A new seismic diagnostics of stellar activity cycles

 Magnetic activity affects the observed properties of solar p modes:
mode frequencies and linewidths increase with solar activity. Using VIRGO/SPM
data from solar cycles 23 and 24 we show that solar-cycle variations are
measurable in the temporal autocorrelation function of the p modes. Following
a method developed for local helioseismology, we measure the p-mode travel
times for multiple skips and propose to average these to enhance the
signal-to-noise ratio. This method is robust to noise, simpler to implement
than peak bagging in the frequency domain, and promising for asteroseismology
applications. We estimate that the activity cycles of Sun-like stars may be
detectable in long photometric time series.