AAS 199th meeting, Washington, DC, January 2002
Session 152. Variable Stars
Oral, Thursday, January 10, 2002, 2:00-3:30pm, Jefferson East

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[152.02] Doppler Tomography of Massive Compact Binary Stars in Multiple Star Systems

J. A. Harvin (Georgia State University)

I present a study of IUE spectra for three O stars in multiple star systems. These spectra were first subjected to cross-correlation analysis to find their radial velocity curves and hence their orbital elements. I then used Doppler tomographic methods to separate the individual component spectra in order to find their MK types, projected rotational velocities, and UV flux ratios, and to search for evidence of unusual abundances. Using the properties derived from the reconstructed spectra, the component stars were placed on the Hertzsprung-Russell diagram and compared to the evolutionary tracks predicted by Schaller et al. (1992), Maeder & Meynet (2001), and Heger & Langer (2001).

These three O stars, \delta~Ori~A, HD~206267, and HD~215835, are all triple star systems in which at least one component is an O star. All three consist of a massive close binary star with a more distant tertiary component recently discovered through speckle interferometry. I examined these systems to try to detect and correct for the effects of the previously unknown third light in their spectra. In the case of \delta~Ori~A, the masses of both components of its close binary were determined, and both components are highly overluminous for their spectroscopically-determined masses. This is probably a result of the close binary having undergone one or more episodes of Roche lobe overflow.

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