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2015 BP519, nicknamed "Caju", is another extreme trans-Neptunian object that points to the existence of Planet Nine. Discovered with data from the Dark Energy Survey, Caju has a relatively large diameter, estimated at around 400-700 km, meaning the object could be a gravitationally rounded dwarf planet. It also has a highly inclined orbit of 54°, which a team of scientists says can be explained by the presence of the hypothetical Planet Nine:
After discovering it, the team tried to investigate 2015 BP519's origins using computer simulations of the Solar System. However, these tests were not able to adequately explain how the object had ended with such an orbit.
But when the team added a ninth planet with properties exactly matching those predicted by the Caltech scientists in 2016, the orbit of 2015 BP519 suddenly made sense. "The second you put Planet Nine in the simulations, not only can you form objects like this object, but you absolutely do," Juliette Becker, a Michigan graduate student and lead author of the study told Quanta.
Some researchers, however, caution that Planet Nine may not be the only explanation for 2015 BP519's strange orbit. Michele Bannister, a planetary astronomer from Queen's University Belfast, in Ireland, who was not involved in the study, told Newsweek that while the latest findings were "a great discovery," other scenarios could account for its tilt. "This object is unusual because it's on a high inclination," she said. "This can be used to maybe tell us some things about its formation process. There are a number of models that suggest you can probably put objects like this into the shape of orbit and the tilt of orbit that we see today."
Also at Quanta Magazine.
Discovery and Dynamical Analysis of an Extreme Trans-Neptunian Object with a High Orbital Inclination (arXiv:1805.05355)
Related: Medieval Records Could Point the Way to Planet Nine
(Score: 3, Interesting) by Grishnakh on Thursday May 17 2018, @02:54PM (20 children)
I am not an astrophysicist, but it seems odd that there's supposedly this huge (10 earth masses) planet out past the Kuiper Belt, but we haven't been able to detect it yet.
Is it possible this Caju dwarf planet's orbit, and other effects explained by "Planet Nine", are actually caused by merely the aggregate gravitational effects of many other smaller objects in that region of the system, rather than one very large one?
(Score: 5, Interesting) by takyon on Thursday May 17 2018, @03:10PM (10 children)
Planet Nine is estimated to be very cold, smaller than Neptune, between 200 and 1,200 AU away, with very low brightness.
WISE [wikipedia.org] is an infrared survey telescope that has discovered lots of cold objects, including the third-closest "star" system in 2013, Luhman 16 [wikipedia.org], which is a binary brown dwarf pair. WISE was used to search for nearby gas giants, but it has some limits on its sensitivity:
An aggregation of objects doesn't necessarily stay aggregated. They could collide with each other or become scattered over time. Whereas a mini-Neptune would stay intact and have a consistent gravitational effect. There's no ruling an aggregation out just yet seeing as no Planet Nine has been discovered.
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(Score: 4, Interesting) by Grishnakh on Thursday May 17 2018, @03:41PM (4 children)
Planet Nine is estimated to be very cold, smaller than Neptune,
According to the Wikipedia article [wikipedia.org], it would be about the size of Uranus or Neptune, and WISE "may have" the capabilities to detect it. Obviously not very definitive.
An aggregation of objects doesn't necessarily stay aggregated. They could collide with each other or become scattered over time.
Sorry, that's not what I meant, I wasn't very clear. What I meant was this: we're still discovering TNOs and other objects way out in that region of the system. The farthest object we've detected has a perihelion (closest distance to Sun) of about 100AU, but it's much smaller than Neptune. My question is this: what if there's a bunch more small objects like these TNOs and various dwarf planets like Sedna out there that we haven't detected, and these things, together (not necessarily close to each other) are causing these effects that are being attributed to a hypothetical super-Earth? I'm sure their simulations are accounting for all the objects they've discovered so far, but probably not a few dozen or so other similar objects even farther out. Would a bunch more smaller objects, in various orbits, that we haven't detected yet, be able to explain these effects, rather than just one big one?
(Score: 5, Interesting) by All Your Lawn Are Belong To Us on Thursday May 17 2018, @04:17PM (2 children)
It's an interesting question. Clearly opinion is divided still on whether it actually exists or not. (There's more than a fair amount of "show me the planet!" advocates among the educated.)
I'm no astrophysicist either, just an amateur astronomer with a primary focus on Lunar study. That is a harsh enough mistress for me. Trying to follow the arguments, though, seems to imply that the fourteen objects under study would have a common effector in a single object. If I get it correctly, the objects are not synchronized in periodicity. Multiple objects exerting influence would therefore have to be in such perfect alignment with each other that they uniformly act on all the objects under study with similarity as if there was a single body acting at the hypothesized Planet Nine orbit. (If they've been acted upon at all - the first alternate explanation is still "coincidence"). A single body seems more likely than a synchronized multiple to me, but that might just be a distortion of Occam's razor. (A one body solution seems neater and tidier, but there isn't a layperson explanation for why it would be truly "simpler").
I think that at least one of the alternative theories in the Wikipedia article, "inclination instability due to mass of undetected objects," proposes exactly what you're describing. Later "de la Fuente Marcos et al. (2014)" under the Kozai theories propose a two-body resonance which is still more than just one.
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(Score: 1) by nitehawk214 on Thursday May 17 2018, @05:39PM
Nice.
"Don't you ever miss the days when you used to be nostalgic?" -Loiosh
(Score: 2) by frojack on Thursday May 17 2018, @08:38PM
Interesting.
Its computationally easier, so lets go with that.
Your other part: Multiple objects exerting influence would therefore have to be in such perfect alignment with each other... (By perfect alignment, I assume you mean a just-so story of planets, big and small, moons, asteroids etc, that over the fullness of time happened to cause an unusual orbit of a small body).
That is likely to be the case that will happen automatically in ANY and EVERY system. Almost by definition. The orbit(s) of all bodies in the system are what they are precisely because they have adjusted to the presence of each other over eons. It isn't the only configuration that COULD exist, but its the only one that DOES exist; at this very moment. Its probably evolving every day, at rates so slow we can not fathom it or simulate it.
No, you are mistaken. I've always had this sig.
(Score: 2) by takyon on Thursday May 17 2018, @04:33PM
WISE has already looked for it and come up with nothing so far: [findplanetnine.com]
Keep in mind that if Planet Nine is currently closer to the 1,200 AU aphelion than the 200 AU perihelion (these are estimates), then it becomes much harder to detect.
Also, it is expected to be smaller than Neptune. Although the estimates for Planet Nine say ≥10 Earth masses and 2-4 Earth radii, it's probably not as large as Neptune, which is 3.883 Earth radii and 17.147 Earth masses.
See also:
http://2.bp.blogspot.com/-_LyEwG4UkPQ/Vp_6haMekPI/AAAAAAAANpw/6ocvJi6yqi8/s1600/Capture.PNG [blogspot.com]
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(Score: 2) by frojack on Thursday May 17 2018, @05:57PM (4 children)
Estimated? You mean "conveniently assumed to be"!
Its a huge game of "Lets see how we could hide a planet in here", with bonus points for every un-testable criteria you could throw in. (Fun with Dark Matter in your own back yard).
Define "Adequately Explain".
There have been many articles about rogue wandering planets [scientificamerican.com].
One could speculate micro-planets would be even more plentiful. That these get picked up in odd orbits by stars they approach purely by chance seems as adequate to me.
No, you are mistaken. I've always had this sig.
(Score: 2) by takyon on Thursday May 17 2018, @06:21PM
There are at least 5 lines of evidence for the existence of Planet Nine:
https://www.jpl.nasa.gov/news/news.php?release=2017-259 [nasa.gov]
A rogue wandering planet wouldn't explain what we see since it would exit the solar system relatively quickly. It wouldn't create the clustering of orbits seen in KBOs. There are also stars that do the same thing, coming as close as 0.1 light years to the Sun. The effects are different than what you would get with a massive planet orbiting the Sun for billions of years.
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(Score: 2) by All Your Lawn Are Belong To Us on Thursday May 17 2018, @07:47PM (2 children)
Estimated as in a combination of Hamiltonian analysis and 3 body solution simulations have an optimax of 700 AU distance with .6 eccentricity being the most likely solution to produce the anomalies of the 14 or so objects in a way that that fits this model, while still allowing other objects to be unaffected by the pertubations of the theorized body. Alleged to be fitting moreso than other theories including "just chance", which for the first six objects alone chance was estimated as a 0.007% probability (though readily conceded as "not completely impossible"). And "adequately explain" as in apparently sufficiently explaining its eccentricity and inclination similarly to 13 other objects and possibly explaining other systemwide anomalies... along with other potential theories to some degree.
"Rogue wandering planets" in the sense of TNO's do not align themselves without something to align them. Were it simply one object there would be nothing to cause any speculation. Correlating the objects together implies there is an acting body which is not conveniently explicable by any actually observed phenomena to date and not fitting other aspects of known models about how they should align. Though we all know correlation isn't causation. (Unless you meant Planet Nine, which could have been a wandering planet or could have been from within the system depending on who you listen to.)
But I have no real dog in this one way or the other. Other than thinking it would be indeed awesome if there is a Neptunian-sized object WAAAY out there but still within our system's influence.
This sig for rent.
(Score: 2) by frojack on Thursday May 17 2018, @08:49PM (1 child)
Certainly they do.
As any body wonders into proximity of another, their mutual gravitational attraction will "align" them, and the original trajectory and speed of the wandering planet or micro planet will have a great deal of input to that alignment, especially if a highly inclined initial approach angle was involved that minimized the perils of "navigating" through the existing planets.
No, you are mistaken. I've always had this sig.
(Score: 2) by All Your Lawn Are Belong To Us on Friday May 18 2018, @03:41PM
And that's very much the argument Planet Nine's proponents are making. Without the presence of a Planet Nine or something similar these TNOs do not have gravitational stuff to make the observed perihelial alignment. They should be expected to have the same random scatteredness of the scattered disk region. Adding Planet Nine in as a third-body mediator could explain why their arguments of perihelion seem to align. Unless you're referring to a possible rogue wandering planet which passed through our system and caused the alignment similar to what a Planet Nine would have done.
This sig for rent.
(Score: 0) by Anonymous Coward on Thursday May 17 2018, @03:47PM (7 children)
It's very far away and faint. One estimate was "at least 600 times fainter than Pluto". It will take awhile to find it visibly if we find it at all.
(Score: 2) by bob_super on Thursday May 17 2018, @04:29PM (6 children)
> One estimate was "at least 600 times fainter than Pluto".
Any astrophysicist to explain to us how you can guess the albedo of an object for which you barely have an estimate of mass and maybe orbit ?
I'm assuming that it's not too hard to guess: "It probably won't be breaking Enceladus's record, or we'd have seen it", but beyond that, given the diversity of objects and materials out there, why say 600 and not 1000 or 100 ? Three-digit law ?
(Score: 4, Interesting) by All Your Lawn Are Belong To Us on Thursday May 17 2018, @05:05PM (1 child)
Because it is estimated to be at least Magnitude 22? (I think that was because the WISE survey didn't find it and at the estimated distance for Planet Nine of 700 AU's it would have been discovered if it was at least Mag. 22.... I could be all wrong about that.) Pluto is known to be Magnitude 14. Each difference in magnitude corresponds to a 2.512 change of brightness. 22-14 = 7. 2.512^7 = 631.157061373. Hence, "at least 600 times fainter than Pluto." If it were at least magnitude 23 it would be more than 1,500 (1,585.46653817) times fainter than Pluto.
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(Score: 2) by All Your Lawn Are Belong To Us on Thursday May 17 2018, @05:09PM
And yeah, 22-14 is actually 8.... Pluto's apparent magnitude ranges between 13.65 and 15.1 according to Wikipedia, so I'm guessing they took 15 as the definitive number - sorry for the math goof.
This sig for rent.
(Score: 2) by frojack on Thursday May 17 2018, @06:03PM (3 children)
Why say "at least 600 times fainter than Pluto".
Why not 1/600th as bright as Pluto.
Fuzzy speaking doesn't may you look smarter.
No, you are mistaken. I've always had this sig.
(Score: 2) by bob_super on Thursday May 17 2018, @06:52PM (1 child)
> Fuzzy speaking doesn't may you look smarter.
It dunn not, may it ?
Would "dimmer" please you more?
I'm a big fan of keeping precise words in circulation, rather than dumbing down the language. There's enough dumbing going on already.
(Score: 0) by Anonymous Coward on Friday May 18 2018, @07:48AM
There is no "dimness" scale.
If there was, to find out how dim 600 time dimmer than Pluto is, we would take the difference between the dimness of Pluto and zero dimness, and multiply that by 600.
To do so would require a reference point for zero dimness.
(Score: 2) by All Your Lawn Are Belong To Us on Thursday May 17 2018, @08:02PM
Because it could be far dimmer in either actual or observed magnitude without much difficulty?
Albedo depends on many factors, but if it were much brighter than 1/600th Pluto the odds favor it would have already been discovered by other surveys. So you have an "at least as faint as" without knowing how faint it actually could be. (It would be an interesting problem to work out - what's the maximum faintness it could be if it were a chunk asphalt or other dull nonreflecting carbon...)
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(Score: 3, Insightful) by bzipitidoo on Friday May 18 2018, @06:09AM
It has everything to do with our current capabilities. Now we are in an age of computation which has in some ways gotten ahead of improvements in our power to directly observe. We can try all the models we care to dream up and easily run many simulations on them all. The computers of just 25 years ago could do it, albeit at far greater cost. 60 years ago, when we still had human calculators, forget it. Takes way more computation than a group of human calculators can handle. That's somewhat academic, as we didn't know about any of the dwarf planets beyond Pluto, so there wouldn't have been any orbital data for the computers to chew on.
It is intense simulation of many different models that has lead to the conclusion that the simplest explanation for the observations we have is one more big planet way out there. It makes sense that we would first see a small fraction of the dwarf planets it affects. Their population is large enough that some were bound to be favorably positioned for detection. But Planet 9 is one body way out there, and it is far more likely to be near apihelion, the worst possible place for finding it.
You might think, hang on, we found Neptune through calculation, way before there were any electronic computers at all. Neptune is far easier to infer, takes far less calculation than Planet 9.