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Seismological insights into solar and stellar magnetic activity cycles
Anne-Marie Broomhall (University of Warwick)
The Sun’s magnetic activity cycle varies primarily on a time scale of approximately 11yrs from minimum to maximum and back again. It is well-known that the properties of the Sun’s acoustic oscillations are affected by the near-surface internal magnetic field: Frequencies, damping rates, and powers are all known to vary systematically with solar cycle. Careful observation of these variations, therefore, allows aspects of the Sun’s internal magnetic field to be inferred. However, the Sun is just one star and with the advent of CoROT and Kepler, oscillations can now be observed for thousands of other stars. However, despite many stars showing signs of magnetic activity in their lightcurves, to date, activity cycle-like variations in the properties of asteroseimic oscillations are sparse. I will discuss recent observations of solar cycle associated variations in helioseismic oscillation parameters, demonstrating connections with other stars and implications for our understanding of solar and stellar magnetic fields. I will finish with a discussion on how seismology can provide insights into a star’s magnetic field, without necessarily observing activity cycle-like behaviour.