The LMC eclipsing binary HV 2274 revisited

Abstract

We reanalyse the UV/optical spectrum and optical broad-band data of the eclipsing binary HV 2274 in the LMC, and derive its distance following the method given by Guinan et al. (1998a,b) of fitting theoretical spectra to the stars' UV/optical spectrum plus optical photometry. We describe the method in detail, pointing out the various assumptions that have to be made; moreover, we discuss the systematic effects of using different sets of model atmospheres and different sets of optical photometric data. It turns out that different selections of the photometric data, the set of model atmospheres and the constraints on the value of the ratio of selective to total extinction in the $V$-band, result in a 25% range in distances (although some of these models have a large $χ^2$). For our best choice of these quantities the derived value for the reddening to HV 2274 is E(B-V) = 0.103 $\pm$ 0.007, and the de-reddened distance modulus is DM = 18.46 $\pm$ 0.06; the DM to the center of the LMC is found to be 18.42 $\pm$ 0.07. This is significantly larger than the DM of 18.30 $\pm$ 0.07 derived by Guinan et al. (1998a).