Investigation of the absorption spectrum of RY SCT : identification of the secondary component's lines, the orbital elements and principles of the component mass determination using spectra of developed circumstellar structures.

The absorption spectrum of the interacting binary RY Sct is investigated on the basis of high-dispersion spectrograms. Wide, shallow Si III, H, He I, and other lines reflecting the orbital motion of the faint secondary component are identified. The half-amplitude of the radial velocity curve of these lines is close to 70 km/s. Elements of the RY Sct orbit are calculated. The mass ratio is 3.32, the mass of the bright B0 component is 8 solar masses, and that of the secondary B2 component is 26 solar masses. Features of the manifestation of developed circumstellar gaseous structures in the spectrum of RY Sct are examined.