J/ApJ/865/68 Abundances for 79 Sun-like stars within 100pc (Bedell+, 2018)
The chemical homogeneity of Sun-like stars in the solar neighborhood.
Bedell M., Bean J.L., Melendez J., Spina L., Ramirez I., Asplund M.,
Alves-Brito A., dos Santos L., Dreizler S., Yong D., Monroe T.,
Casagrande L.
<Astrophys. J., 865, 68 (2018)>
=2018ApJ...865...68B 2018ApJ...865...68B
ADC_Keywords: Abundances; Equivalent widths; Stars, G-type; Spectra, optical
Keywords: planets and satellites: general; stars: abundances; stars: solar-type;
Sun: abundances; techniques: spectroscopic
Abstract:
The compositions of stars are a critical diagnostic tool for many
topics in astronomy such as the evolution of our Galaxy, the formation
of planets, and the uniqueness of the Sun. Previous spectroscopic
measurements indicate a large intrinsic variation in the elemental
abundance patterns of stars with similar overall metal content.
However, systematic errors arising from inaccuracies in stellar models
are known to be a limiting factor in such studies, and thus it is
uncertain to what extent the observed diversity of stellar abundance
patterns is real. Here we report the abundances of 30 elements with
precisions of 2% for 79 Sun-like stars within 100pc. Systematic errors
are minimized in this study by focusing on solar twin stars and
performing a line-by-line differential analysis using high-resolution,
high-signal-to-noise spectra. We resolve [X/Fe] abundance trends in
galactic chemical evolution at precisions of 10-3dex/Gyr and reveal
that stars with similar ages and metallicities have nearly identical
abundance patterns. Contrary to previous results, we find that the
ratios of carbon-to-oxygen and magnesium-to-silicon in
solar-metallicity stars are homogeneous to within 10% throughout the
solar neighborhood, implying that exoplanets may exhibit much less
compositional diversity than previously thought. Finally, we
demonstrate that the Sun has a subtle deficiency in refractory
material relative to >80% of solar twins (at 2σ confidence),
suggesting a possible signpost for planetary systems like our own.
Description:
To achieve sufficient signal-to-noise for high-precision abundance
work, we stacked ≥50 observations for each star. All spectra were
taken with the High Accuracy Radial velocity Planet Searcher (HARPS)
spectrograph on the 3.6m telescope of the European Southern
Observatory (ESO), located at La Silla Observatory in Chile; with
resolving power R=115000 and wavelength coverage between 378-691nm.
A majority of the selected sample were observed by us in the course of
a large ESO observing program on HARPS (Melendez+ 2015Msngr.161...28M 2015Msngr.161...28M).
Other stars had a sufficient number of publicly available spectra in
the online ESO Science Archive Facility.
The solar reference spectrum used in this work was created by
combining multiple exposures of sunlight reflected from the asteroid
Vesta. It was continuum-normalized in the same manner as the target
spectra and has S/N∼1300/pix at 600nm.
Spectra previously obtained with the MIKE spectrograph and analyzed in
Ramirez+ (2014A&A...572A..48R 2014A&A...572A..48R) were also used in some parts of this
analysis. These spectra have S/N∼400/pix at 600nm, resolution
R=83000-65000 (on blue/red CCDs), and wavelength coverage between 320
and 1000nm.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
ews.dat 50 47680 Equivalent width measurements
table2.dat 282 79 Abundances
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See also:
I/259 : The Tycho-2 Catalogue (Hog+ 2000)
J/ApJ/622/1102 : The planet-metallicity correlation. (Fischer+, 2005)
J/ApJS/159/141 : Spectroscopic properties of cool stars. I. (Valenti+, 2005)
J/A+A/508/L17 : Abundances in solar analogs (Ramirez+, 2009)
J/ApJ/715/1050 : Predicted abundances for extrasolar planets. I. (Bond+, 2010)
J/ApJ/725/2349 : C/O vs Mg/Si of planetary systems (Delgado Mena+, 2010)
J/A+A/523/A15 : HARPS XXIII: RV data for the 8 targets (Naef+, 2010)
J/A+A/530/A138 : Geneva-Copenhagen survey re-analysis (Casagrande+, 2011)
J/ApJ/735/41 : Carbon and oxygen abundances in FGK stars (Petigura+, 2011)
J/ApJ/732/55 : Abundances of stars with planets (Schuler+, 2011)
J/A+A/545/A32 : Chemical abundances of 1111 FGK stars (Adibekyan+, 2012)
J/A+A/552/A6 : F-G main-sequence star abundances (Gonzalez Hernandez+, 2013)
J/ApJ/764/78 : Oxygen abundances in nearby FGK stars (Ramirez+, 2013)
J/ApJ/795/23 : Line list for stellar chemical abundances (Bedell+, 2014)
J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)
J/A+A/583/A94 : [X/Fe] scatter derived for spectral lines (Adibekyan+, 2015)
J/A+A/591/A34 : Chemical abundances of zeta Reticuly (Adibekyan+, 2016)
J/ApJ/831/20 : C/O and Mg/Si for solar neighborhood's stars (Brewer+, 2016)
J/ApJ/819/19 : Equivalent widths of WASP-94A and WASP-94B (Teske+, 2016)
J/A+A/605/A89 : Microlensed Bulge dwarf star abundances. VI. (Bensby+, 2017)
J/MNRAS/474/2580 : Evolution of neutron-capture elements (Spina+, 2018)
J/A+A/614/A84 : C/O vs Mg/Si ratios in solar type stars (Suarez-Andres+, 2018)
Byte-by-byte Description of file: ews.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name HIP number or "Sun"
11 A1 --- n_lambda Note on lambda (1)
12- 19 F8.3 0.1nm lambda [4082.9/7775.4] Rest wavelength of line
in Angstroms
21- 21 A1 --- f_lambda Source flag (2)
23- 27 F5.1 --- Ion [6/106] Species identifier (3)
29- 34 F6.4 eV EP [0/9.2] Excitation potential
36- 42 F7.4 [-] log(gf) [-5.8/0.6] Log of the oscillator strength
44- 50 F7.3 10-13m EW [5/130]?=0 Measured equivalent width
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Note (1):
- = hyperfine structure components used by the MOOG blends driver.
Note (2): Most lines were measured from HARPS spectra except:
M = the line was measured from MIKE spectra instead.
Note (3): Species identifier is the atomic number(s) followed by a decimal
point and a single digit indicating ionization state (from MOOG;
Sneden 1973PhDT.......180S 1973PhDT.......180S).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name HIP number
11- 16 F6.3 [-] [CI/H] [-0.17/0.18] Differential abundance of species
CI relative to Solar
18- 22 F5.3 [-] e_[CI/H] [0.003/0.06] Estimated uncertainty in [CI/H]
24- 29 F6.3 [-] [CH/H] [-0.2/0.1] Differential abundance of species
CH relative to Solar
31- 35 F5.3 [-] e_[CH/H] [0.003/0.03] Estimated uncertainty in [CH/H]
37- 42 F6.3 [-] [OI/H] [-0.11/0.2]? Differential abundance of species
OI relative to Solar
44- 48 F5.3 [-] e_[OI/H] [0.003/0.03]? Estimated uncertainty in [OI/H]
50- 55 F6.3 [-] [NaI/H] [-0.16/0.13] Differential abundance of species
NaI relative to Solar
57- 61 F5.3 [-] e_[NaI/H] [0.003/0.03] Estimated uncertainty in [NaI/H]
63- 68 F6.3 [-] [MgI/H] [-0.11/0.21] Differential abundance of species
MgI relative to Solar
70- 74 F5.3 [-] e_[MgI/H] [0.003/0.03] Estimated uncertainty in [MgI/H]
76- 81 F6.3 [-] [AlI/H] [-0.13/0.23] Differential abundance of species
AlI relative to Solar
83- 87 F5.3 [-] e_[AlI/H] [0.001/0.03] Estimated uncertainty in [AlI/H]
89- 94 F6.3 [-] [SiI/H] [-0.12/0.13] Differential abundance of species
SiI relative to Solar
96-100 F5.3 [-] e_[SiI/H] [0.002/0.006] Estimated uncertainty in [SiI/H]
102-107 F6.3 [-] [SI/H] [-0.15/0.18] Differential abundance of species
SI relative to Solar
109-113 F5.3 [-] e_[SI/H] [0.003/0.05] Estimated uncertainty in [SI/H]
115-120 F6.3 [-] [CaI/H] [-0.11/0.15] Differential abundance of species
CaI relative to Solar
122-126 F5.3 [-] e_[CaI/H] [0.003/0.02] Estimated uncertainty in [CaI/H]
128-133 F6.3 [-] [ScI/H] [-0.13/0.14] Differential abundance of species
ScI relative to Solar
135-139 F5.3 [-] e_[ScI/H] [0.004/0.03] Estimated uncertainty in [ScI/H]
141-146 F6.3 [-] [ScII/H] [-0.13/0.2] Differential abundance of species
ScII relative to Solar
148-152 F5.3 [-] e_[ScII/H] [0.005/0.03] Estimated uncertainty in [ScII/H]
154-159 F6.3 [-] [TiI/H] [-0.11/0.17] Differential abundance of species
TiI relative to Solar
161-165 F5.3 [-] e_[TiI/H] [0.003/0.02] Estimated uncertainty in [TiI/H]
167-172 F6.3 [-] [TiII/H] [-0.12/0.17] Differential abundance of species
TiII relative to Solar
174-178 F5.3 [-] e_[TiII/H] [0.004/0.02] Estimated uncertainty in [TiII/H]
180-185 F6.3 [-] [VI/H] [-0.13/0.14] Differential abundance of species
VI relative to Solar
187-191 F5.3 [-] e_[VI/H] [0.003/0.02] Estimated uncertainty in [VI/H]
193-198 F6.3 [-] [CrI/H] [-0.16/0.15] Differential abundance of species
CrI relative to Solar
200-204 F5.3 [-] e_[CrI/H] [0.003/0.02] Estimated uncertainty in [CrI/H]
206-211 F6.3 [-] [CrII/H] [-0.15/0.14] Differential abundance of species
CrII relative to Solar
213-217 F5.3 [-] e_[CrII/H] [0.004/0.02] Estimated uncertainty in [CrII/H]
219-224 F6.3 [-] [MnI/H] [-0.24/0.13] Differential abundance of species
MnI relative to Solar
226-230 F5.3 [-] e_[MnI/H] [0.003/0.02] Estimated uncertainty in [MnI/H]
232-237 F6.3 [-] [CoI/H] [-0.13/0.13] Differential abundance of species
CoI relative to Solar
239-243 F5.3 [-] e_[CoI/H] [0.003/0.02] Estimated uncertainty in [CoI/H]
245-250 F6.3 [-] [NiI/H] [-0.15/0.14] Differential abundance of species
NiI relative to Solar
252-256 F5.3 [-] e_[NiI/H] [0.002/0.01] Estimated uncertainty in [NiI/H]
258-263 F6.3 [-] [CuI/H] [-0.17/0.18] Differential abundance of species
CuI relative to Solar
265-269 F5.3 [-] e_[CuI/H] [0.002/0.06] Estimated uncertainty in [CuI/H]
271-276 F6.3 [-] [ZnI/H] [-0.16/0.2] Differential abundance of species
ZnI relative to Solar
278-282 F5.3 [-] e_[ZnI/H] [0.004/0.04] Estimated uncertainty in [ZnI/H]
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Aug-2019