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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…

Astrophysics · Physics 2009-11-13 S. G. Ryan , W. Aoki , J. E. Norris , T. C. Beers

The origin of carbon-enhanced metal-poor (CEMP) stars and their possible connections with the chemical elements produced by the first stellar generations is still highly debated. We briefly review observations of CEMP stars in different…

Astrophysics of Galaxies · Physics 2016-10-19 Stefania Salvadori , Asa Skuladottir , Matteo de Bennassuti

We critically examine the constraints imposed by carbon-enhanced metal-poor (CEMP) stars on the mixing mechanisms that operate in red giants. CEMP stars are created when the surface layers of a metal-poor dwarf are enriched with He-burning…

Astrophysics · Physics 2009-11-13 Pavel A. Denissenkov , Marc Pinsonneault

We show that the peculiar surface abundance patterns of Carbon Enhanced Metal Poor (CEMP) stars has been inherited from material having been processed by H- and He-burning phases in a previous generation of stars (hereafter called the…

Solar and Stellar Astrophysics · Physics 2017-10-11 Georges Meynet , Raphael Hirschi , Sylvia Ekstrom , Andre Maeder , Cyril Georgy , Patrick Eggenberger , Cristina Chiappini

The chemical compositions of seven Carbon-Enhanced Metal-Poor (CEMP) turn-off stars are determined from high-resolution spectroscopy. Five of them are selected from the SDSS/SEGUE sample of metal-poor stars. The effective temperatures of…

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 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…

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

A significant fraction of all metal-poor stars are carbon-rich. Most of these carbon-enhanced metal-poor (CEMP) stars also show enhancement in elements produced mainly by the s-process (CEMP-s stars) and evidence suggests that the origin of…

Solar and Stellar Astrophysics · Physics 2016-07-13 E. Matrozis , R. J. Stancliffe

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)…

By considering the various CEMP subclasses separately, we try to derive, from the specific signatures imprinted on the abundances, parameters (such as metallicity, mass, temperature, and neutron source) characterizing AGB nucleosynthesis…

Solar and Stellar Astrophysics · Physics 2015-05-13 T. Masseron , J. A. Johnson , B. Plez , S. Van Eck , F. Primas , S. Goriely , A. Jorissen

We discuss radial velocities for a sample of carbon-enhanced, s-process rich, very metal-poor stars (CEMP-s hereafter), analyzed with high-resolution spectroscopy obtained over multiple epochs. We find that ~68% of the stars in the sample…

We investigate anew the distribution of absolute carbon abundance, $A$(C) $= \log\,\epsilon $(C), for carbon-enhanced metal-poor (CEMP) stars in the halo of the Milky Way, based on high-resolution spectroscopic data for a total sample of…

We present new high-resolution chemical-abundance analyses for the well-known high proper-motion subdwarfs G64-12 and G64-37, based on very high signal-to-noise spectra (S/N ~ 700/1) with resolving power R ~ 95,000. These high-quality data…

Solar and Stellar Astrophysics · Physics 2016-10-05 Vinicius M. Placco , Timothy C. Beers , Henrique Reggiani , Jorge Melendez

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

We construct binary-star population nucleosynthesis models of carbon-enhanced metal poor (CEMP) stars. We compare the CEMP to EMP (extremely metal poor) ratio of our models to the observed ratio and find it is an order of magnitude too…

Solar and Stellar Astrophysics · Physics 2015-05-14 Robert G. Izzard , Evert Glebbeek , Richard J. Stancliffe , Onno Pols

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 comprise almost a third of stars with [Fe/H] < --2, although their origins are still poorly understood. It is highly likely that one sub-class (CEMP-$s$ stars) is tied to mass-transfer events in…

Extremely metal-poor (EMP) stars are the living fossils with records of chemical enrichment history at the early epoch of galaxy formation. By the recent large observation campaigns, statistical samples of EMP stars have been obtained. This…

Astrophysics of Galaxies · Physics 2017-10-13 Gen Chiaki , Nozomu Tominaga , Takaya Nozawa

The carbon-enhanced metal-poor (CEMP) stars constitute approximately one fifth of the metal-poor ([Fe/H] ~< -2) population but their origin is not well understood. The most widely accepted formation scenario, invokes mass-transfer of…

Solar and Stellar Astrophysics · Physics 2015-05-14 Robert G. Izzard , Evert Glebbeek , Richard J. Stancliffe , Onno Pols