J/A+A/619/A143 r-process abundances in AMBRE stars (Guiglion+, 2018)
The AMBRE Project: r-process elements in the Milky Way thin and thick discs.
Guiglion G., de Laverny P., Recio-Blanco A., Prantzos N.
<Astron. Astrophys. 619, A143 (2018)>
=2018A&A...619A.143G 2018A&A...619A.143G (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way; Stars, F-type ; Stars, G-type ; Stars, K-type ;
Abundances ; Spectroscopy
Keywords: method: data analysis - stars: abundances - Galaxy: abundances -
Galaxy: stellar content
Abstract:
The chemical evolution of neutron capture elements in the Milky Way
disc is still a matter of debate. There is a lack of statistically
significant catalogues of such element abundances, especially those of
the r-process.
We aim to understand the chemical evolution of r-process elements in
Milky Way disc. We focus on three pure r-process elements Eu, Gd, and
Dy. We also consider a pure s-process element, Ba, in order to
disentangle the different nucleosynthesis processes.
We take advantage of high-resolution FEROS, HARPS, and UVES spectra
from the ESO archive in order to perform a homogeneous analysis on
6500 FGK Milky Way stars. The chemical analysis is performed thanks to
the automatic optimization pipeline GAUGUIN. We present abundances of
Ba (5057 stars), Eu (6268 stars), Gd (5431 stars), and Dy (5479
stars). Based on the [α/Fe] ratio determined previously by the
AMBRE Project, we chemically characterize the thin and the thick
discs, and a metal-rich α-rich population.
First, we find that the [Eu/Fe] ratio follows a continuous sequence
from the thin disc to the thick disc as a function of the metallicity.
Second, in thick disc stars, the [Eu/Ba] ratio is found to be
constant, while the [Gd/Ba] and [Dy/Ba] ratios decrease as a function
of the metallicity. These observations clearly indicate a different
nucleosynthesis history in the thick disc between Eu and Gd-Dy. The
[r/Fe] ratio in the thin disc is roughly around +0.1dex at solar
metallicity, which is not the case for Ba. We also find that the
α-rich metal-rich stars are also enriched in r-process elements
(like thick disc stars), but their [Ba/Fe] is very different from
thick disc stars. Finally, we find that the [r/α] ratio tends to
decrease with metallicity, indicating that supernovae of different
properties probably contribute differently to the synthesis of
r-process elements and α-elements.
We provide average abundance trends for [Ba/Fe] and [Eu/Fe] with
rather small dispersions, and for the first time for [Gd/Fe] and
[Dy/Fe]. This data may help to constrain chemical evolution models of
Milky Way r- and s-process elements and the yields of massive stars.
We emphasize that including yields of neutron-star or black hole
mergers is now crucial if we want to quantitatively compare
observations to Galactic chemical evolution models.
Description:
Thanks to high resolution spectra from the ESO FEROS, UVES and HARPS
archive and high quality atmospheric parameters, we have been able to
build a massive and homogeneous catalogue of Ba, Eu, Gd, and Dy
abundances for several thousands of stars derived with an automatic
method coupling a synthetic spectra grid and a Gauss-Newton algorithm.
These chemical abundances have been validated with literature values.
We provide the star identifier, the atmospheric parameters used to
derive such abundances, the signal-to-noise ratio, the LTE abundance,
its error, the nmber of lines and the spectrograph.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ambre-ba.dat 73 5057 Catalogue of Ba abundances
ambre-eu.dat 73 6268 Catalogue of Eu abundances
ambre-gd.dat 73 5431 Catalogue of Gd abundances
ambre-dy.dat 73 5479 Catalogue of Dy abundances
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See also:
J/A+A/542/A48 : AMBRE project. FEROS archived spectra (Worley+, 2012)
J/A+A/595/A18 : Lithium abundances in AMBRE stars (Guiglion+, 2016)
J/A+A/600/A22 : Iron-peak elements in solar neighbourhood (Mikolaitis+, 2017)
Byte-by-byte Description of file: ambre-ba.dat
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Bytes Format Units Label Explanations
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1- 25 A25 --- Targname ESO Target Name
27- 32 F6.1 K Teff Effective temperature
34- 37 F4.2 [cm/s2] logg Surface Gravity
39- 43 F5.2 [-] [M/H] Metallicity
45- 49 F5.2 [-] [alpha/Fe] Ratio [alpha/Fe]
51- 53 I3 pix-1 S/N Signal to noise ratio
55 A1 --- l_[Ba/Fe] Limit flag on [Ba/Fe]
56- 60 F5.2 [-] [Ba/Fe] Ratio [Ba/Fe] (dex)
62- 65 F4.2 [-] e_[Ba/Fe] ?=- Error on [Ba/Fe] ratio
67 I1 --- Nline ?=- Number of lines
69- 73 A5 --- Spectro Spectrograph (G1)
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Byte-by-byte Description of file: ambre-eu.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Targname ESO Target Name
27- 32 F6.1 K Teff Effective temperature
34- 37 F4.2 [cm/s2] logg Surface Gravity
39- 43 F5.2 [-] [M/H] Metallicity
45- 49 F5.2 [-] [alpha/Fe] Ratio [alpha/Fe]
51- 53 I3 pix-1 S/N Signal to noise ratio
55 A1 --- l_[Eu/Fe] Limit flag on [Eu/Fe]
56- 60 F5.2 [-] [Eu/Fe] Ratio [Eu/Fe]
62- 65 F4.2 [-] e_[Eu/Fe] ?=- Error on [Eu/Fe] ratio
67 I1 --- Nline ?=- Number of lines
69- 73 A5 --- Spectro Spectrograph (G1)
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Byte-by-byte Description of file: ambre-gd.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Targname ESO Target Name
27- 32 F6.1 K Teff Effective temperature
34- 37 F4.2 [cm/s2] logg Surface Gravity
39- 43 F5.2 [-] [M/H] Metallicity
45- 49 F5.2 [-] [alpha/Fe] Ratio [alpha/Fe]
51- 53 I3 pix-1 S/N Signal to noise ratio
55 A1 --- l_[Gd/Fe] Limit flag on [Gd/Fe]
56- 60 F5.2 [-] [Gd/Fe] Ratio [Gd/Fe]
62- 65 F4.2 [-] e_[Gd/Fe] ?=- Error on [Gd/Fe] ratio
67 I1 --- Nline ?=- Number of lines
69- 73 A5 --- Spectro Spectrograph (G1)
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Byte-by-byte Description of file: ambre-dy.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 25 A25 --- Targname ESO Target Name
27- 32 F6.1 K Teff Effective temperature
34- 37 F4.2 [cm/s2] logg Surface Gravity
39- 43 F5.2 [-] [M/H] Metallicity
45- 49 F5.2 [-] [alpha/Fe] Ratio [alpha/Fe]
51- 53 I3 pix-1 S/N Signal to noise ratio
55 A1 --- l_[Dy/Fe] Limit flag on [Dy/Fe]
56- 60 F5.2 [-] [Dy/Fe] Ratio [Dy/Fe]
62- 65 F4.2 [-] e_[Dy/Fe] ?=- Error on [Dy/Fe] ratio
67 I1 --- Nline ?=- Number of lines
69- 73 A5 --- Spectro Spectrograph (G1)
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Global notes:
Note (G1): Spectrograph code as follows:
FEROS = FEROS
HARPS = HARPS
U437 = UVES, setup 437
U580 = UVES, setup 580
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Acknowledgements:
Guillaume Guiglion, gguiglion(at)aip.de
History:
19-Nov-2018: on-line version
03-Jun-2021: file ambre-eu.dat corrected ("<" added for [Eu/Fe] in the
last 665 lines)
(End) Guillaume Guiglion [AIP, Germany], Patricia Vannier [CDS] 11-Sep-2018