In distance space, a water world: Hubble reveals a new class of extrasolar planet

Feb 21, 2012
GJ1214b, shown in this artist's view, is a super-Earth orbiting a red dwarf star 40 light-years from Earth. New observations from the NASA/ESA Hubble Space Telescope show that it is a water world enshrouded by a thick, steamy atmosphere. GJ 1214b represents a new type of planet, like nothing seen in the solar system or any other planetary system currently known. Credit: NASA, ESA, and D. Aguilar (Harvard-Smithsonian Center for Astrophysics)

(PhysOrg.com) -- An international team of astronomers led by Zachory Berta of the Harvard-Smithsonian Center for Astrophysics (CfA) made the observations of the planet GJ 1214b.

"GJ 1214b is like no planet we know of," Berta said. "A huge fraction of its mass is made up of ."

The ground-based MEarth Project, led by CfA's David Charbonneau, discovered GJ 1214b in 2009. This super-Earth is about 2.7 times Earth's diameter and weighs almost seven times as much. It orbits a star every 38 hours at a distance of 2 million kilometres, giving it an estimated temperature of 230 degrees Celsius.

In 2010, CfA scientist Jacob Bean and colleagues reported that they had measured the atmosphere of GJ 1214b, finding it likely that it was composed mainly of water. However, their observations could also be explained by the presence of a planet-enshrouding haze in GJ 1214b's atmosphere.

Berta and his co-authors, who include Derek Homeier of ENS Lyon, France, used Hubble's 3 (WFC3) to study GJ 1214b when it crossed in front of its . During such a transit, the star's light is filtered through the planet's atmosphere, giving clues to the mix of gases.

"We're using Hubble to measure the infrared colour of sunset on this world," Berta explained.

Hazes are more transparent to than to visible light, so the Hubble observations help to tell the difference between a steamy and a hazy atmosphere.

They found the spectrum of GJ 1214b to be featureless over a wide range of wavelengths, or colours. The most consistent with the Hubble data is a dense atmosphere of .

"The Hubble measurements really tip the balance in favour of a steamy atmosphere," Berta said.

Since the planet's mass and size are known, astronomers can calculate the density, of only about 2 grams per cubic centimetre. Water has a density of 1 gram per cubic centimetre, while Earth's average density is 5.5 grams per cubic centimetre. This suggests that GJ 1214b has much more water than Earth does, and much less rock.

As a result, the internal structure of GJ 1214b would be extraordinarily different from that of our world.

"The high temperatures and high pressures would form exotic materials like 'hot ice' or 'superfluid water', substances that are completely alien to our everyday experience," Berta said.

Theorists expect that GJ 1214b formed further out from its star, where water ice was plentiful, and migrated inward early in the system's history. In the process, it would have passed through the star's habitable zone, where surface temperatures would be similar to Earth's. How long it lingered there is unknown.

GJ 1214b is located in the constellation of Ophiuchus (The Serpent Bearer), and just 40 light-years from Earth. Therefore, it's a prime candidate for study by the NASA/ESA/CSA James Webb Space Telescope, planned for launch later this decade.

A paper reporting these results has been accepted for publication in the Astrophysical Journal and is available online.

Explore further: Gravitational waves according to Planck

More information: Research paper: www.spacetelescope.org/static/… _papers/heic1204.pdf

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Lurker2358
2.9 / 5 (11) Feb 21, 2012
"FlyingButtressMonster" and I discussed the possibility of the existence of a planet like this on Physforum several years ago.

I brought up the subject and theorized what it should look like, both a 100% pure water world and a "mostly water world with a small solid core".

This actually confirms my theory that planets do not need comets or asteroids to aquire water. The water is obtained at the time of the planet's own creation, just like any other element or compound.
katesisco
1.4 / 5 (11) Feb 21, 2012
I have this idea that there is a progression of degradation from what we have termed a mini black hole (LT starbit) to a neutron to regular atomic structure. After all when we talk about stars using up their energy it goes down the line, what O Manuel says. G Gammow said that all the previous conversions produced energy and stopped at lead because lead uses energy. So I think that a most pressured matter possible (LT starbit) also degrades in its quantum structure when it looses the pressure that holds everything densely together. And eventually becomes atomic matter.
It does not surprise me that water is so heavily present on this planet so close to its sun. I do not think it originated elsewhere from its present orbit. I think the H2O was produced right there.
katesisco
1.4 / 5 (9) Feb 21, 2012
Remember the discovery of H2O in a planet size bubble in space? Just sitting there? How would that happen except by some degradation of energy? And gas pressure has to exist even to allow the water to be there.
tadchem
5 / 5 (1) Feb 21, 2012
The density of 2 grams per cubic centimeter is consistent with gas hydrate.
HannesAlfven
1 / 5 (5) Feb 21, 2012
@Lurker2358

Wal Thornhill also identifies planets orbiting red dwarfs as the most probable location for the origin of life in the universe. One reason not mentioned in this article, though, is that the atmospheres of these stars are illuminated out to great distances, relative to our own Sun. This suggests that planets can orbit the store within the illuminated envelope. This is ideal because there would be neither days nor seasons. Also, the temp's could be rather ideal, as these stars' temps are reasonable. Unlike the gravitational scientific framework we are all familiar with, the electrical framework which Wal Thornhill subscribes to naturally suggests an origin for life.

What is particularly intriguing is the work of Dwardu Cardona on this point. His series of books, starting with God Star, go into extreme detail on this subject.
Lurker2358
3.7 / 5 (9) Feb 21, 2012
See, I was thinking, a super-earth sized Water World could maintain oceans and atmosphere over cosmic time scales, even without a magnetic field.

Even if it was at 1 A.U. from a sun-like star, it would simply never be hit by enough radiation in it's lifetime to destroy that much water, and even if it did, at seven Earth masses, the planet is massive enough that it should keep most of the hydrogen trapped anyway due to gravity. I mean, this thing is almost as massive as Neptune and Uranus anyway.

So even if there was little or no solid core, or little or no magnetic field, it could easily survive with a water and oxygen atmosphere for the entire lifetime of the parent star, simply because there's so much mass that it would never be completely eroded by radiation over stellar lifetimes.
ShotmanMaslo
1 / 5 (1) Feb 21, 2012
"2.7 times Earth's diameter and weighs almost seven times as much."

How strong would the gravity be on the surface of this world?
Lurker2358
2.7 / 5 (7) Feb 21, 2012
"2.7 times Earth's diameter and weighs almost seven times as much."

How strong would the gravity be on the surface of this world?


Hard to say, because it depends on how you define "surface".

The gravity at the stated distance would actually be less than Earth's surface gravity, 0.96022g, which is 9.49m/s...

But that is probably the top of a ridiculously dense atmosphere.

The surface of the water may be a few dozens or hundreds of kilometers below.

The ocean is probably close to 10,000km deep around the entire planet, maybe even more, and would itself behave much like an atmosphere, since the boundary layer with the solid core would be virtually insignificant compared to oceans on Earth.

On Earth the ocean is bounded by continents, and even the atmosphere is partially bounded by mountain ranges.

On a giant water world like this, the ocean is restricted only by gravity, electromagnetism, and thermodynamics.

Surface gravity on the ocean is very close to that of Earth.
Graeme
5 / 5 (6) Feb 21, 2012
An ocean would not be super deep because under high enough pressure water turns into ice. On earth an ocean would make it about 20km deep before turning solid
Deathclock
4 / 5 (4) Feb 21, 2012
Graeme beat me to it but I was going to say a water world would have to either be very small or have a solid core of ice and other exotic forms that water takes under extreme pressures.
Lurker2358
1 / 5 (3) Feb 22, 2012
An ocean would not be super deep because under high enough pressure water turns into ice. On earth an ocean would make it about 20km deep before turning solid


Hmmm...
Ice VII is a cubic crystalline form of ice. It has a triple point with liquid water and Ice VI at 355 K and 2.216 GPa, with the melt line extending to at least 715 K and 10 GPa.[1] It can also be reached in the solid state by increasing the pressure on ice VI at ambient temperature

10 Gpa = 1E10 N*m^-2 = 1E10 kg*m^-1*s^-2

1E10 (kg*m^-1*s^-2) / 9.49(m*s^-2) = 1053740779.77(kg*m^-2)

*linear approximation since we don't know core density anyway.

Since pascals are measured in N/m^2, then by dividing the mass of the volume of a meter of water, which is 1000kg/m^3, I should get distance in meters.

1053740779.77kg*m^-2 water / 1000kg*m^-3 = 1053740.77977m

Now divide meters by 1000 to get kilometers

1053740.77977m / 1000m/km = 1053.74km depth.

~1000km of depth phase transition, depends on core density.
Lurker2358
1 / 5 (3) Feb 22, 2012
Note above, the planet is 230C which is 503K.

Note, it's actually somewhere between 200km and 1050km depth, due to the range of 2Gpa and 10Gpa.

Also note that is a linear approximation, since we don't know relevant things like the core density in terms of metals or whatever, you could calculate this more exactly using shell theorem and the phase transition table of water, but it's too damn complicated for me to bother with it by hand.

Plus you have to account for other stuff, like the rocky/metallic planet core may be radioactive with it's own heat source, etc.

But the layer of ice would be presumably perfectly smooth and between the rock and water, so it would be almost frictionless contact.
Lurker2358
1 / 5 (3) Feb 22, 2012
Well, whatever the case, I'm thinking this planet may well be, quite deceptively, one of the most complicated, if not the most complicated, yet discovered in any system.

Think of just starting with an Earth sized planet and adding enough water to replicate the conditions, and then move it close enough to the sun to replicate the temperature.

What you have:

Iron/nickel/radionucleid solid core
liquid metal outer core
Liquid silicate and other rocky/metal mantle
Solid Silicate / carbonaceous crust
Ice crust (clean or dirty) many thousands KM thick.
a later of dust from meteors and other space debris*
Liquid / supercritical ocean 200-1000km
supermassive atmosphere at 230C.

* the oceans are so deep, smaller meteors should distribute their energy into the water, and then sink harmlessly to the surface of the ice layer, forming a layer of rock and dust on TOP of the ice. Since the ice is an ultra-dense crystal, the rock or other solids would take eons to work down through it
Ensign_nemo
3 / 5 (2) Feb 22, 2012
"2.7 times Earth's diameter and weighs almost seven times as much."

How strong would the gravity be on the surface of this world?


Well, if we use Newton's Law of Universal Gravitation as a good first-order approximation,

F_Gravity = G (m1 * m2) / R^2,

We see that if the mass is 7 times that of Earth and the radius is 2.7 times that of Earth, the ratio of force is

F_GJ1214b = F_Earth * (7 / [2.7 * 2.7]) = 0.96 F_Earth

Just as Lurker said - a touch less than Earth, assuming that there's a solid surface at 2.7 Earth radii.
Lurker2358
1 / 5 (3) Feb 22, 2012
An ocean would not be super deep because under high enough pressure water turns into ice. On earth an ocean would make it about 20km deep before turning solid


Earth's average surface temperature is like 13C or 286K.

this planet's surface temperature is 230C, or 503K, and that may even be the upper atmosphere, the lower stratosphere/upper troposphere, etc, since they can't even really penetrate it. By comparison, Earth's lower stratosphere can be as cold as -120C in some locations, like above a very powerful cyclone, and widespread -40C.

This means that only extremely exotic forms of ice can form at absurd pressures on this planet. It's not a Goldilocks' water world. It's a hot water world.

Just think of the gas giants that have liquid metal-hydrogen cores at extreme temperatures, even though they are far from the Sun.

This thing is close to it's Sun, so it's incredibly top-heated, which none of the giant planets in our SS are appreciably top-heated by the Sun.
kevinrtrs
1 / 5 (17) Feb 22, 2012
Theorists expect that GJ 1214b formed further out from its star, where water ice was plentiful, and migrated inward early in the system's history. In the process, it would have passed through the star's habitable zone, where surface temperatures would be similar to Earth's. How long it lingered there is unknown

What is unsaid here is that the current position of the planet once again defies the big bang and nebular theory of planet formation. The fact that it's so close to it's star and apparently made up of gaseous material totally contradicts the accepted [but unsubstantiated] accretion theory. Hence it is necessary to make up a scenario which will satisfy the requirements for that theory. No matter that the scenario so made up is even more improbable. People who want to believe it, will do so, without question. This is known as pseudo science since it cannot currently be ascertained in any way that that scenario is actually valid. Yet it will become an acceptable explanatn.
PosterusNeticus
4.6 / 5 (9) Feb 22, 2012
What is unsaid here is that the current position of the planet once again defies the big bang


It was unsaid because to say it would be on the /facepalm side of retarded. Well done.
d_robison
5 / 5 (3) Feb 22, 2012
What is unsaid here is that the current position of the planet once again defies the big bang and nebular theory of planet formation. The fact that it's so close to it's star and apparently made up of gaseous material totally contradicts the accepted [but unsubstantiated] accretion theory. Hence it is necessary to make up a scenario which will satisfy the requirements for that theory. No matter that the scenario so made up is even more improbable... Yet it will become an acceptable explanatn.


It seems as though you are falling prey to your own accusations by holding onto what you believe without opening your eyes to other possibilities. For you, it is simply what is and what isn't, instead of why it is and isn't. Information is correct or incorrect because you believe it to be so, not because the data suggests it to be. You hinder the progress of science, you hinder the progress of humanity.
Lurker2358
1 / 5 (2) Feb 22, 2012
Great, jackasses.

Why people give negative feedback, even when you support your position from known science and show how the math works?

Whatever, idjits.

Yes, my numbers vary widely, but then again, it's not like you can actually test this stuff in a lab, except maybe on the nano-scale using a laser or atomic force probe. How else would you get 10 gigapascals at 500K?

and you can't know how the planet's internal gravitational field evolves without knowing the exact composition and density of the core, and that effects pressure at any given depth, since it effects the weight of the water above any given depth.

My statements about the dust and meteor layer probably forming on top of the ice layer is based on Earth and Solar System observations, since this is how people find the best meteoroid remains on Earth.
TheGhostofOtto1923
3.2 / 5 (9) Feb 22, 2012
Why people give negative feedback, even when you support your position from known science and show how the math works?
Because you proceed to use the thread as a scratch sheet, doing lots of calculating, and then state after the fact all the reasons why its probably not right? The fact that you did not know water turns to ice at certain depth and pressure for instance?

Before you allow your compulsions free reign you should consider the primary reason for your downrating - you dont know what you are doing and are never ashamed to display the fact.
Graeme
not rated yet Feb 22, 2012
Apart from density is there any evidence that this is a H2O world? There would be other possibilities for soemthing of this density too such as carbon monoxide, or nitrogen. If the water vapour was photolysed and H2 escaped, you may end up with a largely oxygen world.
aroc91
5 / 5 (1) Feb 23, 2012
Apart from density is there any evidence that this is a H2O world? There would be other possibilities for soemthing of this density too such as carbon monoxide, or nitrogen. If the water vapour was photolysed and H2 escaped, you may end up with a largely oxygen world.


Spectroscopy-

"We're using Hubble to measure the infrared colour of sunset on this world," Berta explained.


Lurker2358
1 / 5 (1) Feb 23, 2012
The fact that you did not know water turns to ice at certain depth and pressure for instance?


You are a liar...as usual.

I've known that for a very long time.

If you don't believe me, I don't care. You're just a troll anyway.

I discussed this with other people of physforum years ago, and specifically mentioned exotic ices, included ice VII, the most likely candidate.

The article itself mentions the ice, while Graeme was the first person to mention the exotic ice in the thread, that doesn't change the fact that I was PERFECTLY aware of this fact before time.

Anyone doesn't believe me, get over it.

I've even mentioned this in the past on this site and other discussion boards.

Just because I didn't mention the ice layer doesn't mean I didn't know about it.

The board has a 1000 character per post limit, so it's not like there's room to put everything in one post.

Of course, unfortunately for me, that will always give people like Ghost an excuse to cherry pick omissions
baudrunner
3 / 5 (2) Feb 25, 2012
A planet that has an orbital period of 38 hours is a planet very much caught up in the gravity well of its sun. If this were ever a water planet, all the water should have long been torn away by the massive tidal forces. There is no doubt a lot of mist in the atmosphere, but that is probably from subterranean water sources leaking into the atmosphere through vents in the crust. Really more of a geyser world.