Now, a team of researchers have finally found observed these stellar remnants by digging into data collected by the European Space Agency's Gaia spacecraft. Astronomers at the University of Warwick used Gaia's observations of hundreds of thousands of stars to prove that white dwarves, or the star corpses left after the red giant phase, crystallize.
As it cools, it'll form a crystal white dwarf, with a crystal cores of metallic oxygen and carbon - and there are millions of similar crystals out there.
"All white dwarfs will crystallize at some point in their evolution, although more massive white dwarfs go through the process sooner", Pier-Emmanuel Tremblay from the University of Warwick's Department of Physics in the United Kingdom explained in a statement.
Researchers reveal that this crystallisation process is similar to the process we commonly see on Earth where water vapours first turn into liquid and then change into a solid the colder they get.
About 50 years ago, scientists predicted that the gaseous cores of white dwarfs should crystallise and become solid with the cooling of the hot gases inside them.
The Sun might die in 10 billion years' time, and when it does, according to scientists, it will turn into a "crystal ball". It is estimated that in some cases these stars have slowed down their aging by as much as 2 billion years, or 15 percent of the age of our galaxy. "The sun itself will become a crystal white dwarf in about 10 billion years".
Dr. Tremblay included that every single white dwarf will eventually crystallize, implying that "billions of white dwarfs in our universe have officially finished the procedure and are basically crystal spheres in the sky".
Crystallization is the process by which materials turn into a solid form in which the atoms are organized into a structure known as crystals. Sun-like stars swell into red giants before puffing away their outer shells into colorful nebula while their cores collapse into a white dwarf.
"We saw a pile-up of white dwarfs of certain colours and luminosities that were otherwise not linked together in terms of their evolution", says Pier-Emmanuel. Our sun is also expected to end its life in the same manner, crystallizing like a jewel in about 10 billion years.
Dr Tremblay adds: "Not only do we have evidence of heat release upon solidification, but considerably more energy release is needed to explain the observations". Before Gaia, we had 100-200 white dwarfs with precise distances and luminosities - and now we have 200,000. This will push the carbon upwards, and that separation will release gravitational energy. "This experiment on ultra-dense matter is something that simply can not be performed in any laboratory on Earth".