In section 7. Stellar structure and evolution
Super-Keplerian equatorial outflows in SS 433. Centrifugal ejection of the circumbinary disk
SS 433 is one of the brightest and most enigmatic sources in our Galaxy. It is a binary system made by a massive companion and a compact object, probably a black hole. SS 433 shows extended, relativistic jets known to process with a ~160d period. The GRAVITY instrument working with the four Very Large Telescopes together,
observed SS 433 at an unrivaled angular resolution. These unique observations that resolve the system as being formed by two jets, perpendicular to a ~5 au large circumbinary structure.
This disk structure has a very high specific angular momentum and is too extended to be a stable circumbinary disc
in Keplerian rotation. It should instead be a centrifugally ejected disc, possibly similar to the shell ejections observed in Be stars.