Strange Alien World Made of "Hot Ice"

David Shiga writes "The smallest planet ever seen passing in front of its parent star is a strange world of scorching hot ice, astronomers say. The 22-Earth-mass planet has been known since 2004, but recent observations of it passing in front of its parent star have allowed them to learn much more about it. It appears to be made mostly of water, but not in liquid form. The planet orbits so close to its parent star that its surface is a broiling 300 C, keeping any water there in vapor form. Beneath the atmosphere, the water is even hotter, but is at such high pressure because of the planet's large mass that it stays in a solid, "hot ice" form."

Comments

Re:Interesting.

[someone1234]

Yes, iirc it was already done. See Sandia Z machine.

Re:Interesting.

[Control Group]

Short answer: yes.

Longer answer as gleaned from the link above if people don't want to bother clicking: yes; the Z-machine at Sandia is able (at least) to form Ice VII.

Re:Water?

[ArcherB]

No, we have confirmed the existence of water on other planets in our own solar system. Even Jupiter has water vapor in its clouds and Europa is covered in it. Even comets have a bunch of it. It's liquid water that's harder to come by. We're not so much looking for water as much as we are looking for water that can harbor life.

Not ice

[markov_chain]

The solid/liquid phase transition line for water moves toward lower temperatures as pressure goes up, so ice shouldn't be able to form at 300C regardless of pressure. Other than the title there is no mention of this "hot ice." The relevant quote mentions something more reasonable, namely, the supercritical fluid phase:

and it is not even clear if any of the water could be in liquid form, although deep inside where the pressure goes up, there could be a region where the water is in a quasi-liquid state. "It could pass through a strange region where it's not quite solid and not quite liquid," she says.

Re:Not ice

[jimstapleton]

I belive that is only applicable for Ice I[h] (normal ice). One property for such phase transition diagrams is that the solid is less dense than the liquid, rather than the reverse being true. There are several crystaline (and possibly non-crystaline?) forms of ice, which are more dense than water at the same pressure. These types of ice wouldn't match that phase diagram and could exist.

Re:Not ice

[loafula]

there are actually 14 different types of solid water. my guess is they're talking about Amorphous ice ..wikipedia. Also, I believe the 300C temperature is that of the water vapour in the atmosphere.

Re:Water?

[MightyMartian]

One word: spectroscopy.

Re:Strange ice

[HetMes]

This has been proven to be false. Being able to skate on ice has something to do with the upper crystal layer being of unique structure. No links, just Google it.

Re:Water?

[maxwell demon]

Aren't we still speculating whether water exists on other planets within our own solar system?

From the article (emphasize by me):
The inferred composition of the planet is very much like that of Neptune, which is also made mostly of ice, Pont says. "If you bring Neptune nearer to the Sun and it's heated outside to 300 C, that's exactly what you get," he told New Scientist.
I guess this answers your question.

water phase diagram

[excelsior_gr]

The critical point of water is at 647 K (374 C) and 22.1 MPa. This means that a temperature of 300 C is actually subcritical. No matter how high the pressure gets, water will NOT come in the supercritcal area of its phase diagram for that temperature. Moreover, due to the fact that water molecules form hydrogen bonds (this is why the density of ice is lower than the one of liquid water), the melting line of water goes towards lower temperatures with increasing pressure. Therefore, water at 300 C is liquid. Pediod.

Check this out:
http://en.wikipedia.org/wiki/Phase_diagram

Re:water phase diagram

[Anonymous Coward]

The phase diagram in that wikipedia article you referenced is a generic one. Water's phase diagram is much more interesting. Note in particular the phases "available" at 575K (300 C): ice VII forms at 10 GPa; at lower pressures water, and (below 10 MPa) steam phases exist, and at higher pressures ice X (ca. 100 GPa) and XI (ca 800 GPa) phases.

Re:water phase diagram

[Anonymous Coward]

Sorry, I appear to have left of the hyperlink in that post.

Ice Polymorphism

[Jabba_the_Butt]

A fantastic H2O Phase Diagram can be found here (http://www.lsbu.ac.uk/water/phase.html). At 300C (573 K) you can have ice; you just need a lot of pressure. That kind of pressure is in the several gigapascal range (x10^9 Pa, 1 GPa145,000 psi). Any ice that has a designation (e.g. Ice I, Ice Ih, Ice II, III, V, VII, X, etc.) has a set crystal structure. As you can see on the phase diagram you can have ice at very high temperatures if you have enough pressure. What is present on the planet mentioned in the article is strictly dependent on the pressure and temperature conditions there, which we do not really know.

Re:Strange ice

[jae471]

There is a problem with the UVA page -- Ice skates blades aren't flat in any dimension, so you get nowhere near 20cmx3mm in contact when gliding. A hockey skate probably has 8cm of length in contact, and a figure skate about 12cm. The blade itself is hollowed down the middle, like an upside-down U. A very shallow hollow will have a 7.5cm radius, a figure skate about 4-5cm, a normal hockey hollow is closer to 2.5cm, and a suicidally deep hollow has a 1cm radius (But its all a matter of personal preference, really.)

Effectively, a hockey skate will actually have about 8cm*1.5mm = 12 sq mm in contact with the ice, not 60 sq mm. That's a 5x increase in pressure over what the UVACD says, meaning instead of 12 atms (their number), you get 60 atms. Still not enough to raise it one degree (there are other factors -- frictional melting and the temperature of the blade), but their assumptions are wrong.

The blades also bend ALOT when skating, more than you might think. Whenever there is a turn cut in the ice, the blade deforms to match it. And bending a metal creates heat.

As an aside, the best ice for skating should be around 18F (as measured by return brine temp, so the surface will be a few degrees warmer), with an ambient air temp of about 32-40F, and 20-30% relative humidity. Above 40F or 30% humidity, either the surface starts to melt, or water condenses on the ice.

Now that was completely unrelated to the topic at hand, but I had to rant. Sorry.

Re:Correct me if I am wrong

[Control Group]

Yes, we can.

In fact, there are two types of ice that occur naturally on this planet, traditional hexagonal ice (Ice Ih) and ice with a cubic lattice (Ice Ic (I'll avoid the too-obvious "Ice Ic, baby" joke, here. You're welcome)).

According to that Wikipedia page, there are 14 different forms of ice which occur at varying temperatures and pressures. "Common" ice, Ice Ih, is, in fact, the odd one out in some respects - for example, it's the only one that is less dense than liquid water.

Re:Interesting.

[AJWM]

FYI, the pressure at the bottom of the Marianas Trench is something over 1000 atm. The temperature is pretty cold -- a few degrees C. The water isn't solid.

We're talking much higher pressures here, the kind that forms diamonds.

Re:Interesting.

[eclectus]

The water at the bottom of the marianna's trench is very close to freezing, but in this case, the pressure is actually what keeps if from freezing. Water has a strange property where the liquid form can (at certain temp/pressures) have a greater density than the solid form (ice). This is why ice floats, and also what makes ice skates work (the pressure of the skate turns the top layer of ice into a thin film of water. If you compress ice at 0 degrees celsius it will turn into water, while compressing water at 100 degrees celsius will eventually result in hot ice. The phase diagram for H2O can be found here

Re:Strange ice

[LionMage]

Um, your temperature conversions are wrong. 4F = approx. -15.6C, and 20C = 68F. The conversion equations can be found many places, such as here.

I also initially disbelieved your explanation, since my high school physics textbook unambiguously attributed the ice skating phenomenon to regelation, but further digging did turn up this little gem (and a related tidbit showing a classic regelation experiment):

Beware: if you search for ice regelation on google, some web sites propagate the error that the mechanism of ice skaing is regelation. As you can calculate in the question sheet, regelation does not give sufficient depression of the melting point over long enough for it to be important for ice skating.

And from the related page:

It seems clear from the literature (but disappointing) that regelation is not the cause of the ice being slippery when you ice skate. A paper published in Physics Today in December 2005 and listed in the references for this demonstration, discusses the concept, initially proposed by Faraday, that a microscopic layer of water, found on ice even at very low temperatures, is responsible for ice being slippery. On the other hand, regelation apparently is a primary contributing cause for the motion of glaciers, as discussed in one of the references.

Another curious side note from that last link:

There is a lot of discussion about whether this really demonstrates regelation, but rather simply conduction of heat by the wire to the ice cube so that it will melt, followed by freezing over of the cut due to conduction of heat away from the cut to the surrounding ice.

Interestingly enough, a fellow student in high school eliminated this potential problem when she recreated the regelation experiment -- she put the entire experimental apparatus inside a freezer unit with excellent temperature control, so she was able to vary temperature as well as the masses attached to the metal wire, and she was able to insure that the masses and wire were at the same approximate temperature as the block of ice.

More info can be found here, which gives some interesting extra info (such as: the optimum temperature for speed skating with minimal friction is -7C).