Astronomers have traditionally relied on helioseismology to estimate the age of the Sun by analyzing the vibrations that pass through its interior. But recent studies have revealed a significant obstacle: the Sun’s magnetic activity, which follows an 11-year cycle, appears to distort these measurements. Data from the Birmingham Solar Oscillations Network (BISON) and NASA’s SOHO mission, which spans more than 26.5 years, have revealed a 6.5 percent difference in the Sun’s age measured at solar minimum compared to solar maximum.
This discrepancy, attributed to variations in the Sun’s magnetic activity, indicates that similar methods for measuring the ages of other stars, especially those with stronger magnetic fields, may also be subject to variations.
How Magnetic Activity Is Changing Our Perception of the Solar Era
The Sun’s magnetic activity, which fluctuates between solar minimum and maximum, has a bigger impact than previously thought, according to a research paper published in the journal Astronomy & Astrophysics. During periods of high magnetic activity, oscillations within the Sun — detected by instruments such as BISON and GOLF (Global Oscillations at Low Frequency) — produce results that indicate a younger Sun than during periods of low magnetic activity.
These oscillations, caused by internal waves in the Sun, change the brightness and motions of the surface, allowing scientists to infer details about the Sun’s internal structure and, theoretically, its age. But the unexpected effect of magnetic activity on these measurements challenges the long-held assumption that such activity should have little impact on helioseismology.
Challenges for future star observations
The implications of this discovery extend beyond our Sun. As scientists prepare for the European Space Agency’s upcoming PLATO mission, scheduled for launch in 2026, they must now consider the effects of magnetic activity when measuring the age, mass, and radius of distant stars. The PLATO mission aims to detect dips in starlight caused by both transiting exoplanets and asteroseismic oscillations similar to those seen on the Sun.
If magnetic activity significantly changes these measurements, as seen for the Sun, it could require re-evaluating data from previous missions, such as NASA’s Kepler Space Telescope. The finding poses an “upcoming challenge” for the future of asteroseismology, requiring new methods to provide accurate age measurements for stars, especially for stars with more magnetic activity.
