Asteroseismic constraints on active latitudes of solar-type stars: HD173701 has active bands at higher latitudes than the Sun

Abstract

We present a new method for determining the location of active bands of latitude on solar-type stars, which uses stellar-cycle-induced frequency shifts of detectable solar-like oscillations. When near-surface activity is distributed in a non-homogeneous manner, oscillation modes of different angular degree and azimuthal order will have their frequencies shifted by different amounts. We use this simple concept, coupled to a model for the spatial distribution of the near-surface activity, to develop two methods that use the frequency shifts to infer minimum and maximum latitudes for the active bands. Our methods respond to the range in latitude over which there is significant magnetic flux present, over and above weak basal ephemeral flux levels. We verify that we are able to draw accurate inferences in the solar case, using Sun-as-a-star helioseismic data and artificial data. We then apply our methods to Kepler data on the solar analogue HD173701, and find that its active bands straddle a much wider range in latitude than do the bands on the Sun.

13 pages, 15 figures, MNRAS accepted

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• Kepler main-sequence solar-like stars: surface rotation and magnetic-activity evolution
• Flaring Latitudes in Ensembles of Low Mass Stars
• Empirical Relations for the Sensitivities of Solar-like Oscillations to Magnetic Perturbations
• Frequency separation ratios do not suppress magnetic activity effects in solar-like stars
• Lifetimes and Rotation within the Solar Mean Magnetic Field