SS 433 Optical Flares: A New Analysis Reveals Their Origin in L2 Overflow Episodes

Abstract

The microquasar SS 433 exhibits in Hα intermittent flares. A sequence of observations made in 2004 showed flaring Doppler shifted to both the red and the blue simultaneously. The mean shifts varied from day to day, following the orbital phase of the compact object. At the time, this behaviour was interpreted as indicating an origin in the outer rim of the accretion disk. A new analysis of these old data, presented in this paper, shows that the flares are not eclipsed by the Companion that eclipses the photosphere surrounding the compact object. They are therefore not intermittent sightings of an accretion disk. The alternative explanation is plasma expelled through the L2 point, following the phase of the orbit as it invades the space beyond the system. That space has been mapped with comparatively recent GRAVITY observations of a similar flare in Brγ, indeed revealing a strong rotation component.