Solving the Mystery of Stardust Recycling
When middleweight stars near the end of their cosmic lives, they shrug off their outer layers, shedding up to half their mass. But just how the stars manage to dispel so much material has been a mystery, though a new study may hold clues to closing the case. Astronomers have found that dust grains in the outer layers of atmospheres of near-death stars are surprisingly large. The process, researchers say, allows the star dust to deflect light and skim out of the way, transporting their mass into space.
The revelation helps fill in the details on an important process that shapes the evolution of galaxies. When the first stars were born, they were made almost exclusively of hydrogen and helium, the two lightest elements. Inside the cores of these stars, these elements fused to form heavy elements such as carbon and oxygen. Then, as the stars got older, they expelled these elements into space as they lost mass, ultimately seeding the galaxy with the raw materials for new stars. The new stars were then born with heavier elements, which allowed them to create ever heavier elements through fusion inside their cores. And the cycle continued.