observatory was built to capture low-frequency wavelengths, allowing researchers to see objects that are closer to stars. This is how researchers noticed a mysterious object moving relative to Alpha Centauri, exhibiting what scientists call “proper motion.” The researchers suggest the object could be one of several celestial bodies, including a brown dwarf, a super-Earth (a planet larger than Earth but smaller than Neptune), or a much smaller, icy body orbiting beyond Pluto.
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www.astronomy.com...

Here is an abstract of the research paper.

A new submm source within a few arcseconds of α Centauri: ALMA discovers the most distant object of the solar system
R. Liseau, W. Vlemmings, E. O'Gorman, E. Bertone, M. Chavez, V. De la Luz
(Submitted on 8 Dec 2015 (v1), last revised 17 Dec 2015 (this version, v2))

We recently announced the detection of an unknown submillimeter source in our ALMA observations of alpha Cen AB. The source was detected in two epochs, a strong detection at 445~GHz and one at lower significance at 343.5~GHz. After valuable feedback of the community, it turns out that the detection at 343.5~GHz could not be reproduced with a different reduction software nor with fitting within the (u,v)-plane. The detection at 445~GHz has been further confirmed with modeling of the (u,v)-data and was shown to be robust at >12σ, confirming our detection of this unknown source. However, based on only one epoch, further analysis and preferably new data are needed, before publication of an article in which the nature of the new source can be discussed. The analysis has indicated the importance of both (u,v)-plane fitting and alternative data reduction when dealing with low signal to noise source detections.

Comments: withdrawn until further data is available
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:1512.02652 [astro-ph.SR]
(or arXiv:1512.02652v2 [astro-ph.SR] for this version)

arxiv.org...

What these scientists saw could be the super-massive Earth, planet 9 (X) or another object in the fringes of the solar system.

BTW, I am aware that in the Nature paper they say "it could also be a smaller object close to Pluto. But here is the thing.

Two teams of researchers, one from Mexico the other one from Sweden, using ALMA both found two different objects in the outer reaches of the Solar System. The team from Mexico say that they think what they discovered could be a brown dwarf.

(Phys.org)—Two separate teams of researchers (one from Mexico, the other Sweden), have incited skepticism among the astronomy community by posting papers on the preprint server arXiv each describing a different large object they observed in the outer edges of the solar system. Both teams made their observations after reviewing data from ALMA—a cluster of radio dishes in the Chilean mountains.
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The Swedish team nick-named the object they observed Gna, after a Nordic God known for its swiftness, and have told the press they had no intention of suggesting they had found the mythical Planet X which supposedly lies somewhere beyond Pluto. Instead they suggest it might be a large asteroid. The team from Mexico went a little further suggesting that the object they observed might possibly turn out to be a brown dwarf.
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phys.org...

The serendipitous discovery of a possible new solar system object with ALMA

These two teams of scientists saw two different objects.

Here is another article referencing this find, and showing a couple of pictures of the object.

We exclude [this object] to be a sub-/stellar member of the α Centauri system, but argue that it is either an extreme TNO, a Super-Earth or a very cool brown dwarf in the outer realm of the solar system.

Fig. 1. Left: Band 7 observation of α Cen AB on 7 July 2014. Apart from the well known binary αCenA and αCenB, a previously un- known source, and designated U, is seen NNE of the secondary B. Right: That object is more clearly evident in our Band 8 observation on 2 May 2015, 5′·′5 north of α Cen A.
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spaceref.com...

originally posted by: Box of Rain

Where would this brown dwarf be in this scenario? Would it be beyond Planet 9, or inside the orbit of Planet 9?

It would be far beyond planet 9 and somewhere in the Oort cloud.

originally posted by: Box of Rain
The reason I ask is because when I try to think of this logically (although I could be wrong, and someone who better understands orbital mechanics might tell me I am), it seems to me that a brown dwarf at the outside reaches, beyond a hypothetical Planet 9, would have a different effect on planet 9 that the the sun would have sitting in the center of the solar system.
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There are brown dwarfs which have planet orbiting around them, so why do you think it is logical that such a brown dwarf would only slingshot planets out of the solar system? Although eventually it would happen, it takes a long time for it to happen. The pull of a brown dwarf would be small tugs which would take millions if not billions of years to eventually eject such planet/object.

First Planet Discovered Orbiting a Brown Dwarf

Astronomers have long supposed that planets can form around brown dwarfs just as they do around ordinary stars. Now they’ve found the first example

July 29, 2013
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www.technologyreview.com...

The fact that ETNOs, and planet 9 have such highly elliptical orbits point to something out there causing them to orbit in such a manner. If only the sun exists in the solar system and there was no companion failed star (brown dwarf) then ETNOs and planet 9 would have more circular orbits.

Other planets can and do cause elliptical orbits, but highly elliptical orbits can only be caused by the interaction of massive objects with those planets, or by collisions. When you see outer planetary bodies with such highly elliptical orbit there has to be something massive with a stable orbit around that solar system causing such highly elliptical orbits.

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A planet could have a more eccentric orbit for a number of reasons. For example, collisions during the formation period could knock it out of its circular orbit.

Interactions with other planets could also change how they travel around their stars. Of the highly eccentric planets discovered, 78 percent of those with eccentricities greater than 0.5 have only one planet in the system, Hulsebus said. While the other planets could have been kicked out over the course of their evolution, Hulsebus and his team looked for a third option — the presence of a distant brown dwarf that could wreak havoc on the orbit of planets.

As a failed star which never accreted the necessary mass to start fusion in its core, a brown dwarf can be a few times heavier than Jupiter or reach masses up to 80 times as great. Because orbiting bodies travel more slowly the farther away they are from their stars, a distant brown dwarf may barely move across the sky while an interior planet races around its star. As a result, the two bodies would interact gravitationally at roughly the same time of the inner planet’s year. The smaller planet experiences a gravitational tug that pulls it ever-so-slightly away from its star and closer to the brown dwarf. Over time, the process would stretch the orbit of the inner planet, making it steadily more elliptical.
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www.astrobio.net...

Although it is true that eventually such a brown dwarf would cause planets and other objects in the solar system to eventually move away from the sun, and could eject out of that system if the brown dwarf doesn't capture it, it would take millions if not billions of years for this to happen.

Just take a look at object 2014 FE72 which has an eccentricity of 0.980 ± 0.014. Something is pulling it farther, and farther away from the sun. Once it's eccentricity reaches 1 or more, it would have enough momentum to eject out of gravity pull from the sun, and if it is not captured by the brown dwarf it would eject out of the solar system.

There is another solar system anomaly which could also be explained by a brown dwarf companion to our sun.

The secular increase of the astronomical unit in the solar system. What that is is that for some unexplained reason the distance between all planets and the sun is increasing at a rate that cannot be explained in the realm of classical physics or in the usual four-dimensional framework of the Einsteinian general relativity.

Secular increase of the astronomical unit and perihelion precessions as tests of the Dvali–Gabadadze–Porrati multi-dimensional braneworld scenario
Lorenzo Iorio JCAP09(2005)006 doi: 10.1088/1475-7516/2005/09/006


Lorenzo Iorio
Viale Unità di Italia 68, 70125, Bari, Italy
E-mail: [email protected]
Abstract. An unexpected secular increase of the astronomical unit, the length scale of the Solar System, has recently been reported by three different research groups (Krasinsky and Brumberg, Pitjeva, Standish). The latest JPL measurements amount to 7 ± 2 m cy−1. At present, there are no explanations able to accommodate such an observed phenomenon, either in the realm of classical physics or in the usual four-dimensional framework of the Einsteinian general relativity. The Dvali–Gabadadze–Porrati braneworld scenario, which is a multi-dimensional model of gravity aimed at providing an explanation of the observed cosmic acceleration without dark energy, predicts, among other things, a perihelion secular shift, due to Lue and Starkman, of 5 × 10−4 arcsec cy−1 for all the planets of the Solar System. It yields a variation of about 6 m cy−1 for the Earth–Sun distance which is compatible with the observed rate of change for the astronomical unit. The recently measured corrections to the secular motions of the perihelia of the inner planets of the Solar System are in agreement with the predicted value of the Lue–Starkman effect for Mercury, Mars and, at a slightly worse level, the Earth.

www.iop.org...

www.abovetopsecret.com...