By observing the oscillations of stars—known as stellar tremors—scientists have discovered hidden magnetic fields on very old white dwarfs. They believe that these dead stars are the remnants of the red giants from which they originated.
Magnetic fields and starquakes
A team of researchers from the Austrian Institute of Science and Technology has published a study in the journal Astronomy & Astrophysics linking the unusually strong magnetic fields on old white dwarfs to the red giants from which they originated.
White dwarfs are the remnants of medium-mass stars that have shed their outer layers. No nuclear fusion reactions occur on them. They glow with residual light as they gradually cool down. One might think that their magnetic fields would also weaken over time.
However, when scientists began studying asteroseismology—the spontaneous oscillations of white dwarfs caused by the resonance of sound waves passing through them—they discovered extremely powerful magnetic fields hidden beneath the surface.
Magnetic fields of red giants
The source of such powerful magnetic fields in old white dwarfs remained unknown until scientists began studying starquakes on red giants. This led them to discover that the cores of red giants also possess powerful magnetic fields.
Since white dwarfs are essentially the exposed cores of red giants, it stands to reason that the former inherit their properties from the latter. This may explain the observational data, but the theory of “fossil” magnetic fields—which provides a good explanation for all of this—is not currently very popular.
However, behind all this lies a much more interesting question. Since magnetic fields are so stable that white dwarfs inherit them from red giants, might they not form even before the star begins to die?
Specifically, scientists are interested in whether there are similar powerful fields in the core of our Sun. Eventually, it will also turn first into a red giant and then into a white dwarf. This will not happen soon, but what if magnetic fields already exist inside it? Our sun also experiences starquakes. So, it is quite possible that they will help us uncover the truth about it.
According to phys.org
