3 papers
physics.hist-ph2018
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…
astro-ph.SR2016
Time series analysis of long-term photometry of BM Canum Venaticorum
L. Siltala, L. Jetsu, T. Hackman +10
Studying RS CVn binaries is challenging, because in addition to spot activity, other effects such as mass transfer between the components and gravitational distortion of their sphe…
astro-ph.SR2015
Activity trends in young solar-type stars
Jyri Lehtinen, Lauri Jetsu, Thomas Hackman +2
We study a sample of 21 young and active solar-type stars with spectral types ranging from late F to mid K and characterize the behaviour of their activity. We apply the continuous…