Nearby super-Earth likely a diamond planet

Oct 11, 2012
Nearby super-Earth likely a diamond planet
Illustration of the interior of 55 Cancri e — an extremely hot planet with a surface of mostly graphite surrounding a thick layer of diamond, below which is a layer of silicon-based minerals and a molten iron core at the center. Credit: Haven Giguere

(Phys.org)—New research led by Yale University scientists suggests that a rocky planet twice Earth's size orbiting a nearby star is a diamond planet.

"This is our first glimpse of a rocky world with a fundamentally different chemistry from Earth," said lead researcher Nikku Madhusudhan, a Yale in physics and astronomy. "The surface of this planet is likely covered in graphite and diamond rather than water and granite."

The paper reporting the findings has been accepted for publication in the journal .

The planet—called e—has a radius twice Earth's, and a mass eight times greater, making it a "." It is one of five planets orbiting a sun-like star, 55 Cancri, that is located 40 light years from Earth yet visible to the naked eye in the constellation of Cancer.

Nearby super-Earth likely a diamond planet
Star map showing the planet-hosting star 55 Cancri in the constellation of Cancer. The star is visible to the naked eye, though better through binoculars. Credit: Nikku Madhusudhan; created using Sky Map Online

The planet orbits at hyper speed—its year lasts just 18 hours, in contrast to Earth's 365 days. It is also blazingly hot, with a temperature of about 3,900 , researchers said, a far cry from a habitable world.

The planet was first observed transiting its star last year, allowing astronomers to measure its radius for the first time. This new information, combined with the most recent estimate of its mass, allowed Madhusudhan and colleagues to infer its using models of its interior and computing all possible combinations of elements and compounds that would yield those specific characteristics.

Astronomers had previously reported that the has more carbon than oxygen, and Madhusudhan and colleagues confirmed that substantial amounts of carbon and silicon carbide, and a negligible amount of water ice, were available during the planet's formation.

Astronomers also thought 55 Cancri e contained a substantial amount of super-heated water, based on the assumption that its was similar to Earth's, Madhusudhan said. But the new research suggests the planet has no water at all, and appears to be composed primarily of carbon (as graphite and diamond), iron, , and, possibly, some silicates. The study estimates that at least a third of the planet's mass—the equivalent of about three Earth masses—could be diamond.

"By contrast, Earth's interior is rich in oxygen, but extremely poor in carbon—less than a part in thousand by mass," says co-author and Yale geophysicist Kanani Lee.

The identification of a carbon-rich super-Earth means that distant rocky planets can no longer be assumed to have chemical constituents, interiors, atmospheres, or biologies similar to those of Earth, Madhusudhan said. The discovery also opens new avenues for the study of geochemistry and geophysical processes in Earth-sized alien planets. A carbon-rich composition could influence the planet's thermal evolution and plate tectonics, for example, with implications for volcanism, seismic activity, and mountain formation.

"Stars are simple—given a star's mass and age, you know its basic structure and history," said David Spergel, professor of astronomy and chair of astrophysical sciences at Princeton University, who is not a co-author of the study. "Planets are much more complex. This 'diamond-rich super-Earth' is likely just one example of the rich sets of discoveries that await us as we begin to explore planets around nearby stars."

In 2011, Madhusudhan led the first discovery of a carbon-rich atmosphere in a distant gas giant planet, opening the possibility of long-theorized carbon-rich rocky planets (or "diamond "). The new research represents the first time that astronomers have identified a likely diamond planet around a sun-like star and specified its chemical make-up. Follow-up observations of the planet's atmosphere and additional estimates of the stellar composition would strengthen the findings about the planet's chemical composition.

Explore further: Image: NGC 6872 in the constellation of Pavo

More information: "A Possible Carbon-rich Interior in Super-Earth 55 Cancri e," Astrophysical Journal Letters.

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User comments : 21

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WritersWithCats
2 / 5 (6) Oct 11, 2012
Too late.
Rarity Pony has already called dibs. =)
GintsG
2 / 5 (4) Oct 11, 2012
:P Yup, first place to go mining after getting those warp engines fixed finaly!
SteveL
4.5 / 5 (8) Oct 11, 2012
It would be far cheaper and quicker, to just grow any diamond material needed with CVD. In addition; mining diamonds in an environment that is 3,900 deg F under 8 G's and 40 LY away would also be a significant technical challenge. Let's start with our moon, other planets, their moons, and the asteroids first.
El_Nose
4.4 / 5 (7) Oct 11, 2012
If you do the math -- this planet has force of gravity at the surface a bit more than 2.3x that of Earth. And it is so close to its sun it has a year of 18 days. And a surface temperature of 3900 Fahrenheit.

We will not be landing or mining this planet any time in the ... ever... just not worth it.
El_Nose
4.6 / 5 (9) Oct 11, 2012
And as a note -- if you had a planet worth of diamonds -- unless these are industrial grade, you just decreased the value of diamonds by making them common.
Milou
3.5 / 5 (6) Oct 11, 2012
Great way to get the public sector behind space projects:

Claim there is a super earth diamond (gold, sliver,etc.) far away, make it complicated to understand, and sit back watch everyone trip themselves to get there. Either way, I'll be sitting in the dark looking at it tonight.
GSwift7
1.5 / 5 (4) Oct 11, 2012
And a surface temperature of 3900 Fahrenheit.


Only on the sunny side. This planet is so close to its star that it must be tidally locked.

40 LY away is relatively close, but even a robotic probe would be a challenge. The planet is so close to its star that it makes it extremely difficult to get into an orbit around the planet. The gravity of the star will give your spaceship an enormous velocity. Getting a probe from Earth to Mercury or Venus is hard enough. Starting from outside of the solar system in question and going even farther in towards the star makes it even more difficult to do an orbit insertion around a planet. You would need an enormous amount of fuel to slow down, and that's just for orbit. A landing would be even more techincally challenging. Heck, unless you know quite a bit about the atmospher, you can't even begin to design a lander.
Torbjorn_Larsson_OM
2.7 / 5 (3) Oct 11, 2012
The existence of carbonaceous as opposed to silicious planets have been predicted for some time. It is nice if we have confirmation.

This has obvious effects on habitability. Besides the problems for plate tectonics (IIRC, and shored up by Dave B's analysis), the geosphere and attempts to biosphere would drown in carbon akin to how water worlds drown in water.

In fact, the analogy extends further and it is why I am not specifically worried by this pathway for planets. While there is little evidence (I believe) for such theories, it has been suggested that there is a "soot line" analogous to the "ice line". The ice line empties the protoplanetary disks of water close to the star and let the volatile settle where the temperature let it go solid.
Torbjorn_Larsson_OM
2.3 / 5 (4) Oct 11, 2012
[cont] Similarly, the soot line would scour the disk of carbon near the star and let hydrocarbons settle as kerogens outside of the ice line. Hence the same models that predict the necessary scarceness of water (for habitability as we know it) close to the stars predict the necessary dominance of silicious minerals.

Carbonaceous terrestrials in the habitable zone would likely be migrants akin to hot Jupiters, deriving from further out in the disk. The hot superEarth 55 Cancri e seems to test such migratory models.

In sum, we are still good for observing many Earth analogs but we have to characterize the planets well to make appropriate statistics for astrobiology purposes. More work for planetary scientists, they got to love this!
Infinion
1 / 5 (3) Oct 11, 2012
Too late.
Rarity Pony has already called dibs. =)


haha brohoof /)
bronies on physorg ftw
SteveL
3 / 5 (2) Oct 11, 2012
40 LY away is relatively close, but even a robotic probe would be a challenge.
Relatively close, perhaps. But let one bearing lock up or one seal leak or the insulation break down in a signal cable... Considering the logistics involved any equipment would essentially be unserviceable. Any country or corporation that would seriously attempt such a feat would be foolish to say the least. The time spans involved move such a project beyond the reach of we mere humans. Historically, any project that exceeds more than a few political voting cycles or a 10 year plan is doomed to failure.
PhotonX
5 / 5 (2) Oct 11, 2012
This is great news! I have a builder who says he can fix me up with a spaceship as fast as the Voyager probes, so I'll be back with a load of diamonds in about 1.33 million years. Sure hope prices don't crash in the meantime....
jimbo92107
3 / 5 (1) Oct 12, 2012
Oh nearby super-Earth, how you mock our lust for diamonds!
GSwift7
2 / 5 (4) Oct 12, 2012
to SteveL:

Yes, and no. I think we will eventually want to send probes to all of our nearest neighbors, just for science. There's no reason to do it right now, because we don't even know what we would want the probe to do yet. We don't even know what questions to ask, never mind knowing how to get there.

I suspect that we should attempt to reach the limit of what is possible with telescopes before we think about physical probes. At some point we will exhaust what there is to learn remotely. That will be the right time to send out interstellar probes, even if they take centuries to get where they are going.
SteveL
not rated yet Oct 12, 2012
to SteveL:

Yes, and no. I think we will eventually want to send probes to all of our nearest neighbors, just for science. There's no reason to do it right now, because we don't even know what we would want the probe to do yet. We don't even know what questions to ask, never mind knowing how to get there.

I suspect that we should attempt to reach the limit of what is possible with telescopes before we think about physical probes. At some point we will exhaust what there is to learn remotely. That will be the right time to send out interstellar probes, even if they take centuries to get where they are going.
Agreed. We are hundreds of years, at least, from the time when we should reach for the stars in any methodology beyond data colleting probes. There is plenty for us to explore in our own room (solar system). And it's past time we got started in a serious way.
El_Nose
not rated yet Oct 12, 2012
My previous post was incorrect ... its year is actually 18 hours.
Fleetfoot
not rated yet Oct 12, 2012
I suspect that we should attempt to reach the limit of what is possible with telescopes before we think about physical probes. At some point we will exhaust what there is to learn remotely. That will be the right time to send out interstellar probes, even if they take centuries to get where they are going.


If a new design can be found in 50 years that reduces the flight time by 100 years, you might as well wait but if you will only gain 20 years by waiting you should launch. At some point someone will gamble that they are sufficiently close to the best feasible design that a launch won't be caught before it gets there, that is the best time to launch.

The probe payload needs to have the ability to be remotely updated to define the functions, no need to wait until we decide what we want to measure, it's always going to change while we wait for it to get there.
Claudius
2.3 / 5 (3) Oct 13, 2012
It belongs to De Beers.
defactoseven
1 / 5 (2) Oct 15, 2012
But Ann Romney says she wants it. When Ann wants that special something Mitt always buys it for her. "Mitty... I want that planet. I want it NOW."
GSwift7
1 / 5 (1) Oct 16, 2012
To Fleetfoot:

Yes, but that level of technology is currently out of sight. Our current state of the art propulsion system, the ion drive, has only been been successfully operated continuously for something like a year or two, if I recall correctly. (the system accumulates ionized material on the internal parts over time, similar to the accumulation of metals on the cathode of a battery. This cuts down on performance over time and eventually shorts out the system). This places travel time to our nearest neighbors into thousands of years. That assumes advances we don't have yet but could probably work out if the money was provided.

However, you just can't predict when some kid will think of something nobody ever thought of before, and change the picture.

Super-earth sized planets are amazing and difficult to imagine. The conditions are so different that they do things that don't make sense to us. Grains of sand condensing in the air and raining, for example.
Fleetfoot
not rated yet Oct 16, 2012
If a new design can be found in 50 years that reduces the flight time by 100 years, you might as well wait but if you will only gain 20 years by waiting you should launch.


Yes, but that level of technology is currently out of sight.


What I said is true for any technology level but I see your point:

Our current state of the art propulsion system, the ion drive, has only been been successfully operated continuously for something like a year or two, if I recall correctly.


Ion drives are very efficient but very low thrust and they are only effective if solar powered, carrying fuel means you are limited by the "rocket equation" regardless of the propulsion method.

A solar sail can achieve much higher speeds but in all these designs, there is a lot of engineering to be done. Looking at the rate of progress though, I think we will reach the point of meeting the criterion by the end of this century.