S. Sumangala Rao and Sunetra Giridhar
Indian Institute of Astrophysics, Bangalore 560034, India. (sumangala@iiap.res.in, sunetra@iiap.res.in).
Received 2012 October 18.
Accepted 2013 November 22.
]]> RESUMEN
Hemos emprendido un análisis de las abundancias químicas para una muestra de estrellas RV Tauri poco estudiadas, para mejorar nuestro entendimiento de la evolución estelar post-secuencia asintótica de las gigantes (post-AGB).Nuestro estudio se basa en espectros de alta resolución y en una malla de modelos atmosféricos. Encontramos indicaciones de un leve proceso-s para V820 Cen y IRAS 06165+3158. Por otra parte, SU Gem y BT Lac muestran los efectos de una ligera separación polvo-gas. Hemos reunido los datos existentes sobre las abundancias de objetos RV Tauri, y encontramos que una gran parte de ellos muestra efectos de separación polvo-gas. En nuestro estudio encontramos un pequeño grupo de estrellas RV Tauri galácticas con evidencia del proceso-s ligeramente aumentado. Dos de tres objetos con evidencia de proceso-s aumentado pertenecen a la clase C de objetos RV Tauri. Estos objetos, pobres en metales, son candidatos prometedores para el estudio del proceso-s en las estrellas RV Tauri.
ABSTRACT
We have undertaken a comprehensive abundance analysis for a sample of relatively unexplored RV Tauri and RV Tauri like stars to further our understanding of post-Asymptotic Giant Branch (post-AGB) evolution. From our study based on high resolution spectra and a grid of model atmospheres, we find indications of mild s-processing for V820 Cen and IRAS 06165+3158. On the other hand, SU Gem and BT Lac exhibit the effects of mild dust-gas winnowing. We have also compiled the existing abundance data on RV Tauri objects and find that a large fraction of them are afflicted by dust-gas winnowing and aided by the present work, we find a small group of two RV Tauris showing mild s-process enhancement in our Galaxy. With two out of three reported s-process enhanced objects belonging to RV Tauri spectroscopic class C, these intrinsically metal-poor objects appear to be promising candidates to analyse the possible s-processing in RV Tauri stars.
Key Words: stars: abundances — stars: AGB and post-AGB — stars: variables.
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