Long-term variations in the X-ray activity of HR 1099

摘要: Although timing variations in close binary systems have been studied for a long time, their underlying causes are still unclear. A possible explanation is the so-called Applegate mechanism, where strong, variable magnetic field can periodically change gravitational quadrupole moment of stellar component, thus causing observable period changes. One exhibiting such strong orbital RS CVn HR 1099, whose activity cycle has by various authors via photospheric and chromospheric indicators, resulting contradicting periods. We aim at independently determining 1099 using archival X-ray data to allow comparison variations. Archival from 80 different observations acquired with 12 facilities covering almost four decades were used determine fluxes energy range 2-10 keV spectral fitting flux conversion. Via Lomb-Scargle periodogram we analyze long-term light curve search periodicities. do not detect any statistically significant periodicities within data. An analysis optical shows that derivation periods strongly dependent on time coverage available data, since observed deviate pure sine wave. argue this offers an as why other derive wide based conclude our constitutes longest date, yet rather sparse sampling along stochastic flaring activity, does independent determination cycle.