The 35-day cycle in the X-ray binary HZ Her/Her X-1

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

Timing of AR CrB eclipses

AR CrB is a short-period low-mass eclipsing binary. We conducted photometric observations of the system in 2013, 2014, 2016, 2017, and obtained times of its light curves minima. The timing of eclipses (our times of minima combined with data from the literature) shows that the orbital period of AR CrB could possess periodical variations that can be explained by the gravitational influence of a third companion in a highly eccentric orbit around the central binary

Light equation on eclipsing binary CV Boo

Короткопериодическая затменная двойная звезда CV Boo изучена методом светового уравнения. Были использованы данные о моментах минимумов из литературы и из наших наблюдений в мае июле 2014 г. Была найдена периодическая вариация орбитального периода системы с периодом ≈ 75 дней. Эта вариация может быть объяснена гравитационным воздействием третьего тела с массой ≈ 0.4 M⊙ на вытянутой орбите с эксцентриситетом e ≈ 0.9. Также обсуждается возможность изменения орбитального периода на больших шкалах времени. Предлагаемое третье тело находится близко к хаотической зоне вокруг центральной двойной, поэтому оно может быть интересно для изучения его динамической эволюции.A short period eclipsing binary star CV Boo is tested for the possible existence of new bodies in the system with a help of the light equation method. We use data about moments of minima from the literature and our observations during May—July 2014. A periodical variation of CV Boo’s orbital period is found, the variation’s period is ≈ 75 days. This variation can be explained by the gravitational influence of a third star with a mass ≈ 0.4M⊙ in an eccentric orbit with e ≈ 0.9. A possibility for orbital period changes in long time scales is discussed. The suggested tertiary companion is near the chaotic zone around the central binary, so it is an interesting example to test its dynamical evolution

Coordinated integral and optical observations of SS433

Results of simultaneous INTEGRAL and optical observations of galactic microquasar SS433 in May 2003 are presented. The analysis of the X-ray and optical eclipse duration and hard X-ray spectra obtained by INTEGRAL together with optical spectroscopy obtained on the 6-m telescope allows us to construct a model of SS433 as a massive X-ray binary. X-ray eclipse in hard X-rays has a depth of ∼ 80% and extended wings. The optical spectroscopy allows us to identify the optical companion as a A5-A7 supergiant and to measure its radial velocity semiamplitude Kv = 132 km/s. A strong heating effect in the optical star atmosphere is discovered spectroscopically. The observed broadband X-ray spectrum 2-100 keV can be described by emission from optically thin thermal plasma with kT ∼ 15 - 20keV

INTEGRAL observations of SS433: Results of a coordinated campaign

Results of simultaneous INTEGRAL and optical observations of the galactic microquasar SS433 in May 2003 and INTEGRAL/RXTE observations in March 2004 are presented. Persistent precessional variability with a maximum to minimum uneclipsed hard X-ray flux ratio of ∼4 is discovered. The 18-60 keV X-ray eclipse is found to be in phase with optical and near infrared eclipses. The orbital eclipse observed by INTEGRAL in May 2003 is at least two times deeper and apparently wider than in the soft X-ray band. The broadband 2-100 keV X-ray spectrum simultaneously detected by RXTE/INTEGRAL in March 2004 can be explained by bremsstrahlung emission from optically thin thermal plasma with kT ∼ 30 keV. Optical spectroscopy with the 6-m SAO BTA telescope confirmed the optical companion to be an A5-A7 supergiant. For the first time, spectorscopic indications of a strong heating effect in the optical star atmosphere are found. The measurements of absorption lines which are presumably formed on the non-illuminated side of the supergiant yield its radial velocity semi-amplitude Kv = 132 ±9 km s-1. The analysis of the observed hard X-ray light curve and the eclipse duration, combined with the spectroscopically determined optical star radial velocity corrected for the strong heating effect, allows us to model SS433 as a massive X-ray binary. Assuming that the hard X-ray source in SS433 is eclipsed by the donor star that exactly fills its Roche lobe, the masses of the optical and compact components in SS433 are suggested to be Mv ≈ 30 M⊙ and Mx ≈ 9 M⊙, respectively. This provides further evidence that SS433 is a massive binary system with supercritical accretion onto a black hole. © ESO 2005