The apsidal motion in extragalactic stars: the masses of the eclipsing binary HV 2274 in the Large Magellanic Cloud.

Abstract

Theoretical apsidal motion rates based on evolutionary stellar models are used to evaluate masses and radii of an extragalactic eclipsing binary (HV 2274) in the Large Magellanic Cloud. As radial velocity curves are not available, from the results of the analysis of the light curve and the detected apsidal motion it was possible to constrain the values of the masses and radii for both components. Assuming a mass ratio of 1 (which is supported by evidence from the light curves), the masses of HV 2274 were inferred to be between 10 and 12 M_sun_. Adopting the effective temperatures given by IUE data, the masses were constrained to 10.3 M_sun_ and the radii to about 9R_sun_. A distance modulus of 18.4+/-0.3 is found, in good agreement with that obtained by different methods. The predicted masses and radii should be compared with observational ones when radial velocity curves as well as an improved apsidal motion period become available.