We revisit the determination of binary mass ratio in the Galactic microquasar
SS433 based on recent GRAVITY VLTI measurements of mass and angular momentum
outflow through a circumbinary disc. The new observations combined with the
constancy of the binary orbital period over ∼30 yrs confirm that the mass
ratio in SS433 is q=Mx​/Mv​≳0.6. For the assumed
optical star mass Mv​ ranging from ∼8 to 15 M⊙​ such a
mass ratio suggests a low limit of the compact object mass of Mx​∼5−9M⊙​, placing the compact object in SS433 as a stellar-mass black hole.Comment: 4 pages, 3 figures, accepted in MNRAS, Main Journa