Starspot coverage and differential rotation on PZ Tel

Abstract

We present Doppler images of the young, late-type star, PZ Tel from spectroscopic observations at two epochs. The 0.95d period necessitated dual-site observations in order to obtain full phase coverage. By making use of the large number of spectral lines available in an echelle spectrum, least squares deconvolution is used to derive a series of low noise absorption profiles. The high S:N ratio profiles enable increased latitude discrimination in Doppler imaging. The resulting maximum entropy reconstructions reveal the presence of starspots at all latitudes. Since the lifetimes of individual spots are greater than the two day gap between data sets, we cross-correlated constant-latitude strips from the images, in order to derive a measure of rotation as a function of latitude. The close agreement with the solar and AB Doradus (K0V) values, suggests that the differential rotation rate is at most only weakly dependent upon rotation rate and spectral type.