Trans-Neptunian Planets: Questions and Discussion

jmilsom · Nov 7, 2005

Like many here, I have been watching carefully for news of discoveries of new planetary bodies in the outer solar system. If we include Pluto, the seven largest of these (ranked from largest to smallest) are: <ul type="square"><li>2003 UB313 (Unofficial: Xena)<li>Pluto<li>2005 FY9 (Unofficial: Easterbunny)<li>2003 EL61 (Unofficial: Santa - the weird cigar-shaped one)<li>90377 Sedna<li>90482 Orcus<li>50000 Quaoar </li></li></li></li></li></li></li></ul> It seems that we are now discovering most of them have satellites. Pluto as we now all know has three! 2003 UB313 has one. Can anyone fill in details on the rest? I have a few questions: 1. There has been a lot of debate as to whether Pluto and other bodies discovered should been labelled planets. I recently read that Isaac Asimov had once suggested that the icy Trans-Neptunian Planets be given a special category: mesoplanets. I quite like this idea, i.e. of Pluto being the first of the mesoplanets. They still then get named as planets within their own special category. Has this been seriously considered by the IAU? 2. I also read (on Wikipedia which has been blocked by China meaning I cannot access it while at my work location) that there is a large gap within the Kuiper Belt (not the Kuiper gap from 30 to 50 AU) that suggests that there may be one very large planet (i.e. Mars size or greater) orbiting out there somewhere. Is anyone looking for this? Is 2003 UB313 in this vicinty? 3. Could anyone post tabulated data comparing these seven bodies? What is the total number of KBOs larger than Ceres now discovered? <div class="Discussion_UserSignature"> </div>

vogon13 · Nov 7, 2005

An aside: IIRC, shortly after the discovery of Pluto, Tombaugh and others at the Lowell Observatory considered the possibility that Pluto was a distant satellite of the actual planet they were looking for. And that someone else would figure this all out. Also, it seems I recall a computer simulation back in the seventies that implied a large planet 'way out' that would account for variances in the orbit of Halley's Comet. That distant objects have been under consideration for a long time is clear, the great thing about today's outer solar system exploration is that there are real objects being found. <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

harmonicaman · Nov 7, 2005

Mesoplanet size comparison chart: http://www.nationmaster.com/wikimir/images/upload.wikimedia.org/wikipedia/en/3/30/Mesoplanets.png

Philotas · Nov 7, 2005

3.Nice link here: http://www.ifa.hawaii.edu/faculty/jewitt/kb.html Note: 2004 DW aka 90482 Orcus Edit: found another one: http://en.wikipedia.org/wiki/Kuiper_Belt#Largest_KBOs <div class="Discussion_UserSignature"> </div>

CalliArcale · Nov 7, 2005

Actually, those are not all trans-neptunian objects. Many orbit permanently beyond the orbit of Neptune, and are Kuiper Belt Objects. Sedna is a particularly dramatic example -- it orbits so far away it's not even a KBO. It orbits beyond the Kuiper Belt, and may actually be the first detected Oort Cloud object (if the Oort Cloud is found to exist as predicted by Jan Oort). <div class="Discussion_UserSignature"> "People assume that time is a strict progression of cause to effect, but actually from a non-linear, non-subjective viewpoint it's more like a big ball of wibbly wobbly . . . timey wimey . . . stuff." -- The Tenth Doctor, "Blink" </div>

jmilsom · Nov 8, 2005

Yes. I guess we are all struggling with definitions. If all the small planets beyond the orbit of Neptune are small and icy perhaps a single definition such as mesoplanet will suffice. But what if we discover something really big, say, out where Sedna orbits? I assume what we will find is a continuous gradation of bodies ranging from tiny up to planet size, so where to make boundaries for definitions? Maybe diameter > 1000km in the Kuiper Belt = Kuiper mesoplanets and > 1000km in the Oort Cloud = Oort mesoplanets?!?! We've had quite a few discussions on specific points related to these bodies over the past two years. To link these to the discussion: IAU looking to decide if 2003 UB313 is a major planet Fun thread: name Pluto's moons! Two more moons discovered orbiting Pluto 2003 UB 313 is the lost moon of Triton POLL: How many Planets in our Solar System Scientists Discover 10th Planet's Moon http://uplink.</safety_wrapper <div class="Discussion_UserSignature"> </div>

mlorrey · Nov 16, 2005

The Uranus and Neptune mass measurements that the Voyager probes made helped scientists refine their orbital math so that all thepreviously calculated 'perturbations' they found in the numbers that made them think there was a high mass "Planet X" beyond Neptune just disappeared. It is thus pretty much accepted that there is not likely to be anything in Kuiper Belt space more than, say, twice the mass of Pluto or Sedna. Planet X is now considered fringe theory, bordering on a cargo cult (especially if you look at the other kooky things that a lot of Planet X adherents believe in, and at the fact that they have a very poor grasp of orbital mechanics). BTW: Sednas perigee is in the KB, while its apogee is out in the KB/Oort boundary zone that at this point is pretty much guesswork as to its extent. I'd call Sedna a KBO given it spends most of its time in the KB, and that it happens to be in it at the moment.

mikeemmert · Nov 16, 2005

You forgot Triton! Although it is a moon now, it's strange orbit strongly implies that it is a captured body. In order to be captured by Neptune, Triton had to have transfered momentum to some third body. I have done a series of orbital simulations with GravitySimulator that show reasonable original moons of Neptune (I copied Uranus' moons onto Neptune) won't do the job. It had to have been something roughly the same mass as Triton. I'll bet anybody here a dollar to a doughnut that the mass of Triton is within 15% of the mass of 2003 UB313, or Xena as I prefer to call it for now. I think Xena's probably somewhat larger than Triton, since geysers have been observed on Triton which might be lost mass for that moon, and Xena doesn't have any resonable energy source for such geyser activity. I think Pluto used to be the same size but has evaporated under the influence of sunlight. And 2003 EL61, "Santa", also; it's now made out of stone with a thin veneer of ice. How it lost it's ice mantle is a big mystery to me. I'm stumped. We'll soon find out, since Hubble is to observe Xena and it's moon (Gabriella) and settle this question.

mikeemmert · Nov 16, 2005

Thank you for your post. Planet X is dead, unless they name 2003 UB313 Xena, which is my choice. Anything but Beelzebub! (The Ba'al of Zebub was the Lord of the Flies for the city of Ekron (Accaron), according to ancient Hebrew records. This was done to insult the Philistines (modern Palestinians) so it's a really bad name in view of the murderous war that continues to rage between the two peoples. Christians have expropriated Beelzebub as the Prince of Darkness). I think most of the Kuiper Belt came from Neptune's L-4 and L-5 Lagrange points. Neptune won't fling escaped Lagrange objects much farther than 47 AU unless they are part of a binary system. I invite potential debunkers to present a binary farther out than that, I don't know, I haven't looked. Xena has a moon, but I think that's from a later collision with something closer. If there's a Planet X, it would be a Sedna type object, which may have come from a passing brown dwarf. It would currently be somewhere around aphelion at 50,000 km or it would have been detected by the Voyager and Pioneer tracking data. Or it's very small for a planet.

Philotas · Nov 16, 2005

<blockquote>In reply to:<hr />If there's a Planet X, it would be a Sedna type object, which may have come from a passing brown dwarf. It would currently be somewhere around aphelion at 50,000 km or it would have been detected by the Voyager and Pioneer tracking data. Or it's very small for a planet .<hr /></blockquote> I`ve heard the possiblities of Earth sized planets out there....proposed by Alan Stern, a somewhat serious scientist. Can more Earth/Mars sized planets in our solar system be 100% ruled out? <div class="Discussion_UserSignature"> </div>

jmilsom · Nov 16, 2005

Thanks mlorrey. Some excellent points there. Re; Definitions - I guess we'll have to wait and see what the IAU eventually settle on. I'm all for giving Pluto (and larger bodies) planetary status, but as there is such a diversity of objects, a more defined sub-class may be necessary. And I guess many bodies like Sedna, will spend time in both the Kuiper Belt and Oort Cloud, so separating definitions between these two regions would not be viable. Concerning Planet X. I once read of the Sumerian tablet that has a tenth planet and tried to find hard archaeological science on it - but it was impossible as the web has so many crackpot sites dedicated to it, I simply could not find it. However, I veer strongly away from that crackpot stuff. My speculation on a large body, came not from any Planet X literature, but from the source Philotas mentions and something I read on Wikipedia. Basically that there is an unexplained gap within the Kuiper Belt (not the Kuiper gap itself) that could indicate the presence of a body much larger than Pluto. I cannot find this now, so am starting to wonder if I misread something. My interest in KBOs or all large bodies from Neptune outwards has led me to believe there are hundreds of bodies out there from tiny up to maybe twice the size of Pluto. I suspect the Sumerian tablet was an artistic fluke! <div class="Discussion_UserSignature"> </div>

mikeemmert · Nov 17, 2005

Philotas asked: " Can more Earth/Mars sized planets in our solar system be 100% ruled out? " I'm not really sure. The Voyager/Pioneer article I read about a decade ago ruled out a "Nemesis" or "Planet X", but they didn't give any quantitative constraints to the best of my memory. There are no red dwarfs, brown, dwarfs, or Jupiters. Obviously the tracking data missed Xena. Damn print articles...you can't google them. In a million years, they will consider record-keeping to have started in the 1990's by Al Gore. They will actually be able to find "W who?". Before that is fragmentary. I would like to comment on Dr. Stern's ideas about the outer solar system. They require about 40 Earth masses of material. While I was laid up in the hospital, a friend gave me some magazines to read (no computer). I read about a pencil probe that was done where about 80 objects were expected to be found in the small, highly magnified field of view, according to Dr. Stern's hypotheses. They found three. You will have to take my memory about the pencil survey article with a grain of salt. I was in extreme pain and the doctor prescribed opiate dope. I can't remember who did the article or even the name of the magazine...there was a big stack of them. My roommate wanted to watch "Apollo 13". So did I. But I am real sure of the 80/3 figure because I talked to the nurse about it. It was pretty exciting. My hypothesis that most KBO's come from the Sun/Neptune Lagrange point calls for about 8 Triton masses (actually Xena masses, we'll find out next month, and that's if Xena hasn't been evaporating as Pluto and Triton have been seen to do). However, there are objects out there, Quaoar and 2005 FY9, that have orbits much like the ones planets would have if there was enough material out there to form them. So that would call for more than 8 Triton masses. I have no idea, theory, or hypothesis about how much material might be

jmilsom · Nov 17, 2005

I think I may have misread. Here is an excerpt from a basic Kuiper Belt article written by Alan Stern for Encarta: “Nearly 600 Kuiper Belt Objects had been found by 2005. Astronomers estimate that over 100,000 KBOs larger than 50 km (30 mi) in diameter may exist. The Kuiper Belt therefore is far more extensive and with far more large objects than the asteroid belt. Including the billions of comets that are believed to orbit in the Kuiper Belt, it is estimated that the belt’s total mass is about one-tenth the mass of Earth.” This seems to contradict the 40 earth masses idea. Perhaps this belongs to an earlier speculative hypothesis that has since been debunked? I also found a running list of TNOs / KBOs that is upated daily: http://cfa-www.harvard.edu/iau/lists/TNOs.html <div class="Discussion_UserSignature"> </div>

mikeemmert · Nov 18, 2005

Dear jmilsom: Thank you for these informative links: http://cfa-www.harvard.edu/iau/lists/TNOs.html There are slightly more than 1000 objects on this list. Please forgive me, my count crashed at about 700... It's true that the 40 Earth mass estimate I read is very old, dating to the beginning of the KBO finds. That estimate used to be widely believed. http://encarta.msn.com/text_701509040__1/Kuiper_Belt.html I noticed that this article is being updated piecemeal; for instance, the rocket for the New Horizons mission, an Atlas with five solid boosters and a solid rocket atop the Centaur upper stage, was selected before the dicovery of 2003 UB313. Dr. Stern might consider a complete rewrite, but it's probably a little premature to do that this afternoon (11-18-2005). More information about the Kuiper belt will be available after the launch from Hubble and other sources. Besides, Dr. Stern is busy with the launch. We all eagerly await the results from New Horizons and wish for it's success. "The second largest known KBO, tentatively named Sedna, is more than half the diameter of Pluto" There is no reliable basis for making this statement that I know of. Sedna is too far away to show a disc. I am unaware of any infrared measurements that will show it's albedo, the other way of estimating diameter. "KBOs have a wide range of surface colors, varying from almost gray to very red. Their surfaces are usually quite dark, only reflecting from 3 percent to perhaps 25 percent of the light that falls on them. " Initial headlines concerning the discoveries of Quaoar and Varuna used estimates of their diameters based on an albedo of 4%. Later the albedos of these objects have been found to be substantially higher and therefor

vogon13 · Nov 19, 2005

I'll throw in a few points, make of them what you will. The 'black stuff' on D type asteroids and Iapetus is kerogen or something very similar. Kerogen is a precusor chemical to petroleum. The presence of kerogen does not necessarily imply life forms. Kerogen, in my opinion, is the black gunk in the bottom of the deep craters of Hyperion. Kerogen, in my view, can be formed in a temperature environment from the outer asteroid belt to roughly around Saturn. Kerogen is either formed in a specific temperature range or in a specific temperature range with solar UV, I'm not sure. I do not know how kerogen and tholins are related. I suspect they are polymereric forms of carbon and nitrogen, but I do not know if they are chemically 'family'. The presence of methane ice on Pluto and not Charon may be explained by tidal interactions between the two thermally driving off methane from Charon. Methane may also be absent from Charon if Charon is condensed impact debris from a Plutonian impact. To my knowledge, the chief form of carbon on Phoebe was frozen carbon dioxide. That kerogen (or similar materials) are not found on moons interior of Titans orbit implies (to me) that kerogen on Iapetus and Hyperion is derived from CH4 and N2 from Titans atmospheric leakage carried outward via the Saturnian magnetotail. I don't recall kerogen or tholin being detected on Triton. Due to the low temperatures, I don't feel kerogen will be found on Pluto or any body further out (that formed further out than Pluto did). <div class="Discussion_UserSignature"> TPTB went to Dallas and all I got was Plucked !!So many people, so few recipes !!Let's clean up this stinkhole !! </div>

jmilsom · Jan 16, 2006

Hi mike, I just got a back copy of New Scientist (23 July 2005) and have found the article in which Alan Stern talks about 40 earth masses. If you have discussed this in a later thread please let me know and direct me to the discussion. Basically it relates to the oligarchic model of planet formation, which proposes that the dust disk initially coalesced into 60 rocky planets called oligarchs. Models predict an early period of violent interaction in which the major planets are formed, but then predicts up to a dozen planets all larger than Mars to be orbiting in wild orbits anywhere from 1,000 to 10,000 AU away from the sun. This puts them way beyond the Kuiper Belt and even the 'scattered disk' zone of Sedna at about 100AU. I understand that this is not the favoured theory but the key piece of evidence is now Neptune's first 'trojan' 2001 QR322. Its very existence apparently suggests a miniature version of oligarchic planet formation around Neptune. In trying to explain QR322, the main investigator (Eugene Chiang, Universityof California) realised it could have formed in situ from dusty debris that fell into Neptune's gravitational no man's land. Apparently most computer models show that it is almost impossible for Neptune to capture asteroids, its gravity being much weaker than that of Jupiter. This latter explanation is easily explained by computer models apparenty, which predicts about 20 more Neptunian trojans. Anyway, probably you know all this and apologies if you've discussed it elsewhere. Of these hypothetical planets dubbed 'halo planets' Stern is quoted in the article as saying "I think it is a 100 percent certainty... definitely there are Earth-sized objects out there and some will be larger than the earth." There are projects in the works to look for these objects. <div class="Discussion_UserSignature"> </div>

mikeemmert · Jan 16, 2006

Hi, jmilsom; (google, google, google...) The first phase is pretty easy here. This very thread is on my favorites list because it has several links posted by none other than you yourself. Thank you. One of the links is to my very first post, "2003 UB313 is the lost moon of Triton": http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=297646&fpart=1&PHPSESSID= To answer your query about what went wrong with Dr. Stern's oligarch idea, we have to figure out where the estimate of a lot of material came from. I started a thread about that called, "Olber's Paradox and the Kuiper Belt": http://uplink.space.com/showflat.php?Cat=&Board=sciastro&Number=416759&page=&view=&sb=&o=&vc=1 It has links to stuff outside Uplink that are interesting. I wound up giving my own description of what Olber's Paradox is <img src="/images/icons/crazy.gif" /> in a later post there. I have the whole thread in the link. Here's a short thread about rapid planet formation. I disagree with some of the other poster's ideas, but the link is OK. Besides, that theory about rapid planet formation has gotten a lot of press lately. What I like about rapid planet formation is that it might strand a small amount of gas in the solar nebula, which would add just a tiny amount of friction. That seems to help in the formation of Lagrangians. Well, read the thread. Here's a thread I started when 2003 EL61 was found to have a second moon, called, "Santa's Second Moon": http://uplink.space.com/showflat.ph...ber=401201&page=&view=&sb=&am</safety_wrapper

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