The Distance and Interstellar Sight Line to GX 339−4

• DOI: 10.1086/421014
• Publication Date: 2004-06-21T14:28:36Z
• Authors: R. I. Hynes; D. Steeghs; J. Casares; P. A. Charles; K. O’Brien
• Keywords: Line-of-sight; Line (geometry)

The distance to the black hole binary GX339-4 remains a topic of debate. We examine high-resolution optical spectra NaD lines resolving velocity structure along line sight. find this be complex, with at least nine components, mostly blue-shifted, spanning range nearly 200km/s. presence components large blue-shift rules out nearby location and requires that located or beyond tangent point, implying lower limit ~6kpc. significant red-shifted component +30km/s is even more intriguing as also has slightly positive systemic velocity, suggesting source, cloud, could on far side Galaxy, where radial velocities due Galactic rotation become again. If case, we require ~15kpc. This less secure than 6kpc however. discuss implications these possible distances for outburst quiescent luminosities, nature companion star, argue consistent characteristics. In particular, it would explain non-detection star during faintest states.