SIMBAD references

Radial velocity curves for 14 bright subdwarf B close binary systems have been measured using high precision radial velocity measurements from high S/N optical high-resolution spectra. The companions for all systems are unseen. The periods range from about 0.18 days up to about 6 days. The radial velocity semi-amplitudes are found to lie between 15 and 130 km/s. The invisible companions for three of our program stars are undoubtedly white dwarfs. In the other cases they could be either white dwarfs or main-sequence stars. For two stars the secondaries could possibly be brown dwarfs. The orbits for most observed systems are circular. However, small periodic deviations of the measured radial velocity points from the adopted theoretical sine curve are discovered for four program stars. These deviations can be perfectly matched assuming slightly eccentric orbits with small eccentricities of e = 0.02-0.06. Possibly, this is the first time that non-circular orbits have been detected in sdB binaries.