A new study indicates that in billions of years our dead Sun is transforming into a large cosmic pearl. Stars are born, evolve and die. Our star should eventually become a white dwarf - an exotic object that is 200,000 times more dense than Earth (a teaspoonful of a white dwarf substance is equal in weight to an elephant).
Half a century ago, scientists predicted that over time, white dwarfs become crystals. A new study confirms this assumption. At a certain point in evolution, all white dwarfs crystallize. It turns out that the billions of white dwarfs of the Milky Way have already completed this process and act as crystalline celestial spheres. From the Sun expect this in 10 billion years.
Artistic vision of a white dwarf in the process of solidification
The researchers base the findings on data analysis of the Gaia spacecraft, published in 2013. It helps to create the best 3D map of the Milky Way, as it tracks the location of a huge number of stars. The team seeks to explore 1 billion stars during the operation of Gaia.
For the study, scientists looked at measurements for 15,000 white dwarfs distant 330 light-years from the Sun. This made it possible to detect an oversupply of white dwarfs with certain colors and brightness levels, which cannot be explained by the age or mass of a celestial body. The simulation indicates that crystallization of the inner parts of the white dwarfs occurred, which generated enough heat to slow down the cooling over time. This is the first proof that these objects are moving from a liquid to a solid state.
The crystallization of a white dwarf resembles the freezing of water. But in the specific case it is about oxygen and carbon, which do not crystallize at frosty temperatures. The process starts when the inner space of the white dwarf cools down to 10 million degrees Celsius. As a result, the core remains represented by crystallized oxygen and mantle with a predominance of carbon.
These findings also suggest that many white dwarfs are much older than previously thought. In some cases, the difference reaches 15%. Usually their age is measured by temperature, but crystallization slows down the cooling process, knocking down data.