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J/ApJ/807/171  SkyMapper Survey metal-poor star spectroscopy  (Jacobson+, 2015)

High-resolution spectroscopic study of extremely metal-poor star candidates from the SkyMapper survey. Jacobson H.R., Keller S., Frebel A., Casey A.R., Asplund M., Bessell M.S., Da Costa G.S., Lind K., Marino A.F., Norris J.E., Pena J.M., Schmidt B.P., Tisserand P., Walsh J.M., Yong D., Yu Q. <Astrophys. J., 807, 171 (2015)> =2015ApJ...807..171J (SIMBAD/NED BibCode)
ADC_Keywords: Abundances ; Stars, metal-deficient ; Equivalent widths ; Radial velocities ; Surveys Keywords: stars: abundances Abstract: The SkyMapper Southern Sky Survey is carrying out a search for the most metal-poor stars in the Galaxy. It identifies candidates by way of its unique filter set which allows for estimation of stellar atmospheric parameters. The set includes a narrow filter centered on the CaII K 3933Å line, enabling a robust estimate of stellar metallicity. Promising candidates are then confirmed with spectroscopy. We present the analysis of Magellan Inamori Kyocera Echelle high-resolution spectroscopy of 122 metal-poor stars found by SkyMapper in the first two years of commissioning observations. Forty-one stars have [Fe/H]≤-3.0. Nine have [Fe/H]≤-3.5, with three at [Fe/H]~-4. A 1D LTE abundance analysis of the elements Li, C, Na, Mg, Al, Si, Ca, Sc, Ti, Cr, Mn, Co, Ni, Zn, Sr, Ba, and Eu shows these stars have [X/Fe] ratios typical of other halo stars. One star with low [X/Fe] values appears to be "Fe-enhanced", while another star has an extremely large [Sr/Ba] ratio: >2 Only one other star is known to have a comparable value. Seven stars are "CEMP-no" stars ([C/Fe]>0.7, [Ba/Fe]<0). 21 stars exhibit mild r-process element enhancements (0.3≤[Eu/Fe]<1.0), while four stars have [Eu/Fe]≥1.0. These results demonstrate the ability to identify extremely metal-poor stars from SkyMapper photometry, pointing to increased sample sizes and a better characterization of the metal-poor tail of the halo metallicity distribution function in the future. Description: Most of the candidate metal-poor stars were first observed with the Wide Field Spectrograph on the ANU 2.3m telescope, providing medium-resolution (R∼3000) optical spectra. The spectra analyzed in this work were obtained with the Magellan Inamori Kyocera Echelle (MIKE) spectrograph on the 6.5m Magellan Clay Telescope at Las Campanas Observatory. Observations spanned multiple campaigns from 2011 to 2013 November. File Summary:
FileName Lrecl Records Explanations
ReadMe 80 . This file table1.dat 100 135 Observing details table2.dat 56 122 Stellar parameters table3.dat 66 29122 Equivalenth width measurements of the 122 stars table4.dat 62 2442 Element abundances of the 122 stars table7.dat 44 122 Corrected carbon abundances
See also: III/272 : RAVE 4th data release (Kordopatis+, 2013) VII/240 : Millennium Galaxy Catalogue (Liske+, 2003) J/ApJ/798/110 : Equivalent widths of LAMOST metal-poor stars (Li+, 2015) J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014) J/ApJ/778/56 : Hamburg/ESO Survey extremely metal-poor stars (Cohen+, 2013) J/ApJS/208/27 : Sun and HD 84937 TiII log(gf) and abundances (Wood+, 2013) J/ApJ/769/57 : Equivalent widths of metal-poor stars (Frebel+, 2013) J/MNRAS/429/126 : Atmospheric parameters from Fe lines (Ruchti+, 2013) J/ApJ/762/27 : Most metal-poor stars. III. [Fe/H]≤-3.0 stars (Yong+, 2013) J/ApJ/762/26 : Most metal-poor stars. II. Galactic halo stars (Yong+, 2013) J/ApJ/762/25 : The most metal-poor stars in HES and SDSS. I. (Norris+, 2013) J/AJ/145/13 : Metal-poor stars from SDSS/SEGUE. I. Abundances (Aoki+, 2013) J/A+A/546/A90 : NLTE analysis of Sr lines (Bergemann+, 2012) J/ApJ/751/102 : Equivalent widths of 9 RGB in Carina dSph (Venn+, 2012) J/AJ/142/188 : Metal-poor stars from the HES using CH G-band (Placco+, 2011) J/ApJ/742/54 : CASH project II. 14 extremely metal-poor stars (Hollek+, 2011) J/AJ/141/175 : Abundances in M15 RGB/RHB stars (Sobeck+, 2011) J/ApJ/724/975 : Heavy elements abund. of metal-poor stars (Roederer+, 2010) J/ApJ/719/931 : Chemical evolution of the UMi dSph (Cohen+, 2010) J/AN/331/474 : Abundances of metal-poor stars (Frebel, 2010) J/ApJ/711/573 : Detailed abundances in a halo stellar stream (Roederer+, 2010) J/A+A/503/541 : Late-type stars neutral Li non-LTE calculations (Lind+, 2009) J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009) J/ApJ/681/1524 : Detailed abundances for 28 metal-poor stars (Lai+, 2008) J/A+A/484/721 : HES survey. IV. Candidate metal-poor stars (Christlieb+, 2008) J/ApJ/655/492 : Equivalent widths of 26 metal-poor stars (Aoki+, 2007) J/ApJ/652/1585 : Bright metal-poor stars from HES survey (Frebel+, 2006) J/A+A/439/129 : HERES II. Spectroscopic analysis (Barklem+, 2005) J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004) J/A+A/403/1105 : Extremely metal-poor giants EWs (Francois+, 2003) J/ApJS/123/639 : UBV photometry of metal-weak candidates (Norris+, 1999) J/A+A/326/751 : Chemical composition of halo and disk stars (Nissen+, 1997) J/AJ/103/1987 : Stars of very low metal abundance (Beers+ 1992) Byte-by-byte Description of file: table1.dat
Bytes Format Units Label Explanations
1- 24 A24 --- ID Star identifier (SMSS or 2MASS 26 A1 --- f_ID [b] b: indicates ID is a suspected binary 28- 29 I2 h RAh [0/23] Hour of Right Ascension (J2000) 31- 32 I2 min RAm Minute of Right Ascension (J2000) 34- 38 F5.2 s RAs Second of Right Ascension (J2000) 40 A1 --- DE- [-] Sign of the Declination (J2000) 41- 42 I2 deg DEd [0/85] Degree of Declination (J2000) 44- 45 I2 arcmin DEm Arcminute of Declination (J2000) 47- 50 F4.1 arcsec DEs Arcsecond of Declination (J2000) 52- 57 F6.3 mag gmag [12.5/16.7]? The g band magnitude 59- 63 F5.3 mag g-i [0.3/1.4]? The (g-i) color index 65- 75 A11 "YYYY/MMM/DD" Date UT date of the observation 77- 81 I5 s Texp [50/10140] Exposure time 83- 85 F3.1 arcsec Slit [0.7/1] Slit size 87- 92 F6.1 km/s RVel [-492.1/450.5] Radial velocity 94- 95 I2 --- S/N45 [3/82] Signal-to-noise per pixel at 4500Å 97-100 I4 --- S/N60 [6/125] S/N per pixel at 6000 Angstroms
Byte-by-byte Description of file: table2.dat
Bytes Format Units Label Explanations
1- 24 A24 --- ID Star identifier 26- 29 I4 K Teff [4432/5890] Effective temperature 31- 34 F4.2 [cm/s2] log(g)L [0.5/3.4] Log LTE derived surface gravity 36- 40 F5.2 [-] [Fe/H]L [-4/-1.3] LTE derived metallicity 42- 45 F4.2 km/s Vt [1.3/3.3] Microturbulent velocity 47- 50 F4.2 [cm/s2] log(g)N [0.9/3.6] Log NLTE derived surface gravity 52- 56 F5.2 [-] [Fe/H]N [-3.8/-1.2] NLTE derived metallicity
Byte-by-byte Description of file: table3.dat
Bytes Format Units Label Explanations
1- 24 A24 --- ID Star identifier 26- 33 F8.3 0.1nm lambda [3387.8/6979] Wavelength 35- 38 F4.1 --- Sp [8/63.1] Species numeric identifier (1) 40- 44 F5.3 eV ExPot [0/5.1] Excitation potential 46- 52 F7.3 [-] log(gf) [-10.4/0.7] Log oscillator strength 54- 58 F5.1 10-13m EW [1.3/437]? Equivalent width 60 A1 --- f_EW [s] Flag on EW (2) 62- 66 F5.2 [-] logX [-3.3/8.1] Log number abundance
Note (1): In the format XX.Y where XX is the atomic number and Y is the ionization level. Note (2): s = Absorption feature analyzed via spectrum synthesis.
Byte-by-byte Description of file: table4.dat
Bytes Format Units Label Explanations
1- 4 A4 --- Sp Species identifier 6- 29 A24 --- ID Star identifier 31 A1 --- l_logX Limit flag on logX 32- 37 F6.2 [-] logX [-3.3/7.5]? Log number abundance 39- 41 I3 --- Num [0/203] Number of lines used 43- 46 F4.2 --- SD [0/0.5]? Standard deviation 48 A1 --- l_[X/H] Limit flag on [X/H] 49- 54 F6.2 [-] [X/H] [-5.8/-0.4]? Log Species abundance relative to hydrogen 56 A1 --- l_[X/Fe] Limit flag on [X/H] 57- 62 F6.2 [-] [X/Fe] [-2.4/2]? Log Species abundance relative to iron
Byte-by-byte Description of file: table7.dat
Bytes Format Units Label Explanations
1- 24 A24 --- ID Star identifier 26 A1 --- l_[C/Fe]o Limit flag on [C/Fe]o 27- 32 F6.2 [-] [C/Fe]o [-0.8/1.3]? Original log C/Fe abundance 34- 37 F4.2 [-] Cor [0/0.8]? Correction for log C/Fe 39 A1 --- l_[C/Fe]c Limit flag on [C/Fe]c 40- 44 F5.2 [-] [C/Fe]c [-0.4/1.4]? Corrected log C/Fe abundance
History: From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Oct-2015
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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