HD 179821 (V1427 Aql, IRAS 19114+0002) -- A Massive Post-Red Supergiant Star?

Abstract

We have derived elemental abundances of a remarkable star, HD 179821, with unusual composition (e.g. [Na/Fe]=1.0$\pm$0.2 dex) and extra-ordinary spectral characteristics. Its metallicity at [Fe/H]=0.4 dex places it among the most metal-rich stars yet analyzed. The abundance analysis of this luminous star is based on high resolution and high quality (S/N$\approx$120--420) optical echelle spectra from McDonald Observatory and Special Astronomy Observatory. The data includes five years of observations over twenty-one epochs. Standard 1D {\sc LTE} analysis provides a fresh determination of the atmospheric parameters over all epochs: \Teff = 7350$\pm$200 \kelvin, \logg = +0.6$\pm$0.3, and a microturbulent velocity $\xi =$ 6.6$\pm$1.6 km s${}^{-1}$ and [Fe/H] = 0.4$\pm$0.2, and a carbon abundance [C/Fe]= $-$0.19$\pm$0.30. We find oxygen abundance [O/Fe]= $-$0.25$\pm$0.28 and an enhancement of 0.9 dex in N. A supersonic macroturbulent velocity of 22.0 $\pm$ 2.0 km s${}^{-1}$ is determined from both strong and weak Fe\,{\sc i} and Fe\,{\sc ii} lines. Elemental abundances are obtained for 22 elements. HD 179821 is not enriched in s-process products. Eu is overabundant relative to the anticipated [X/Fe] $\approx$ 0.0. Some peculiarities of its optical spectrum (e.g. variability in the spectral line shapes) is noticed. This includes the line profile variations for H$\alpha$ line. Based on its estimated luminosity, effective temperature and surface gravity, HD 179821 is a massive star evolving to become a red supergiant and finally a Type II supernova.

arXiv comment19 pages, 8 figures, accepted for publication in MNRAS

References in corpus (24)

• The chemical composition of the Sun
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Exploring the Milky Way stellar disk. A detailed elemental abundance study of 714 F and G dwarf stars in the Solar neighbourhood
• New Grids of ATLAS9 Model Atmospheres
• Non-LTE calculations for neutral Na in late-type stars using improved atomic data
• Stellar Iron Abundances: non-LTE Effects
• NLTE line formation of Fe in late-type stars II: 1D spectroscopic stellar parameters
• The ELODIE archive
• The elemental composition of the Sun II. The iron group elements Sc to Ni
• The Stagger-grid: A Grid of 3D Stellar Atmosphere Models - I. Methods and General Properties
• A Catalog of Diffuse Interstellar Bands in the Spectrum of HD 204827
• The Distribution of the Elements in the Galactic Disk III. A Reconsideration of Cepheids from l = 30 to 250 Degrees
• Keplerian discs around post-AGB stars: a common phenomenon?
• Improved Laboratory Transition Probabilities for Neutral Chromium and Re-determination of the Chromium Abundance for the Sun and Three Stars
• Improved Ti II log(gf) Values and Abundance Determinations in the Photospheres of the Metal-Poor Star HD 84937
• Non-LTE Line-Formation and Abundances of Sulfur and Zinc in F, G, and K Stars
• Grid of theoretical NLTE equivalent widths of four Ba II lines and barium abundance in cool stars
• Mg line formation in late-type stellar atmospheres: II. Calculations in a grid of 1D models
• Non-LTE Balmer line formation in late-type spectra: Effects of atomic processes involving hydrogen atoms
• Arcsecond-resolution 12CO mapping of the yellow hypergiants IRC +10420 and AFGL 2343
• Accurate luminosities from the oxygen 7771-4 A triplet and the fundamental parameters of F-G supergiants
• High Resolution Optical Spectroscopy of the F Supergiant Proto-Planetary Nebula V887 Her=IRAS 18095+2704
• What next for the Likely Pre-Supernova, HD 179821?
• A revised calibration of the Mv-W(OI 7774) relationship using Hipparcos data: Its application to Cepheids and evolved stars

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