Fundamental Properties and Distances of Large Magellanic Cloud Eclipsing Binaries. IV. HV 5936

Abstract

We have determined the fundamental properties and distance of a fourth eclipsing binary (EB) system in the Large Magellanic Cloud, HV 5936 (~B0.5 V + ~B2 III). As in our previous studies, we combine classical EB light-curve and radial velocity curve analyses with modeling of the UV/optical spectral energy distribution of HV 5936 to produce a detailed characterization of the system. In this paper, we also include an analysis of the high-resolution optical absorption line spectra of the binary components. 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 and 4.7 M☉, respectively. The properties of the primary star are indistinguishable from those of a normal 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. The distance derived to the system, 43.2 ± 1.8 kpc, implies a distance of ~44.3 kpc to the optical center of the LMC. This is several kiloparsecs closer than found in our analyses of other systems, and we suggest that HV 5936 lies above the LMC disk. This is supported by the very low interstellar H I column density and low E(B-V) found for the system—both of which are consistent with expected Milky Way foreground material—and may be associated with HV 5936's location near the LMC supergiant shell LMC 4.