Talk:514107 Kaʻepaokaʻawela

Diagrams need editing

@Nwbeeson: Please see the edit I have just done. These diagrams are for a rotating frame of reference, which means Jupiter stays almost stationary over on the right. So I don't think the diagrams should show the orbit of Jupiter as a circle or a line segment. Eric Kvaalen (talk) 19:57, 6 April 2017 (UTC)

@Eric Kvaalen:Yes, that is wonderful. I did not pay enough attention to the fact that the original data is in the rotating frame with Jupiter stationary. I have edited, the originals to put Jupiter in its place. Thanks for the help, it is a demonstration of the power of Wikipedians working together to get it right. Nick Beeson (talk) 20:08, 10 April 2017 (UTC)

@Nwbeeson: Great, thanks a lot! Eric Kvaalen (talk) 08:40, 11 April 2017 (UTC)

Interstellar origin

A new paper claims it originated outside the solar system: http://www.ras.org.uk/news-and-press/3126-first-interstellar-immigrant-discovered-in-the-solar-system Rps (talk) 14:12, 21 May 2018 (UTC)

Paper can be found at https://academic.oup.com/mnrasl/article/477/1/L117/4996014 .©Geni (talk) 15:20, 21 May 2018 (UTC)

I added a mention of that study. Please edit that as needed. Cheers, Rowan Forest (talk) 17:35, 21 May 2018 (UTC)

Here's some skeptics views.

“It is very extreme—particularly since they don’t have any dynamic modeling approach—to support their ideas is ["is" was probably a typo in the Nat. Geo. article] by saying that everything else is impossible,” says Southwest Research Institute scientist Hal Levison, who wasn't involved with the new study. ... Bottke and his colleague David Nesvorny suspect that BZ509 is actually an inactive comet from the Oort Cloud, a zone of icy debris on the far outskirts of the solar system. After being nudged long ago into a backward orbit, it could have entered its current loop just a few million years ago, they suggest.Tom Ruen (talk) 20:19, 21 May 2018‎ (UTC)

Reading the paper I came across this:

"However if such orbits exist then they are the ones that correspond to the actual motion of the asteroid and not the short-lived unstable orbits. Choosing the former orbits over the latter is motivated by the Copernican principle that 2015 BZ509 is not being observed at a preferred epoch in Solar system history."

They are assuming that since there search identified some stable orbits exists (27 out of 1 million) the object must be in that orbit because otherwise we are observing it at some special time. But there is another possibility: many objects could have spent a short time in a similar orbit and BZ509 is just the current example. Concluding that this object has been on its orbit since the beginning of the solar system instead of being one of many temporary objects should only follow a study of the probability of comets from the Oort cloud entering this orbit. Agmartin (talk) 20:42, 21 May 2018 (UTC)

An interstellar origin would have one advantage: the drag from the gas in the protoplanetary disk could slow an object into a circular orbit, retrograde objects would likely spiral into the sun so it would require good timing relative to the loss of the gas. There was even a recent article discussing this. This might also work for solar system objects too if they were captured in the Oort cloud then soon after were perturbed by a nearby star and reentered on a retrograde orbit. Agmartin (talk) 20:55, 21 May 2018 (UTC)

Here's another one, including talk of Planet Nine, [1] Tom Ruen (talk) 22:59, 21 May 2018 (UTC)

@Rps, Geni, Rowan Forest, Tomruen, and Agmartin: I agree that Namouni and Morais have not made a good case. They simulated backwards in time and found that about half "fell" into the sun and half were expelled. Now obviously the ones that "fell" into the sun, going backwards in time, would have had to jump out of the sun going forwards in time, which of course didnt't happen. (Same for the ones that "collided" with planets.) The ones that were "expelled" are actually trajectories that came from interstellar space and ended up in BZ's retrograde orbit. The question then is how often do objects approach the sun slowly enough that they can get captured and end up in this kind of orbit. Even if it happened 4 milliard years ago, it would still have to have happened like that. It seems to me that it's much more likely to have happened some time during the last 4 milliard years, rather than just after the planets formed. Namouni and Morais have proved that most orbits like that of BZ are only stable for a few million years. So it seems to me that the most probable scenario is that it was captured in the last few million years and will only last a few million more years. Interstellar yes, but not 4 from milliard years ago. It is interesting though to know that there exist very small islands in phase space which are stable for milliards of years. Eric Kvaalen (talk) 14:28, 16 June 2018 (UTC)

Something I spotted on arxiv that offers some perspective to the claim of interstellar origin: Centaurs potentially in retrograde co-orbit resonance with Saturn The authors identified four objects potentially in 1:−1 resonance with Saturn, conclude that "Small bodies in retrograde co-orbit resonance with giant planets may be more common than previously expected." Agmartin (talk) 17:59, 7 July 2018 (UTC)

A talk at the DPS conference discussed possible origin in asteroid belt, evolutionary path causes object to become near earth object before becoming retrograde co-orbital. Something to look out for when it is eventually published. Agmartin (talk) 21:11, 23 October 2018 (UTC)

Wording about the Copernican principle

The phrase "observed at a special time using XYZ" means absolutely nothing and even if it was technical. Delete! 184.158.95.207 (talk) 16:48, 24 May 2018 (UTC)

Retrojan

The authors of a new paper on arxiv discussing retrograde co-orbitals of Saturn have coined a new word: retrojan. Agmartin (talk) 18:19, 1 February 2019 (UTC)