On the Status of the Star Schulte 12 in the Association Cyg OB2

Abstract

High-resolution spectra of the LBV candidate Schulte 12 in the Cyg OB2 association were obtained at the 6-m BTA telescope with the NES echelle spectrograph on the arbitrary dates in 2001-2022. Variability of the emission profile of H_α and absorptions of He I, Si II with time was found. Based on the radial velocity measurements at 10 observation dates, radial velocity variability with an amplitude of $Δ {{V}_r} ≈ $ 8 km/s relative to the average value of the heliocentric velocity ${{V}_r} = - 15.6 ± 2.6$ km/s was revealed. This indicates the presence of a companion in the system. Based on the reliable intensity measurements of a sample of DIBs, color excess $E(B - V) = 1.74 ± {{0.03}^m}$ was found. This results in the interstellar extinction value ${{A}_{{v}}} ≈ {{5.6}^m}$ that is only about half of the total extinction. Taking modern Schulte 12 parameters, including Gaia EDR3 parallax, we estimated its absolute magnitude as M_v ≈ $ - {{9.2}^m}$ and luminosity ${log}(L{/}{{L}_{ \odot }}) ≈ 5.5$, which does not exceed the Humphreys-Davidson limit.