Identification of the Mass Donor Star’s Spectrum in SS 433
Identification of the Mass Donor Star’s Spectrum in SS 433
We present spectroscopy of the microquasar SS 433 obtained near primary eclipse and disk precessional phase Ψ = 0.0, when the accretion disk is expected to be most "face-on." The likelihood of observing the spectrum of the mass donor is maximized at this combination of orbital and precessional phases, since …