Spectral analysis of the He-enriched sdO-star HD 127493

TL;DR

This study performs a detailed spectral analysis of the He-enriched sdO star HD 127493 using optical and ultraviolet data, revealing its atmospheric parameters and chemical composition, including CNO elements and iron-group enrichment.

Contribution

It provides the first comprehensive non-LTE spectral analysis of HD 127493, determining its atmospheric parameters and detailed chemical abundances, especially for metals like Fe and Ni.

Findings

Strong CNO signature detected.

Enrichment in iron and nickel observed.

Atmospheric parameters consistent with parallax distance.

Abstract

The bright sdO star HD 127493 is known to be of mixed H/He composition and excellent archival spectra covering both optical and ultraviolet ranges are available. UV spectra play a key role as they give access to many chemical species that do not show spectral lines in the optical, such as iron and nickel. This encouraged the quantitative spectral analysis of this prototypical mixed H/He composition sdO star. We determined atmospheric parameters for HD 127493 in addition to the abundance of C, N, O, Si, S, Fe, and Ni in the atmosphere using non-LTE model atmospheres calculated with TLUSTY/SYNSPEC. A comparison between the parallax distance measured by Hipparcos and the derived spectroscopic distance indicate that the derived atmospheric parameters are realistic. From our metal abundance analysis, we find a strong CNO signature and enrichment in iron and nickel.