Tomographic separation of composite spectra. VII. The physical properties of the massive triple system HD 135240 (delta Circini)

We present the results of a radial velocity study of the massive, double-li ned, O binary HD 135240 based primarily on UV spectroscopy from the Interna tional Ultraviolet Explorer. Cross-correlation methods indicate the presenc e of a third stationary spectral line component which indicates that the sy stem is a triple consisting of a central 3.9 day close binary with a distan t companion. We measured radial velocities from the cross-correlation funct ions after removal of the third component, and we combined these with veloc ities obtained from H alpha spectroscopy to reassess the orbital elements. We applied a Doppler tomography algorithm to reconstruct the individual UV spectra of all three stars, and we determine spectral classifications of O7 III-V, O9.5 V, and B0.5 V for the primary, secondary, and tertiary, respec tively, using UV criteria defined by Penny, Gies, & Bagnuolo. We compare th ese reconstructed spectra to standard single-star spectra to find the UV fl ux ratios of the components (F-2/F-1 = 0.239 +/- 0.022, and F-3/F-1 = 0.179 +/- 0.021). Hipparcos photometry reveals that the central pair is an eclip sing binary, and we present the first model Dt of the light curve from whic h we derive an orbital inclination, i = 74 degrees +/- 3 degrees. This anal ysis indicates that neither star is currently experiencing Roche lobe overf low. We place the individual components in the theoretical H-R diagram, and we show that the masses derived from the combined spectroscopic and photom etric analysis and (M-p/M. = 21.6 +/- 2.0 M-s/M. = 12.4 +/- 1.0) are signif icantly lower than those computed from evolutionary tracks for single stars .