2026AJ....171...49Y

A method of obtaining bolometric corrections (BC_V) from observed high-resolution, high signal-to-noise spectra is described. The method is applied to the spectra of 128 stars collected from the literature with well-determined effective temperatures (T_eff) with the S_λ(V) transparency profiles of Bessell and Landolt. The computed BC_V values are found to be accurate within several millimagnitudes, and the effect of different S_λ(V) values is found to be no more than 0.015 mag. The measured visual-to-bolometric ratio (L_V/L) from the sample spectra and classically determined BC_V from bolometric (M_Bol) and visual (M_V) absolute magnitudes helped us to determine the zero-point constant (C₂) of the BC_V scale. The determined C₂ for each star for each S_λ(V) profile revealed C₂ = 2.3653 ± 0.0067 mag if the S_λ(V) profile of Bessell is used and C₂ = 2.3826 ± 0.0076 mag if the S_λ(V) profile of Landolt is used. Expanding C_Bol = 71.197425... mag and c_Bol = - 18.997351... mag announced by IAU2015GARB2, and using the definition of C₂ = C_Bol-C_V = c_Bol-c_V, where capital C is the absolute magnitude and lowercase c is the apparent magnitude and subscripts indicate bolometric and visual, the zero-point constants-C_V = 68.8321 ± 0.0067 mag and c_V = -21.3627 ± 0.0067 mag, if L_V and are in SI units-were determined corresponding to S_λ(V) of Bessell. The zero-point constants corresponding to S_λ(V) of Landolt are smaller, but the difference is not more than 0.02 mag. Typical and limiting accuracies for predicting a stellar luminosity from an apparent magnitude and a distance are analyzed.