New Scientist has an article discussing new measurements taken of the giant KBO named Quaoar with the 8 meter Subaru telescope on Hawaii that suggest it may once have been warmer, and possible is being warmed by internal heating. The measurements indicated crystaline water ice, which can only form above -163 C, while Quaoar orbits in a region where the Sun could only heat it to -223 C. The possible, but disputed, presence of ammonia may be responsible, but it is being suggested the internal heating from the radioactive decay of heavy isotopes such as uranium may be created cryo-vulcanism on distant Quaoar. Just as Neptunes large moon Triton has nitrogen geysers, Quaoar could be a surprisingly active word.

Here is a link to David Jewitt's site discussing the new measurements of Quaoar, which includes a further link near the bottom to a PDf of the paper submitted to Nature.

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That's an interesting story. One of the points in the longer article is that such ice most likely can only exist at the surface for about ten million years or so, so there needs to be a frequent/continuous source for it. Quaoar is not orbiting closely to something like Neptune [as has Triton].

Another possibility they didn't consider, but should if Quaoar is unusual among the KBOs for the property is that it has had a large collision in the last ten million years.

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David Jewitt, in one of those links, comments that a large collision would have blown most of the ice out into space rather than exposed/melted it on the surface.

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The actual behavior would depend highly on collision mass and velocity. If it were a slow-speed collision with a larger object, [should be a very rare event] a lot of heat would be retained.

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This is a really cool observation. The KBO is too small to have retained heat from its formation. As a guess, I would also think a low-velocity impact with another object, smiilar to the impact experienced by the proto-earth which apparently formed the moon.

There is no tidal heating, as nothing is close enough to cause it. Maybe radioactive decay of some sort?

Interesting!

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Humanity must rise above the Earth, to the top of the atmosphere and beyond, for only then will we fully understand the world in which we live.~Socrates, 500 B.C. ~

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How common are radioactive elements in the solar system? As common as they are on Earth? The moon and Mars are totally cooled, now, aren't they? would it be an anomoly to have something with enough radioactive material to keep it that hot that far away, and that long after its formation? Wouldn't it have to be pure uranium almost to still be decaying and generating enough heat?

hmm...thats too many questions. How about this one:

"Assuming the solar system is made of roughly the same stuff, and knowing bodies like the moon and mars have already cooled off, wouldn't this have to be pure uranium or something of the sort to still be decaying and generating enough heat?"

Thanks in advance for your enlightenment. Always a pleasure to learn something from youses guyseses...

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Most radioactive nuclei on the earth were formed in various supernova, mostly before the creation of the Earth. There are man-made isotopes, and some that form from the interaction of cosmic rays with the atmosphere [such as Carbon-14].

Quaoar should have a lower concentration of these things than the Earth does, because the it was never stripped of it's light elements, which tend to have only stable or short-lived isotopes.

On the other hand, the standard for 'heating' on Quaoar is not very high. It only has to elevate the well-insulated core fifty to a hundred degrees to get into the temperature ranges that are required for the occasional cryogeyser.

I'm predicting that radioactivity isn't the cause of recent ice crystalization, but it is certainly within an order of magnitude or two of being possible.

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The trouble with heating by big impacts is that these are very rare. Quaoar is big and the likelihood of having an impact large enough to substantially resurface the object is tiny. Micrometeorite impacts are probably common, though, so we think that they could be implicated in exposing the crystalline ice within the last 10 Myr (and continually, in fact). The main heat source for making the ice crystalline almost has to be radiactive decay. There's not much else.
Quaoar is not in any useful dynamical resonance (that could caue flexing of the body shape and therefore heating). It is not big enough to have formed really hot from its own gravitational binding energy (probably). So radiactivity is left.

But "hot" is not very hot. 170 K would probably be enough to mobilize interior ice and allow it to
convect and erupt. We also report ammonia hydrate in our paper - that is a kind of antifreeze for ice at these low temperatures and may have played a role in convection in other small outer bodies, like some of the strange satellites of Uranus.

Regards

Dave

Thanks David, that clears a few things up.

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WOW! THE David Jewitt posted here?!?! This was his discovery, his work. I love this forum! B)

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...and we'll be saying a big hello to all intelligent life forms everywhere; and to everyone else out there, the secret is to bang the rocks together, guys...

Thank you, thank you very much B)

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All civilizations become either spacefaring or extinct.~ Carl Sagan ~

Humanity must rise above the Earth, to the top of the atmosphere and beyond, for only then will we fully understand the world in which we live.~Socrates, 500 B.C. ~

Let every man judge according to his own standards, by what he has himself read, not by what others tell him. ~Albert Einstein~

ahhh, "170K" hot. Not "hot" hot.

...so I guess I shouldn't have re-scheduled my Carribean vacation so hastily...

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~ cogito cogito ergo cogito sum ~

Nothing in life is good nor bad; thinking makes it so.