AGB nucleosynthesis in the Large Magellanic Cloud. Detailed abundance analysis of the RV Tauri star MACHO?47.2496.8
Context: Abundance analysis of post-AGB objects as probes of AGBnucleosynthesis. Aims: A detailed photospheric abundance study isperformed on the carbon-rich post-AGB candidate MACHO 47.2496.8 in theLMC. Methods: High-resolution, high signal-to-noise ESO VLT-UVESspectra of MACHO 47.2496.8 are analysed by performing detailed spectrumsynthesis modelling using state-of-the-art carbon-rich MARCS atmospheremodels. Results: The spectrum of MACHO 47.2496.8 is not onlydominated by bands of carbon bearing molecules, but also by lines ofatomic transitions of s-process elements. The metallicity of [Fe/H] =-1.4 is surprisingly low for a field LMC star. The C/O ratio, howeverdifficult to quantify, is greater than 2, and the s-process enrichmentis large: the light s-process elements are enhanced by 1.2 dex comparedto iron ([ls/Fe] = +1.2), while for the heavy s-process elements an evenstronger enrichment is measured: [hs/Fe] = +2.1. The lead abundance iscomparable to the [hs/Fe]. With its low intrinsic metallicity and itsluminosity at the low end of the carbon star luminosity function, thestar represents likely the final stage of a low initial mass star. Conclusions: .The LMC RV Tauri star MACHO 47.2496.8 is highly carbonand s-process enriched, and is most probable a genuine post-C(N-type)AGB star. This is the first detailed abundance analysis of anextragalactic post-AGB star to date.
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Secondary UVBY standards in the Harvard E-regions
Photoelectric uvby photometry for 201 stars which are already UBV (RI)cstandards is presented. The photoelectric data are closely tied to theCousins uvby standards and the stars should be suitable for use asfainter (7-11 mag) secondary standards.
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Secondary standards for H-beta photometry in the Southern Hemisphere (second series).
Not Available
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UBV (RI)c standard stars in the E- and F-regions and in the Magellanic Clouds - a revised catalogue.
Not Available
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HD 47147 - A small-amplitude extreme metal-poor RRab pulsating variable
The photometric variations and physical and kinematical properties of HD47147, a ninth magnitude metal-deficient star, are discussed. The longperiod (0.79732 days), the small amplitude (0.17 mag in the visualband), and the mean effective temperature of 6160 K of this RR Lyraepulsating variable can be understood by its location near the red edgeof the instability strip. The extreme Population II characteristics ofHD 47147 are confirmed by its kinematical properties. The temperatureand the relatively high luminosity derived are consistent with bothpossibilities that HD 47147 is a red horizontal branch star or that itis a suprahorizontal branch star actually evolving redward toward theasymptotic branch. Its low amplitude suggests the possibility that thered edge of the instability strip corresponds to a smooth transitionfrom variable to non-variable stars.
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UBV photometry of E region standard stars of intermediate brightness
Photometry data are given for 335 stars in the nine E regions.Observations were made using a photometer and filters on the 47 cmreflector at Cape Town. The stellar dispersions are summarized. Data arepresented in tabular form.
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Up-To UBVRI Values for the E-Region Standard Stars
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1981A&AS...46....7V&db_key=AST
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Photometric standard stars for the UBV and (RI)KC systems.
Not Available
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Fainter Standards for VRI Photometry in the E Regions
Not Available
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Standard magnitudes in the E regions.
Not Available
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