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Long-term variations in the X-ray activity of HR 1099
Schmitt, J. H. M. M.; Robrade, J.; Schneider, P. C. +6 more
Context. 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 a strong, variable magnetic field can periodically change the gravitational quadrupole moment of a stellar component, thus causing observable pe…
Spectral energy distribution variations of nearby Seyfert galaxies during AGN watch monitoring programs
Vestergaard, M.; Kilerci Eser, Ece
We present and analyse quasi-simultaneous multi-epoch spectral energy distributions (SEDs) of seven reverberation-mapped active galactic nuclei (AGNs) for which accurate black hole mass measurements and suitable archival data are available from the `AGN Watch' monitoring programs. We explore the potential of optical-UV and X-ray data, obtained wit…