A non-LTE abundance analysis of the post-AGB star ROA 5701

Abstract

An analysis of high-resolution Anglo-Australian Telescope (AAT)/ University College London Echelle Spectrograph (UCLES) optical spectra for the ultraviolet (UV)-bright star ROA 5701 in the globular cluster omega Cen (NGC 5139) is performed, using non-local thermodynamic equilibrium (non-LTE) model atmospheres to estimate stellar atmospheric parameters and chemical composition. Abundances are derived for C, N, O, Mg, Si and S, and compared with those found previously by Moehler et al. We find a general metal underabundance relative to young B-type stars, consistent with the average metallicity of the cluster. Our results indicate that ROA 5701 has not undergone a gas-dust separation scenario as previously suggested. However, its abundance pattern does imply that ROA 5701 has evolved off the AGB prior to the onset of the third dredge-up.

arXiv comment9 pages, 2 figures. Accepted for publication in MNRAS (Online Early)

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Cited by in corpus (4)

• Giants in the globular cluster omega Centauri: dust production, mass loss and distance
• Iron abundances of B-type post-Asymptotic Giant Branch stars in globular clusters: Barnard 29 in M 13 and ROA 5701 in omega Cen
• Iron abundances from optical Fe III absorption lines in B-type stellar spectra
• High resolution spectroscopy of the high velocity hot post-AGB star LS III +52 24 (IRAS 22023+5249)