dc.contributor.author | Norris, John | |
dc.contributor.author | Yong, David | |
dc.contributor.author | Bessell, Michael | |
dc.contributor.author | Christlieb, Norbert | |
dc.contributor.author | Asplund, Martin | |
dc.contributor.author | Gilmore, G.F. | |
dc.contributor.author | Wyse, Rosemary F. G. | |
dc.contributor.author | Beers, Timothy | |
dc.contributor.author | Barklem, Paul | |
dc.contributor.author | Frebel, Anna | |
dc.contributor.author | Ryan, Sean G. | |
dc.date.accessioned | 2015-04-02T11:33:48Z | |
dc.date.available | 2015-04-02T11:33:48Z | |
dc.date.issued | 2013-01-01 | |
dc.identifier.citation | Norris , J , Yong , D , Bessell , M , Christlieb , N , Asplund , M , Gilmore , G F , Wyse , R F G , Beers , T , Barklem , P , Frebel , A & Ryan , S G 2013 , ' The Most Metal-Poor Stars. IV : The Two Populations with [Fe/H] <~ -3.0 ' , The Astrophysical Journal , vol. 762 , no. 1 , pp. 28-46 . https://doi.org/10.1088/0004-637X/762/1/28 | |
dc.identifier.issn | 0004-637X | |
dc.identifier.other | ORCID: /0000-0001-9069-5122/work/30501320 | |
dc.identifier.uri | http://hdl.handle.net/2299/15740 | |
dc.description.abstract | We discuss the carbon-normal and carbon-rich populations of Galactic halo stars having [Fe/H] lsim -3.0, utilizing chemical abundances from high-resolution, high signal-to-noise model-atmosphere analyses. The C-rich population represents ~28% of stars below [Fe/H] = -3.1, with the present C-rich sample comprising 16 CEMP-no stars, and two others with [Fe/H] ~ -5.5 and uncertain classification. The population is O-rich ([O/Fe] gsim +1.5); the light elements Na, Mg, and Al are enhanced relative to Fe in half the sample; and for Z > 20 (Ca) there is little evidence for enhancements relative to solar values. These results are best explained in terms of the admixing and processing of material from H-burning and He-burning regions as achieved by nucleosynthesis in zero-heavy-element models in the literature of "mixing and fallback" supernovae (SNe); of rotating, massive, and intermediate-mass stars; and of Type II SNe with relativistic jets. The available (limited) radial velocities offer little support for the C-rich stars with [Fe/H] < -3.1 being binary. More data are required before one could conclude that binarity is key to an understanding of this population. We suggest that the C-rich and C-normal populations result from two different gas cooling channels in the very early universe of material that formed the progenitors of the two populations. The first was cooling by fine-structure line transitions of C II and O I (to form the C-rich population); the second, while not well defined (perhaps dust-induced cooling?), led to the C-normal group. In this scenario, the C-rich population contains the oldest stars currently observed. | en |
dc.format.extent | 19 | |
dc.format.extent | 823767 | |
dc.language.iso | eng | |
dc.relation.ispartof | The Astrophysical Journal | |
dc.subject | early universe, Galaxy: formation, Galaxy: halo, nuclear reactions, nucleosynthesis, abundances, stars: abundances | |
dc.title | The Most Metal-Poor Stars. IV : The Two Populations with [Fe/H] <~ -3.0 | en |
dc.contributor.institution | Centre for Astrophysics Research (CAR) | |
dc.description.status | Peer reviewed | |
rioxxterms.versionofrecord | 10.1088/0004-637X/762/1/28 | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true | |