Trans neptunian in retrograde orbit

[magnemoe]

http://www.nextbigfuture.com/2016/08/discovery-of-odd-trans-neptunian-object.html
How did this happen?
The orbit looks fairly circular on the image, circular as in not an comet style orbit 
400 km make is an dwarf planet and not junk. 
 

[Mitchz95]

Hmm ... Planet Nine?

[legoclone09]

6 minutes ago, Mitchz95 said:

Hmm ... Planet Nine?

No, it's too close in to even be influenced by Sol 9, at least I head that on r/space.

[insert_name]

the article says there are more objects in a similar orbital plane and clustered ascending nodes. I only know of one other retrograde object, and its inclination is only a little over 90

[DDE]

Captured object?

[Jovus]

Capture should be rare, though, and it sounds like there might be significantly more than one.

Time to start noodling around on alternate formation theories?

[wumpus]

2 hours ago, Jovus said:

Capture should be rare, though, and it sounds like there might be significantly more than one.

Time to start noodling around on alternate formation theories?

A planet by the new definition must 'clear its orbit'.  Sounds like if you aren't capturing a certain percentage of your path, you don't qualify as a planet.

[Mitchz95]

15 hours ago, legoclone09 said:

No, it's too close in to even be influenced by Sol 9, at least I head that on r/space.

But isn't it thought that Planet Nine might have formed closer to the sun and migrated outward over time?

[magnemoe]

29 minutes ago, Mitchz95 said:

But isn't it thought that Planet Nine might have formed closer to the sun and migrated outward over time?

or its orbit has been shifted by Neptune or Nr9 on later passes. 

Plenty of stuff in the outer solar system in weird orbits gives some proof of the Oort cloud 

[Bill Phil]

3 hours ago, Mitchz95 said:

But isn't it thought that Planet Nine might have formed closer to the sun and migrated outward over time?

That's likely for most of the outer planets...

[cantab]

"Retrograde", though technically correct, might be a bit misleading. I'd rather describe Niku as near-polar.

As for how it got there, my first guess is a close encounter with Neptune.

[kerbiloid]

It would be nice if they tell its eccentricity value. Is its orbit as round as on the picture.

[Frida Space]

13 hours ago, kerbiloid said:

It would be nice if they tell its eccentricity value. Is its orbit as round as on the picture.

When you have questions such as this, I always suggest you refer to the original discovery papers. They should have answers to most questions, or at least, they should give all the answers we know so far

In this case, these are the object's orbital parameters, taken from the discovery paper by Chen et al. (arXiv:1608.0180):

Perihelion: 23.81 AU

Semimajor Axis: 35.725 AU

Eccentricity: 0.334

Inclination: 110.3°

...

Edited August 16, 2016 by Frida Space

[kerbiloid]

9 hours ago, Frida Space said:

Eccentricity: 0.334

Thank you.

So, not so nice and round as on the picture. Very eccentric, as it should be if thrown away by giants.