Optical spectrum of distant OH/IR star V1648 Aql (IRAS 19386+0155)
arXiv:1908.04986 · doi:10.1134/S1990341319030040
Abstract
An optical spectrum of the star V1648 Aql (=IRAS 19386+0155) was obtained at the 6-meter telescope with a spectral resolution of R60\,000. Heliocentric radial velocity measured from numerous metallic absorptions is equal to V= km s (V=18.1 km s). We determined the atmospheric, circumstellar, and interstellar components in the profile of the NaI D~lines at V=9.2, , and km s respectively. The averaged over twenty identified DIBs velocity V(DIBs)= km~s coincides with the interstellar NaI component. Weak emissions with an intensity of about 10% of the local continuum level were detected in the spectrum; they are identified as low-excitation metal lines. Their averaged position, V= km s, may point to the presence of a weak velocity gradient in the upper layers of the stellar atmosphere. Based on the spectroscopic data and taking into account the interstellar and circumstellar reddening, we estimated the star's luminosity M and also obtained the lower estimate of distance d kpc. Using the model atmosphere method, we determined the fundamental parameters and chemical abundances in the atmosphere approving the status of a post-AGB star for V1648 Aql.
16 pages, 4 figures, 4 tables
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