Fundamental Parameters of the Double-lined Spectroscopic and Detached Eclipsing Binary EPIC 211391083

EPIC 211391083 is a double-lined spectroscopic and detached eclipsing binary (SB2-DEB). Jointly modelling the APOGEE DR17 and LAMOST DR13 MRS radial velocities together with the K2 light curve yields an orbital period P = 39.23944 d, eccentricity e = 0.6783, and component masses and radii: M₁ = 1.509+0.016-0.015\, M, M2 = 1.394 ± 0.015 M⊙, R₁ = 1.615+0.015-0.013\, R, and R2 = 1.506 ± 0.013 R⊙. Atmospheric parameters are derived from LAMOST MRS spectra disentangled with FDBinary and fitted with PySME, yielding Teff, 1 = 6795 ± 42 K, log g1 = 4.06 ± 0.04 dex, [M/H]1 = −0.17 ± 0.01 dex, vsin i1 = 32.9 ± 0.3 km s−1 for the primary, and Teff, 2 = 6741 ± 28 K, log g2 = 4.13 ± 0.05 dex, [M/H]2 = −0.15 ± 0.01 dex, vsin i2 = 34.3 ± 0.4 km s−1 for the secondary. An independent two-component SED fit returns effective temperatures consistent with the spectroscopic values to within 1σ. Comparison with PARSEC and MIST isochrones at the spectroscopic metallicity gives a common evolutionary age of 1.10–1.14 Gyr. With both component masses and radii determined to ~1percnt, EPIC 211391083 adds a well-characterized benchmark to the sample of detached eclipsing binaries and provides a target for tidal dissipation studies in highly eccentric systems.