The calculation procedure of optical characteristics of stellar atmospheres is described for the model of homogeneous partially ionized nonrelatlvistic isotropic plasma with the account of indlvidual particles collision. A advance is described for calculation of the refracted electromagnetic radiation magnitude of an eclipsed component in the atmosphere of an eclipsing one in the close binary system during total eclipse.The frequencies of the incident electromagnetic wave and the characteristics of the atmosphere layer are indicated in which the real refraction effect in the latter may generate some additional radiation throughout the total eclipse observed in twelve close binary system.
Radial velocity variations of the K supergiant Xi Cygnl are Investlgated on the basis of publlshed as well as new values from spectrograms In the visual and near infrared region obtalned In the period of 1977-1984 at Ondřejov, Shemakha, and Crlmea observatories. A circular orbit (P = 113.3873 days, Tmax = 2430214.33 HJD, K1 = 3,47 km/s, Vo = -20.0 km/s), still preliminary. confirms the period derlved by Parsons (1983). More accurate data are needed and the problem of the long period (Reimers 1981)
should be investigated.