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Related papers: Chemical Abundances in 35 Metal-Poor Stars. I. Bas…

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High resolution spectra of 34 halo population dwarf and subgiant stars have been obtained with VLT/UVES and used to derive sulphur abundances from the 8694.0, 8694.6 A and 9212.9, 9237.5 A SI lines. In addition, iron abundances have been…

Astrophysics · Physics 2009-11-10 P. E. Nissen , Y. Q. Chen , M. Asplund , M. Pettini

CCD photometry on the uvbyCa system has been obtained for 521 candidate metal-poor stars from the northern hemisphere HK survey of Beers and colleagues. Reddening corrections, classifications of stars by luminosity class, and the derivation…

The relative abundances of the Fe-peak elements (Ti-Zn) at the lowest metallicities are intimately linked to the physics of core-collapse supernova explosions. With a sample of 25 very metal-poor damped Lyman-alpha systems, we investigate…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-12 Ryan Cooke , Max Pettini , Regina A. Jorgenson , Michael T. Murphy , Gwen C. Rudie , Charles C. Steidel

We present a first systematic investigation of the iron abundance in very hot (Teff>50,000K) hydrogen-deficient post-AGB stars. Our sample comprises 16 PG1159 stars and four DO white dwarfs. We use recent FUSE observations as well as HST…

Astrophysics · Physics 2009-11-07 S. Miksa , J. L. Deetjen , S. Dreizler , J. W. Kruk , T. Rauch , K. Werner

We report on the first high spectral resolution analysis of extremely metal-poor halo stars from the Hamburg/ESO objective-prism survey (HES). The spectra were obtained with UVES at VLT-UT2. The two stars under investigation (\object {HE…

Astrophysics · Physics 2007-05-23 E. Depagne , V. Hill , N. Christlieb , F. Primas

Elements heavier than the iron group are found in nearly all halo stars. A substantial number of these elements, key to understanding neutron-capture nucleosynthesis mechanisms, can only be detected in the near-ultraviolet. We report the…

Aims. We aim to derive the chemical pattern of the young clusters 25 Orionis and lambda Orionis through homogeneous and accurate measurements of elemental abundances. Methods. We present FLAMES/UVES observations of a sample of 14 K-type…

Solar and Stellar Astrophysics · Physics 2015-05-27 K. Biazzo , S. Randich , F. Palla , C. Briceno

Differential abundances of C, O, Mg, Al, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Zn, Y, and Zr were determined from high signal-to-noise VLT/UVES spectra for 25 turnoff stars with -2.4 < [Fe/H] < -1.3. Effective temperatures were obtained from…

Astrophysics of Galaxies · Physics 2026-05-01 Poul Erik Nissen , Anish Amarsi

We present basic stellar parameters of 99 late-type G giants based on high resolution spectra obtained by the High Dispersion Spectrograph attached to Subaru Telescope. These stars are targets of a Doppler survey program searching for…

Solar and Stellar Astrophysics · Physics 2015-05-30 Liang Wang , Yujuan Liu , Gang Zhao , Bun'ei Sato

We present a method for the determination of [alpha/Fe] ratios from low-resolution (R = 2000) SDSS/SEGUE stellar spectra. By means of a star-by-star comparison with degraded spectra from the ELODIE spectral library and with a set of…

The chemical evolution of neutron capture elements in the Milky Way is still a matter of debate. Although more and more studies investigate their chemical behaviour, there is still a lack of a significant large sample of abundances of a key…

Solar and Stellar Astrophysics · Physics 2024-08-30 G. Contursi , P. de Laverny , A. Recio-Blanco , M. Molero , E. Spitoni , F. Matteucci , S. Cristallo

We present a spectral analysis of the binary G 224-58 AB that consists of the coolest M extreme subdwarf (esdM5.5) and a brighter primary (esdK5). This binary may serve as a benchmark for metallicity measurement calibrations and as a…

Solar and Stellar Astrophysics · Physics 2015-10-21 Ya. V. Pavlenko , Z. H. Zhang , M. C. Gálvez-Ortiz , I. O. Kushniruk , H. R. A. Jones

We employ a new Infrared Flux Method (IRFM) temperature scale (Ramirez & Melendez 2005, ApJ 626, 446; ApJ 626, 465) in order to determine Li, O, and Fe NLTE abundances in a sample of relatively unevolved (dwarfs, turn-off, subgiants)…

Astrophysics · Physics 2009-11-11 Jorge Melendez , Nataliya G. Shchukina , Ivan Ramirez , Irina Vasiljeva

Using a high resolution spectrum of the secondary star in the black hole binary A0620-00, we have derived the stellar parameters and veiling caused by the accretion disk in a consistent way. We have used a chi^2 minimization procedure to…

Astrophysics · Physics 2009-11-10 Jonay I. Gonzalez-Hernandez , R. Rebolo , G. Israelian , J. Casares , A. Maeder , G. Meynet

HARPS-N spectra with S/N > 250 and MARCS model atmospheres were used to derive abundances of C, O, Na, Mg, Al, Si, Ca, Ti, Cr, Fe, Ni, Zn, and Y in ten stars from the Kepler LEGACY sample (including the binary pair 16 Cyg A and B) selected…

Solar and Stellar Astrophysics · Physics 2017-12-13 P. E. Nissen , V. Silva Aguirre , J. Christensen-Dalsgaard , R. Collet , F. Grundahl , D. Slumstrup

We have determined Li abundances for eleven metal-poor turn-off stars, among which eight have [Fe/H]<-3, based on LTE analyses of high-resolution spectra obtained with the HDS on the Subaru telescope. The Li abundances for four of these…

We present stellar parameters and abundances of 13 elements for 18 very metal-poor (VMP; [Fe/H] $<$ -2.0) stars, selected as extremely metal-poor (EMP; [Fe/H] $<$ -3.0) candidates from SDSS and LAMOST survey. High-resolution spectroscopic…

The chemical composition of stars with extremely low metal contents (taking ``metals'' to mean all elements other than hydrogen and helium) provides us with information on the masses of the stars that produced the first metals. Such a…

Astrophysics · Physics 2015-06-24 Piercarlo Bonifacio , Marco Limongi , Alessandro Chieffi

For the first time, we present an extensive study of stars with individual non-local thermodynamic equilibrium (NLTE) abundances for 17 chemical elements from Li to Eu in a sample of stars uniformly distributed over the $-2.62 \le$ [Fe/H]…

We map the trends of elemental abundance ratios across the Galactic disk, spanning R = 3-15 kpc and midplane distance |Z|= 0-2 kpc, for 15 elements in a sample of 20,485 stars measured by the SDSS/APOGEE survey (O, Na, Mg, Al, Si, P, S, K,…

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