Talk:Five-planet Nice model

Article is confusing

This article seems to be about a general class of objects, not just one, so I wonder why the confusing title? Several terms are non-standard, such as "lacunae" and need to be changed to something for general readers.AstroCog (talk) 00:56, 10 October 2011 (UTC)

Article is confusing and there is no mention of Tyche, the current theorical planet/star which is about to be revealed or disposed. Eduemoni^↑talk↓ 20:35, 5 October 2012 (UTC)

This article should probably not even mention Tyche, as Tyche at 1–4 Jupiter masses would be too massive from Jupiter to eject. This article should be about hypothetical low-mass gas giants like Planet Nine. Tyche would be much further out and ~30 times more massive (Jupiter is 318 Earth masses and Planet Nine would be ~10 Earth masses). -- Kheider (talk) 19:28, 20 January 2016 (UTC)

Not planet nine

This article focuses on a fifth giant planet in the context of the Nice model. Planet Nine's capture in a large semi-major axis should be early when the sun was in a cluster or when the gas disk was massive enough to alter its orbit. If the Nice model timing matches the LHB this planet would be lost much later.Agmartin (talk) 17:32, 21 January 2016 (UTC)

In the lede we should mention that research on this hypothesis lead to the Planet Nine hypothesis but that it is an open question whether the two hypothesized planets are the same one, or not. This is a convenience to the reader who might otherwise be confused. Jehochman ^Talk 12:38, 22 January 2016 (UTC)

The creation of the Planet Nine solution for the Detached objects was developed separately. Without a direct quote from the author it is wp:synth to state otherwise. The two theories do not require one another. -- Kheider (talk) 18:16, 22 January 2016 (UTC)

Move to five giant planet Nice model?

As this article focuses on a specific version of the Nice model should it be moved to five giant planet Nice model? Perhaps the current title could be used as a disambiguation page instead. Agmartin (talk) 18:15, 22 January 2016 (UTC)

Just looked at the list of pages linking here, I guess all of those links would need to be changed before using the current title as a disambiguation page. Agmartin (talk) 18:14, 22 January 2016 (UTC)

Shorter titles are normally preferred, but in this case the longer title might be beneficial to differentiate from the Planet Nine concept. -- Kheider (talk) 18:16, 22 January 2016 (UTC)

Kaib and Chambers

Some comments regarding their paper:

• Their result is not entirely new, Agnor and Lin discussed this in 2012.
• Although they are using five and six planet models the impacts on terrestrial planet orbits are due to the encounters driving a jump in Jupiter's and Saturn's semi-major axis while also exciting their eccentricities, causing the resonance crossings to occur at significant eccentricities. This impact would also occur if the planet was not ejected, for example, in a four-planet model.
• Most of their simulations start with the added planet in an orbit quite close to Saturn so the encounters start quickly saving computational time. The encounters may begin with the fifth planet in a lower eccentricity and/or a lower semi-major axis orbit than if started at a larger distance which may affect how the encounters proceed. It also avoids the delay while Neptune migrates out through the planetesimal disk which was recently shown to reproduce the inclinations of the KBO's.
• The angular momentum deficit (AMD) is roughly proportional to the size of the jump in the period ratios. I would be interested to see what the results would have been if they started with Jupiter and Saturn in a 2:1 resonance (although this has its own issues) instead which requires a smaller jump.
• The simulations that have the period ratio jump to 2.3 as needed to hop over the secular resonances have a median AMD not much larger than the current solar system.
• The simulations done by Nesvorny and Morbidelli also found a small percentage of 'successful' runs, about 5% for the best starting conditions, it appears hopping the secular resonances and stopping before crossing crossing the 5:2 resonance is a low probability event.
• I note that the Ethan Siegel article about this result changed the title to remove the claim that the Nice model is disproved.
• Low percentage things do happen, to use a recent example, Planet Nine's capture and survival are also though to be unlikely. And the low percentage may actually be useful, for example, with regards to the Fermi paradox. Agmartin (talk) 19:46, 13 May 2016 (UTC)

Forgot what I think are issues with the 2:1 resonance: if a grand tack occurs in this resonance Jupiter and Saturn are left with sizable eccentricities which would leave fossil Kirkwood gaps in the asteroid belt (not observed) and if Neptune's migration into the planetesimal belt preceded the encounters of the fifth planet with Jupiter and Saturn the secular resonance crossing involving Mars and Earth would occurs slowly and with the sizable eccentricities for Jupiter and Saturn which I expect would destabilize the inner solar system. These eccentricities may survive the clearing of planetesimals near Jupiter and Saturn, I'd be interested in seeing if this changes if the ice giants clearing their neighborhood is included in that model. Agmartin (talk) 20:00, 13 May 2016 (UTC)

Agreed. I am not saying that these authors are wrong and those are right. I am not judging their work. I try to refer to their papers. If they claim that their work "shows", this is what I report on Wikipedia. If they claim that their work "suggests", I do the same. I find it difficult to accept that Wikipedia states that some simulations "show" and other simply "suggest", not because the sources say so, but just because an editor believes so!

If a Grand Tack occurs in the 2:1 mean-motion resonance, there is some indication that Jupiter and Saturn are left with a sizable orbital eccentricities (The Astrophysical Journal Letters, 795:L11, 2014, doi:10.1088/2041-8205/795/1/L11) Messier8 (talk) 20:26, 13 May 2016 (UTC)

The fifth giant

I like thus 198.38.49.103 (talk) 22:08, 15 September 2022 (UTC)