Former Sun-like Star Is Now a Diamond Planet

By Joseph Castro | August 26, 2011 4:52 pm

spacing is importantArtist’s concept of the pulsar and its planet. The system could fit into our Sun, represented by the yellow surface.

What’s the News: An international team of astronomers has found an exotic planet possibly made of diamond, located about 4,000 light-years away from Earth. The researchers believe that the unusual planet was once a sun-like star, transformed into its current state by its hungry stellar companion, a millisecond pulsar.

How the Heck:

  • When a massive star dies in a supernova, it sometimes collapses into a pulsar, a highly compacted stellar corpse that emits periodic beams of electromagnetic radiation from its poles. If a pulsar is part of a binary system, it can feed on its nearby stellar friend and speed up its spin to hundreds of rotations per second, effectively becoming a millisecond pulsar. (About 30% of millisecond pulsars found are solitary—astronomers don’t know how they formed.)
  • Astronomers detected the pulsar, known as PSR J1719-1438, during a large survey using the CSIRO Parkes Observatory near Sydney, Australia. When they studied the pulsar’s radio beams, they noticed slight variations in the signals, likely caused by the gravitational tug of an orbiting body. By analyzing this signal modulation, they were able to determine that the second object has a little more mass than Jupiter and revolves around the pulsar every two hours and ten minutes at a distance of about 600,000 kilometers (at its closest, Mercury is about 46 million km from the Sun).
  • But at this distance, a planet the size of Jupiter would be ripped apart by the intense gravity of J1719-1438. The researchers calculated that the planet could be no larger than 60,000 km in diameter, less than half the size of Jupiter, giving it a density about 18 times that of water (via National Geographic).
  • With the planet’s density and distance from the pulsar, the astronomers reasoned that the object was once a star itself—J1719-1438 siphoned matter from the surface of the star, stripping it of its outer layers of hydrogen and helium. This left a white dwarf—the core of a dead sun-sized star—that is made up of mostly carbon (with a bit of oxygen) and has only 0.1 percent of its original mass. Under the high pressure of the planet’s own gravity, the carbon would crush into a crystalline form—that is, diamond. The team is unable to specify what percentage of the planet would be diamond, but they believe it’s pretty high, according to TIME.

What’s the Context:

  • PSR J1719-1438 is one of only two millisecond pulsars found to have orbiting planets. The other, PSR B1257+12, has three planets, none of which are thought to be made of diamond.
  • Last year, there were reports of another “diamond planet.” This body, called WASP-12b, was the first planet found to have more carbon than oxygen in its atmosphere, leading astronomers to believe that its surface is rich in diamonds.
  • With better technology and techniques, astronomers have been finding extra-solar planets at an accelerated rate over the last few years. Some of the exoplanets are about as strange as the diamond planet, like the planet that reflects practically no incident light.

Reference: M. Bailes et al. Transformation of a Star into a Planet in a Millisecond Pulsar Binary. Science, 2011; DOI: 10.1126/science.1208890

Image courtesy of Swinburne Astronomy Productions

  • Relativity

    Just wondering if this companion “planet” in a liquid or plasma-state instead of a crystallized carbon? Is this liquid state possible with carbon at all?

  • Mike Lemonick

    Hey, thanks for the link to my story in TIME!

  • Yatima

    Can we name it Emma Frost?

  • megan

    I’m RWICH I’m RWICH!!! I’m GWEEDY LITTLE MIZER. BACK BACK AWAY FROM MY RWICHES. I shall hoard it in a few thousand years after light speed travel. DON’T FOLLOW ME!!

  • Jimmy

    wonder if there is Gold Planet to be discovered in near future.

  • Daniel

    A Kardashian just put it on layaway.

  • Chris

    This reminds me of the Doctor Who episode with the kid saying
    “The stars are made of diamonds”
    Didn’t have to wait till the year 100 trillion.

  • yanom


  • Georg

    Even if I accept that this “companion” is pure carbon,
    (which I think is rather unlikely)
    one needs to be a sciene ignorant to say it is diamond.
    Depending on size of the “planet” (gravity on surface)
    the surface will be graphite or diamond, but more inward
    there will be layers of carbon modifications unknown
    to us still.
    How do we know? Diamond is a high (some thousands of bars)
    pressure modification, but it is far from a structure with
    closest packing of atoms. So, at even higher pressures there
    will exist metal-like modifications.
    Is this due to : „season of the very smallest potatoes“?

  • Fred Jones

    Diamond seems very unlikely to me since the density of diamond is only about 3.52 g/cm3 (pure water is 1) and will withstand phenomenal pressures without compression. A BUNCH of GOLD, with a density of about 19.3, would seem much more likely, though certainly material forms and even additional elements would almost certainly exist in such an alien environment. If it’s carbon, it wouldn’t be diamond; it would have to be some different form.

  • floodmouse

    Wow . . . I just read a science fiction anthology, vintage 1966-1967, and it had a short story about a planet called “Aurora” where the surface was studded with diamonds. Everyone was geeked, until they found out the clouds of diamond dust blowing around destroyed all their machinery through friction. The only way to get back to Earth was to discover how to build an anti-gravity drive. I think the story was called “Mother of Invention.” It seems prescient, except for the fact that with high enough pressure to crystallize carbon into diamond, all machinery and human bodies must be instantly crushed. They would have bigger things to worry about than a little wear-and-tear on the transmission of their Jeep . . .

  • Roy F

    It is not the size of this diamond planet, that bothers me. It is the size of the hand that might be wearing it.

  • Ben

    My wife wants to know how many karats it is.

  • Messier Tidy Upper

    Shades of Arthur C. Clarke’s Space Odyssey series where the core of Jupiter was a giant diamond.

    Clarke explained in an afterword :

    “The startling idea that gas giants might have diamond cores has been seriously put forward by M. Ross and F. Ree of the Lawrence Livermore laboratory, University of California, for the cases of Uranus and Neptune. It seems to me that anything they can do, Jupiter could do better, DeBeers shareholders please note.”
    (Italics original, Page 296, ‘2010: Odyssey Two’ Clarke, Grafton, 1983.)

    In actual fact, further study makes it seem unlikely the cores of “gas giants” Jupiter and Saturn are similar because they have different chemical composition and internal conditions to the “ice giants” Neptune & Uranus.

    Still makes you wonder though.

    @10. Fred Jones : Well carbon is a lot more common and abundant an element in our cosmos than gold so diamond makes more sense from that perspective.

    Besides as everyone knows the Cybermen destroyed the last planet of gold! 😉


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