Mysterious gamma-ray 'heartbeat' detected from cosmic gas cloud

From the link provided, the report says "SS 433 is a unique Galactic microquasar containing a compact object, most probably a black hole of ~10–20 solar masses (M⊙) orbiting an ~30 M⊙ A3-7 supergiant star with an orbital period of 13.082 days (ref. 2). The rate of mass transfer from the companion is determined from analysis of optical lines3 and is thought to be as high as 10^−4 M⊙ yr−1, which is orders of magnitude larger than the Eddington limit. This steady supercritical accretion state powers highly collimated jets of plasma and mass-loaded non-polar outflows at a similar level4–6, with kinetic powers exceeding ∼10^39 erg s−1."

Follow up studies are coming and these should be very interesting to read. A 20 solar mass BH could have Schwarzschild radius ~ 59 km.