Observations of non-solar-type dynamo processes in stars with shallow convective zones★

Abstract

The magnetic field topology and differential rotation are fundamental signatures of the dynamo processes that generate the magnetic activity observed in the Sun and solar-type stars. To investigate how these dynamo processes evolve in stars with shallow convective zones, we present high-resolution spectropolarimetric observations of the young GO dwarf HD171488 over three epochs. Using the Zeeman-Doppler tomographic imaging technique, we have reconstructed surface brightness images that are dominated by polar and high-latitude starspots and a magnetic field topology that shows large-scale radial and azimuthal magnetic field components. Over the time-span of our observations, we do not observe a reversal of the magnetic field polarity as has been observed in other solar-type stars with shallow convective zones. The phase coverage of our data was sufficient to determine the differential rotation for two epochs where in conjunction with previous work, we conclude that there is no evidence for the temporal evolution of differential rotation.