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

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The light elements, Li, Be, and B, provide tracers for many aspects of astronomy including stellar structure, Galactic evolution, and cosmology. We have taken spectra of Be in 117 metal-poor stars ranging in metallicity from [Fe/H] = -0.5…

Solar and Stellar Astrophysics · Physics 2015-05-30 Ann Merchant Boesgaard , Jeffrey A. Rich , Emily M. Levesque , Brendan P. Bowler

We discuss the detailed composition of 28 extremely metal-poor dwarfs, 22 of which are from the Hamburg/ESO Survey, based on Keck Echelle spectra. Our sample has a median [Fe/H] of -2.7 dex, extends to -3.5 dex, and is somewhat less…

In this work, we study the chemical compositions and kinematic properties of six metal-poor stars with [Fe/H] $< -2.5$ in the Galactic halo. From high-resolution (R $\sim$~110,000) spectroscopic observations obtained with the Lick/APF, we…

Astrophysics of Galaxies · Physics 2019-09-04 Mohammad K. Mardini , Vinicius M. Placco , Ali Taani , Haining Li , Gang Zhao

Modern spectroscopy of early-type stars often aims at studying complex physical phenomena. Comparatively less attention is paid to identifying and studying the "normal" A- and B-type stars and testing how the basic atomic parameters and…

Solar and Stellar Astrophysics · Physics 2015-05-13 L. Fossati , T. Ryabchikova , S. Bagnulo , E. Alecian , J. Grunhut , O. Kochukhov , G. Wade

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

A comprehensive model atom for Fe with more than 3000 energy levels is presented. As a test and first application of this model atom, Fe abundances are determined for the Sun and five stars with well determined stellar parameters and…

Solar and Stellar Astrophysics · Physics 2015-05-27 L. Mashonkina , T. Gehren , J. -R. Shi , A. J. Korn , F. Grupp

We present results from high-resolution (R $\sim 40,000$) spectroscopic observations of over 200 metal-poor stars, mostly selected from the RAVE survey, using the Southern African Large Telescope. We were able to derive stellar parameters…

Solar and Stellar Astrophysics · Physics 2022-03-14 Joseph Zepeda , Kaitlin C. Rasmussen , Timothy C. Beers , Vinicius M. Placco , Yang Huang , Éric Depagne

We present carbon and strontium abundances for 100 metal-poor stars measured from R$\sim $7000 spectra obtained with the Echellette Spectrograph and Imager at the Keck Observatory. Using spectral synthesis of the G-band region, we have…

Astrophysics · Physics 2009-11-13 David K. Lai , Jennifer A. Johnson , Michael Bolte , Sara Lucatello

We present detailed chemical analyses for a sample of twelve stars selected from the CH star catalogue of Bartkevicius (1996). The sample includes two confirmed binaries, four objects that are known to show radial velocity variations and…

Solar and Stellar Astrophysics · Physics 2014-12-12 Drisya Karinkuzhi , Aruna Goswami

The detection and subsequent characterisation of exoplanets are intimately linked to the characteristics of their host star. Therefore, it is necessary to study the star in detail in order to understand the formation history and…

Solar and Stellar Astrophysics · Physics 2018-07-18 M. G. Soto , J. S. Jenkins

The chemical composition of extremely metal-poor stars (EMP stars; [Fe/H]<~ -3) is a unique tracer of early nucleosynthesis in the Galaxy. As such stars are rare, we wish to find classes of luminous stars which can be studied at high…

We used moderately high-resolution, high S/N spectra to study the chemical composition of 10 field ab-type RR Lyrae stars. A new temperature scale was determined from literature Infrared Flux Method measures of subdwarfs and the Kurucz…

Astrophysics · Physics 2009-11-24 G. Clementini , E. Carretta , R. Gratton , R. Merighi , J. R. Mould , J. K. McCarthy

Abundances of about 18 elements including the heavy elements Y and Zr are determined from Hubble Space Telescope Space Telescope Imaging Spectrograph ultraviolet spectra of seven extreme helium stars (EHes): LSE 78, BD+10 2179, V1920 Cyg,…

Astrophysics · Physics 2016-08-30 Gajendra Pandey , David L. Lambert , C. Simon Jeffery , N. Kameswara Rao

Chemical abundances of 26 metal-poor dwarfs and giants are determined from high-resolution and high signal-to-noise ratio spectra obtained with Subaru/HDS. The sample is selected so that most of the objects have outer-halo kinematics.…

Astrophysics of Galaxies · Physics 2009-11-18 Lan Zhang , Miho Ishigaki , Wako Aoki , Gang Zhao , Masashi Chiba

We present our chemical abundance investigation of the metal-poor ([Fe/H]=-1.60 dex), r-process-enriched ([Eu/Fe]=0.73 dex) halo star HD 20 using novel and archival high-resolution spectra at outstanding signal-to-noise ratios. By combining…

We report new statistical equilibrium calculations for Fe I and Fe II in the atmosphere of Late-Type stars. We used atomic models for Fe I and Fe II having respectively 256 and 190 levels, as well as 2117 and 3443 radiative transitions.…

Astrophysics · Physics 2016-08-30 F. Thevenin , T. P. Idiart

We present high-resolution Magellan/MIKE spectroscopy of the brightest star in the ultra-faint dwarf galaxy Leo IV. We measure an iron abundance of [Fe/H] = -3.2, adding to the rapidly growing sample of extremely metal-poor stars being…

Astrophysics of Galaxies · Physics 2015-05-18 Joshua D. Simon , Anna Frebel , Andrew McWilliam , Evan N. Kirby , Ian B. Thompson

We have determined Li abundances in 55 metal-poor (3.6 < [Fe/H] < -0.7) stars with extreme orbital kinematics. We find the Li abundance in the Li-plateau stars and examine its decrease in low-temperature, low-mass stars. The Li observations…

Astrophysics · Physics 2009-11-13 Ann Merchant Boesgaard , Alex Stephens , Constantine P. Deliyannis

Extremely metal-poor stars provide us with indirect information on the first generations of massive stars. The TOPoS survey has been designed to increase the census of these stars and to provide a chemical inventory that is as detailed as…

We present new abundances derived from Cu I, Cu II, Zn I, and Zn II lines in six warm (5766 < Teff < 6427 K), metal-poor (-2.50 < [Fe/H] < -0.95) dwarf and subgiant (3.64 < log g < 4.44) stars. These abundances are derived from archival…

Solar and Stellar Astrophysics · Physics 2018-04-25 Ian U. Roederer , Paul S. Barklem
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