We present results from an optical spectroscopic investigation of the massive binary system [ L72 ] LH 54-425 in the LH 54 OB association in the Large Magellanic Cloud .
We revise the ephemeris of [ L72 ] LH 54-425 and find an orbital period of 2.24741 \pm 0.00004 days .
We find spectral types of O3 V for the primary and O5 V for the secondary .
We made a combined solution of the radial velocities and previously published V -band photometry to determine the inclination for two system configurations , i = 52 ^ { +2 } _ { -3 } degrees for the configuration of the secondary star being more tidally distorted and i = 55 \pm 1 degrees for the primary as the more tidally distorted star .
We argue that the latter case is more probable , and this solution yields masses and radii of M _ { 1 } = 47 \pm 2 ~ { } M _ { \odot } and R _ { 1 } = 11.4 \pm 0.1 ~ { } R _ { \odot } for the primary , and M _ { 2 } = 28 \pm 1 ~ { } M _ { \odot } and R _ { 2 } = 8.1 \pm 0.1 ~ { } R _ { \odot } for the secondary .
Our analysis places LH 54-425 amongst the most massive stars known .
Based on the position of the two stars plotted on a theoretical HR diagram , we find the age of the system to be \sim 1.5 Myr .