Doppler Imaging of spotted stars - Application to the RS Canum Venaticorum star HR 1099

Abstract

We discuss a technique for imaging the surfaces of certain rapidly rotating spotted stars The method exploits the correspondence between wavelength position accorss a rotationally broadened spectral line and spatial position across the stellar disk. Preliminary Doppler IMages of the RS CVn star HR 1099 show spots which exhibit a striking similarity in shape and location to X-ray images of solar coronal holes. We suggest that the large star spots on RS CVn's and other active late-type stars emerge at low latitude as scaled -up stellar analogs of solar complexes, but as they migrate poleward, they move closely resemble photospheric analogs of solar coronal holes. The evolution of starspots appears remarkably similar to that of large-scale magnetic fields of the sun.