СПЕКТРОСКОПІЧНЕ ДОСЛІДЖЕННЯ ПОДВІЙНОЇ ЗОРІ ПІСЛЯ AGB HR 4049

We present a new spectroscopic study of HR 4049, a post-AGB star in a binary system, based on échelle spectra obtained between 2019/03/19 and 2025/04/08 with the 0.81 m telescope of the Three College Observatory (North Carolina, USA) at a resolution of R ≈ 12,000. A cross-correlation analysis of 83 spectra in the 4760–4780 Å range yielded the following orbital parameters: period P = 428.47 ± 0.01 days, eccentricity e = 0.29 ± 0.01, argument of periastron ω = 242.3° ± 0.3°, epoch of periastron T₀ = 2,458,383.2 ± 0.6, systemic radial velocity γ = -30.12 ± 0.09 kms⁻¹, and semi-amplitude K₁ = 15.52 ± 0.13 kms⁻¹. Using the Gaia DR3 parallax (d = 1397⁺¹⁷⁶₋₁₆₈ pc) and the average maximum brightness (mᵥ = 5.35 mag), the luminosity was estimated as log(L/L⊙) = 4.22 ± 0.12, consistent with an initial mass of 3–4 M⊙. The mass function combined with likely orbital inclinations implies current masses of ∼ 0.75 M⊙ for the primary and 0.70–0.82 M⊙ for the secondary. These results confirm the long-term orbital stability of HR 4049 and provide new constraints on the properties of post-AGB binaries.