A model for the 89 Herculis system.

Abstract

We report new radial velocity measurements of the F2 supergiant 89 Her that confirm the binary nature of this star. A period search yields an orbital period of 288.4 +/- 0.7 days, in close agreement with earlier results. We also present intermediate resolution spectra in the wavelength range 3500 - 11,000 A, with numerous emission lines. We use the available spectroscopic and photometric data to construct a qualitative model for the circumstellar envelope of 89 Her, and suggest that it is highly nonspherical as a result of binary evolution. We discuss the evolutionary status of the 89 Her system.