Sunday, July 2, 2017

Status Update (Part 2)

I ended the last post by pointing out that the Planet Nine hypothesis, as currently formulated, entails a theoretical solution to five seemingly-unrelated observational puzzles: (i) orbital clustering of a>250AU KBOs, (ii) dynamical detachment of KBO perihelia from Neptune, (iii) generation of perpendicular large-semi-major axis centaurs, (iv) the six-degree obliquity of the sun, and (v) pollution of the more proximate Kuiper belt by retrograde orbits. Virtually all of the discussion surrounding the new OSSOS dataset to date has focused on long-period orbits and the statistical significance of perihelion clustering beyond ~250AU - a concern relevant exclusively to point (i). Breaking with this trend, in this post I want to examine a shorter-period component of the new data, and discuss how it relates to arguably the most unexpected consequence of P9-driven evolution: generation of retrograde orbits with semi-major axes smaller than ~100AU (i.e. aforementioned point (v)).

Those of you who have been following the P9 saga for more than a year might remember the article by Chen et al. from last August, which reported the detection of Niku, a ‘rebellious’ Kuiper belt object that orbits the sun in the retrograde direction (see news coverage here and here). While the orbit of Niku itself is in some sense unremarkable (because it is acutely similar to the orbit of Drac - another retrograde object that was detected back in 2008), this discovery did successfully reinvigorate the community’s interest in the high-inclination population of the trans-Neptunian region. 

Here is a look at all objects within the current dataset with inclinations greater than 60 degrees, semi-major axes in the range of 30AU to 100AU, and perihelion distance in excess of Jupiter’s orbit:


For scale, Neptune’s orbit is shown here as a blue circle, and the orbits of Niku and Drac are emphasized in gray. Generally speaking, these bodies trace out an apparently-random orbital structure and raise an important question regarding the physics of their origins, since none of them can be reproduced by conventional simulations of the solar system’s early evolution.

Unlike objects such as Sedna and 2012 VP113, Niku and Drac are currently quite close to Neptune itself, and have semi-major axes that are much too small to interact with Planet Nine directly. Nevertheless, in a paper published last October, we showed that Planet Nine naturally leads to their production. The crux of our result is that the current orbits of these bodies are very different from their primordial ones. Specifically, in our simulations we noticed that Kozai-Lidov type oscillations experienced by distant Kuiper belt objects due to Planet Nine can drive them onto highly inclined, Neptune crossing orbits. Subsequently, close encounters with Neptune shrink the orbit, freezing it onto a retrograde state. Mark Subbarao from Adler Planetarium has kindly created this visualization of one of our simulated particles, that ends up on an orbit that is almost an exact replica of Niku and Drag (grab the video here if the player below does not work):



Despite a rather complicated and genuinely chaotic evolution, our P9-facilitated generation mechanism of these objects predicts a rather specific orbital distribution in (semi major axis a) - (inclination i) - (perihelion distance q) space. This prediction is shown below as a background green/gray grid, with observed data over-plotted as purple/black points.


In addition to the observed objects that were already known back in October of last year, this plot shows two new data points that also fit the simulated pattern beautifully. Thus, the predictions of the Planet Nine hypothesis have held up very well within the more proximate part of the trans-Neptunian region, where the planet’s direct influence is minimal. 

So where does the new data leave us? Let’s summarize: while the membership of the primary perihelion cluster has gone from six to ten, the distant belt now also has some objects that do not belong to the apsidally anti-aligned population of long-period KBOs. Despite worries of Planet Nine’s immediate demise, it is pretty clear that these bodies fit well with other dynamical classes predicted by the model, so there’s no real conflict there. Closer to Neptune, we’ve picked up a couple high-inclination objects that also agree well with the model. Sigh…


Cumulatively, I can’t help but feel an uneasy combination of relief and disappointment. On one hand, the agreement between simulations and data implies that the theoretical model remains on solid footing. As we head into upcoming P9 observing season, this is important and reassuring. On the other hand, we haven’t learned anything genuinely new from the expanded dataset, and P9’s precise location on its orbit as well as a well-founded qualitative description of P9-induced dynamics remain somewhat elusive. Clearly, much work - both theoretical and observational - remains to be done. So back to research.

62 comments:

  1. How confident are you that you or someone will find it in the next search season?

    How probable is it that it is not an ice giant but a rather rocky planet?

    Thanks! Hope you find it :)

    ReplyDelete
    Replies
    1. These things are notoriously difficult to predict because weather is involved, as well as telescope malfunctions, etc. I'd give us a ~20-25% chance of finding it in this observing season. We designed our search with a ~5 year timeline in mind. Given its mass, it's probably an ice-giant.

      Delete
  2. What would the effects of P9's mass be? For example, if the mass was greater, would a wider orbit be more likely? Or would it only influence to what extent there can be outliers?

    ReplyDelete
    Replies
    1. Yes - there is a tradeoff between P9's semi-major axis, mass and eccentricity. To leading order, the more massive the object, the wider the orbit should be.

      Delete
  3. You forgot to add two links (see news coverage here and here).

    ReplyDelete
  4. Could Kat Volk's and Renu Malholtra's new planet explain why ETNO's haven't been found with perihelia between 50 AU and 70 AU?

    ReplyDelete
  5. I realize this question is probably "beneath" a lot of the bloggers here, but do these models only work if Planet Nine is still in our Solar System? In other words, if Planet Nine had been ejected from the Solar System entirely at some point, would we expect TNO's like Sedna to have returned to a different orbit than the one that they currently had? I am just wondering how we are sure that Planet Nine is still with us. (Though it would still be interesting to think our Sun might have a poor, lost "rogue baby" wandering the interstellar void somewhere...)

    Some of the recent posts here make me think that the only way to get the orbits of Sedna et al. into their current position is for them to have been acted on *constantly* by Planet Nine all the way from its formation to present day, but I wanted to rule out the idea that the reason we haven't found Planet Nine thus far is that it existed but has long since "left the building."

    Sorry for such an elementary question, but I wanted to check whether my understanding is sound.

    ReplyDelete
    Replies
    1. As I understand it, the models all point to requiring P9 to be here currently. In K Batygin's first update here, he says "something is holding the orbits together right now"...

      Delete
    2. I would also assume that while the objects would remain on extreme orbits if P9 was already gone, other gravitational disturbances would cause them to lose their specific properties that point to a common source.

      Delete
    3. Not at all an elementary question! But thankfully one that has a well-defined answer. If the clustering we see were due to some gravitational disturbance in the past, and not due to an extant perturber, this disturbance would have had to happen relatively recently (in cosmic terms). This is because due to the well-understood effects of Jupiter, Saturn, Uranus and Neptune, the distant orbits of Sedna, etc would precess differentially on a timescale of ~100 million years, and the observed pattern would be destroyed.

      Delete
    4. Thank you for such a nice answer, Konstantin Yurievich! :-) I appreciate your taking the time to explain why the model only works with P9 still being present.

      Delete
  6. P9 is likely to have satellites of significant size. IF they are close and are ice covered, this ice surface might be renewed by Ice volcanoes / surface plate activities. With a high albedo might this complicate the computer recognition of the steady orbit of P9?

    ReplyDelete
    Replies
    1. Our theoretical models that *predict* the existence of P9 don't say anything about its physical appearance - only its mass. If P9 has a high albedo, however, that greatly helps the astronomical search.

      Delete
    2. I think "Unknown" meant that the computer might not recognize a larger grey orb if a smaller white orb would move around it. The bright moon's movement would not be regular, and therefore not recognized, and the dimmer planet would be outshone by its moon.

      (I think if one takes Jupiter and its largest moon Ganymede as a comparison, Jupiter's surface is nearly 700 times larger. So even if Ganymede had an albedo of 100% and Jupiter of 4%, Jupiter would still be 28 times brighter, or 3.5 magnitudes. In the end, it might depend on how many pixels the body's image is spread to)

      Delete
    3. Ambi, that is correct. All of the planets beyond Earth have satellites and certainly there are plenty of icy bodies to be captured. We have one " double planet " in the solar system ( Earth) where the moon has a significant mass compared to the planet. if P9 has a terrestrial Moon the size of Earth or Mars, it may outshine a P9 of say, 8 earth masses. Its path would be back and forth across the sky in short steps, and hard to pick out especially with an unfavorable survey cadence.

      Delete
  7. I was also interested in knowing how the orbit of P9 has evolved. If it has impacted the angular moment of the rest of the solar system by 6 degrees, that means it has "moved" the orbits of Jupiter, Saturn, Neptune and Uranus. certainly the inclination of P9 has shifted by a lot and this shift can be modeled . Is this shift consistent with constantly evolving "scattered objects" orbits?
    In the computer models is the orbit of P9 allowed to change over time, with only initial parameters set?

    ReplyDelete
  8. PS as "unknown" I am new to this blog. My normal handle is JD Kittle.

    ReplyDelete
  9. Heliopause Planet?

    Had a thought. Could most stars have a "heliopause planet"? I read that the solar wind blows out about 1 Earth mass of material every 150 million years. If the galaxy or other forces do not strip this material away, it will pool. Our sun's heliopause is about 120 AU. A body orbiting in this region could accrete some of this material and grow into a significant planet. Of course the heliopause is roughly spherical, while an orbit is a thin ring, so maybe not. I suppose Planet 9 is too far out for this effect, but Planet 10 might be at the optimum distance for it.

    ReplyDelete
    Replies
    1. Interstellar matter and the Solar System are moving through the galaxy in different ways. From the viewpoint of the Solar System, there is more interstellar matter coming from one direction that the others (and in that direction the heliopause is closest to the Sun).

      So matter lost by the Sun will be stopped by the heliopause and then be carried off with the interstellar matter, and would not remain in place until it would gain enough mass to contract to a body.

      Delete
  10. How much longer does the observational season last and how does that translate into depth of the search against targeted areas?
    Have you had good conditions and any equipment problems? Exciting times..

    ReplyDelete
  11. Excellent writing, thank you!

    ReplyDelete
  12. Hi Everyone,
    Just wondering if there have been any ew thoughts or findings now that we are in the middle of September.?

    ReplyDelete
  13. Thank you for writing this blog, Konstantin - could Planet 9 be the "Guest Star" of 1054AD that the Chinese recorded?

    ReplyDelete
  14. Status is a hierarchy, shaped like a pyramid and represents your standing of respect and esteem in the eyes of those people you see everyday; at its extreme it is referred to as a pecking order. Status

    ReplyDelete
  15. Thanks for sharing this amazing article and i think you know about lucky patcher apk download no root and i think it works like a charm. PLease post more article like this and i will visit here again.

    ReplyDelete
  16. Perhaps you've watched all the popular Christmas movies.9 movies online

    ReplyDelete
  17. Hi admin
    Thanks for sharing this amazing article and i think you know about paytm download for pc windows 7
    and i think it works like a charm. Please post more article like this and i will visit here again.

    ReplyDelete
  18. The post contains lots of knowledgeable facts with step by step guide.For more exiting post related to Tech you must visit about whatsapp sattus
    holi image

    holi whatsapp dp

    holi facebook dp cover

    holi shayari

    advance holi sms

    advance holi status

    holi quotes

    holi quotes

    holi wishes

    holi romantic status





    ReplyDelete
  19. This comment has been removed by the author.

    ReplyDelete
  20. May I simply just say what a relief to discover someone that actually knows what they are talking about online. You actually know how to bring an issue to light and make it important. A lot more people ought to look at this and understand this side of the story. It's surprising you aren't more popular given that you definitely possess the gift.
    la luna sangre
    pinoy tambayan
    pinoy channel
    online pinoy channel
    pinoy tv

    ReplyDelete
  21. sharing this amazing article and i think you know about Lucky Patcher Apk download no root and i think it works like a charm. PLease post

    ReplyDelete
  22. If you're a first-time user of the website, there is a part of software that serves as a tutorial which walks you through the whole procedure of working with the website. Drama | 123Movies - Watch Movies $ TV Shows - 123Moviesfun.net

    ReplyDelete
  23. Hi, I am Rahul thank you for this informative post.Thank you so much and for you all the best. (fmovies.in.net) That is a great job. Wish you more success. Takes Down
    fmovies

    ReplyDelete
  24. Hi, I am Rahul thank you for this informative post.Thank you so much and for you all the best. (fmovies.in.net) That is a great job. Wish you more success. Takes Down
    fmovies

    ReplyDelete
  25. Health Is God aims to deliver the best possible health reviews of the supplement collections and other wellness production that range from skincare to brain, muscle, male enhancement and brain health conditions. You, the user are of utmost importance to us, and we are committed to being the portal that sustains your healthy lifestyle.
    HealthIsGod.com | Health And Fitness Tips

    ReplyDelete
  26. Health Is God aims to deliver the best possible health reviews of the supplement collections and other wellness production that range from skincare to brain, muscle, male enhancement and brain health conditions. You, the user are of utmost importance to us, and we are committed to being the portal that sustains your healthy lifestyle.
    HealthIsGod.com | Health And Fitness Tips

    ReplyDelete

  27. She started her career in the year 2007 with a reality TV show which is named as Keeping Up with Kardashians and proved successful. Soon, she posed for a nude pictorial for Playboy once she got success spending years on TV shows. In the year 2008, she started her career in feature film, Spoof Disaster Movie which is the debut film of her. With the consistency of effectiveness throughout her career, she made cameo in an episode of sitcom How I Met Your Mother, in “Benefits” then, she also launched an endorsement with ShoeDazzle shopping. Then, she continues endorsing multiple projects such as vanilla cupcake for a bakery of Los Angeles, she released a workout DVD series and then, Kardashian become a guest host of Wrestlemania XXIV and guest judge of America’s Next Top Model. Read more kim kardashian sex tape,kim kardashian sex video,kim kardashian porn, kim kardashian porn video, Kim kardashian nude, Visit at http://crazyvideohub.com/kim-kardashian/

    ReplyDelete
  28. Most likely this is a phenomenal post I got a ton of learning in the wake of perusing good fortunes. Subject of website is magnificent there is very nearly everything to peruse, Brilliant post.
    best commercials

    ReplyDelete