2024-03-12 07:00:13
Traditionally, white dwarfs are seen as the cold, dim remnants of stars that have exhausted their nuclear fuel. They mark the end of stellar evolution for the majority of stars, including our Sun. However, some of these stars defy expectations by maintaining a brightness (Brightness designates the characteristic of what emits or reflects…) equivalent to that of much younger stars, for billions of years. The mystery behind this phenomenon finds an explanation in the depths of their internal structure.
At the heart of these white dwarfs, a remarkable process takes place: less dense crystals form and rise to the surface, while materials (A material is a material of natural or artificial origin that man shapes to…) denser ones sink. This sort of distillation (Distillation is a process of separating mixtures of liquid substances…) between solids and liquids creates an energy balance, thus maintaining the brightness of thestar (A star is a celestial object emitting light autonomously, similar to a…) over a much longer period than expected. This discovery, resulting (In mathematics, the resultant is a notion that applies to two polynomials….) of the work of Simon Blouin and his team, revolutionizes our understanding of the final stages of the life of stars.
The observation of these particularly luminous white dwarfs was made possible thanks to the satellite Gaia (The Gaia satellite is an astrometric mission of the European Space Agency (ESA) ahead…) of the’European Space Agency (The European Space Agency (ESA) is…). Gaia has revealed the existence of a group of white dwarfs whose cooling appears to have been paused for more than eight billion years. This discovery raises important questions about the age and formation of our galaxy, the Milky Way (The Milky Way (also called “our galaxy”, or sometimes…)and questions the use of white dwarfs as cosmic chronometers.
The role of Simon Blouin and his contributions to this research are essential. Their study, published in the journal Naturenot only reveals the internal mechanism allowing these stars to remain hot, but also highlights the importance of taking this process into account to better understand evolution stellar (Stellaria is a genus of annual or perennial herbaceous plants, starworts,…). This work reminds us how much our Universe (The Universe is the totality of everything that exists and the laws that govern it.) is full of surprises and puzzles yet to be solved.
Schematic of the crystallization of an ordinary white dwarf (left) and the solidification (Solidification is the operation during which a liquid changes to a state…) massive white dwarfs (right)
© Bedard, Blouin et al, Nature (2024)
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