Instability in the System of the Distant Post-AGB Star LS III +52°24 (IRAS 22023+5249)

The optical spectra of the B-supergiant LS III +52°24 (IRAS 22023+5249) obtained at the 6-m BTA telescope with a resolution in 2010–2021 revealed signs of wind variability and velocity stratification in the extended atmosphere. The neutral hydrogen lines H and H have a P Cyg profile; their wind absorption component changes position in the range from to km/s. The H emission intensity reaches record-high values with respect to the local continuum: . The stationary radial velocity according to the positions of symmetric forbidden emissions and pemitted metal emissions is taken as the systemic velocity km/s. For the first time for this star, a time variability of the radial velocity in the range from to km/s was found based on the positions of absorptions of NII and OII ions, which indicates the possible presence of a companion and/or atmospheric pulsations. The variability of the oxygen triplet profile (OI 7774) due to the appearance of unstable emission was recorded. The set of interstellar absorptions of the NaI D-line profile in the range from to km/s is formed in the Local Arm and subsequent arms of the Galaxy. The distance to the star, kpc, combined with the high velocity indicates that the star is located in the interarm space of the Galaxy beyond the Scutum–Crux arm.