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The Similarity of Abundance Ratio Trends and Nucleosynthetic Patterns in the Milky Way Disk and Bulge

Griffith, Emily ; Weinberg, David H. ; Johnson, Jennifer A. LU ; Beaton, Rachael ; García-Hernández, D. A. ; Hasselquist, Sten ; Holtzman, Jon LU ; Johnson, James W. ; Jönsson, Henrik LU orcid and Lane, Richard R. , et al. (2021) In Astrophysical Journal 909(1).
Abstract

We compare abundance ratio trends in a sample of ∼11,000 Milky Way bulge stars (R GC < 3 kpc) from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to those of APOGEE stars in the Galactic disk (5 kpc < R GC < 11 kpc). We divide each sample into low-Ia (high-[Mg/Fe]) and high-Ia (low-[Mg/Fe]) populations, and in each population, we examine the median trends of [X/Mg] versus [Mg/H] for elements X = Fe, O, Na, Al, Si, P, S, K, Ca, V, Cr, Mn, Co, Ni, Cu, and Ce. To remove small systematic trends of APOGEE abundances with stellar log(g), we resample the disk stars to match the log(g) distributions of the bulge data. After doing so, we find nearly identical median trends for low-Ia disk and bulge stars for all... (More)

We compare abundance ratio trends in a sample of ∼11,000 Milky Way bulge stars (R GC < 3 kpc) from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to those of APOGEE stars in the Galactic disk (5 kpc < R GC < 11 kpc). We divide each sample into low-Ia (high-[Mg/Fe]) and high-Ia (low-[Mg/Fe]) populations, and in each population, we examine the median trends of [X/Mg] versus [Mg/H] for elements X = Fe, O, Na, Al, Si, P, S, K, Ca, V, Cr, Mn, Co, Ni, Cu, and Ce. To remove small systematic trends of APOGEE abundances with stellar log(g), we resample the disk stars to match the log(g) distributions of the bulge data. After doing so, we find nearly identical median trends for low-Ia disk and bulge stars for all elements. High-Ia trends are similar for most elements, with noticeable (0.05-0.1 dex) differences for Mn, Na, and Co. The close agreement of abundance trends (with typical differences ≲0.03 dex) implies that similar nucleosynthetic processes enriched bulge and disk stars despite the different star formation histories and physical conditions of these regions. For example, we infer that differences in the high-mass slope of the stellar initial mass function between disk and bulge must have been ≲0.30. This agreement, and the generally small scatter about the median sequences, means that one can predict all of a bulge star's APOGEE abundances with good accuracy knowing only its measured [Mg/Fe] and [Mg/H] and the observed trends of disk stars.

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organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Astrophysical Journal
volume
909
issue
1
article number
77
publisher
American Astronomical Society
external identifiers
  • scopus:85103215456
ISSN
0004-637X
DOI
10.3847/1538-4357/abd6be
language
English
LU publication?
yes
id
3808dfe5-1a6a-4976-9551-8203e5bf6161
date added to LUP
2021-04-08 09:09:20
date last changed
2024-04-20 04:22:15
@article{3808dfe5-1a6a-4976-9551-8203e5bf6161,
  abstract     = {{<p>We compare abundance ratio trends in a sample of ∼11,000 Milky Way bulge stars (R GC &lt; 3 kpc) from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) to those of APOGEE stars in the Galactic disk (5 kpc &lt; R GC &lt; 11 kpc). We divide each sample into low-Ia (high-[Mg/Fe]) and high-Ia (low-[Mg/Fe]) populations, and in each population, we examine the median trends of [X/Mg] versus [Mg/H] for elements X = Fe, O, Na, Al, Si, P, S, K, Ca, V, Cr, Mn, Co, Ni, Cu, and Ce. To remove small systematic trends of APOGEE abundances with stellar log(g), we resample the disk stars to match the log(g) distributions of the bulge data. After doing so, we find nearly identical median trends for low-Ia disk and bulge stars for all elements. High-Ia trends are similar for most elements, with noticeable (0.05-0.1 dex) differences for Mn, Na, and Co. The close agreement of abundance trends (with typical differences ≲0.03 dex) implies that similar nucleosynthetic processes enriched bulge and disk stars despite the different star formation histories and physical conditions of these regions. For example, we infer that differences in the high-mass slope of the stellar initial mass function between disk and bulge must have been ≲0.30. This agreement, and the generally small scatter about the median sequences, means that one can predict all of a bulge star's APOGEE abundances with good accuracy knowing only its measured [Mg/Fe] and [Mg/H] and the observed trends of disk stars. </p>}},
  author       = {{Griffith, Emily and Weinberg, David H. and Johnson, Jennifer A. and Beaton, Rachael and García-Hernández, D. A. and Hasselquist, Sten and Holtzman, Jon and Johnson, James W. and Jönsson, Henrik and Lane, Richard R. and Nataf, David M. and Roman-Lopes, Alexandre}},
  issn         = {{0004-637X}},
  language     = {{eng}},
  number       = {{1}},
  publisher    = {{American Astronomical Society}},
  series       = {{Astrophysical Journal}},
  title        = {{The Similarity of Abundance Ratio Trends and Nucleosynthetic Patterns in the Milky Way Disk and Bulge}},
  url          = {{http://dx.doi.org/10.3847/1538-4357/abd6be}},
  doi          = {{10.3847/1538-4357/abd6be}},
  volume       = {{909}},
  year         = {{2021}},
}