289 citations · 895 across the 26 of their papers we have counts for
3 papers · 1 filter
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…
Long-term spot monitoring of the young solar analogue V889 Her
T. Willamo, T. Hackman, J. J. Lehtinen +6
Starspots are important manifestations of stellar magnetic activity. By studying their behaviour in young solar analogues, we can unravel the properties of their magnetic cycles. T…
Algol as Horus in the Cairo Calendar: the possible means and the motives of the observations
Sebastian Porceddu, Lauri Jetsu, Tapio Markkanen +4
An ancient Egyptian Calendar of Lucky and Unlucky Days, the Cairo Calendar (CC), assigns luck with the period of 2.850 days. Previous astronomical, astrophysical and statistical an…