Dynamical Masses for the Large Magellanic Cloud Massive Binary System [L72] LH 54-425

S. J. Williams; D. R. Gies; T. J. Henry; J. A. Orosz; M. V. McSwain; T. C. Hillwig; L. R. Penny; G. Sonneborn; R. Iping; K. A. van der Hucht; L. Kaper

doi:10.1086/589687

arXiv · 0802.4232

Dynamical Masses for the Large Magellanic Cloud Massive Binary System [L72] LH 54-425

S. J. Williams·D. R. Gies·T. J. Henry·J. A. Orosz·M. V. McSwain·T. C. Hillwig·L. R. Penny·G. Sonneborn·R. Iping·K. A. van der Hucht·L. Kaper

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Abstract

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 2.247409 +/- 0.000010 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 degrees for the configuration of the secondary star being more tidally distorted and i = 55 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 +/- 2 M_Sun and R_1 = 11.4 +/- 0.1 R_Sun for the primary, and M_2 = 28 +/- 1 M_Sun and R_2 = 8.1 +/- 0.1 R_Sun 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 about 1.5 Myr.

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S. J. Williams, D. R. Gies, T. J. Henry, J. A. Orosz, M. V. McSwain, T. C. Hillwig, L. R. Penny, G. Sonneborn, R. Iping, K. A. van der Hucht, L. Kaper. 2008-02-28. Dynamical Masses for the Large Magellanic Cloud Massive Binary System [L72] LH 54-425. https://doi.org/10.1086/589687

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