35 citations · 35 across the 1 of their papers we have counts for
3 papers
Shapes of stellar activity cycles
T. Willamo, T. Hackman, J. J. Lehtinen +4
Magnetic activity cycles are an important phenomenon in both the Sun and other stars. The shape of the solar cycle is commonly characterised by a fast rise and a slower decline, bu…
Starspot activity of HD 199178. Doppler images from 1994--2017
Thomas Hackman, Iya Ilyin, Jyri J. Lehtinen +4
Context. Studying the spots of late-type stars is crucial for distinguishing between the various proposed dynamo mechanisms believed to be the main cause of starspot activity. For…
Updated sunspot group number reconstruction for 1749-1996 using the active day fraction method
Teemu Willamo, Ilya G. Usoskin, Gennady A. Kovaltsov
Sunspot number series are composed from observations of hundreds of different observers that requires careful normalization of the observers to the standard conditions. Here we pre…