Constraints on M and R from various observables. The solid curve gives the relation obtained for the Eddington temperature T_Edd,∞ = 1.64 × 10⁷ K using Eqs. (37) and (38) for pure hydrogen atmosphere (X = 1). Dotted curves are for the Eddington flux F_Edd, − 7 = 0.561 (using Eq. (39)), dashed curves are for A = 0.167 (from Eq. (40)), shown for two different distances, D₁₀ = 0.53 (thick curves) and 0.77 (thin curves). For the distance below the upper limit (41) there are solutions at the interception of the curves. If the assumed distance is too large, there are no solutions (the curves shown by thin lines do not cross).