Optical spectroscopy of the low-mass X-ray binary GX 9+9
Optical spectroscopy of the low-mass X-ray binary GX 9+9
Phase-resolved medium-resolution VLT spectroscopy of the low-mass X-ray binary GX 9+9 has revealed narrow C iii emission lines that move in phase relative to our new estimate of the ephemeris, and show a velocity amplitude of 230 ± 35 km s−1. We identify the origin of these lines as coming …