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Related papers: Lithium abundances in CEMP stars

200 papers

The genesis and chemical patterns of the metal poor stars in the galactic halo remains an open question. Current models do not seem to give a satisfactory explanation for the observed abundances of Lithium in the galactic metal-poor stars…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Rachid Ouyed

We present the first release of a large-scale study of relatively bright (V < 13.5) metal-poor stars observed with the Southern African Large Telescope (SALT), based on high-resolution spectra of 50 stars with a resolving power of R ~…

The HERMES spectrograph installed on the 1.2-m Mercator telescope has been used to monitor the radial velocity of 13 low-metallicity carbon stars, among which 7 Carbon-Enhanced Metal-Poor (CEMP) stars and 6 CH stars. All stars but one show…

Solar and Stellar Astrophysics · Physics 2016-02-17 A. Jorissen , S. Van Eck , H. Van Winckel , T. Merle , H. M. J. Boffin , J. Andersen , B. Nordstroem , S. Udry , T. Masseron , L. Lenaerts , C. Waelkens

We explore the kinematics and orbital properties of a sample of 323 very metal-poor stars in the halo system of the Milky Way, selected from the high-resolution spectroscopic follow-up studies of Aoki et al. and Yong et al. The combined…

Astrophysics of Galaxies · Physics 2015-06-18 Daniela Carollo , Ken Freeman , Timothy Beers , Vinicius Placco , Jason Tumlinson , Sarah Martell

Carbon-enhanced metal-poor (CEMP) stars are the living fossils holding records of chemical enrichment from early generations of stars. In this work, we perform a set of numerical simulations of the enrichment from a supernova (SN) of a…

Astrophysics of Galaxies · Physics 2020-07-29 Gen Chiaki , John H. Wise , Stefania Marassi , Raffaella Schneider , Marco Limongi , Alessandro Chieffi

CEMP-s stars are long-lived low-mass stars with a very low iron content as well as overabundances of carbon and s-elements. Their peculiar chemical pattern is often explained by pollution from a AGB star companion. Recent observations have…

Solar and Stellar Astrophysics · Physics 2017-11-08 Arthur Choplin , Raphael Hirschi , Georges Meynet , Sylvia Ekström

We present a study on the detailed elemental abundances of newly identified bright very metal-poor stars with the detection of lithium, initially observed as part of the SDSS/MARVELS pre-survey. These stars were selected for high-resolution…

Solar and Stellar Astrophysics · Physics 2022-10-05 Avrajit Bandyopadhyay , Thirupathi Sivarani , Timothy C. Beers , A. Susmitha , Prasanta K Nayak , Jeewan C Pandey

We report on an abundance analysis for a pilot study of seven Carbon-Enhanced Metal-Poor (CEMP) stars, based on medium-resolution optical and near-infrared spectroscopy. The optical spectra are used to estimate [Fe/H], [C/Fe], [N/Fe], and…

We propose and apply a new classification for the CEMP-no stars, which are "carbon-enhanced metal-poor" stars with no overabundance of s-elements and with [Fe/H] generally inferior or equal to -2.5. This classification is based on the…

Solar and Stellar Astrophysics · Physics 2015-07-29 Andre Maeder , Georges Meynet

We present NLTE Li abundances for 88 stars in the metallicity range -3.5 < [Fe/H] < -1.0. The effective temperatures are based on the infrared flux method with improved E(B-V) values obtained mostly from interstellar NaI D lines. The Li…

Solar and Stellar Astrophysics · Physics 2015-05-19 Jorge Melendez , Luca Casagrande , Ivan Ramirez , Martin Asplund , William Schuster

We provide *lambda*6708 Li 1 measurements in 37 metal-poor stars, most of which are poorly-studied or have no previous measurements, from high-resolution and high-S/N spectroscopy obtained with the McDonald Observatory 2.1m and 2.7m…

Solar and Stellar Astrophysics · Physics 2015-06-03 Marc Schaeuble , Jeremy R. King

We revisit the observed frequencies of Carbon-Enhanced Metal-Poor (CEMP) stars as a function of the metallicity in the Galaxy, using data from the literature with available high-resolution spectroscopy. Our analysis excludes stars…

Solar and Stellar Astrophysics · Physics 2015-06-23 Vinicius M. Placco , Anna Frebel , Timothy C. Beers , Richard J. Stancliffe

From high-resolution VLT/UVES spectra (R~43,000), we determine abundances or upper limits for Li, C, N, O, and other important elements, as well as 12C/13C isotopic ratio for three Carbon enhanced metal poor stars. All three stars have…

(Abridged) Carbon-enhanced metal-poor (CEMP) stars in the halo components of the Milky Way are explored, based on accurate determinations of the carbon-to-iron ([C/Fe]) abundance ratios and kinematic quantities for over 30000 calibration…

Astrophysics of Galaxies · Physics 2015-05-27 D. Carollo , T. C. Beers , J. Bovy , T. Sivarani , J. E. Norris , K. C. Freeman , W. Aoki , Y. S. Lee , C. R. Kennedy

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…

We present high resolution observations (FWHM=15 km/sec) of the Li region in 5 stars belonging to the old (14 Gyrs), metal rich ([Fe/H]=-0.7) globular cluster 47Tuc. At the ESO NTT telescope we obtained EMMI spectra for three V about 17.4…

Astrophysics · Physics 2011-05-23 Luca Pasquini , Paolo Molaro

It is known that the carbon-enhanced, extremely metal-poor (CEMP) stars constitute a substantial proportion in the extremely metal-poor (EMP) stars of the Galactic Halo, by far larger than CH stars in Population II stars. We investigate…

Context. The study of old, metal-poor stars deepens our knowledge on the early stages of the universe. In particular, the study of these stars gives us a valuable insight into the masses of the first massive stars and their emission of…

Solar and Stellar Astrophysics · Physics 2021-10-04 A. Matas Pinto , M. Spite , E. Caffau , P. Bonifacio , L. Sbordone , T. Sivarani , M. Steffen , F. Spite , P. Francois , P. Di Matteo

We explore the nature of carbon-rich ([C/Fe]_{1D,LTE} > +0.7), metal-poor ([Fe/H_{1D,LTE}] < -2.0) stars in the light of post 1D,LTE literature analyses, which provide 3D-1D and NLTE-LTE corrections for iron, and 3D-1D corrections for…

Astrophysics of Galaxies · Physics 2019-07-10 John E. Norris , David Yong

\sdsszeroeight\ (V = 11.4; [Fe/H] = $-$3.1) and \sdssonethree\ (V = 12.4; [Fe/H] = $-$3.2) were observed with the SDSS 2.5-m telescope as part of the SDSS-MARVELS spectroscopic pre-survey, and were identified as extremely metal-poor (EMP;…