Asymmetry of the interstellar lines Na I λ 589.0 and 589.6 nm in the spectrum of the Wolf-Rayet type star HD 192163

Abstract

The results of spectral studies of the interstellar absorption lines for Na I λ 589.0 nm (D2) and Na I λ 589.6 nm (D1) in the spectrum of the Wolf-Rayet (WR) type star HD 192163 = WR 136 are presentes. The observations have been carried out with an echelle spectrometer at the Cassegrain focus of the 2-m telescope at the Tusi Shamakha Astrophysical Observatory (ShAO) in Azerbaijan during 2005–2010. The 46 echelle spectrograms of HD 192163 and four echelle spectrograms of another WR-type star HD 191765 = WR 134 and the standard star HD 18947 have been obtained. The profiles of the interstellar Na I doublet absorption lines are shown to be asymmetric in the spectrum of HD 192163 and not asymmetric in those of the stars used for comparison. The asymmetry of the Na I doublet lines in the spectrum of HD 192163 can be explained by the contribution of the ring nebula NGC 6888, which is genetically related to this star. The echelle spectrograms of HD 192163 are used to determine the equivalent widths and radial velocities of the Na I doublet lines.