Parameters of X-Ray Binary Sco X-1 in the Model of Partial Filling of Roche Lobe by Optical Star

• Published in: Astronomy reports 2022, Vol.66 (4), p.348-358
• Main Authors: Cherepashchuk, A. M., Khruzina, T. S., Bogomazov, A. I.
• Format: Article
• Language: English
• Subjects: Accretion disks; Astronomy; Binary stars; Companion stars; Light curve; Luminosity; Mathematical models; Neutron stars; Neutrons; Observations and Techniques; Parameters; Physics; Physics and Astronomy; Stars; Stellar winds; X ray binaries; X ray stars
• ISSN: 1063-7729; 1562-6881
• DOI: 10.1134/S1063772922040023

We have simulated optical orbital light curves of the Sco X-1 system obtained by the Kepler space observatory during K2 mission. Simulation was carried out under assumption that the optical star partially fills its Roche lobe and neutron star accretes the matter of the companion stellar wind induced by strong X‑ray heating. By such a model, it is possible to describe consistently observed optical light curves in the low and high states (as well as the average light curve) and to find the optimal values of the system parameters: mass ratio of components , inclination of the orbit , temperature of the unheated part of the optical star K, the radius of this star , its bolometric luminosity erg/s and mass  . The star is on the main- sequence. Accretion disk dominates in total luminosity in the optical range, the contribution of the optical star is %. The mass of a neutron star is . The radius of accretion disk is relatively small, , much smaller than the Roche lobe radius of the neutron star. This is consistent with the model of accretion from the stellar wind. Transition from a low to a high state of the system corresponds to increase in the X-ray luminosity of the central source by a factor .