Crystallizing White Dwarf From a Quadruple Star System Turns Into a Cosmic Diamond

In the field of astronomy, it is widely known that dead stars harden and crystallize when they cool down. Just recently, an international team of experts discovered such a star near the vicinity of our home planet.

Star Crystallization in Our Cosmic Backyard

The discovery involves a white dwarf only 104 light years from Earth. The temperature-mass profile of the star suggests that its center is turning into a dense, hard diamond composed of carbon and oxygen.

Alexander Venner of the University of Southern Queensland in Australia leads the team. While using the Gaia data in searching for multiple star systems, they found a new quadruple system resembling the Sirius star at 32 parsecs distance. It comprises a crystallizing white dwarf member to a system of three stars known as HD 190412.

Scientists named the white dwarf HD 190412 C. Although it is still unknown if it is made up of diamond, some of its properties suggest a crystallization process. For instance, its 1 million kilograms per cubic meter density could mean it is a denser allotrope of carbon.

Venner explains that HD 190412 C is the first crystallizing white dwarf whose total age can be restricted externally. The team used this fact in measuring the cooling delay brought by the crystallization of the white dwarf's core.

Formation of White Dwarf Star

All stars in the universe, no matter how big or small, will one day run out of fuel from atomic fusion and turn into a new entity. This is one of the realities in astronomy that cannot be reversed. Stars that are eight times larger than the mass of the Sun are likely to evolve into white dwarf stars.

When the star's fuel runs out, its outer material is discarded into the surroundings. The remaining part, the core, will collapse into a very dense material since there is no more outward pressure to support it through fusion. This ultradense object could be as small as the Earth or moon, but its mass is as heavy as 1.4 Suns.

Even if the matter in white dwarf stars is highly compressed, it cannot collapse further because the electron degeneracy pressure prevents it. Two electrons cannot occupy identical states, preventing the white dwarf from becoming denser. This phenomenon is seen in a neutron star or a black hole.

Although the white dwarf stars are dim, they can still shine using residual heat. As time passes, they cool down and evolve into black dwarf stars upon losing their stored heat. Finally, the black dwarf stars will turn into a cold chunk of crystallized carbon.

This process of star transformation can take a very long time, up to a quadrillion years. We cannot expect to find one of them anytime soon since the universe is only 13.8 billion years old. We can only depend on the signs of crystallization that begin in the core of the white dwarf stars near our planet.

The carbon and oxygen atoms inside the white dwarf star cannot move freely and instead form chemical bonds by arranging themselves into a crystal pattern. This process produces energy which is released in the form of heat.