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J/AJ/154/52 Metal-poor stars from SDSS/SEGUE. I Unevolved stars (Matsuno+, 2017)

High-resolution spectroscopy of extremely metal-poor stars from SDSS/SEGUE. III. Unevolved stars with [Fe/H]≤-3.5. Matsuno T., Aoki W., Beers T.C., Lee Y.S., Honda S. <Astron. J., 154, 52-52 (2017)> =2017AJ....154...52M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, metal-deficient ; Abundances ; Equivalent widths Keywords: Galaxy: halo - stars: abundances - stars: atmospheres - stars: Population II Abstract: We present elemental abundances for eight unevolved extremely metal-poor (EMP) stars with Teff>5500K, among which seven have [Fe/H]<-3.5. The sample is selected from the Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration (SDSS/SEGUE) and our previous high-resolution spectroscopic follow-up with the Subaru Telescope. Several methods to derive stellar parameters are compared, and no significant offset in the derived parameters is found in most cases. From an abundance analysis relative to the standard EMP star G64-12, an average Li abundance for stars with [Fe/H]←3.5 is A(Li)=1.90, with a standard deviation of σ=0.10dex. This result confirms that lower Li abundances are found at lower metallicity, as suggested by previous studies, and demonstrates that the star-to-star scatter is small. The small observed scatter could be a strong constraint on Li-depletion mechanisms proposed for explaining the low Li abundance at lower metallicity. Our analysis for other elements obtained the following results: (i) a statistically significant scatter in [X/Fe] for Na, Mg, Cr, Ti, Sr, and Ba, and an apparent bimodality in [Na/Fe] with a separation of ∼0.8dex, (ii) an absence of a sharp drop in the metallicity distribution, and (iii) the existence of a CEMP-s star at [Fe/H]≃-3.6 and possibly at [Fe/H]≃-4.0, which may provide a constraint on the mixing efficiency of unevolved stars during their main-sequence phase. Description: The targets in our present study are selected from Aoki et al. 2013 (Cat. J/AJ/145/13; Paper I). We have obtained new, higher-quality spectra for eight targets with the High Dispersion Spectrograph on the Subaru Telescope. The spectral resolution is R=60000 with 2*2 CCD binning; the wavelength coverage is 4000-6000Å. We also analyze the spectra of two bright EMP main-sequence turnoff stars, G64-12 ([Fe/H]=-3.38) and LP815-43 ([Fe/H]=-2.96). The spectrum of G64-12 was taken on 2002 December 22 with R∼90000 and S/N∼650 at 6708Å (S/N∼454 at 4880Å) (Aoki et al. 2009ApJ...698.1803A). The spectrum of LP815-43, which was taken from the Subaru-Mitaka-Okayama-Kiso Archive (SMOKA; Baba et al. 2002ASPC..281..298B), was originally obtained on 2005 May 18 with R∼90000 and S/N∼260 at 6708Å (S/N∼142 at 4880Å). File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 86 9 Observation log for the SDSS sample table5.dat 52 424 Measured equivalent widths table6.dat 49 112 Results of the chemical abundance analysis
See also: I/337 : Gaia DR1 (Gaia Collaboration, 2016) V/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015) V/139 : The SDSS Photometric Catalog, Release 9 (Adelman-McCarthy+, 2012) J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013) J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013) J/ApJ/667/1267 : CrI transition probabilities (Sobeck+, 2007) J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 24 A24 --- Object Object name (1) 26- 36 A11 "Y:M:D" Date1 Starting date of the observing run 38- 48 A11 "Y:M:D" Date2 Second/ending date of the observing run 50- 60 A11 "Y:M:D" Date3 Ending date of the observing run 62- 66 F5.2 mag Vmag ? The V band magnitude 68- 73 A6 s Exp Exposure time 75- 76 I2 --- S/N1 ? Signal-to-Noise ratio at 4877Å 78- 79 I2 --- S/N2 ? Signal-to-Noise ratio at 6708Å 81- 86 F6.1 km/s RV ? Radial velocity (vr)
Note (1): Objects identifiers given by SDSS can be found in Aoki et al. 2013 (Cat. J/AJ/145/13; Paper I). The object name is abbreviated throughout the other tables, e.g., SDSS J0120-1001 for SDSS J012032.63-100106.5. In this table, G64-12 was added at CDS.
Byte-by-byte Description of file: table5.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Name Abbreviated object identifier 17- 21 A5 --- Species Species identifier 23- 30 F8.3 0.1nm lambda [4045.8/6495] Wavelength λ; in Å 32- 36 F5.3 eV EP [0/4.35] Excitation potential 38- 43 F6.3 [-] log(gf) [-3.36/0.57] Log oscillator strength 45- 49 F5.1 0.1pm EW [1/159.8] Equivalent width; in mÅ 51- 52 I2 --- Ref [1/23] Reference code (1)
Note (1): The reference codes are defined as follows: 1 = Morton (1991ApJS...77..119M); 2 = Froese Fischer (1975CaJPh..53..184F); 3 = Aldenius et al. (2007A&A...461..767A); 4 = Wiese & Martin (; 5 = Smith & Raggett (1981JPhB...14.4015S); 6 = Ivans et al. 2006 (Cat. J/ApJ/645/613); 7 = Lawler & Dakin (1989JOSAB...6.1457L); 8 = Piskunov et al. (1995A&AS..112..525P); 9 = Lawler et al. (2013ApJS..205...11L); 10 = Grevesse et al. (1989A&A...208..157G); 11 = Wood et al. 2013 (Cat. J/ApJS/208/27); 12 = Pickering et al. (2001ApJS..132..403P); 13 = Ryabchikova et al. (1994MNRAS.267..697R); 14 = Martin et al. (; 15 = Sobeck et al. 2007 (Cat. J/ApJ/667/1267); 16 = O'Brian et al. (1991JOSAB...8.1185O); 17 = Fuhr et al. (1988JPCRD..17S....F); 18 = Bard et al. (1991A&A...248..315B); 19 = Melendez & Barbuy (2009A&A...497..611M); 20 = Moity (1983A&AS...52...37M); 21 = Pinnington et al. (1995JPhB...28.2095P); 22 = Grevesse et al. (1981LIACo..23..211G); 23 = Grevesse et al. (2015A&A...573A..27G).
Byte-by-byte Description of file: table6.dat
Bytes Format Units Label Explanations
1- 15 A15 --- Name Abbreviated object identifier 17- 22 A6 --- Species Species identifier 24- 25 I2 --- N [1/78]? Number of lines used 27 A1 --- l_log(e) [<] Upper limit flag on log(e) 28- 32 F5.2 --- log(e) [-2.07/7.34] Abundance logε(X) (1) 34- 37 F4.2 --- e_log(e) [0.02/0.29]? The 1σ error in log(e) (2) 39 A1 --- l_[X/Fe] [<] Upper limit flag on [X/Fe] 40- 44 F5.2 [Sun] [X/Fe] [-1/6] Log abundance relative to iron (3) 46- 49 F4.2 [Sun] e_[X/Fe] [0.01/0.31]? The 1σ error in [X/Fe] (2)
Note (1): Abundances are determined differentially using G64-12 as a reference. Note (2): The uncertainty represents internal precision only. Note (3): [X/Fe] is calculated using the solar abundance from Asplund et al. (2009ARA&A..47..481A).
History: From electronic version of the journal References: Aoki et al., Paper I 2013AJ....145...13A, Cat. J/AJ/145/13 Aoki et al., Paper II 2015AJ....149...39A
(End) Prepared by [AAS]; Sylvain Guehenneux [CDS] 25-Oct-2017
The document above follows the rules of the Standard Description for Astronomical Catalogues.From this documentation it is possible to generate f77 program to load files into arrays or line by line

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