J/ApJ/857/2 Abundances in 6 metal-poor stars (Roederer+, 2018)
A new test of copper and zinc abundances in late-type stars using ultraviolet
Cu II and Zn II lines.
Roederer I.U., Barklem P.S.
<Astrophys. J., 857, 2-2 (2018)>
=2018ApJ...857....2R 2018ApJ...857....2R (SIMBAD/NED BibCode)
ADC_Keywords: Spectra, ultraviolet; Spectra, optical; Equivalent widths;
Stars, metal-deficient
Keywords: nuclear reactions, nucleosynthesis, abundances; stars: abundances;
stars: atmospheres; stars: individual; stars: population II;
ultraviolet: stars
Abstract:
We present new abundances derived from CuI, CuII, ZnI, and ZnII lines
in six warm (5766≤Teff≤6427K), metal-poor (-2.50≤[Fe/H]≤-0.95)
dwarf and subgiant (3.64≤logg≤4.44) stars. These abundances are
derived from archival high-resolution ultraviolet spectra from the
Space Telescope Imaging Spectrograph on board the Hubble Space
Telescope and ground-based optical spectra from several observatories.
Ionized Cu and Zn are the majority species, and abundances derived
from CuII and ZnII lines should be largely insensitive to departures
from local thermodynamic equilibrium (LTE). We find good agreement
between the [Zn/H] ratios derived separately from ZnI and ZnII lines,
suggesting that departures from LTE are, at most, minimal (≲0.1dex).
We find that the [Cu/H] ratios derived from CuII lines are
0.36±0.06dex larger than those derived from CuI lines in the most
metal-poor stars ([Fe/H]<-1.8), suggesting that LTE underestimates
the Cu abundance derived from CuI lines. The deviations decrease in
more metal-rich stars. Our results validate previous theoretical
non-LTE calculations for both Cu and Zn, supporting earlier
conclusions that the enhancement of [Zn/Fe] in metal-poor stars is
legitimate, and the deficiency of [Cu/Fe] in metal-poor stars may not
be as large as previously thought.
Description:
We download UV spectra from the Mikulski Archive for Space Telescopes
(MAST). These spectra were collected using the Space Telescope Imaging
Spectrograph (STIS) on board the Hubble Space Telescope (HST). We
consider a star for inclusion in the sample if extant R∼30000 or
R∼114000 spectra cover at least 2037≤λ≤2127Å, where the
CuII and ZnII lines are found.
We supplement the UV spectra with high-resolution optical spectra
downloaded from online archives, including the European Southern
Observatory (ESO) Science Archive Facility and the Keck Observatory
Archives. These data were collected with the Ultraviolet and Visual
Echelle Spectrograph (UVES) on the Very Large Telescope, the High
Accuracy Radial velocity Planet Searcher (HARPS) on the ESO 3.6m
Telescope at La Silla, and the High Resolution Echelle Spectrometer
(HIRES) on the Keck I Telescope.
An optical spectrum of one star was collected previously using the
Robert G. Tull Coude Spectrograph at the Harlan J. Smith Telescope at
McDonald Observatory (see the details in Roederer+ 2014, J/AJ/147/136).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 91 14 Characteristics of archival UV and optical spectra
table2.dat 38 850 Fe lines and equivalent widths
table3.dat 83 6 V magnitudes, model atmosphere parameters, and
derived iron abundances
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See also:
II/237 : Stellar Photometry in Johnson's 11-color system (Ducati, 2002)
J/ApJ/855/63 : Yields of Fe & Zn for different types of SNe (Hirai+, 2018)
J/A+A/608/A46 : Constraining cosmic scatter (Reggiani+, 2017)
J/ApJ/824/L19 : CEMP star BD+44493 equivalent widths (Roederer+, 2016)
J/ApJ/821/37 : Abundances of metal-poor star HD 94028 (Roederer+, 2016)
J/ApJ/817/53 : Fe-group abundance analysis in HD84937 (Sneden+, 2016)
J/A+A/585/A102 : Copper abundances in solar neighborhood stars (Yan+, 2016)
J/A+A/580/A23 : Stroemgren-Crawford uvbyβ photometry (Paunzen, 2015)
J/ApJ/807/171 : SkyMapper Survey metal-poor star spectro. (Jacobson+, 2015)
J/ApJS/215/23 : FeI radiative lifetimes (Den Hartog+, 2014)
J/AJ/148/81 : APASS BVgri photometry of RAVE stars. I. (Munari+, 2014)
J/MNRAS/444/392 : Synthetic Stellar Photometry. I. (Casagrande+, 2014)
J/MNRAS/441/3127 : FeI oscillator strengths for Gaia-ESO (Ruffoni+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)
J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013)
J/ApJ/771/67 : Abundances for 97 metal-poor stars. II. (Ishigaki+, 2013)
J/ApJ/755/89 : Metallicities of damped Lyα systems (Rafelski+, 2012)
J/ApJ/750/76 : r-process peaks elements in HD 160617 (Roederer+, 2012)
J/ApJ/742/54 : CASH project II. 14 EMP stars (Hollek+, 2011)
J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011)
J/A+A/530/A138 : Geneva-Copenhagen survey re-analysis (Casagrande+, 2011)
J/A+A/530/A15 : Abundances of 94 stars (Nissen+, 2011)
J/ApJ/724/975 : Abundances of metal-poor stars (Roederer+, 2010
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)
J/ApJS/182/51 : Transitions of rare earth elements (Lawler+, 2009)
J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005)
J/A+A/435/373 : Broadening of Fe II lines by H collisions (Barklem+, 2005)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/MNRAS/340/304 : [X/Fe] of Galactic disc F and G dwarfs (Reddy+, 2003)
J/A+AS/142/467 : Broadening of metallic lines by H collisions (Barklem+ 2000)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- Set UV or Opt. spectra
5- 12 A8 --- Name Star name
14- 18 A5 --- Inst Instrument
20- 32 A13 --- Prog Program ID
34 A1 --- f_Prog Flag on Prog (1)
36- 61 A26 --- Data UV data sets
63- 72 A10 --- PI Principal Investigator's name
74- 86 A13 --- R Resolution(s)
87 A1 --- f_R Flag on R (1)
89- 91 I3 --- S/N [25/550]? Signal to noise ratio at 2100 and
5000Å for the UV and optical spectra,
respectively
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Note (1): Flag as follows:
b = Values for the blue and red components of the spectrum.
c = See Roederer+ (2014, J/AJ/147/136) for observational details.
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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- 8 A8 --- Name Star name
10- 13 A4 --- Ion Species (FeI or FeII)
15- 21 F7.2 0.1nm lambda [3724.3/7748.3] Wavelength in Angstroms
23- 26 F4.2 eV ExPot [1.4/4.8] Excitation potential in eV
28- 32 F5.2 --- log(gf) [-4.2/0.4] Log of degeneracy times oscillator
strength
34- 38 F5.1 0.1pm EW [1.5/137.3] Equivalent width in milli Angstroms
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Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 8 A8 --- Name Star name
10- 13 F4.2 mag Vmag [5.8/8.8] Johnson V-band magnitude (1)
15- 18 I4 K Teff [5766/6427] Effective temperature
20- 21 I2 K e_Teff [64/93] Teff uncertainty
23- 26 F4.2 [cm/s2] logg [3.6/4.5] Log of surface gravity
28- 31 F4.2 [cm/s2] e_logg [0.1/0.2] logg uncertainty
33- 36 F4.2 km/s Vt [1.1/1.6] Microturbulent velocity
38- 41 F4.2 km/s e_Vt [0.1] Vt uncertainty
43- 46 F4.1 [-] [M/H] [-2.6/-1] Metallicity
48- 50 F3.1 [-] e_[M/H] [0.1] [M/H] uncertainty
52- 56 F5.2 [-] [FeI/H] [-2.6/-0.9] [FeI/H] abundance
58- 61 F4.2 [-] e_[FeI/H] [0.04/0.07] [FeI/H] uncertainty
63- 67 F5.2 [-] [FeII/H] [-2.5/-0.9] [FeII/H] abundance
69- 72 F4.2 [-] e_[FeII/H] [0.04/0.06] [FeII/H] uncertainty
74- 78 F5.2 [-] Fe2-Fe1 [-0.03/0.09] [FeII/H] - [FeI/H]
80- 83 F4.2 [-] e_Fe2-Fe1 [0.06/0.1] Fe2-Fe1 uncertainty
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Note (1): Optical magnitudes for these stars are available in catalogs
by Ducati (2002, II/237) and Munari+ (2014, J/AJ/148/81) for
Johnson B and V.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 14-Feb-2019