Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Default user image.

Sofia Feltzing

Professor

Default user image.

Principal Component Abundance Analysis of Microlensed Bulge Dwarf and Subgiant Stars

Författare

  • B. H. Andrews
  • D. H. Weinberg
  • J. A. Johnson
  • Thomas Bensby
  • Sofia Feltzing

Summary, in English

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 PC I, which suffices to describe the abundance patterns of most stars in the sample, shows a strong contribution from alpha-elements, reflecting the relative contributions of Type II and Type 1a 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 PC I 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 alpha-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 PC I. In PC I, the metal-rich and metal-poor bulge dwarfs track kinematically selected thin and thick disk dwarfs, respectively, suggesting broadly similar alpha-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.

Avdelning/ar

  • Astronomi - Har omorganiserats

Publiceringsår

2012

Språk

Engelska

Sidor

269-279

Publikation/Tidskrift/Serie

Acta Astronomica

Volym

62

Issue

3

Dokumenttyp

Artikel i tidskrift

Förlag

Copernicus GmbH

Ämne

  • Astronomy, Astrophysics and Cosmology

Nyckelord

  • Galaxy: general
  • Galaxy: bulge
  • Galaxy: evolution
  • Galaxy: formation
  • Galaxy: stellar content
  • Stars: abundances

Aktiv

Published

ISBN/ISSN/Övrigt

  • ISSN: 0001-5237