Principal Component Abundance Analysis of Microlensed Bulge Dwarf and Subgiant Stars

• Autorzy: Andrews B. H. , Weinberg D. H. , Johnson J. A. , Bensby T. , Feltzing S.
• Języki publikacji: EN

Abstrakty

EN

Elemental abundance patterns can provide vital clues to the formation and enrichment history of a stellar population. Here we present an investigation of the Galactic bulge, where we apply principal component abundance analysis (PCAA) - a principal component decomposition of relative abundances [X/Fe] - to a sample of 35 microlensed bulge dwarf and subgiant stars, characterizing their distribution in the 12-dimensional space defined by their measured elemental abundances. The first principal component PC1, which suffices to describe the abundance patterns of most stars in the sample, shows a strong contribution from α-elements, reflecting the relative contributions of Type II and Type Ia supernovae. The second principal component PC2 is characterized by a Na-Ni correlation, the likely product of metallicity-dependent Type II supernova yields. The distribution in PC1 is bimodal, showing that the bimodality previously found in the [Fe/H] values of these stars is robustly and independently recovered by looking at only their relative abundance patterns. The two metal-rich stars that are α-enhanced have outlier values of PC2 and PC3, respectively, further evidence that they have distinctive enrichment histories. Applying PCAA to a sample of local thin and thick disk dwarfs yields a nearly identical PC1. In PC1, the metal-rich and metal-poor bulge dwarfs track kinematically selected thin and thick disk dwarfs, respectively, suggesting broadly similar α-enrichment histories. However, the disk PC2 is dominated by a Y-Ba correlation, likely indicating a contribution of s-process enrichment from long-lived asymptotic giant branch stars that is absent from the bulge PC2 because of its rapid formation.

Słowa kluczowe

EN

galaxy: general; galaxy: bulge; galaxy: evolution; galaxy: formation; galaxy: stellar content; stars: abundances

• Wydawca: Copernicus Foundation for Polish Astronomy
• Czasopismo: Acta Astronomica
• Rocznik: 2012
• Tom: Vol. 62, No. 3
• Strony: 269--279
• Opis fizyczny: Bibliogr. 33 poz., rys., wykr.

Twórcy

autor

Andrews B. H.

• Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210

autor

Weinberg D. H.

• Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210
• Center for Cosmology and Astro-Particle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210

autor

Johnson J. A.

• Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210
• Center for Cosmology and Astro-Particle Physics, The Ohio State University, 191 West Woodruff Avenue, Columbus, OH 43210

autor

Bensby T.

• Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, SE-22100 Lund, Sweden

autor

Feltzing S.

• Lund Observatory, Department of Astronomy and Theoretical Physics, Box 43, SE-22100 Lund, Sweden

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