The mass of the black hole in the X-ray binary LMC X-1

Abstract

A dynamical estimate of the mass of the black hole in the LMC X-1 binary system is obtained in the framework of a Roche model for the optical star, based on fitting of the He I 4471 A and He II 4200 A absorption lines assuming LTE. The mass of the black hole derived from the radial-velocity curve for the He II 4200 A line is mx = 10.55 M⊙, close to the value found earlier based on a model with two point bodies [1].