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Title: Abundance Analyses of Field RV Tauri Stars. IV. AD Aquilae, DS Aquarii, V360 Cygni, AC Herculis, and V453 Ophiuchi
Authors: Giridhar, S
Lambert, D. L
Gonzalez, G
Keywords: Stars:Circumstellar Matter;Stars:Abundances;Stars:Variables
Issue Date: Dec-1998
Publisher: The American Astronomical Society
Citation: The Astrophysical Journal, Vol. 509, No. 1, pp. 366 - 378
Abstract: Abundance analyses are presented and discussed for five RV Tauri variables. Three stars-DS Aqr, V360 Cyg, and V453 Oph-are RV C stars by spectroscopic classification, i.e., metal lines are weak. They are shown to be metal poor with [Fe/H] from -1.0 to -2.2 with normal relative abundances of other elements. By contrast, AD Aql and AC Her are RV B stars with an odd abundance pattern: elements that condense into grains at a high temperatures are underabundant (i.e., [Fe/H] = -2.1 for AD Aql) but elements with a low condensation temperatures are much less underabundant (i.e., [S/H] = 0.0 and [Zn/H] = -0.1 for AD Aql). This abundance pattern is ascribed to a separation of dust and gas in the upper atmosphere of the star. The present analyses with previously published results are used to investigate the systematics of the dust-gas separation in RV Tauri variables. The process is apparently inoperative in stars with an initial metallicity of about [Fe/H] <~ -1.0 RV C stars and similar variables in globular clusters are immune to the dust-gas separation. The process achieves more severe effects in RV B than in RV A stars. The strength of the abundance anomalies attributed to dust-gas separation is not correlated with reported infrared excesses. After correction for the effects of the dust-gas separation, there is no strong evidence from the abundances that evolution along the AGB and experience of the third dredge-up preceded the formation of the majority of the RV Tauri variables.
ISSN: 0004 - 637x
Appears in Collections:IIAP Publications

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