Please use this identifier to cite or link to this item: http://hdl.handle.net/2248/3279
Title: Abundance Analyses of the Field RV Tauri Variables: EP Lyrae, DY Orionis, AR Puppis, and R Sagittae
Authors: Gonzalez, G
Lambert, D. L
Giridhar, S
Keywords: Stars: Abundances;Stars: AGB And Post-AGB;Stars: Variables: Other RV Tauri
Issue Date: Apr-1997
Publisher: The American Astronomical Society
Citation: Astrophysical Journal, Vol. 479, No. 1, pp. 427 - 440
Abstract: Analyses of the photospheric compositions of the four field RV Tauri stars, EP Lyr, DY Ori, AR Pup, and R Sge, indicate that to varying degrees they have experienced fractionation processes that have preferentially depleted their atmospheres of elements with high condensation temperatures. The depletion, as indicated by, for instance, [S/Fe], is greatest for DY Ori, [S/Fe] = 2.5, and least for R Sge, [S/Fe] = 0.9. The initial composition, presumably indicated by the sulfur abundance, was nearly solar for AR Pup, R Sge, and DY Ori, while it was about 0.6 dex less than solar for EP Lyr. This implies that the RV Tauri stars as a group may not be as metal-poor as previously thought---they are instead "metal-depleted." The field RV Tauri's are not halo stars, but probably belong to the thick disk. This brings to seven the number of type II Cepheids that show such a trend; the other three are IW Car and V1 in omega Cen, RV Tauri stars, and ST Pup, a W Virginis star. The 12C/13C ratios for EP Lyr and DY Ori are 9 +/- 1 and 6 +/- 3, respectively, indicating that CN-cycled material has been mixed with their surface layers. This is consistent with the general consensus that RV Tau stars are in a post-AGB evolutionary stage. There is also evidence that EP Lyr has a stellar mass companion, but additional observations are required to calculate an orbit; hence, EP Lyr could be a link to the group of metal-depleted, high-latitude A--F supergiants, all of which are binaries.
URI: http://hdl.handle.net/2248/3279
ISSN: 0004-637X
???metadata.dc.relation.uri???: http://www.journals.uchicago.edu/doi/abs/10.1086/303852
Appears in Collections:IIAP Publications

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