1 Department of Physics, PO Box 64, 00014 University of Helsinki, Finland
2 Finnish Centre for Astronomy with ESO, University of Turku, Väisäläntie 20, 21500 Piikkiö, Finland
3 ReSoLVE Centre of Excellence, Department of Computer Science, PO Box 15400, 00076 Aalto University, Finland
4 Leibniz-Institut für Astrophysik Potsdam, An der Sternwarte 16, 14882 Potsdam, Germany
5 Department of Physics and Astronomy, Uppsala University, Box 516, 751 20 Uppsala, Sweden
Received: 1 December 2014
Accepted: 13 July 2015
Aims. We study the spot distribution on the surface of LQ Hya during the observing seasons October 1998–November 2002. We look for persistent active longitudes, trends in the level of spot activity and compare to photometric data.
Methods. We apply the Doppler imaging technique on photospheric spectral lines using an inversion code to retrieve images of the surface temperature.
Results. We present new temperature maps using multiple spectral lines for a total of 7 seasons.
Conclusions. We find no evidence for active longitudes persisting over multiple observing seasons. The spot activity appears to be concentrated to two latitude regions. Using the currently accepted rotation period, we find spot structures to show a trend in the phase-time plot, indicative of a need for a longer period. We conclude that the long-term activity of LQ Hya is more chaotic than that of some magnetically active binary stars analyzed with similar methods, but still with clear indications of an activity cycle from the photometry.
Key words: stars: activity / stars: imaging / starspots
Based on observations made with the Nordic Optical Telescope, operated on the island of La Palma jointly by Denmark, Finland, Iceland, Norway, and Sweden, in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias.
Table 2 is available in electronic form at http://www.aanda.org
© ESO, 2015