The Star That Turned Into a Diamond

September 6, 2023. By Rini Saha '25

The world can be a very special place, full of gems hidden everywhere, even in the sky. Well, in this case, past the sky- the galaxy! A star, in specific... Perhaps you heard of the story of the ex-star that was turned into a diamond? A diamond planet- in the constellation of Serpens (the snake) which is around 4,000 light-years away? Even better…

Image centered on PSR J1719-1438, taken with the Keck LRIS instrument.

There were two solar bodies, PSR J 1719-1438 and PSR J 1719-1438b, forming a binary system…


PSR J1719-1438A (‘a’ stands for the first body discovered in the system, capitalized because a star), a pulsar star that hosts a planet.

PSR J1719-1438b (‘b’ stands for the second body discovered in the system, but not capitalized, indicating a planet), the orbiting body.

The location of PSR J1719-1438 (circled in red)

The diamond planet’s discovery ensued from the discovery of a used-to-be normal binary star named PSR J 1719-1438 in 2009 from the use of a Parkes 64 m Radio Telescope of the Australian Commonwealth Scientific and Industrial Research Organisation (CSIRO) in New South Wales.

Parkes 64 m Radio Telescope

The backstory:

A larger star near 1438 went into a supernova and after exploding, made 1438 become a neutron star. The atmosphere of the dying star fell onto neutron star 1438, transferring orbital energy and making 1438 spin faster and faster into a (millisecond) pulsar! Pulsars are neutron stars that give off a beam of radio waves. As the star spins and the radio beam glides over Earth, radio telescopes start to pick up on a regular pattern of radio pulses (hence, 1438 was detected). Neutron stars have very strong magnetic fields, some a trillion times stronger than Earth’s own field. However, the axis of the magnetic field not lining up with the neutron star’s rotational axis makes the star shake a bit, and the pulsar’s beam gliding over us consistently, allows us to find out how fast the pulsar is spinning. Pulsars also have at least 1.4 times the mass of our sun and are about 12mi across, equivalent to the size of a small city. Having a small size and a large mass means extreme density. To put it in perspective, one teaspoon of this material on Earth would weigh about a billion tons. A millisecond pulsar spins super fast, (the fastest one is 1.6 milliseconds, meaning it rotates 640 times each second!) 1438 rotates about 10,000 times a minute! In a follow-up study of the motion of the pulsar using the Parkes Telescope and the Lovell Telescope at Jodrell Bank in Cheshire, England as well as the Keck 10m Telescope in Hawaii, the discovery suggested that there was a companion orbiting pulsar star 1438. Due to the pulses consistently appearing, scientists came to the conclusion that this was due to the gravitational pull of a small planet (PSR J 1719-1438b), orbiting the pulsar in that binary system.

When a second star in the system came to the end of its life, it stretched into a red giant and turned into a white dwarf. The pulsar–1438– began to take the mass off the red giant, causing it to spin faster and faster, eventually turning it into a white dwarf, known as PSR J 1719-1438b.

1438b is a planet that has a mass that is nearly the same as Jupiter’s, 20 times denser, but it is only 40% the size of the planet, making it the densest planet out there. Wait– I thought 1438b was a white dwarf, how’d it become a planet? Scientists believe that 1438b is the remains of a star whose outer layers were stripped by 1438, leaving behind a carbon core that now has features of a planet.

White dwarfs are stars that stopped undergoing nuclear fusion but are still producing heat and light because of gravitational effects. The powerful beam of radiation 1438 was giving off was slowly evaporating the dense, white dwarf because of how close they were– to 99% of its original mass. Over time, it became Earth-sized, but still nearly as massive as our Sun. The planet, 1438b, is actually even larger than its sun, and with a diameter of about 37,300 miles (60,000 km), is 3,000 times larger than 1438, the millisecond pulsar it orbits. Somehow, the white dwarf got into an orbit around the pulsar, and radio pulses told astronomers that 1438b orbits around the pulsar in about two hours and ten minutes (probably due to tidal forces), with the distance between the two objects being 600,000 km– meaning that the entire system would fit within the diameter of our sun. Interestingly enough, 1438b is probably still evaporating.

White dwarfs like 1438b have a dense, carbon core, and under intense pressure, crystallize, which 1438b did.. into a diamond… a diamond 5 times larger than the Earth, but unfortunately it’s not gem quality because of the large amounts of impurities like nitrogen and oxygen, and even bits of neon and magnesium. Under the pressure, it would also have a weird cubic crystal structure instead of the octahedral structure of normal diamonds. Nevertheless, it’s a very fascinating planet to learn about!

Sometimes, you just need to help each other shine a bit brighter… after all, diamonds can be made from dust…


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