TOMOGRAPHIC SEPARATION OF COMPOSITE SPECTRA .5. THE TRIPLE STAR SYSTEM 55-URSAE-MAJORIS

We present moderate-resolution spectra obtained with the Georgia State University Multi-Telescope Telescope of 55 UMa, a triple system consi sting of a 2.55 day spectroscopic binary and a third star in a 1873 da y orbit (detected by speckle interferometry). We observed the spectral lines of all three stars, and we present radial velocity curves for b oth the close and wide orbits. We also present new speckle interferome tric measurements and a revised solution of the astrometric (wide) orb it. The spectrum of each star was reconstructed using Doppler tomograp hy, and we measured ratios of Fe I and Fe II lines in both the reconst ructions and model synthetic spectra to estimate the stellar effective temperatures. These temperatures correspond to spectral types of A1 V and A2 V for the close pair and A1 V for the distant third star. We s how that the metallic lines of the close pair are systematically stron g, and we suggest that both objects are moderate Am stars. All the com ponents have masses close to 2 M., and continued spectroscopic and ast rometric observations will yield precise masses and absolute magnitude s.