National Geographic

Astronomers Find Slow-Cooked Diamond the Size of Earth

About 900 light-years away, an ancient white dwarf star has cooled into a crystallized chunk of carbon — a diamond. But this isn’t just any old diamond hiding in space: It’s the size of Earth, and it’s 11 billion years old.

The diamond-star, described in a study published in The Astrophysical Journal, is among the coldest white dwarfs astronomers have found. In fact, it’s so cool and dim that it can’t even be seen — its feeble light isn’t nearly powerful enough to pierce the darkness of the cosmos, even from relatively nearby.

Instead, teams inferred the presence of the crystallized dwarf based on the way its gravity perturbs the normally steady radio pulses coming from a spinning companion star.

Yep, the system gets even cooler. The dwarf is orbiting a pulsar — a rapidly rotating neutron star — known by the charismatic moniker PSR J2222-0137. The system is similar to another that was described in 2011, with a crystallized white dwarf orbiting a pulsar — but this new diamond is bigger (there’s also a planet hypothesized to be somewhat diamond-like).

If you were to look in the sky in the direction of the constellation Aquarius, you’d be looking in roughly the right direction to see the system, which is actually a pair of dead stars: The spinning neutron star is the extremely dense remnant of a formerly huge star that ended its life in a supernova. A white dwarf is all that remains of a formerly Sun-like star, contracted into a clump the size of Earth. Left on their own, dwarfs will slowly cool and fade to black over billions of years (but sometimes, with the help of a stellar companion, they can detonate and create dazzling supernovas the outshine entire galaxies).

A field of ancient white dwarf stars, spied by the Hubble Space Telescope in 2002. (NASA/H.Richer)

A field of ancient white dwarf stars, spied by the Hubble Space Telescope in 2002. (NASA/H.Richer)

Anyway, astronomers first spotted the pulsar in 2007. Then-graduate student Jason Boyles began studying the spinner, using the Green Bank Telescope at the National Radio Astronomy Observatory in West Virginia. Normally, pulsars spin so steadily that they rival the best atomic clocks. Boyles measured this pulsar’s spin rate at a relatively pokey 30 times per second — some can spin around themselves in only a few thousandths of a second.

But something was different. The pulses arriving at Earth were periodically delayed, as if some unseen companion were causing the pulsar’s radio emission to take a somewhat circuitous route to Earth. This can happen when an orbiting, massive companion’s gravity messes with the fabric of space, causing things like light and radio waves to travel along twisted pathways.

Boyles and his colleagues suspected a dense, hidden object was paired up with the pulsar; more observations suggested the unseen body orbited the pulsar every 2.4 days, and that it was roughly as massive as the Sun. The team guessed they were dealing with either another neutron star (which would be a very rare pairing) or a dense white dwarf star.

To identify the missing object, astronomers needed to know more accurately how far from Earth the pulsar and its friend were. So, Adam Deller at the Netherlands Institute for Radio Astronomy led the charge to determine that distance, using the Very Long Baseline Array telescopes.

Two more years of measurements, beginning in 2010, helped the team pin that distance at 267.3 parsecs, or about 871 light-years.

With that information in hand, and with the delay time measurements, astronomers could now begin to un-mask the pulsar’s friend. They calculated that the companion must be about 1.05 times as massive as the Sun (within the range of both a white dwarf and a neutron star), and that the pulsar was slightly more massive, at 1.2 Suns. But scientists also determined that the pulsar and its friend were in a roughly circular, rather than elliptical (or eccentric) orbit. That suggested the system hadn’t been walloped by something like a second, neutron star-forming supernova.

“If there were two neutron stars that means two supernova explosions. And a supernova explosion should make the orbit pretty eccentric,” says study coauthor David Kaplan of the University of Wisconsin, Madison. “We see that the orbit is very circular.”

That suggested the team was looking for a white dwarf. At that measured distance, astronomers reasoned, such a star should be visible from Earth. So, the team tried to get a visual on the object, using telescopes in Chile and Hawaii. They searched the region in multiple wavelengths, in the infrared and visible.

And failed.

The trouble was, no matter how hard they tried, scientists just couldn’t coax the dwarf to reveal itself.

The only way that’s possible, the astronomers write, is if the dwarf is cooler than 3,000 Kelvin — which would make it among the chilliest white dwarfs ever discovered. And the only way the star could have cooled to that temperature and NOT be older than the Milky Way galaxy is if it were already crystallized into diamond.

Kaplan says that such diamond stars are probably sprinkled throughout the galaxy — they’re just too cold and dim for us to see them. But, up above the world so high, a sky full of ancient, glittering diamonds is an astonishingly beautiful thing to imagine.

There are 26 Comments. Add Yours.

  1. nwcolorist
    June 24, 2014

    So there are huge diamonds in outer space. That ought to be a great incentive to fund our space program.

  2. Patrick Smith
    June 24, 2014

    Perhaps…perhaps not. The hypothesis for the existence of these types of dwarfs, and for the accuracy of the detection, are both pretty solid and coherent. The precise character of the object(s), however, is rather more speculative than demonstrated. Sensationalism makes for great press, but not such great science. Many possible forms of carbon are also possible, as well as varieties never before seen. But Diamond gets attention, so I guess Diamond it will be.

  3. A Gem
    June 24, 2014

    The science is fascinating. More importantly, I immediately emailed my wife and told her that I had a gift for her unmatched by any other husband in the known universe. All she has to do is go pick it up.

  4. Nick R.
    June 25, 2014

    De Beers has just claimed the planet and is now called De Beers DIA-PSR J2222-0137… lol

  5. Bigus
    June 25, 2014

    Diamonds are only artificially valuable even here on earth.

  6. thomas vesely
    June 25, 2014

    who can eat diamonds ?

  7. Davidinark
    June 25, 2014

    No, they did’t FIND a diamond. They didn’t FIND a diamond the size of Earth. They think they might have found something that might or might not be there based on what might or might not be happening. It walks the way way we think a bird would walk, should a bird be there. It makes noise the way a bird would, if there were a bird there. So, it must be a duck!

  8. ali
    June 25, 2014

    how does pulsar spin so fast “some can spin around themselves in only a few thousandths of a second.”

  9. greg
    June 25, 2014

    Don’t you just love these guys—anythings possible in a scientists mind—-the scarey thing is alot of their crazy ideas come true!!

  10. Kimmo
    June 26, 2014

    Astronomy rocks.

  11. skaban53
    June 26, 2014

    I thought that’s what science does–turn crazy ideas and fantasies into reality. Charming!

  12. Gerrie
    June 26, 2014

    Lucy In The Sky With Diamonds…

  13. Rednip
    June 26, 2014

    “who can eat diamonds ?”
    As long as they’re not too large, anyone can ‘eat’ diamonds. However, I wouldn’t expect any nutritional value. You’d be better off selling them while DeBeers can keep the price of them artificially high.

  14. ryan
    June 26, 2014

    now we just need to weaponize it. add a laser array behind, etch in soem focusing and BOOM, death ray. death star aint got shit on us,lol.

  15. ImpishGrin
    June 26, 2014

    Twinkle, twinkle, little star,
    How I wonder what you are.
    Up above the world so high,
    Like a diamond in the sky.

  16. dabble53
    June 26, 2014

    “I thought that’s what science does–turn crazy ideas and fantasies into reality. Charming!”
    Actually, that’s what engineers do :)

  17. cj
    June 29, 2014

    With a diamond so big what would it’s value be ?

  18. Danny
    July 1, 2014

    That sounds like a money maker! But in reality it would bring down the value, as there is so much.

  19. Roger tomlinson
    July 2, 2014

    Is this the same found about 15yrs ago .? Roger

  20. Peter G
    July 7, 2014

    I believe the idea would be to send a spacecraft to the planet, and have it scoop off a cubic yard of the surface and return that to Earth. That way it would pay its own costs without totally devaluing the artifically high cost of diamonds today. Of course, it would take a few lifetimes to travel that distance, and who knows: By then we may be eating diamonds. ♦ ♫

  21. Moosie
    July 7, 2014

    The only reason diamonds are valuable on earth is because they are relatively rare.

  22. CharJeweler
    July 8, 2014

    Diamonds on earth aren’t rare. The price is so high because they are hoarded & only sold so many @ a time. Nativecraftscouncil.com

  23. Anjum Zuberi
    July 8, 2014

    Let the big diamond come to earth and no body would like to wear such cheap thing!

  24. John
    July 8, 2014

    Surely, diamonds are valuable only after they have been cut. These diamond stars may be rather ordinary looking pebbles.

  25. JPW
    July 11, 2014
  26. Foolish Pride
    July 15, 2014

    It’s not a diamond in any sense we would understand it. FAR too dense. This object has the mass of the Sun in Earth’s diameter. The core of our Sun is over 40x as dense as a diamond.

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