That was a shock—and a potential indication that one thing essential was lacking in these fashions: magnetism.
Stellar Symmetry
Final yr, Gang Li, an asteroseismologist now at KU Leuven, went digging by way of Kepler’s giants. He was trying to find a mixed-mode sign that recorded the magnetic subject within the core of a pink big. “Astonishingly, I truly discovered just a few cases of this phenomenon,” he mentioned.
Sometimes, mixed-mode oscillations in pink giants happen nearly rhythmically, producing a symmetric sign. Bugnet and others had predicted that magnetic fields would break that symmetry, however nobody was in a position to make that tough statement—till Li’s crew.
Li and his colleagues discovered a large trio that exhibited the anticipated asymmetries, they usually calculated that every star’s magnetic subject was as much as “2,000 occasions the power of a typical fridge magnet”—robust, however per predictions.
Nevertheless, one of many three pink giants shocked them: Its mixed-mode sign was backward. “We have been a bit puzzled,” mentioned Sébastien Deheuvels, a examine creator and an astrophysicist at Toulouse. Deheuvels thinks this consequence means that the star’s magnetic subject is tipped on its aspect, that means that the approach may decide the orientation of magnetic fields, which is essential for updating fashions of stellar evolution.
A second examine, led by Deheuvels, used mixed-mode asteroseismology to detect magnetic fields within the cores of 11 pink giants. Right here, the crew explored how these fields affected the properties of g-modes—which, Deheuvels famous, could present a approach to transfer past pink giants and detect magnetic fields in stars that don’t present these uncommon asymmetries. However first “we wish to discover the variety of pink giants that present this habits and evaluate them to totally different situations for the formation of those magnetic fields,” Deheuvels mentioned.
Not Only a Quantity
Utilizing starquakes to research the interiors of stars kicked off a “renaissance” in stellar evolution, mentioned Conny Aerts, an astrophysicist at KU Leuven.
The renaissance has far-reaching implications for our understanding of stars and of our place within the cosmos. To date, we all know the precise age of only one star—our solar—which scientists decided based mostly on the chemical composition of meteorites that fashioned throughout the beginning of the photo voltaic system. For each different star within the universe, we solely have estimated ages based mostly on rotation and mass. Add inner magnetism, and you’ve got a approach to estimate stellar ages with extra precision.
