The mass of SS 433: a conflict resolved?
  The Galactic microquasar SS\,433 is very luminous and launches
oppositely-directed jets of cool hydrogen at a quarter of the speed of light.
Observations of emission lines from the circumbinary disk imply a system mass
exceeding 40 $ M_\odot$. The most recent attempts to establish a mass via
observation of absorption lines in the spectrum of the companion imply a system
mass of no more than 20 $ M_\odot$. Aims. To examine these conflicting data and
present a possible resolution of this conflict. Methods. Interpretation of data
through the application of simple trigonometry to the configuration of the SS
433 system. Results. The absorption spectra which, attributed to the atmosphere
of the companion, yield an orbital speed of $\sim$ 60 km s$^{-1}$ could well be
attributable to absorption of light from the companion in material of the
circumbinary disk. Then the absorption spectra predict an orbital speed for the
circumbinary disk material of $\sim$ 240 km s$^{-1}$, in agreement with the
emission line data. Conclusions. If continuum light from the companion is
absorbed in passage through the circumbinary disk material rather than in the
atmosphere of the companion itself, the periodic Doppler shifts in the
absorption spectra are entirely consistent with observations of the
circumbinary disk and a system mass exceeding $\sim$ 40 $M_\odot$. The striking
consistency implies that the compact object is a rather massive stellar black
hole.
