J/ApJ/953/31 Abundances in warm VMP stars from Keck/HIRES sp. (Sneden+, 2023)
Iron-peak element abundances in warm very metal-poor stars.
Sneden C., Boesgaard A.M., Cowan J.J., Roederer I.U., Den Hartog E.A.,
Lawler J.E.
<Astrophys. J., 953, 31 (2023)>
=2023ApJ...953...31S 2023ApJ...953...31S
ADC_Keywords: Abundances; Stars, metal-deficient; Spectra, optical; Ultraviolet
Keywords: Nucleosynthesis ; Chemical abundances ; Population II stars ;
Stellar spectral lines
Abstract:
We have derived new detailed abundances of Mg, Ca, and the Fe-group
elements Sc through Zn (Z=21-30) for 37 main-sequence turnoff very
metal-poor stars ([Fe/H]≲-2.1). We analyzed Keck HIRES optical and
near-UV high signal-to-noise spectra originally gathered for a Be
abundance survey. Using typically ∼400 Fe-group lines with accurate
laboratory transition probabilities for each star, we have determined
accurate LTE metallicities and abundance ratios for neutral and
ionized species of the 10 Fe-group elements as well as α
elements Mg and Ca. We find good neutral/ion abundance agreement for
the six elements that have detectable transitions of both species in
our stars in the 3100-5800Å range. Earlier reports of correlated
Sc-Ti-V relative overabundances are confirmed, and appear to slowly
increase with decreasing metallicity. To this element trio we add Zn;
it also appears to be increasingly overabundant in the
lowest-metallicity regimes. Co appears to mimic the behavior of Zn,
but issues surrounding its abundance reliability cloud its
interpretation.
Description:
Here we present new abundances of Fe-group elements in 37 very
metal-poor main-sequence turnoff stars ([Fe/H]≲-2.0), from our
analyses of B11 (Boesgaard+ 2011, J/ApJ/743/140) Keck HIRES spectra.
The spectra were all obtained with Keck I/HIRES which yielded spectral
resolving power R∼42000 in the near-UV. These echelle spectra have
near-continuous wavelength coverage in the interval
3050Å≲λ≲5900Å.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 55 37 Model atmosphere parameters
table2.dat 44 666 Abundances for individual stars
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See also:
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/357 : Gaia DR3 Part 3. Non-single stars (Gaia Collaboration, 2022)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
J/ApJS/182/51 : Transition prob. of rare earth elements (Lawler+, 2009)
J/ApJS/182/80 : Rare earth abundances (Sneden+, 2009)
J/ApJ/743/140 : Abund. (Be,α) in metal-poor stars (Boesgaard+, 2011)
J/ApJS/194/35 : Atomic transition probabilities of Mn (Den Hartog+, 2011)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/ApJS/215/23 : FeI radiative lifetimes (Den Hartog+, 2014)
J/ApJS/215/20 : Vanadium log(gf) & transition probabilities (Lawler+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)
J/ApJS/214/18 : VII log(gf) values, and V abundance in HD 84937 (Wood+ 2014)
J/ApJS/211/20 : NiI transition probability measurements (Wood+, 2014)
J/ApJS/220/13 : Co I transition probabilities (Lawler+, 2015)
J/ApJ/817/53 : Fe-group elemental abundances in HD84937 (Sneden+, 2016)
J/ApJS/228/10 : Transition prob. for 183 lines of Cr II (Lawler+, 2017)
J/A+A/615/A151 : Lithium abund. in 714 F and G dwarf stars (Bensby+, 2018)
J/ApJ/857/2 : Abundances in 6 metal-poor stars (Roederer+, 2018)
J/ApJS/234/25 : Vanadium transitions in the sp. of Arcturus (Wood+, 2018)
J/ApJ/870/2 : PUSH. III. Nucleosynthesis yields (Curtis+, 2019)
J/ApJ/890/119 : Iron abund. in 3 very metal-poor stars (Cowan+, 2020)
J/ApJ/900/106 : Vanadium abundances for 255 metal-poor stars (Ou+, 2020)
J/ApJ/907/10 : Initial vs final sample of VMP HK/HES stars (Limberg+, 2021)
J/ApJ/931/147 : Very metal-poor stars with LAMOST & Subaru. II. (Li+, 2022)
J/ApJS/260/27 : R-Process Alliance: UV sp. of HD 222925 (Roederer+, 2022)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 11 A11 --- Name Star name
13- 16 I4 K Teff [5500/6350] Effective temperature
18- 21 F4.2 [cm/s2] logg [3.1/4.5] Log of surface gravity
23- 26 F4.2 km/s Vt [1/1.5] Microturbulent velocity, ξt
28- 32 F5.2 Sun [FeI/H] [-3.6/-1.4] [Fe/H], FeI transition
34- 37 F4.2 Sun e_[FeI/H] [0.08/0.12] [FeI/H] uncertainty
39- 41 I3 --- NlFeI [85/288] Number of FeI lines used
43- 47 F5.2 Sun [FeII/H] [-3.51/-1.44] [Fe/H], FeII transition
49- 52 F4.2 Sun e_[FeII/H] [0.08/0.16] [FeII/H] uncertainty
54- 55 I2 --- NlFeII [7/25] Number of FeII lines used
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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- 11 A11 --- Name Star name
13- 17 F5.2 [Sun] [Fe/H] [-3.56/-1.42] Metallicity (1)
19- 29 A11 --- Species Species identifier (2)
31- 35 F5.2 [Sun] [X/Fe] [-0.92/0.7]? Abundance ratio of Species
relative to iron
37- 40 F4.2 [Sun] e_[X/Fe] [0/0.3]? Statistical uncertainty in [X/Fe]
42- 44 I3 --- Nl [1/112]? Number of Species lines
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Note (1): [Fe/H] is the mean of [FeI/H] and [FeII/H] values.
Note (2): The designation "no 0eV" means the abundance computed for this
species without inclusion of lines arising from the ground state.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 19-Sep-2025