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Publisher: Tatranská Lomnica : Astronomický Ústav SAV ×

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    The enigmatic highly peculiar binary system HD 66051
    (Tatranská Lomnica : Astronomický Ústav SAV, 2020) Paunzen, E.; Niemczura, E.; Kolaczek-Szymanski, P.A.; Hubrig, S.
    HD 66051 (V414 Pup) is an eclipsing and spectroscopic double-lined binary, hosting two chemically peculiar stars: a highly peculiar B star as pri-mary and an Am star as secondary. It also shows out-of-eclipse variability that is due to chemical spots. Using a set of high-resolution spectropolarimetric observations, a weak magnetic field on the primary was found. The investigation of the new high-resolution UVES spectrum of HD 66051 allowed us to decide on the chemical peculiarity type of both components with more reliability. © 2020 Astronomical Institute, Slovak Academy of Sciences.
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    The 35-day cycle in the X-ray binary HZ Her/Her X-1
    (Tatranská Lomnica : Astronomický Ústav SAV, 2020) Kolesnikov, D.; Shakura, N.; Postnov, K.; Volkov, I.; Bikmaev, I.; Irsmambetova, T.; Staubert, R.; Wilms, J.; Irtuganov, E.; Shurygin, P.; Golysheva, P.; Shugarov, S.; Nikolenko, I.; Trunkovsky, E.; Schonherr, G.; Schwope, A.; Klochkov, D.
    We present the results of modelling the 35-day superorbital changes in the B and V lightcurves and X-ray flux of HZ Her/Her X-1. The model is implemented in a computer program written in the C programming language, with a module for parameter optimisation written in Python. The model in-cludes a tilted precessing and warped accretion disc around a freely precessing neutron star. The disc is warped near its inner edge due to interaction with the rotating neutron star magnetosphere. The magnetic torque depends on the precessional phase of the neutron star. The neutron star X-ray emission flux also depends on the free precession phase, which modulates the X-ray illumi-nation of the optical star's atmosphere and the intensity of gas streams. We demonstrate that this model is able to reproduce both the optical observations of HZ Her and the behaviour of the system's 35-day X-ray cycle. © 2020 Astronomical Institute, Slovak Academy of Sciences.