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Fraser
2007-May-17, 04:51 PM
One of the most dramatic extrasolar planetary discoveries of the year was announced this week; unfortunately, with little fanfare. Planet hunters uncovered a Neptune-sized planet orbiting a nearby star. ...

Read the full blog entry (http://www.universetoday.com/2007/05/17/neptune-sized-planet-covered-in-superhot-ice/)

lpgeorge123
2007-May-17, 08:14 PM
This planet is close enough to its parent star that it’s extremely hot - above 250 degrees Celsius. And yet the intense pressure from gravity forces large quantities of liquid water into solid ice.

That's pretty cool.

Triclyde
2007-May-17, 11:50 PM
Hi,

Good story. Just one question though...

Why would water turn to ice because of high pressure? I thought that ice was actually less dense than water, and that water was most dense at about 4 degrees Celsius. Shouldn't the water on the planet be a liquid if it is under high pressure?

EDG
2007-May-18, 12:03 AM
Because that's what water does :)

Solid Water (ice) comes in many phases, not just the Ice I that we're familiar with on Earth - the other phases occur at different combinations of temperature and pressure. See here for more details:

http://www.lsbu.ac.uk/water/phase.html

(10^5 Pa on that diagram is equal to 1 earth atmosphere)

Under enough pressure (which you'd get under hundreds of km of water) the water would change to ice III or V or VI, which would then itself change phase again as you went deeper to ice VII.

You'd only get ice II or VIII at very low temperatures and high pressures, which are unlikely or impossible in planetary interiors.

Northwind
2007-May-18, 12:29 AM
From article
A planet with this amount of water ice must have formed outside the star’s “snow line”, where the protoplanetary disc is cool enough for water to condense. Some process must have brought it gradually closer to the parent star, to its current position today. Once the planet got close enough to the star its outer envelope of hydrogen and helium would have evaporated away, leaving the smaller icy core.

???

What a joke :p:p:clap:

Whats the process?? :shifty:

I bet it's the same one that can make high temperature minerals found inside a comet nucleus! The same "process" must have made them (comets) form inside the "snow line" and then
Some process must have brought it gradually more eccentric to the parent star

It's a game of cosmic musical chairs!!! :lol:

We collectively have no idea :silenced:

Come on people, we have a lot of smart people here, what process under mainstream theory, allows a planet (at least Neptune sized) to move closer to its parent star? and for that matter high temp minerals found in the "primordial building blocks" comets move further (or at least more eccentric) from there star?

Blob
2007-May-18, 01:06 AM
Come on people, we have a lot of smart people here, what process under mainstream theory, allows a planet (at least Neptune sized) to move closer to its parent star?

Perhaps Type-I migration

EDG
2007-May-18, 01:08 AM
The process is most likely related to gas drag through the nebula as the planets are forming - that pulls them towards the star. It's not fully understood at the moment but it does actually make some kind of sense.



I bet it's the same one that can make high temperature minerals found inside a comet nucleus! The same "process" must have made them (comets) form inside the "snow line"

Not that I know what you're referring to here, but it's quite possible for material from the inner part of the nebula to get into the outer part of the nebula. If you imagine the solar nebula as containing billions and billions of grains of dust and ice orbiting the sun during planetary formation, then obviously some of those grains are going to get tossed around gravity from larger grains, or ejected by impacts.



We collectively have no idea :silenced:

I wouldn't say that. We know enough to grasp the basics of planetary migration. We also know that it happened in our own system - Jupiter moved out from the sun by about 0.5 AU based on the orbits of the Hilda asteroids that are in a 3:2 resonance with it. Uranus and Neptune also migrated somewhat too (I forget whether it was in or out, but there's evidence from asteroid/KBO resonances IIRC).



Come on people, we have a lot of smart people here, what process under mainstream theory, allows a planet (at least Neptune sized) to move closer to its parent star? and for that matter high temp minerals found in the "primordial building blocks" comets move further (or at least more eccentric) from there star?

Just because you think it sounds silly doesn't mean that it actually is. It's one thing to dismiss an idea because the facts don't support it, but it's another to dismiss it because it sounds unbelievable to you. Our concepts of planetary formation have changed a lot since the first Hot Jupiters were discovered - we used to think that every system would look like our own, with gas giants far from the star and rocky planets close to the star. It was pretty unbelievable to imagine a Jupiter-mass world orbiting a star closer than Mercury. But now we know better based on our observations - and we've expanded and adapted our theories of planetary formation and orbital dynamics to account for them - that's how science works.

Northwind
2007-May-18, 01:47 AM
It was pretty unbelievable to imagine a Jupiter-mass world orbiting a star closer than Mercury. But now we know better based on our observations - and we've expanded and adapted our theories of planetary formation and orbital dynamics to account for them - that's how science works.
Reply With Quote


Unbelievable? I know of one theory that predicts such events, that the majority of extra solar planets will be gas giant/brown dwarf size and orbit close to the parent star.

I've heard a few silly things that scientists/researchers have come up with lately :) Ice this close to a star is pretty good!

Triclyde
2007-May-18, 01:52 AM
Thanks EDG. Most enlightening. I always knew that water had some pretty amazing properties, but had no idea about all those types of ice.

According to the phase diagram, water at -10C will go from solid to liquid and back to solid as you increase the pressure. :surprised

EDG
2007-May-18, 04:11 AM
Unbelievable? I know of one theory that predicts such events, that the majority of extra solar planets will be gas giant/brown dwarf size and orbit close to the parent star.

Which theory would that be? I presume you're talking about a mainstream one published in a peer-reviewed journal, right?



I've heard a few silly things that scientists/researchers have come up with lately :) Ice this close to a star is pretty good!

Well, whether you think it's silly or not doesn't change the fact that it's there.

temarc
2007-May-18, 03:44 PM
Ten replies, and nobody knows what year this is?

"In August 2008, astronomers captured the first hint of the planet using the Observatoire Francois-Xavier Bagnoud (OFXB) observatory in St-Luc Switzerland. It was then confirmed using the Euler 1.2m telescope at La Silla Observatory in Chile."

LOL!

Scirocco
2007-May-18, 05:42 PM
Ten replies, and nobody knows what year this is?


Thank you! I was JUST coming over here to mention that. :eh: One presumes they meant August 2006.

Blob
2007-May-18, 06:25 PM
Hum,
it could be simply a case of Fraser stooping to a new low by publishing next years news today in order to Toseek us all...

http://www.bautforum.com/showthread.php?t=58157

Fraser
2007-May-18, 07:45 PM
Uh yeah, that was my plan. The only way to stay ahead of Toseek is with a time machine.

Kullat Nunu
2007-May-19, 04:30 PM
I have one nitpick about the article...


The planet was discovered orbiting the nearby M-dwarf star GJ 436 using the planetary transit technique.

The planet was not discovered using the transit technique--in fact, when Geoff Marcy's team found it in 2004 was the first known "hot Neptune" along with 55 Cnc e (Mu Arae d was announced a few days earlier by the Swiss team). Naturally, the star was searched for possible transits, but none was found. Apparently nobody looked hard enough.

John Mendenhall
2007-May-24, 04:49 PM
How about life in high temperature/high pressure water? Black smokers have it here on Earth.

Noclevername
2007-May-24, 05:03 PM
Oops, spotted a boo-boo:

"...and the chemical composition of the light changes..."

Of course, should have said "the spectral composition of light changes".

VARN
2007-Jun-18, 03:26 AM
Could a person survive there in an igloo or something?