Radial velocities of ups Sgr

At the same time, thorough studies of them are extremely important for better understanding the process of large-scale mass exchange and possible mass loss from the system. One of these objects is probably upsilon Sgr.

By analyzing 35 new electronic spectra and numerous published spectral and photometric observations, we derived the new orbital elements, an upper limit to a secular period change, and also the peculiar RV curve of the blue-shifted H{alpha} absorption. Possible models of the binary and its evolutionary stage are then discussed critically.