J/ApJ/900/106 Vanadium abundances for 255 metal-poor stars (Ou+, 2020)
Vanadium abundance derivations in 255 metal-poor stars.
Ou X., Roederer I.U., Sneden C., Cowan J.J., Lawler J.E., Shectman S.A.,
Thompson I.B.
<Astrophys. J., 900, 106 (2020)>
=2020ApJ...900..106O 2020ApJ...900..106O
ADC_Keywords: Abundances; Stars, metal-deficient; Spectra, optical
Keywords: Nucleosynthesis ; Population II stars ; Stellar abundances
Abstract:
We present vanadium (V) abundances for 255 metal-poor stars derived
from high-resolution optical spectra from the Magellan Inamori Kyocera
Echelle spectrograph on the Magellan Telescopes at Las Campanas
Observatory, the Robert G. Tull Coude Spectrograph on the Harlan J.
Smith Telescope at McDonald Observatory, and the High Resolution
Spectrograph on the Hobby-Eberly Telescope at McDonald Observatory. We
use updated VI and VII atomic transition data from recent laboratory
studies, and we increase the number of lines examined (from one to
four lines of VI, and from two to seven lines of VII). As a result, we
reduce the V abundance uncertainties for most stars by more than 20%
and expand the number of stars with V detections from 204 to 255. In
the metallicity range -4.0<[Fe/H]<-1.0, we calculate the mean ratios
[VI/FeI]=-0.10±0.01 (σ=0.16) from 128 stars with ≥2VI lines
detected, [VII/FeII]=+0.13±0.01 (σ=0.16) from 220 stars with
≥2 VII lines detected, and [VII/VI]=+0.25±0.01 (σ=0.15) from
119 stars. We suspect that this offset is due to departures from local
thermodynamic equilibrium, and we recommend using [VII/FeII], which is
enhanced relative to the solar ratio, as a better representation of
[V/Fe]. We provide more extensive evidence for abundance correlations
detected previously among scandium, titanium, and vanadium, and we
identify no systematic effects in the analysis that can explain these
correlations.
Description:
In this work, we adopt the same sample and spectra as were used in the
Roederer+ (2014, J/AJ/147/136) study without change.
For most of the stars, the spectroscopy was obtained using the
Magellan Telescopes at Las Campanas Observatory using the Magellan
Inamori Kyocera Echelle (MIKE) spectrograph (3350-7250Å; R∼41000).
Some observations were made with the Robert G. Tull Coude Spectrograph
on the 2.7m Harlan J. Smith Telescope at McDonald Observatory (MCD;
3700-5700Å, R∼30000).
Other observations were made with the High Resolution Spectrograph on
the 9.2m Hobby-Eberly Telescope (HET) at McDonald Observatory, with
wavelength coverage 3900-6800Å and R∼30000.
In total, 250 stars were observed with MIKE, 52 with MCD, and 19 with HET.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table2.dat 32 456 Abundances derived from neutral vanadium lines
table3.dat 32 1159 Abundances derived from ionized vanadium lines
table4.dat 84 319 Final abundances
--------------------------------------------------------------------------------
See also:
J/A+A/354/169 : Metal-poor field stars abundances (Gratton+, 2000)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/ApJ/608/405 : Explosive yields of massive star (Chieffi+, 2004)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013)
J/ApJS/211/31 : Atomic data of vanadium (V I) (Wang+, 2014)
J/ApJS/215/20 : Vanadium log(gf) and transition probabilities (Lawler+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/ApJS/214/18 : VII log(gf) values, and V abundance in HD 84937 (Wood+ 2014)
J/ApJ/817/53 : Fe-group elemental abund. analysis in HD84937 (Sneden+, 2016)
J/ApJS/224/35 : New lifetimes and log(gf) for vanadium (V I) (Holmes+, 2016)
J/ApJS/231/18 : Energy levels of vanadium (V I) (Saloman+, 2017)
J/ApJS/231/19 : Energy levels of ionized vanadium (V II) (Saloman+, 2017)
J/ApJ/860/125 : Six warm metal-poor stars iron abundances (Roederer+, 2018)
J/ApJ/870/2 : Spherical symmetry. III. (Curtis+, 2019)
J/ApJ/890/119 : Iron element abund. in 3 very metal-poor stars (Cowan+, 2020)
J/A+A/654/A118 : Vanadium measurements for 135 M dwarfs (Shan+, 2021)
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the star
14- 21 F8.3 0.1nm lambda [4111.7/4408.2] Line wavelength in Angstroms
23- 27 F5.2 [-] log(eps) [-0.31/2.77] Log epsilon vanadium abundance
29- 32 F4.2 [-] e_log(eps) [0.05/0.5] Fitting uncertainty of log(eps)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 12 A12 --- Name Name of the star
14- 21 F8.3 0.1nm lambda [3517.29/4023.4] Line wavelength in Angstroms
23- 27 F5.2 [-] log(eps) [-0.2/3.02] Log epsilon vanadium abundance
29- 32 F4.2 [-] e_log(eps) [0.06/0.51] Fitting uncertainty of log(eps)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 A11 --- Name Name of the star
13- 14 A2 --- Class Evolutionary stage (1)
16- 19 I4 K Teff [4320/7500] Effective temperature
21- 24 F4.2 [cm/s2] log(g) [0.5/4.4] Surface gravity
26- 30 F5.2 [-] [FeI/H] [-4.6/-1.08] Metallicity from neutral iron
32- 36 F5.2 [-] [FeII/H] [-4.5/-1.07] Metallicity from ionized iron
38 I1 --- l_[VI/FeI] [0/1] Upper limit flag for neutral
vanadium (2)
40- 47 F8.3 0.1nm lamULVI [4111.7/4408.2]? Wavelength of the line
setting the upper limit
49- 53 F5.2 [-] [VI/FeI] [-0.61/1.75] Neutral vanadium abundance
55- 58 F4.2 [-] e_[VI/FeI] [0.09/0.32]? Uncertainty of [VI/FeI]
60 I1 --- NVI [0/4] Number of neutral lines used
62 I1 --- l_[VII/FeII] [0/1] Upper limit flag for ionized
vanadium (2)
64- 71 F8.3 0.1nm lamULVII [3517.29/4023.4]? Wavelength of the line
setting the upper limit
73- 77 F5.2 [-] [VII/FeII] [-0.5/1.63] Ionized vanadium abundance
79- 82 F4.2 [-] e_[VII/FeII] [0.13/0.43]? Uncertainty of [VII/FeII]
84 I1 --- NVII [0/7] Number of ionized lines used
--------------------------------------------------------------------------------
Note (1): Evolutionary stage as follows:
BS = blue straggler-like class (3 occurrences)
MS = main sequence (20 occurrences)
HB = horizontal branch (40 occurrences)
RG = red giant branch (102 occurrences)
SG = supergiant branch (152 occurrences)
Note (2): "1" means only an upper limit is available.
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 30-Dec-2021