When you buy through links on our articles, Future and its syndication partners may earn a commission.The sun seen in two different X-ray wavelengths, 17.4 and 30.4 nanometers, on 21 May 2024. | Credit: ESA & NASA/Solar Orbiter/EUI TeamActing as stellar archaeologists, scientists have found fossilized magnetism on long-dead stars known as “white dwarfs.” This discovery may help explain how stars evolve from their “puffed out” red giant phase to their compact and smoldering white dwarf phase, a process our sun will undergo in around 5 billion years.The team behind this research linked a theoretical model to observations of stars at different stages of their evolution, connecting evidence of magnetic fields at the surfaces of white dwarfs to magnetism detected at the cores of red giants. The team’s model hinges on the idea that magnetic fields, which form early in a star’s life, persist throughout all of their later stages, finally emerging on white dwarfs billions of years later as “fossil fields.”AdvertisementAdvertisementWith this information in hand, the researchers then used measurements of stellar oscillations, or simply “starquakes,” by tapping into techniques in the field of asteroseismology. This allowed them to further develop the fossil field theory as an explanation for stellar magnetism.”The magnetic field in a star is important for how the star works on the inside and how long it lives and evolves,” team co-leader Lukas Einramhof of the Institute of Science and Technology Austria (ISTA) said in a statement. “Generally, more of the older white dwarfs tend to be more magnetic than younger white dwarfs.”To understand the connection between red giants and white dwarfs, consider the final evolution of our own star, the sun.From red giants to white dwarfsIn around 5 billion years, the sun will have exhausted the hydrogen in its core, no longer able to perform its nuclear fusion process that converts this element into helium. As this process is the main source of energy produced by the sun, this will mean the outward pressure that stops the sun from collapsing under its own gravity also ceases.AdvertisementAdvertisementAs the sun’s core collapses, its outer layers, where nuclear fusion is still occurring, will puff out to around 100 times the original width of the sun — maybe more. This is the red giant phase. the solar system, it could see the sun swallow the rocky planets, including Earth, right out to the orbit of Mars.The red giant phase of the sun will be relatively short-lived, expected to last just 1 billion years. The outer layers of the star will eventually cool and disperse, leaving a nebula of ex-stellar material surrounding the sun’s core, which will then become an exposed cooling stellar remnant called a white dwarf. That is the final stage of life for all stars of a similar mass to that of the sun.The hot core in the center of a red giant star rotates 10 times faster than …
