Eclipsing binaries in the Magellanic Clouds - II. Absolute dimensions and distance modulus for HV 5936 in the Large Magellanic Cloud*

Absolute dimensions and the distance modulus have been established for the early-type eclipsing binary HV 5936 in the LMC. Analyses of new radial velocities, reported here, and CCD light curves published by Jensen, Clausen & Giménez yield masses of $$7.2 \pm 0.9\enspace \text {and} \enspace 3.3 \pm 0.5 \enspace \text M_{\odot}$$ for the primary and secondary components respectively. The corresponding radii are $$4.6 \pm 0.3 \enspace \text {and} \enspace 5.7 \pm 0.3\enspace \text R_{\odot}$$ with the cooler star filling its Roche lobe. More radial-velocity data are needed for definitive orbital parameters of HV 5936. The system appears to be similar to HV 2226 in the SMC in the sense of being a post-mass-transfer system, but due to case AB or B evolution rather than case A. A distance modulus of $$(m_{V} - M_{V})_{0} = 18.1 \pm 0.3$$ mag is derived, which marginally favours the ‘short’ distance to the LMC noted by Westerlund of $$(m_{V} - M_{V})_{0} = 18.2$$ mag; the range of $$(m_{V} - M_{V})_{0}$$ values reported in Westerlund's review is 17.9 – 18.7 mag. As for HV 2226 in the SMC, the accuracy of the estimate of $$(m_{V} - M_{V})_{0}$$ is limited by uncertainties of ≈ 2000 K in the effective temperatures, and by the limited radial- velocity data.