• stars: individual: HD 82558;
  • stars: late-type;
  • stars: magnetic fields

We present a model for the differential rotation and dynamo activity of the young rapidly rotating K0 dwarf LQ Hya (Prot=1.6 d). As might be expected from observations of the similar rapid rotator AB Dor, the predicted differential rotation is small (≃0.8 per cent) but extremely efficient in generating magnetic fields. The dynamo, which is of a distributed type, produces a globally axisymmetric field with radial and azimuthal components that are of the same magnitude and display a phase-lag in their evolution of about π/2. This is consistent with the long-term Zeeman–Doppler imaging study by Donati. The latitudinal distribution of flux is, however, a little different from that observed and the cycle period of 3.2 yr is somewhat shorter than suggested by the observations.