Key points are not available for this paper at this time.
(shortened) Spectroscopic observations of the soft X-ray transient 4U 1543-47 reveal a radial velocity curve with a period of P=1. 123 +/- 0. 008 days and a semi-amplitude of K₂ = 124 +/- 4 km/sec. The mass function is f (M) = 0. 22 +/- 0. 02 solar masses. We derive a distance of d = 9. 1 +/-1. 1 kpc if the secondary is on the main sequence. The V and I light curves exhibit two waves per orbital cycle with amplitudes of about 0. 08 mag. We modeled the light curves as ellipsoidal variations in the secondary star and derive extreme inclination limits of 20 1. However, there are systematic effects in the data that the model does not account for, so the above constraints should be treated with caution. We argue that the secondary star is still on the main sequence and if the secondary star has a mass near the main sequence values for early A-stars (2. 3 <= M₂ <= 2. 6 solar masses), then the best fits for the 3 sigma inclination range (24 <= i <= 36 deg) and the 3 sigma mass function range (0. 16 <= f (M) <= 0. 28 solar masses) imply a primary mass in the range 2. 7 <= M₁ <= 7. 5 solar masses. Thus the mass of the compact object in 4U 1543-47 is likely to be in excess of approximately 3 solar masses and we conclude 4U 1543-47 most likely contains a black hole.
Orosz et al. (Wed,) studied this question.