Characteristics of the photometric modulation of HZ Her/Her X-1 in active states over a very long time interval

摘要: Abstract The properties of the photometric orbital modulation X-ray binary HZ Her / X-1 and its variations over a long time interval (decades) are studied by statistical methods using photographic plates Sonneberg Observatory. moving averages light curve in long-lasting active state (1959–1993) show that both smoothed scatter residuals σ mag display striking asymmetries with respect to phase φ orb =0.5; they apparent whole data set segments 35 day cycle. near 0.5 can be characterized maximum either flat-topped symmetric or sharp lagging behind =0.5. course is largely asymmetric primary minimum, usually smooth decrease within =0.2–0.6 steep rise =0.6–0.85. All these facts suggest presence an additional source variations, addition geometric effects precessing disk. role interaction mass stream warped disk suggested as possible explanation. Our for extended years 1959–1993 revealed mean brightness at all phases remains stable displays most marginal secular trends. during short states (1934–1937 1941–1949) shown lower than attributed degree heating secondary star.