Astrophysicists Unveil Theoretical Link Between Fossilized Magnetic Fields and the Final Evolution of Stars

Astrophysicists at ISTA use starquakes to prove that magnetic fields survive a star's evolution, emerging as fossil fields on white dwarfs billions of years later.

By: AXL Media

Published: Apr 14, 2026, 11:30 AM EDT

Source: Information for this report was sourced from EurekAlert!

A Unified Theory of Stellar Magnetism

New research published in Astronomy & Astrophysics has provided a crucial link between the magnetism observed in long-dead stellar remnants and the active cores of dying stars. Led by PhD student Lukas Einramhof and Assistant Professor Lisa Bugnet, the team from the Institute of Science and Technology Austria (ISTA) has utilized theoretical modeling to bridge independent observations across different stages of a star’s life. The study proposes that magnetic fields originate in the earliest stages of stellar formation and survive through the transition from main-sequence stars to red giants, eventually emerging at the surface of white dwarfs. This "fossil field" scenario offers a cohesive explanation for why older white dwarfs often exhibit stronger surface magnetism than their younger counterparts.

Probing the Deep Interior via Starquakes

The breakthrough relies heavily on the emerging field of asteroseismology, which allows scientists to observe "starquakes" to measure the internal dynamics of celestial bodies. Much like seismic waves reveal the Earth’s internal structure, stellar oscillations provide a window into the core of red giants, which are the progenitors of white dwarfs. According to Einramhof, because a white dwarf is essentially the exposed core of a red giant that has discarded its outer layers, these measurements allow researchers to examine the same region of a star at different points in its history. These observations have confirmed the presence of magnetic fields in the cores of dying stars millions of years before they become the magnetic remnants seen today.

The Structural Evolution of Fossil Fields

The ISTA team’s simulations have uncovered that the shape and distribution of magnetic fields change significantly as a star evolves. Rather than being concentrated at a single central point, the researchers found that these fields can form shell-like structures, which Einramhof compares to the surface of a basketball. Their findings suggest that for these fields to eventually be observed at the surface of an older white dwarf, a much larger fraction of the progenitor star's core must be magnetized. This "magneto-archaeology" indicates that while the fields may not necessarily be stronger than previously thought, they must be more widely distributed within the star's interior to survive the evolu...