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We report the discovery of a new subclass of carbon-enhanced metal-poor (CEMP) stars, characterized by high absolute carbon abundances (A(C) > 7.39) and extremely low metallicity ([Fe/H] $<=$ -3.1) but notably lacking enhancements in…

太阳与恒星天体物理 · 物理学 2025-09-23 Young Sun Lee , Timothy C. Beers , Yutaka Hirai , Jihye Hong , Miji Jeong , Changmin Kim , Young Kwang Kim

We identify six new CEMP stars ([C/Fe]>+0.7 and [Fe/H]< -1.8) and another seven likely candidates within the APOGEE database following Data Release 12. These stars have chemical compositions typical of metal-poor halo stars, e.g., mean…

Carbon-enhanced metal-poor (CEMP) stars span a wide range of stellar populations, from bona fide second-generation stars to later forming stars that provide excellent probes of, e.g., binary mass transfer. Here we analyse 11 metal-poor…

The chemical compositions of 26 metal-poor stars that exhibit strong CH and/or C2 molecular bands are determined based on high-resolution spectroscopy. We define carbon-enhanced stars taking account of the carbon abundance ratio ([C/Fe])…

Very metal-deficient stars that exhibit enhancements of their carbon abundances are of crucial importance for understanding a number of issues -- the nature of stellar evolution among the first generations of stars, the shape of the Initial…

天体物理学 · 物理学 2009-11-10 B. Marsteller , T. C. Beers , S. Rossi , N. Christlieb , M. Bessell , J. Rhee

(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…

星系天体物理 · 物理学 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

Carbon-enhanced metal-poor (CEMP) stars comprise a large percentage of stars at the lowest metallicities. The stars in the CEMP-no subcategory do not show any s-process enhancement and therefore cannot easily be explained by transfer of…

太阳与恒星天体物理 · 物理学 2019-01-30 Anke Arentsen , Else Starkenburg , Matthew D. Shetrone , Kim A. Venn , Éric Depagne , Alan W. McConnachie

Carbon-enhanced metal-poor (CEMP) stars represent a sizeable fraction of all known metal-poor stars in the Galaxy. Their formation and composition remains a significant topic of investigation within the stellar astrophysics community. We…

太阳与恒星天体物理 · 物理学 2018-06-20 E. Caffau , A. J. Gallagher , P. Bonifacio , M. Spite , S. Duffau , F. Spite , L. Monaco , L. Sbordone

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…

太阳与恒星天体物理 · 物理学 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

We report on the discovery of five carbon-enhanced metal-poor (CEMP) stars in the metallicity range of $-3.3<$ [Fe/H] $<-2.4$. These stars were selected from the LAMOST DR3 low-resolution (R$ \sim$ 2,000) spectroscopic database as…

Carbon-enhanced metal poor stars (CEMP) form a significant proportion of the metal-poor stars, their origin is not well understood. Three very metal-poor C-rich turnoff stars were selected from the SDSS survey, observed with the ESO VLT…

We estimate the frequency of Carbon-Enhanced Metal-Poor (CEMP) stars among very metal-poor stars, based on an analysis of 349 stars with available high-resolution spectra observed as part of the Hamburg/ESO R-process Enhanced Star (HERES)…

The detailed composition of most metal-poor halo stars has been found to be very uniform. However, a fraction of 20-70% (increasing with decreasing metallicity) exhibit dramatic enhancements in their abundances of carbon - the so-called…

太阳与恒星天体物理 · 物理学 2016-02-24 T. T. Hansen , J. Andersen , B. Nordström , T. C. Beers , V. M. Placco , J. Yoon , L. A. Buchhave

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…

太阳与恒星天体物理 · 物理学 2015-06-23 Vinicius M. Placco , Anna Frebel , Timothy C. Beers , Richard J. Stancliffe

Detailed spectroscopic studies of metal-poor halo stars have highlighted the important role of carbon-enhanced metal-poor (CEMP) stars in understanding the early production and ejection of carbon in the Galaxy and in identifying the…

太阳与恒星天体物理 · 物理学 2016-03-23 T. T. Hansen , J. Andersen , B. Nordström , T. C. Beers , V. M. Placco , J. Yoon , L. A. Buchhave

We have compiled composition, luminosity, and binarity information for carbon-enhanced, metal-poor (CEMP) stars reported by recent studies. We divided the CEMP star sample into two classes, having high and low abundances, respectively, of…

天体物理学 · 物理学 2009-11-13 S. G. Ryan , W. Aoki , J. E. Norris , T. C. Beers

Carbon-enhanced metal-poor (CEMP) stars are a unique resource for Galactic archaeology because they probe the properties of the First Stars, early chemical evolution and binary interactions at very low metallicity. Comparing the fractions…

Context: Carbon Enhanced Metal-Poor (CEMP) stars ($\mathrm{[C/Fe]} > 0.7$) are known to exist in large numbers at low metallicity in the Milky Way halo and are important tracers of early Galactic chemical evolution. However, very few such…

太阳与恒星天体物理 · 物理学 2023-06-28 T. T. Hansen , J. D. Simon , T. S. Li , A. Frebel , I. Thompson , S. Shectman

We have developed a new procedure to search for carbon-enhanced metal-poor (CEMP) stars from the Hamburg/ESO (HES) prism-survey plates. This method employs an extended line index for the CH G-band, which we demonstrate to have superior…

The most metal-deficient stars hold important clues about the early build-up and chemical evolution of the Milky Way, and carbon-enhanced metal-poor (CEMP) stars are of special interest. However, little is known about CEMP stars in the…

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