OPTICAL SPECTROSCOPY OF SYMBIOTIC STAR EG And. Hα ORBITAL VARIABILITIES

This paper includes the results of the studies of the orbital variability of the emission and absorption components of the Hα line of the eclipsing symbiotic system EG And. We used medium-resolution amateurs about 30 spectra (R = 9,000–11,000) taken from the Astronomical Ring for Access to Spectroscopy (ARAS) database obtained during 2020–2025. Radial velocity curves of the cool component were derived from the mean of the measured radial velocities of selected absorption lines forming in the atmosphere of a M-type red giant. The system’s orbital period is approximately 483.3 days (Kenyon & Garcia, 2016). It is assumed that the emission lines, and in particular the Hα line, are formed in the vicinity of a hot white dwarf. We have established that the intensity of the emission component of the Hα line has the greatest value at an orbital phase of about 0.5 (corresponding to the eclipsing of the cold primary component by the white dwarf) and the lowest at about 0.1 (the red giant eclipses the hot secondary component and the region of formation of strong emission lines), and an average at about a phase of 0.8.