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Star clusters, particularly those objects in the disk-bulge-halo interface are as of yet poorly charted, albeit carrying important information about the formation and the structure of the Milky Way. Here, we present a detailed chemical…

Astrophysics of Galaxies · Physics 2017-12-27 Andreas Koch , Terese T. Hansen , Andrea Kunder

We report on the elemental abundances of the carbon-enhanced metal-poor (CEMP) star J2217+2104 discovered by our metal-poor star survey with LAMOST and Subaru. This object is a red giant having extremely low Fe abundance ([Fe/H]=-4.0) and…

Solar and Stellar Astrophysics · Physics 2018-09-26 Wako Aoki , Tadafumi Matsuno , Satoshi Honda , Miho Ishigaki , Haining Li , Takuma Suda , Yerra Bharat Kummar

A non-LTE analysis of C I lines at 1.068-1.069 micron was carried out for selected 46 halo/disk stars covering a wide metallicity range (-3.7 <[Fe/H]< +0.3), based on the spectral data collected with IRCS+AO188 of the Subaru Telescope, in…

Solar and Stellar Astrophysics · Physics 2015-06-15 Yoichi Takeda , Masahide Takada-Hidai

We present the first high-resolution abundance study of ESO 280-SC06, one of the least luminous and most metal-poor gravitationally bound Milky Way globular clusters. Using Magellan/MIKE spectroscopy for ten stars, we confirm the cluster's…

We describe a method for the determination of stellar [C/Fe] abundance ratios using low-resolution (R = 2000) stellar spectra from the SDSS and SEGUE. By means of a star-by-star comparison with a set of SDSS/SEGUE spectra with available…

The globular cluster HP~1 is projected at only 3.33 degrees from the Galactic center. Together with its distance, this makes it one of the most central globular clusters in the Milky Way. It has a blue horizontal branch (BHB) and a…

Solar and Stellar Astrophysics · Physics 2016-06-22 B. Barbuy , E. Cantelli , A. Vemado , H. Ernandes , S. Ortolani , I. Saviane , E. Bica , D. Minniti , B. Dias , Y. Momany , V. Hill , M. Zoccali , C. Siqueira-Mello

Isotopic abundance ratios 24^Mg:25^Mg:26^Mg are derived for 20 stars from high- resolution spectra of the MgH A-X 0-0 band at 5140AA. With the exception of the weak g-band giant HR 1299, the stars are dwarfs that sample the metallicity…

Astrophysics · Physics 2009-10-31 Pamela Gay , David L. Lambert

High resolution CASPEC and EMMI spectra (R$\approx$10$^4$) of the faint metal- deficient candidates CS 22891--209, CS 22897--8, CS 22948--66 and CS 22968--14 taken from the survey of Beers, Preston and Shectman (1985, BPS) are analyzed for…

Astrophysics · Physics 2007-05-23 Francesca Primas , Paolo Molaro , Fiorella Castelli

We present radial velocities, equivalent widths, model atmosphere parameters, and abundances or upper limits for 53 species of 48 elements derived from high resolution optical spectroscopy of 313 metal-poor stars. A majority of these stars…

High resolution, high S/N spectra have been obtained for a sample of 90 F and G main-sequence disk stars covering the metallicity range -1.0 < [Fe/H] < +0.1, and have been analysed in a parallel way to the work of Edvardsson et al. (1993).…

Astrophysics · Physics 2009-10-31 Y. Q. Chen , P. E. Nissen , G. Zhao , H. W. Zhang , T. Benoni

A comprehensive abundance analysis providing rare insight into the chemical history of lead stars is still lacking. We present results from high resolution (R ~ 50000), spectral analyses of three CH stars, HD 26, HD 198269, HD 224959, and,…

Solar and Stellar Astrophysics · Physics 2015-11-11 Aruna Goswami , Wako Aoki , Drisya Karinkuzhi

We performed detailed chemical abundance analysis of the extremely metal-poor ([Ar/H]-2) halo planetary nebula H4-1 based on the multi-wavelength spectra from Subaru/HDS, GALEX, SDSS, and Spitzer/IRS and determined the abundances of 10…

Solar and Stellar Astrophysics · Physics 2015-06-17 Masaaki Otsuka , Akito Tajitsu

We obtained high resolution, high S/N spectroscopy for the very metal-poor star HD122563 with the Subaru Telescope High Dispersion Spectrograph. Previous studies have shown that this object has excesses of light neutron-capture elements,…

Astrophysics · Physics 2009-11-11 S. Honda , W. Aoki , Y. Ishimaru , S. Wanajo , S. G. Ryan

Infrared OH lines at 1.55 - 1.56 um in the H-band were obtained with the Phoenix high-resolution spectrograph at the 2.1m telescope of the Kitt Peak National Observatory for a sample of 14 metal-poor stars. Detailed analyses of the sample…

Astrophysics · Physics 2011-02-11 Jorge Melendez , Beatriz Barbuy , Francois Spite

We describe the discovery of HE 1327-2326, a dwarf or subgiant with [Fe/H]}=-5.4. The star was found in a sample of bright metal-poor stars selected from the Hamburg/ESO survey. Its abundance pattern is characterized by very high C and N…

We measure chemical abundances for over 20 elements of 15 N-rich field stars with high resolution ($R \sim 30000$) optical spectra. We find that Na, Mg, Al, Si, and Ca abundances of our N-rich field stars are mostly consistent with those of…

Astrophysics of Galaxies · Physics 2021-06-02 Jincheng Yu , Baitian Tang , J. G. Fernandez-Trincado , Douglas Geisler , Hongliang Yan , M. Soto

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…

We have carried out a detailed abundance analysis for a sample of 16 carbon stars found among candidate extremely metal-poor (EMP) stars from the Hamburg/ESO Survey. We find that the Fe-metallicities for the cooler C-stars (Teff ~ 5100K)…

An increasing fraction of carbon-enhanced metal-poor (CEMP) stars is found as their iron abundance, [Fe/H], decreases below [Fe/H] = -2.0. The CEMP-s stars have the highest absolute carbon abundances, [C/H], and are thought to owe their…

Solar and Stellar Astrophysics · Physics 2016-03-21 C. J. Hansen , B. Nordstroem , T. T. Hansen , C. R. Kennedy , V. M. Placco , T. C. Beers , J. Andersen , G. Cescutti , C. Chiappini

ABRIDGED: METHODS: We have conducted a high-resolution spectroscopic study of 714 F and G dwarf and subgiant stars in the Solar neighbourhood. The star sample has been kinematically selected to trace the Galactic thin and thick disks to…

Astrophysics of Galaxies · Physics 2015-06-17 T. Bensby , S. Feltzing , M. S. Oey