Dynamic models of HY Eri in the M₁ − M₂ plane. The irradiation model is BR08, ranges from 111 to 159 km s⁻¹ in steps of 2 km s⁻¹, and the bloating factor f₃ ranges from 1.000 to 1.300 in steps of 0.005. The models with main sequence (MS) secondaries are marked by blue dots. Red dots denote the models that match both, the measured radial-velocity amplitude of Mg Iλ5170 and the spectroscopically measured WD radius within their 90% confidence errors.