V. S. Niemela

THE WOLF-RAYET SPECTROSCOPIC BINARY HD 92740

A radial velocity study of RD 92740, a WN7 star, shows it to be a binary with P = 10d04 Preliminary velocity curves derived from various lines suggest differing amplitudes; and the weak hydrogen absorption lines present in the spectrum share the orbital motion of the WN star. Undetected violet absorption is shown to cause the redward displacement of He II x4686. The possibility of an outward accelerating atmosphere is suggested by the presence of a Balmer progression. Key words: spectroscopic binary - Wolf-Rayet spectrum

The O-type spectroscopic binary system HD 165921.

The first determination of the spectroscopic orbital elements, the spectral types, and the flux ratio in blue light has been made of the components of the double-lined spectroscopic binary HD 165921. The period is 1.744215 d + or - 0.000005 d, and the orbit is essentially circular. The mass ratio is 1.41 + or - 0.05, and the minimum mass of the primary is 19 + or - 1 solar. The spectral types of the components are estimated to be O7 V and O9 V. The magnitude difference in blue light is 0.7 + or - 0.2 mag. Measurements of He I linewidths yielded v sin i = 185 + or - 13 km/s for the primary and 180 + or - 9 km/s for the secondary. These values suggest that the rotational and orbital motions are nearly synchronous. The system is probably near contact. The mass ratio and the luminosity ratio are consistent with both stars being on the ZAMS.

ON THE WOLF-RAYET STARS HD 90657 AND HD 117688

Recent Spectrographic observations of HD 90657 and HD 117688 do not confirm their earlier classification as W-R objects that are intermediate to those that belong to the WN and WC sequences. HD 90657 is very probably a spectroscopic binary with a period of a few days. Key words: Wolf-Rayet stars - spectral observations