Going the Wrong Way Round
A new Trans-Neptunian Object has been discovered whose quirkiness is breaking into new territory. This object, currently named ‘Niku’ after the Chinese adjective for ‘rebellious’, is seriously off-piste and heading in a highly inclined, retrograde motion around the Sun (1). Does this sound familiar? The retrograde motion is something which Zecharia Sitchin claimed for the rogue planet Nibiru. Niku…Nibiru. It sounds like the team who discovered this object, based at the Harvard-Smithsonian Center for Astrophysics (2), are having a bit of fun with us. Rest assured, this is not Nibiru, or anything like it. That said, something in the past interacted with this object to fling it into its strange orbital path, and at the moment the identity of that strongly perturbing influence is a definitive ‘unknown‘.
Additionally, Niku’s discovery has prompted the astrophysics team to consider a new cluster of objects (high inclination TNOs and Centaurs) which appear to share the same orbital plane. This, in itself, is an unexpected and exciting development. Could the influencing factor be the mysterious Planet Nine (3)?
“…The new TNO appears to be part of another group orbiting in a highly inclined plane, so [Matthew] Holman’s team tested to see if their objects could also be attributed to the gravitational pull of Planet Nine. It turns out Niku is too close to the solar system to be within the suggested world’s sphere of influence, so there must be another explanation. The team also tried to see if an undiscovered dwarf planet, perhaps similar to Pluto, could supply an explanation, but didn’t have any luck. “We don’t know the answer,” says Holman.” (1)
Dynamically, Niku is very similar to an object described in 2008, which also moves the wrong way round the solar system. This Kuiper Belt Object is known as 2008 KV 42, and nicknamed Drac (due to its vampire-like ability to walk on walls), also has an inclination greater than 90 degrees, which creates the retrograde motion (4).
It is thought that this KBO originated from the inner Oort Cloud, some 2000-5000AU away, and is in a transitional phase prior to becoming a Halley Comet-like object.
In which case, the next logical question to ask is what knocked these objects off their perch in the inner Oort Cloud, sending them into this highly inclined cluster of orbital paths in the vicinity of the Edgeworth-Kuiper Belt? Is this a hint that the orbital path of Planet Nine, itself inclined to the ecliptic by about thirty degrees (5), might extend far enough out into the outer solar system to skirt the inner edge of the Oort Cloud? If so, then this could explain this perturbing effect, but also extend the aphelion distance of Planet Nine out far further than currently thought. The implication of this, if we follow this argument to its natural conclusion, is that Planet Nine’s mass would then be far greater than the ten Earth masses currently anticipated for it. Otherwise, it would be incapable, at these greater average distances, of pulling up the anomalous cluster of Sednoids (6) into the extended scattered disk beyond in the first place.
Note, also, that two of the lead authors of this new paper are astronomers from Harvard who, when scrutinising astrometry data on Pluto and other trans-Neptunian objects, have previously argued for either the existence of a second perturbing planet, or a significantly more massive Planet Nine body (7). I asked one of them, Dr Matthew Holman, whether the proposed Planet Nine body – this time with greater mass and orbital period – might have been capable of drawing down Niku from the inner Oort Cloud, to which he responded:
“I really have not figured out the explanation for the common plane, prograde and retrograde, that these objects seem to share, but it’s not clear to me that if something like a Planet Nine is perturbing them that it would need to have such a large aphelion. The gravitational influence of the disk and bulge of the galaxy are strong enough [to] reduce the pericenters of inner Oort cloud objects into the region of the planets.” (8)
This seems to boil down to whether objects originally located in the inner Oort Cloud require a special perturbing nudge to send them down towards the Kuiper Belt, or whether the standard forces at play in the galactic environment are sufficient to the task. In the case of Drac, Brett Gladman of the University of British Columbia, whose team discovered 2008 KV42, may seem more inclined towards a more localised nudging mechanism, as reported here:
“It seems likely that Drac was gravitationally disturbed from its home in the inner Oort Cloud by a passing star, or some other disturbance in its local space. It then fell toward the inner Solar System where it found its new home near the Kuiper Belt.” (4)
Although the press release by the Canada France Ecliptic Plane Survey discusses a possible migration between the inner Oort Cloud and the Kuiper Belt, it does not specify how such a movement may have been initiated (9).
A connection between Drac and Planet Nine has also been alluded to on the Wikipedia page devoted to 2008 KV42:
“2008 KV42 may even provide evidence of Planet Nine. The Kozai effect inside the mean-motion resonances with Planet Nine may cause a periodic exchange between its inclination and its eccentricity. When the elongated perpendicular centaurs get too close to a giant planet, orbits such as that of 2008 KV42 are created.” (9)
This note builds upon Mike Brown’s essay about Planet Nine, where he discusses its potential connection to Drac:
“And Drac, which had been such a disappointment? Once we started looking we realized that our gravitational simulations create Drac, too. Sometimes, when the elongated perpendicular Centaurs do get too close to giant planet
[sic], that planet pulls their orbit a little close, and also swings the orbit around randomly. Another Drac is born. The Planet Nine hypothesis requires the existence of objects with orbits like Drac, which otherwise had no plausible explanation.” (10)
So, according to Dr Brown, Drac was originally a Centaur object located between Jupiter and Neptune, which was dragged out into its perpendicular, retrograde orbit by Planet Nine, presumably when near perihelion. Perhaps he has not yet considered that it might have pulled Drac in from the inner Oort Cloud?
Written by Andy Lloyd, 14th August 2016
1) Shannon Hall “Mystery object in weird orbit beyond Neptune cannot be explained” 10th August 2016 https://www.newscientist.com/article/2100700-mystery-object-in-weird-orbit-beyond-neptune-cannot-be-explained/ with thanks to Mart and Lee
2) Ying-Tung Chen et al “Discovery of A New Retrograde Trans-Neptunian Object: Hint of A Common Orbital Plane for Low Semi-Major Axis, High Inclination TNOs and Centaurs” 5th August 2016, ApJ Letters, http://arxiv.org/abs/1608.01808
3) “Mystery Object in Weird Orbit Beyond Neptune Cannot Be Explained” https://www.youtube.com/watch?v=93oBy-x5gjs
4) Ian O’Neill “Kuiper Belt Object Travelling the Wrong Way in a one-way solar system” 5th September 2008 http://www.universetoday.com/17712/kuiper-belt-object-travelling-the-wrong-way-in-a-one-way-solar-system/
5) K. Batygin & M. Brown “Evidence for a Distant Giant Planet in the Solar System” 20th January 2016, The Astronomical Journal, Volume 151, Number 2, http://iopscience.iop.org/article/10.3847/0004-6256/151/2/22
6) C. A. Trujillo & S. S. Sheppard “A Sedna-like body with a perihelion of 80 astronomical units” 27th March 2014, Nature, 507, 471-474, http://www.nature.com/nature/journal/v507/n7493/full/nature13156.html
7) Matthew Holman and Matthew Payne “Observational Constraints on Planet Nine: Astrometry of Pluto and Other Trans-Neptunian Objects” 30th Mar 2016, http://arxiv.org/pdf/1603.09008v1.pdf
8) Correspondence from Matthew Holman, 18th August 2016
9) CFEPS Press Release “Discovery of the Retrograde Trans-Neptunian Object 2008 KV42” 16th July 2008 http://www.cfeps.net/KV42_Press.html
10) Mike Brown “Why I believe in Planet Nine” 12th February 2016 http://www.findplanetnine.com/2016/02/why-i-believe-in-planet-nine.html