Application of Time-Frequency Distributions to Variable
Star Data and Solar Activity

Zoltan Kollath



We used modern time-frequency analysis to get information about the
modulation of frequencies in variable star light curves. Strong
changes around the harmonic frequencies were found as an indication of
interacting pulsational modes. Understanding the variability of solar
activity is very important since its effects on our global climate.
Besides the 11 year quasi periodicity (Schwabe cycle) of solar activity
lots of different rhythms were discovered or at least suggested by
different studies. We reanalyzed the available data to give a complete
picture of the beating of the Sun in the period range from 1 year to 200
years. A new 3-year-long cycle was found which is in close resonance
condition with the Schwabe cycle. Variations in one of the longest time
scale cycle are uncovered: the period of the Gleissberg (100 yr) cycle has
been continously increasing since an abrupt decrease at the end of the
Maunder minimum.