2009ApJ...691..407B

This paper presents a photometric and spectroscopic study of the bright blue eclipsing binary LMC-SC1-105, selected from the Optical Gravitational Lensing Experiment catalog as a candidate host of very massive stars (≥30 M_☉). The system is found to be a double-lined spectroscopic binary, which indeed contains massive stars. The masses and radii of the components are M₁= 30.9±1.0 M_☉, M₂= 13.0±0.7 M_☉, and R₁= 15.1±0.2 R_☉, R₂= 11.9±0.2 R_☉, respectively. The less massive star is found to be filling its Roche lobe, indicating the system has undergone mass transfer. The spectra of LMC-SC1-105 display the Struve-Sahade effect, with the He I lines of the secondary appearing stronger when it is receding and causing the spectral types to change with phase (O8+O8 to O7+O8.5). This effect could be related to the mass transfer in this system. To date, accurate (≤10%) fundamental parameters have only been measured for 15 stars with masses greater than 30 M_☉, with the reported measurements contributing valuable data on the fundamental parameters of very massive stars at low metallicity. The results of this work demonstrate that the strategy of targeting the brightest blue stars in eclipsing binaries is an effective way of studying very massive stars.