Principal Component Abundance Analysis of Microlensed Bulge Dwarf and Subgiant Stars
Andrews, B. H. ; Weinberg, D. H. ; Johnson, J. A. ; Bensby, Thomas LU
and Feltzing, Sofia
LU
(2012)
In Acta Astronomica
62(3).
p.269-279
- Abstract
- 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... (More)
- 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. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/3284034
- author
- Andrews, B. H.
; Weinberg, D. H.
; Johnson, J. A.
; Bensby, Thomas
LU
and Feltzing, Sofia
LU
- organization
- publishing date
- 2012
- type
- Contribution to journal
- publication status
- published
- subject
- keywords
- Galaxy: general, Galaxy: bulge, Galaxy: evolution, Galaxy: formation, Galaxy: stellar content, Stars: abundances
- in
- Acta Astronomica
- volume
- 62
- issue
- 3
- pages
- 269 - 279
- publisher
- Copernicus GmbH
- external identifiers
-
- wos:000310490900003
- scopus:84869025104
- ISSN
- 0001-5237
- language
- English
- LU publication?
- yes
- id
- 766cd299-dbe7-485f-9f3b-04617842c7dd (old id 3284034)
- date added to LUP
- 2016-04-01 13:47:05
- date last changed
- 2024-04-10 10:48:14
@article{766cd299-dbe7-485f-9f3b-04617842c7dd,
abstract = {{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.}},
author = {{Andrews, B. H. and Weinberg, D. H. and Johnson, J. A. and Bensby, Thomas and Feltzing, Sofia}},
issn = {{0001-5237}},
keywords = {{Galaxy: general; Galaxy: bulge; Galaxy: evolution; Galaxy: formation; Galaxy: stellar content; Stars: abundances}},
language = {{eng}},
number = {{3}},
pages = {{269--279}},
publisher = {{Copernicus GmbH}},
series = {{Acta Astronomica}},
title = {{Principal Component Abundance Analysis of Microlensed Bulge Dwarf and Subgiant Stars}},
volume = {{62}},
year = {{2012}},
}