The European space observatory Gaia gave us another interesting discovery. Its observations show that white dwarves crystallize over time. Our Sun will crystallize in about ten billion years.
It sounds almost like mythology. Red giants will slowly evaporate in the darkness of the Universe and their fading remains will turn into gigantic crystals. But in reality, it is just what research from the British University in Warwick shows will one day happen. It was astronomers from the university that brought the first direct evidence that white dwarves crystallize.
Pier-Emmanuel Tremblay and his coworkers used the observations coming from the European space observatory Gaia. Using it they found that the remains of red giants – white dwarves go through a phase change during which a solid core of oxygen and carbon is created. It’s almost like if water froze. And if they are right then many white dwarves might be much older than we thought.
Some of the white dwarves are among the oldest stellar objects that we know of in the Universe. That make they quite useful for astronomers that use they as sort of a “space clock” to tell how old they are but also whole groups of stars that surround them. Currently, we think that white dwarves slowly cool off after they are born from the ashes of red giants and because we can measure that temperature we can say how old they are. But now it seems the “white dwarf clock” might not be that precise.
Tremblay’s team chose fifteen thousand white dwarves that were observed by the Gaia observatory in around three hundred light years from Earth. From the data, they analyzed their brightness and color. The analysis shows that the cooling process is slowing down. The researchers say that in some cases this could reduce the age of white dwarves by up to two billion years.
Tremblay says that this is the first direct evidence of a phase shift in white dwarves from a liquid state into solid matter – crystallization. This has been predicted over fifty years ago. Crystallization is a process during which a material turns solid and electrons get free of the shackles of tightly packed atoms. This creates a conductive quantum electron gas and positively charged atomic cores in a state of a sort of a weird liquid. And when the core of the white dwarf cools of to about ten million degrees Celsius the liquid starts to crystallize.
This shows how much of a treasure the Gaia observatory actually is. Before Gaia existed we knew the exact distance and brightness of about one to two hundred white dwarves. Now we know of about two hundred thousand. And now we also know that they crystallize and that the Sun will turn into crystal as well – in about ten billion years.