AbstractFrom three VLBA observations at 5 GHz, spanning 13 months, we have measured the trigonometric parallax of Sco X-1 of 0.23 ± 0.28 mas; hence its distance is > 1300 pc. This supports the hypothesis that the the x-ray luminosity is near the Eddington Limit.All three VLBA observations show a radio core of flux density 0.5 mJy and size < 4 mas. However, the third VLBA observation revealed two additional radio components, separated by 12 mas (≈ 20 au) on opposite sides of the radio core. The evolution of these new components is unknown until additional observations can be made. The relative luminosity and separation of the two radio components are inconsistent with the Doppler beaming of two identical ejecta from the radio core.
The Evolution and Distance to SCORPIUS X-1