1998A&A...332..909L

We present a spectroscopic and photometric analysis of a complex multiple system: the early-type eclipsing binary SZ Cam (O9 IV + B0.5 V) is physically bound to a third body, which itself is a close binary; this quadruple system has a visual companion, which shows evidence for duplicity as well. A careful deconvolution of spectral lines in our CCD spectra yields rv curves of the SB2 system (K₁=180km/s, K₂=261km/s; P=2.6984d) and of its SB1 companion (K_1,T=25km/s; P=2.7966d). UBV light curves of Kitamura & Yamasaki (1970) are reanalyzed and absolute dimensions of the eclipsing pair are derived. Both components of this close detached binary are overluminous for their masses. The photometric solution suggests third light of ≃20-30%, which confirms the spectroscopic and speckle interferometric detection (Mason 1995) of the third component. The observed light time effect encompasses the long period range to ∼50-60 years. Comparison of calculated orbits with the speckle interferometric result yields a distance of 1050pc, which is ∼10% larger than the value derived from the absolute bolometric magnitude, and ∼20% above the photometric distance of the open cluster NGC 1502. The minimum mass of the third component is 20-30M_☉, depending on the long orbital period and inclination assumed. This high mass supports the binary nature of the third body. An analysis of the spectra of the visual companion ADS 2984 A confirms its binarity.