On the Nature of 17 Leporis

We have obtained many optical spectra of 17 Lepris during its 1991-1992, 1992-1993, and 1993-1994 observing seasons. We determined that the secondary's spectral type is about M4, later than the M1 type commonly assumed. We measured the M star secondary's radial velocity for each observation from lines in the far red and determined orbital elements from those data. In particular, we find that the eccentricity is significantly smaller (e = 0.024) than the previously published value (e = 0.132), on which the classical interpretation of the system has been based. We have measured radial velocities for the Mg II 4481 A line of the A star primary, and have determined the mass ratio to be 3.5 +/- 0.6. Based on the small eccentricity we determined we find no evidence for the classical model of post-periastron mass transfer, although the four shell outbursts we observed did all occur within 0.6 orbit after periastron. A small upper limit on Li I 6707 A equivalent width argues against the recent suggestion that 17 Lep is a pre-main-sequence binary system, as does its apparent HR diagram location, although other spectroscopic considerations support its pre-main-sequence status.