AAS 201st Meeting, January, 2003
Session 4. Eclipsing and Spectroscopic Binaries
Poster, Monday, January 6, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[4.05] Fundamental Properties of the LMC Eclipsing Binary HV5936

E.L. Fitzpatrick (Villanova University), I. Ribas (Universitat de Barcelona), E.F. Guinan, F.P. Maloney (Villanova University), A. Claret (Instituto de Astrofisica de Andalucia)

We have determined the fundamental properties of a fourth eclipsing binary system in the Large Magellanic Cloud, HV5936. The approximate spectral types of the two stars in the system are ~B0.5 V and ~B2 III. As in our previous studies, we combine ``classical'' EB light curve and radial velocity curve analyses with modeling of the UV-through-optical spectral energy distribution of HV5936 to produce a detailed characterization of the system. In this study, we also include an analysis of the high-resolution optical absorption line spectra of the binary components. The optical spectra of the primary and secondary were extracted separately from spectra of the system via a Fourier ''disentangling'' algorithm.

We find HV~5936 to be an Algol-class system, in which the masses of the primary and secondary stars have evolved via mass transfer to their current values of 11.6 Mo and 4.7 Mo, respectively. We suggest that the initial masses of the two stars were approximately 7.5Mo and 13 Mo, respectively. The properties of the primary star (i.e., temperature, mass, luminosity, and radius) are indistinguishable from those of a ``normal'' single star of the same current mass. The secondary is found to be overluminous for its current mass and exhibits a factor-of-2 enhancement in its surface He abundance. These results are compatible with ``Case A'' mass exchange occurring during the core hydrogen burning phase of the current secondary.

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.