Spots on the surface of the active late-type star PZ Mon
The photometric properties of the late-type star PZ Mon are analysed assuming the presence of spots on its surface. The long-term variability in brightness is considered using photographic data together with photoelectric data in the B band. The combined light curve covers the time span from 1898 to 2004 and shows two deep minima which might be interpreted as an activity cycle with a period of 50 years. The investigation of seasonal variations is based on UBVRI observations carried out with the 1.25Âm telescope at the Crimean Astrophysical Observatory in 1992–2004. The derived colours of PZ Mon indicate that the spectral type of the star is K5 and therefore the parameters of spots were calculated adopting a value for the temperature of the photosphere of 4800ÂK. Applying the simple model of star spots we found that a seasonal variability can be produced by spots which cover 17–30% of the hemisphere. The spot temperatures are constant and close to 2700ÂK. If the deep minima on the long-term curve are also produced by the spots, the spotted area should be extended in these epochs to 50%.
Document Type: Research Article
Affiliations: Crimean Astrophysical Observatory, Nauchny, Crimea, 98409, Ukraine
Publication date: 2006-04-01