The Mass Donor of Scorpius X-1 Revealed

  title={The Mass Donor of Scorpius X-1 Revealed},
  author={D. Steeghs and J. Casares},
  journal={The Astrophysical Journal},
We present the first detection of the mass donor star in the prototype X-ray binary Scorpius X-1. Phase-resolved spectroscopy revealed narrow emission line components from the irradiated secondary star. Radial velocity fits to the Bowen blend emission are used to establish an absolute orbital ephemeris and derive an accurate value for the systemic velocity, γ = -113.8 ± 0.6 km s-1. Emission from the irradiated front side of the secondary leads to solid limits to the radial velocity of the mass… Expand

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