We present a photometric and spectroscopic study of four G-K dwarfs, namely HD 166, epsilon Eri, chi1 Ori and kappa1 Cet. In three cases, we find a clear spatial association between photospheric and chromospheric active regions. For chi1 Ori we do not find appreciable variations of photospheric temperature, and chromospheric Halpha emission. We applied a spot/plage model to the observed rotational modulation of temperature and flux to derive spot/plage parameters and to reconstruct a rough three-dimensional map of the outer atmosphere of kappa1 Cet, HD 166 and epsilon Eri.
@article{arxiv.astro-ph/0609525,
title = {Photospheric and chromospheric activity in four young solar-type stars},
author = {Katia Biazzo and Antonio Frasca and Gregory W. Henry and Santo Catalano and Ettore Marilli},
journal= {arXiv preprint arXiv:astro-ph/0609525},
year = {2008}
}