Hunt For Ninth Planet Reveals Distant Solar System Objects (carnegiescience.edu)

schwit1 writes: Astronomers have discovered several new objects orbiting the Sun at extremely great distances beyond the orbit of Neptune. The most interesting new discovery is 2014 FE72: "2014 FE72 is the first distant Oort Cloud object found with an orbit entirely beyond Neptune," reports Carnegie Institution for Science. "It has an orbit that takes the object so far away from the Sun (some 3000 times farther than Earth) that it is likely being influenced by forces of gravity from beyond our Solar System such as other stars and the galactic tide. It is the first object observed at such a large distance." This research is being done as part of an effort to discover a very large planet, possibly as much as 15 times the mass of Earth, that the scientists have proposed that exists out there.

Comments

Wow, and I thought the existing Sednoids were neat

[Rei]

A sednoid (2014 FE72) with an orbit out to 3000 AU (0,05 light years)? Talk about extreme, I would have been happy just for a couple more "ordinary" sednoids! But that's exactly the sort of thing you want to see if you're of the view that trying to group the universe into a neat collection of "stars" with "planets" orbiting them is oversimplistic. This lends credence to the notion that you're going to get shared debris between different stars, rogue planets that don't orbit stars, etc. Because with large bodies reaching that far out, it becomes pretty easy to perturb them to leave the solar system altogether.

I have no clue what the discovery of 2013 FT28 is going to say about the possibility of an additional large planet in our solar system, but I look forward to the papers on it! Hopefully it won't rule one out, and will instead better constrain an orbit

Re:Wow, and I thought the existing Sednoids were n

[Rei]

Looking at their graph (since I don't see the perihelion stated anywhere), it looks to be about 60 AU (about double that of Neptune). That's some tremendous temperature changes on that body! The equilibrium temperatures are:

((1368 / D^2 - 3.127e-6) / 4 / 5.670e-8 ) ^ 0.25 ... where D is the distance in AU. So at perihelion it'd be about 36K, but at aphelion only about 5K.

Now, this particular body is probably too small to retain significant hydrogen or helium, but you could imagine what it would be like for a large planetary one in such an orbit. It'd transition between being a hydrogen-ice planet with a helium mantle and water ice/rock core; and an ice giant like Uranus and Neptune. In its solid phase, its hydrogen-ice surface would be resurfaced entirely with every cycle and thus might be expected to be perfectly smooth, except because of the heat involved in the settling processes - and how low viscosity and structural integrity in general hydrogen ice has - I'd be willing to wager that you'd get helium volcanism and maybe even plate tectonics.

It gets even weirder if a planet at such distances as this one's aphelion were to have a moon that loses helium vapour to its planet (perhaps, for example, on an eccentric orbit getting it back at each perihelion as the planet inflates, to repeat the cycle at the next aphelion). After all, even below the boiling point, there's always some vapour pressure for helium. If you're taking that vapour away, then you're looking at evaporative cooling, and you really don't need to lose it that fast to cool to below the cosmic microwave background (because radiative exchange is so slow at those temperatures) and thus to helium's lambda point. Now you have a body with superfluid helium on it, and all of the crazy weirdness that superfluids do.

Back to our solar system - aka, a small body like 2014 FE72 - you're not going to have much hydrogen or helium. But even still, that crust is going to be going through some crazy thermal stresses at the very least. Also, neon - while not as common as hydrogen and helium, but should be more common in the outer reaches of our solar system than the inner - would pass through all three phases (melting point 24K, boiling point 27K at 1 bar; lower at reduced pressures). I wonder what sort of minerology neon would form? "Neonothermal" crystal veins, analogous to crystals in hydrothermal systems on Earth? :)

If the singularity doesn't happen...

[wisebabo]

and we never get anything better than fusion drives (and Bussard ramjets don't work), then maybe a high density of these "rogue" worlds will allow the (very slow) colonization of the galaxy.

If there are roughly 1000x as many these large planetary bodies floating in interstellar space as there are stars, then perhaps it'll be feasible to travel to them in tens of years traveling at speeds achievable by nuclear fusion (hundredths of "C"). Then, using the resources there, colonies could be set up. Eventually, these will sprout new colonies, further pushing the boundaries of inhabited space until finally they reach a star.

This scheme of colonization would be unlike anything the western world, even in the days of years long voyages via sailing ships, has known. Perhaps the closest would be the voyages of the far flung polynesians who managed to spread across the vastness of the pacific ocean over a period measured in centuries(?). If any of them made it to South America (some say they did), it would be like these future voyagers making it to the next star.

Of course, we all hope for a Star Trek/Star Wars future with warp/hyperdrive bringing the stars within an afternoon's jaunt. Failing that I guess the runner up desirable future would be the hyper broadband interstellar communications network in which our downloaded selves could be digitally transferred at the speed of light to the next instancing hub (such as in Greg Egan stories of the post-singularity future).

However if neither of those pan out and if we don't learn how to make/harness anti-matter, micro-blackholes, zero-point energy, giant laser driven solar sails or ??? then perhaps this is our most optimistic future.

Maybe with immortality and suspended animation it won't be too bad. Slow trips around the galaxy indeed

Re:If the singularity doesn't happen...

[Rei]

First off, there is no "theoretical maximum speed" to how fast a given propulsion mechanism can get you. You can get to 0,999c by shooting tennis balls out the back of a spacecraft with a slingshot - if you're willing to build a spacecraft comparable in size to the universe ;)

Secondly, nuclear pulse drives really are an antiquated idea, I don't know why people obsess over it. Their minimum sizes are way too large and they're inefficient, with low ISP compared to more modern ideas. Longshot, BTW, is technically NPP, although a more modern variety. Still inefficient and very heavy, and nowhere close to a technology that could be achieved in a reasonable timeframe from where we are today.

Of the many, many concepts now available, I'd personally go for fission fragment propulsion. It's so straightforward: get the most out of fission by having individual fission reactions propel your spacecraft directly. And from a design perspective, it's pretty straightforward particle physics / fission reactor design, just in an unusual (suspended) configuration - the suspension already demoed in the lab. But that's, again, just one of many possibilities.

Re:If the singularity doesn't happen...

[Rei]

Stop feeding the troll ;) If a person can't handle an argument without name calling, they're not worth your time.

For what anyone not trolling :) There is nothing magical about existing on Earth that allows a nuclear reactor to run. Earth does provide a few conveniences, mind you - your mass budgets are unlimited, and cooling is easier. But nothing about either bulk nor mass prevents nuclear reactors from operating in space, by any stretch, and the two main things limiting their use have been a lack of need and NIMBY (the former being little applicable in the former USSR, they used them quite a bit, although they still lacked a need for high powers and so generally kept them fairly small; in the US, NIMBY limited the US to just one launch, although the US developed a number of other systems, some to flight-ready status, on the ground).

The typical mass balance for a in-solar system fission fragment rocket (measured simply by MWt, not MWe, since thrust is direct) is about 20% payload, 20% structural, 35% reactor, and most of the rest toward various aspects of cooling. The nuclear fuel makes up only about 2% of the total mass (figures from the Callisto baseline). For an interstellar mission, however, the fuel would make up the a large minority or the majority of the mass, trading significantly reduced acceleration for significantly longer acceleration times. On an in-solar-system version, power density is about 6kWt per kilogram of reactor mass (that 35% figure above). This is actually quite low by large-space-reactor standards; many modern multi-megawatt reactor research projects for NEP and defense purposes (example) often deal with density figures of 50-100 kWe per kilogram, including cooling. But a fission fragment reactor has a sparse core and has to rely extensively on moderation / reflection to keep up a sufficient neutron flux; higher core density is prohibited because then the fragments would thermalize.

One thing that's neat about a fission fragment reactor is that, like systems like VASIMR, it can operate in various output modes, trading ISP for thrust as needed. In pure fission fragment mode it's ISP is is ridiculously high, nearly 1m sec; your thrust is purely the relativistic fission fragments from each reaction, carrying the majority of the reaction's energy away. However, you can inject gas into the stream as reaction mass, limited only by the density to which your magnetic nozzle can keep the stream confined. So where higher thrust maneuvers are needed, you can use the same engine (up to the aforementioned extent, of course; you're not going to take off from a planet with a FFRE!)

Re:Nibiru

[Maritz]

The proposed ninth planet is only suggested by looking at the orbits of other bodies.

Nibiru, on the other hand, is made up by the same dickheads who believe in chemtrails and reptilians, and who for some reason think the ancient fucking sumerians were our masters in all things astronomy.

So there is a difference, for those that have brains functioning well enough to discern it.

Re:Wow, and I thought the existing Sednoids were n

[K. S. Kyosuke]

This lends credence to the notion that you're going to get shared debris between different stars, rogue planets that don't orbit stars, etc.

But how many? I don't think the process of exchange can be fast - if those bodies had galactic escape velocity, after all, they wouldn't stay here for long. So they must be comparatively slow. But the distances are still large (tens of thousands of AUs) and the volume in which they could be present is really big. Would a frequent exchange mean that most of this mass (or mess?) is actually in the interstellar space? And not in some neat belts close around stars?

Re:Wow, and I thought the existing Sednoids were n

[Rei]

I don't think the process of exchange can be fast - if those bodies had galactic escape velocity, after all, they wouldn't stay here for long

They don't have escape velocity; they're stuck with us until something perturbs them. But the key point is that when something is that far out, it's very easy to perturb. And our stellar neighborhood is not static. Indeed, one of the alternative theories to explain the sednoids is that rather than a planet X, the orbits are due to one or more stellar passes nearby our solar system.

So far we're still not seeing very far out, we're just barely spotting these things, and only when they're near perihelion. There's much more out there yet to discover, and so far all signs point to that our solar system doesn't just "stop" anywhere, it just keeps on going. Heck, we only know about the Oort cloud because comets have such distant aphelions.

There is a 9th planet

[Cornwallis]

Pluto

Re:There is a 9th planet

[Rei]

You mean 10th. You forgot about Ceres.

Under no reasonable standard is Pluto 9th. 10th, fine. I'd go out on a limb and argue at least 17th, also adding in the "planetary moons" that meet a hydrostatic definition even better than Pluto: Luna, Ganymede, Callisto, Europa, Io, Titan, and Triton. Using "planet" on the basis of of "body large enough to assume hydrostatic equilibrium but not undergo fusion" and moon as "body that orbits a planet".

Hydrostatic equilibrium is a very meaningful definition. A body not in hydrostatic equilibrium is made of primitive materials; it's the sort of place you'd go to learn about the formation of our solar system. A body in hydrostatic equilibrium has experienced internal heating, movement of fluids, chemical reactions, etc. It's the sort of place you go to learn about geology and search for life.

Or if you'd rather, you can apply the Captain Kirk test. Put it up alone by itself on a viewscreen. Would Captain Kirk say "Beam me down to that planet" or "Beam me down to that asteroid?" It's silly, but it's basically another way to say, "is the word functioning as normal people would use the word?" Of course, if there was another, bigger body in the background, they might say "beam me down to that moon". But we've all seen sci-fi where we're told that a body is a moon but people keep accidentally referring to it as a planet. The Forest Moon of Endor, for example. If it's a gigantic round thing, a part of us wants to call it a planet, even if we also know it's a moon. No reason not to just have them both as descriptive terms: a "planetary moon".

(And IMHO, if there's anything we should be kicking out of the "planet" club, it should be the gas giants... followed next by the ice giants. Seriously, how much is Jupiter like Mars?)

As for Stern, he once presented a rather interesting classification scheme (ironically, in the same paper as the Stern-Levison parameter was proposed). Basically, forget about all of these nouns, just have a good list of adjectives. You can have various things from sub-dwarf planet to super-giant planet to indicate the mass; prefixes like "gas" or "ice" or "rocky" to indicate the character: other adjectives to indicate its orbital parameters (including its "neighborhood" if you prefer), etc. Why limit yourself? Cite as many adjectives to describe it as are appropriate to the situation.

What the hell is the big deal with "planet"?

[Opportunist]

Pluto is no planet!
Why?
Because it's not cleared its orbit.
So?
Well, we have found almost a dozen others out there like Pluto!
So?
We'd have to call all of them planets!
SO?

What the fuck is the big deal? I am still waiting for a really good reason that explains why "clearing its orbit" is so friggin' important. Technically, given its Trojans, Jupiter hasn't even done that. So let's call that biggest gasball outside the sun itself a planetoid.

I can see the "has to be large enough to have enough gravity to get round". Ok. Just for the sake of having a lower limit in mass. I can of course see the "has to orbit the sun itself and not another object" so we can tell it apart from a moon (which gets our very own planet into rather hot water, considering that outside Pluto we have the biggest moon compared to planet mass, at what point do you have a dual-planet system rather than a planet-moon system? Probably when the common center of mass is outside both bodies, I'd say).

But "clearing out the orbit"? C'mon, find a better reason if you want to keep the planet club exclusive and not include the likes of Pluto. I bet it's just 'cause you noticed that it's half-black, isn't it?

Re:Wow, and I thought the existing Sednoids were n

[Rei]

Another thing I think argues for a universe full of planets: star frequency is proportional to size. The largest are rarest while the smallest are the most common. This continues all the way down: M class stars (red and brown dwarfs) make up 75% of the stars in the universe. We have more trouble estimating brown dwarf counts than red because they're not easy to observe, but they appear very abundant. But once you get below the cutoff for D-D fusion... we just can't see them. Why should we assume that the distribution just stops at brown dwarfs?

Re:Wow, and I thought the existing Sednoids were n

[Applehu Akbar]

Not in the Oort cloud, where all the volatiles are. We already have an example of weird low-temperature chemistry in Pluto.

Re:Improving taxonomy

[Rei]

While far be it from me to defend the IAU, that is just nonsense. If anything we need better definitions and more categories and the IAU got the ball rolling on this.

What the IAU "got the ball rolling on" was chaos. They had a bunch of astronomers telling planetary scientists to use a definition that they disagree with. Many have taken to just ignoring it, in the peer reviewed research. To give two examples of how absurd the definition is: 1) the definition states that something is only a planet if it revolves around the sun, not other stars - and yet the IAU has an exoplanets working group. Exoplanets aren't planets! 2) The concept that "a dwarf X isn't an X" is not only linguistically absurd, it's a view not even shared by the IAU itself, which is more than happy to consider, for example, dwarf stars to be stars.

The main reason stated by most astronomers who backed the decision is almost invariably (seriously, read interviews with them), "I don't want my daugther having to memorize the names of sixty different planets". As if that's even slightly a valid reason for making a scientific decision.

Jupiter and Earth bear almost no resemblance to each other and yet they both are planets.

Exactly! And yet rather than kick the gas giants out, they kicked out another solid body that has far more in common with Earth (including, I should add, active geology and weather) rather than the bodies that have almost nothing to do with Earth.

In reality they should probably be different categories of entities. We used to consider Ceres a planet a long time ago

And we should. Believe it or not, because some scientists in the 1800s changed their mind about something doesn't mean that this is some sort of eternally correct decision. They had no clue about the concept of what bodies would end up in hydrostatic equilibrium and the consequences thereof.

Let's go to biology. We label species all the time based on location and proximity to other similar animals rather than the much simpler "can they mate" question.

How do you see this as even remotely similar? If you take a shrew from Ohio and you place it in Nepal, does it cease being a shrew and become a dwarf shrew that no longer counts as a shrew?

Or geography. We label mountains and bodies of water precisely based on what they are next to. You could reasonably consider the Mediterranean Sea as a part of the Atlantic Ocean if you really wanted to.

So because it hasn't "cleared its neighborhood" does it suddenly become the Mediterranean Pond despite being a size that we traditionally call a sea? Do we arbitrarily declare that there's only 8 mountains in the world and all others are "dwarf mountains" that aren't really mountains because we think there's too many mountain names for kids to memorize?

Umm, ok. Presuming that is true...

Seriously, you're going to cast doubt on the guy who came up with the Stern-Levison parameter that's used to make that distinction?

It would be equally true to say that Earth wouldn't be a planet if it wasn't orbiting the Sun but equally irrelevant as well because it manifestly does.

Right. Because it totally makes sense to have an perfect copy of Earth orbiting in a larger star's habitable zone (and thus have a lower Stern-Levison parameter) not be a planet while its perfect copy is.

Pluto is very much like Ceres and other big rocks

Pluto is absolutely not "much like" "big rocks", and the fact that you'd make this claim is a profound expression of ignorance on the topic. And should I add, one of my greatest peeves about the IAU's decision. Since their discoveries long, long ago both Pluto and Ceres had been nothing more than specks

Prove your assertion

[sjbe]

Enough with the "we used to think" the earth was flat, humans couldn't fly, etc. We don't. We know physics now. It isn't going to happen

Yes some of us do know something about physics though it sounds as if you might not be in that particular group. To my knowledge there is nothing we know about physics that prohibits us from someday traveling at a significant fraction of C. There are abundant engineering challenges and dangers to be sure but that's a different issue. I'm claiming that there is no known reason why we couldn't accomplish that feat. You are claiming it is categorically impossible. Ergo the onus is on you to disprove the null hypothesis that high velocity travel is possible.

You can always detect a space nutter because they always say "well we USED to think" and then extrapolate that all things are possible.

You can detect a cynic because they claim things are impossible without any actual evidence to back them up. Since you seem to think you are smarter than the rest of us go ahead and show why it is provably impossible for humans to ever travel at a meaningful percent of C. Your Nobel prize awaits if you can do it. Otherwise you can leave your cynicism at the door.

Re:Prove your assertion

[Greystripe]

To be fair to110010001000, everything is impossible... if you do not try.

Re: Prove your assertion

[nitehawk214]

What a sad and grey world you live in where everyone that dares to look up and dream is a "space nutter" to be ignored.

I bet you say libtard a lot too. Got to have those labels you can slap on people so you can ignore them and make sure their ideas don't infect you.

Re: Prove your assertion

[DanielRavenNest]

Ignore him. Go look at my space systems engineering book ( http://en.wikibooks.org/wiki/S... ) for a survey ot propulsion methods.

Re:Wow, and I thought the existing Sednoids were n

[Anonymous Coward]

well ... except that planetoids typically accrete around rocky objects after supernova, so without a previous star going nova, there's nothing to create the rocks to create the protoplanets to accrete planets. Consequently, the planet is full of gas clouds, and stars with significant planets pretty rare.

Re: Nibiru

[Maritz]

Read some of that. Painful fucking drivel. "awakening human" = wishful thinking gimp who has to feel like a special snowflake who has seen "behind the curtain". You've seen fuck all. Nibiru is bullshit and only the gullible accept it. Cheers.

The universe.

[malditaenvidia]

When I was child, there were thought to be 9 planets. Now there are 90 planets.