Doppler images of DI Piscium during 2004–2006⋆
Department of Physics, PO Box 64, 00014 University of Helsinki,
2 Finnish Centre for Astronomy with ESO (FINCA), University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
3 Aalto University, Department of Information and Computer Science, PO Box 15400, 00076 Aalto, Finland
4 Niels Bohr Institute, Juliane Maries Vej 30, 2100 University of Copenhagen, Denmark
5 Leibniz Institute for Astrophysics (AIP), an der Sternwarte 16, 14882 Potsdam, Germany
6 Department of Physics and Astronomy, Uppsala University, Box 516, Uppsala 751 20, Sweden
Accepted: 15 January 2014
Methods. We apply the Doppler imaging method on high-resolution optical spectroscopy obtained during 2004–2006.
Results. In July–August 2004, no clear spot structures were visible, but the spot coverage increased in July 2005, and cool spots emerged, especially at intermediate latitudes. Later on in September 2006, the spot coverage increased and cool spots were visible on both sides of the equator. However, the map of 2006 suffers from bad phase coverage, meaning it is not possible to draw definite conclusions on the spot locations during that season.
Conclusions. Compared with earlier Doppler maps of DI Psc and temperature maps obtained for other late-type stars with similar rotation rates, DI Psc seems to be in a low activity state especially during the observing season of July–August 2004. During the 2005 and 2006 observing seasons, the spot activity seen in the spectral line profiles and inferred from Doppler images increases, and the temperature contrast in our last map is more comparable to what was reported in an earlier study. Therefore, it can be concluded that the spot activity level of the star is variable over time. However, the present and previous Doppler images form too short a time series to draw conclusions about a possible activity cycle in DI Psc.
Key words: stars: individual: HD 217352 / stars: activity / stars: imaging / starspots
© ESO, 2014