IR-source IRAS20508+2011: spectral variability of the central star

TL;DR

This study presents five years of high-resolution spectroscopic observations of IRAS20508+2011, revealing spectral variability, atmospheric parameters, and chemical composition, indicating it is an O-rich AGB star with dynamic spectral features.

Contribution

The paper provides detailed spectral variability analysis and atmospheric modeling of IRAS20508+2011, a previously less-studied IR source, highlighting its classification as an O-rich AGB star.

Findings

Radial velocity varies between 15-30 km/s.

Halpha profile changes from emission with absorption to double-peaked emission.

Star's atmosphere has Te=4800K, log g=1.5, [Fe/H]=-0.36.

Abstract

Over the five years of high-resolution spectroscopy of the cool star identified with the IR source IRAS20508+2011, the photospheric radial velocity variability Vr=15-30km/s is detected. In the same time, the Halpha profile varied from an intense bell-shaped emission line with a small absorption to 2-peaked emission with a central absorption feature below the continuum level. The NaD doublet lines shown a complex profile with broad (FWHM \approx 120km/s) emission and photospheric absorption, as well as an interstellar component. We used model atmospheres to determine the physical parameters and chemical composition of the star's atmosphere: Te=4800K, log g=1.5, [Fe/H]=-0.36, [O/Fe] =+1.79 (with the ratio [C/O]=-0.9). The totality of the parameters suggests that the optical component of IRAS20508+2011 is an O-rich AGB star with luminosity Mv