The Distance and Interstellar Sight Line to GX 339โ4
The Distance and Interstellar Sight Line to GX 339โ4
The distance to the black hole binary GX339-4 remains a topic of debate. We examine high-resolution optical spectra of the NaD lines resolving the velocity structure along the line of sight. We find this to be complex, with at least nine components, mostly blue-shifted, spanning a velocity range of nearly โฆ