J/A+A/630/A104 Disk and halo stars C, O and Fe abundances (Amarsi+, 2019)
Carbon, oxygen, and iron abundances in disk and halo stars.
Implications of 3D non-LTE spectral line formation.
Amarsi A.M., Nissen P.E., Skuladottir A.
<Astron. Astrophys. 630, A104 (2019)>
=2019A&A...630A.104A 2019A&A...630A.104A (SIMBAD/NED BibCode)
ADC_Keywords: Stars, late-type ; Abundances
Keywords: line: formation - radiative transfer - stars: abundances -
stars: atmospheres - stars: late-type
Abstract:
The abundances of carbon, oxygen, and iron in late-type stars are
important parameters in exoplanetary and stellar physics, as well as
key tracers of stellar populations and Galactic chemical evolution.
However, standard spectroscopic abundance analyses can be prone to
severe systematic errors, by the assumption that the stellar
atmosphere is one-dimensional (1D) and hydrostatic, and by ignoring
departures from local thermodynamic equilibrium (LTE). To address
this, we carry out 3D non-LTE radiative transfer calculations for CI
and OI, and 3D LTE radiative transfer calculations for FeII, across
the stagger-grid of 3D hydrodynamic model atmospheres. The absolute 3D
non-LTE versus 1D LTE abundance corrections can be as severe as
∼0.3dex for CI lines in low-metallicity F dwarfs, and ∼0.6dex for OI
lines in high-metallicity F dwarfs. The 3D LTE versus 1D LTE abundance
corrections for FeII lines are less severe, typically less than
+0.15dex. We use the corrections in a re-analysis of carbon, oxygen,
and iron in 187 F and G dwarfs in the Galactic disk and halo. Applying
the differential 3D non-LTE corrections to 1D LTE abundances visibly
reduces the scatter in the abundance plots. The thick disk and high-
halo population rise in carbon and oxygen with decreasing metallicity,
reaching a maximum of [C/Fe]~=0.2 and a plateau of [O/Fe]~=0.6 at
[Fe/H]~≃1.0. The low- halo population is qualitatively similar,
albeit offset towards lower metallicities and with larger scatter.
Nevertheless, these populations overlap in the [C/O] versus [O/H]
plane, decreasing to a plateau of [C/O]~=0.6 below [O/H]~=1.0. In the
thin-disk, stars having confirmed planet detections tend to have
higher values of C/O at given [O/H]; this potential signature of
planet formation is only apparent after applying the abundance
corrections to the 1D LTE results. Our grids of line-by-line abundance
corrections are publicly available and can readily be used to improve
the accuracy of spectroscopic analyses of late-type stars.
Description:
Spectrum synthesis calculations were performed on four different
families of model atmospheres: 3D hydrodynamic model atmospheres from
the STAGGER-grid (Magic et al. 2013A&A...557A..26M 2013A&A...557A..26M, Cat.
J/A+A/557/A26); 1D model atmospheres determined by averaging the <3D>
STAGGER model atmospheres (henceforth <3D> model atmospheres;
Magic et al. 2013A&A...560A...8M 2013A&A...560A...8M, Cat. J/A+A/560/A8); theoretical 1D
hydrostatic model atmospheres from the ATMO-grid (the 1D equivalent
of the STAGGER-grid, see Appendix A of Magic et al.
2013A&A...557A..26M 2013A&A...557A..26M, Cat. J/A+A/557/A26); and theoretical 1D
hydrostatic model atmospheres from the MARCS-grid (Gustafsson et al.
2008A&A...486..951G 2008A&A...486..951G).
Table1 contains the line parameters that were adopted for the grids of
abundance corrections. Table2 contains the 3D non-LTE versus 1D LTE
abundance corrections for CI lines. Table3 contains the 3D non-LTE
versus 1D LTE abundance corrections for OI lines. Table4 contains the
3D LTE versus 1D LTE abundance corrections for FeII lines. Table5
contains the 1D non-LTE versus 1D LTE abundance corrections for CI
lines. Table6 contains the 1D non-LTE versus 1D LTE abundance
corrections for OI lines. Table7 contains the stellar parameters and
abundances for the 187 sample stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table7.dat 362 187 Parameters/abundances of 187 stars
table1.dat 88 185 Line parameters
table2.dat 59 33966 3N-1L abundance corrections for CI
table3.dat 59 33966 3N-1L abundance corrections for OI
table4.dat 51 223650 3L-1L abundance corrections for FeII
table5.dat 59 829413 1N-1L abundance corrections for CI
table6.dat 59 829413 1N-1L abundance corrections for OI
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Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 [-] Star Name of star
14- 25 A12 [-] Pop Population assigned in the paper
29 I1 [-] Nplanet Number of planet detections
33- 39 F7.4 Mjup Maxmass Maximum planet mass in system
43- 46 I4 K Teff Effective temperature
50- 54 F5.2 [cm/s2] logg Logarithm of surface gravity
58- 62 F5.2 km/s vmic 1D microturbulence parameter
66- 77 F12.4 [-] [Fe/H]3L ?=-9999 3D LTE iron abundance (1)
81- 92 F12.4 [-] e_[Fe/H]3L ?=-9999 Uncertainty on [Fe/H]3L (1)
96-107 F12.4 [-] [Fe/H]1L ?=-9999 1D LTE iron abundance (1)
111-122 F12.4 [-] e_[Fe/H]1L ?=-9999 Uncertainty on [Fe/H]1L (1)
126-137 F12.4 [-] [C/H]3N ?=-9999 3D non-LTE carbon abundance (1)
141-152 F12.4 [-] e_[C/H]3N ?=-9999 Uncertainty on [C/H]3N (1)
156-167 F12.4 [-] [C/H]1N ?=-9999 1D non-LTE carbon abundance (1)
171-182 F12.4 [-] e_[C/H]1N ?=-9999 Uncertainty on [C/H]1N (1)
186-197 F12.4 [-] [C/H]3L ?=-9999 3D LTE carbon abundance (1)
201-212 F12.4 [-] e_[C/H]3L ?=-9999 Uncertainty on [C/H]3L (1)
216-227 F12.4 [-] [C/H]1L ?=-9999 1D LTE carbon abundance (1)
231-242 F12.4 [-] e_[C/H]1L ?=-9999 Uncertainty on [C/H]1L (1)
246-257 F12.4 [-] [O/H]3N ?=-9999 3D non-LTE oxygen abundance (1)
261-272 F12.4 [-] e_[O/H]3N ?=-9999 Uncertainty on [O/H]3N (1)
276-287 F12.4 [-] [O/H]1N ?=-9999 1D non-LTE carbon abundance (1)
291-302 F12.4 [-] e_[O/H]1N ?=-9999 Uncertainty on [O/H]1N (1)
306-317 F12.4 [-] [O/H]3L ?=-9999 3D LTE carbon abundance (1)
321-332 F12.4 [-] e_[O/H]3L ?=-9999 Uncertainty on [O/H]3L (1)
336-347 F12.4 [-] [O/H]1L ?=-9999 1D LTE carbon abundance (1)
351-362 F12.4 [-] e_[O/H]1L ?=-9999 Uncertainty on [O/H]1L (1)
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Note (1): Missing values are assigned a value of -9999. For the Sun,
absolute abundances are shown.
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Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 4 A4 --- Species Species identifier (CI, OI or FeII)
7- 14 A8 --- Line Line label
18- 25 F8.3 nm wlair Air wavelength
29- 36 F8.3 nm wlvac Vacuum wavelength
40- 50 F11.7 eV chipot Excitation potential
54- 61 F8.3 [-] loggf Logarithm of lower level statistical weight
times oscillator strength
65- 72 F8.3 [s-1] loggamnat Logarithm of natural broadening
76- 80 I5 --- sigmaABO ? ABO cross-section at 104m/s
in a02 unit (1)
84- 88 F5.3 --- alphaABO ? ABO velocity exponent (1)
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Note (1): Data are not provided where ABO theory was not applicable.
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 4 I4 K Teff Effective temperature
8- 12 F5.2 [cm/s2] logg Logarithm of surface gravity
16- 20 F5.2 [-] [Fe/H] Iron abundance relative to the Sun
24- 28 F5.2 km/s vmic 1D microturbulence parameter
32- 37 F6.3 [-] logeps Absolute abundance
41- 48 A8 --- Line CI line label
52- 59 F8.3 --- Delta 3D non-LTE versus 1D LTE correction
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
8- 12 F5.2 [cm/s2] loggg Logarithm of surface gravity
16- 20 F5.2 [-] [Fe/H] Iron abundance relative to the Sun
24- 28 F5.2 km/s vmic 1D microturbulence parameter
32- 37 F6.3 [-] logeps Absolute abundance
41- 48 A8 --- Line OI line label (1)
52- 59 F8.3 --- Delta 3D non-LTE versus 1D LTE correction
--------------------------------------------------------------------------------
Note (1): The line labels '777nm', '844nm', and '926nm' correspond to the
average correction of the respective multiplet, derived via integration
across all components simultaneously.
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Byte-by-byte Description of file: table4.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
8- 12 F5.2 [cm/s2] logg Logarithm of surface gravity
16- 20 F5.2 km/s vmic 1D microturbulence parameter
24- 29 F6.3 [-] logeps Absolute abundance
33- 40 A8 --- Line FeII line label
44- 51 F8.3 --- Delta 3D LTE versus 1D LTE correction
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Byte-by-byte Description of file: table5.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
8- 12 F5.2 [cm/s2] logg Logarithm of surface gravity
16- 20 F5.2 [-] [Fe/H] Iron abundance relative to the Sun
24- 28 F5.2 km/s vmic 1D microturbulence parameter
32- 37 F6.3 [-] logeps Absolute abundance
41- 48 A8 --- Line CI line label
52- 59 F8.3 --- Delta 1D non-LTE versus 1D LTE correction
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 4 I4 K Teff Effective temperature
8- 12 F5.2 [cm/s2] logg Logarithm of surface gravity
16- 20 F5.2 [-] [Fe/H] Iron abundance relative to the Sun
24- 28 F5.2 km/s vmic 1D microturbulence parameter
32- 37 F6.3 [-] logeps Absolute abundance
41- 48 A8 --- Line OI line label (1)
52- 59 F8.3 --- Delta 1D non-LTE versus 1D LTE correction
--------------------------------------------------------------------------------
Note (1): The line labels '777nm', '844nm', and '926nm' correspond to the
average correction of the respective multiplet, derived via integration
across all components simultaneously.
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Acknowledgements:
Anish Mayur Amarsi, amarsi(at)mpia.de
(End) Patricia Vannier [CDS] 28-Aug-2019