First stars IX- mixing in extremely metal-poor giants. Variation of the 12C/13C, [Na/Mg] and [Al/Mg] ratios

  title={First stars IX- mixing in extremely metal-poor giants. Variation of the 12C/13C, [Na/Mg] and [Al/Mg] ratios},
  author={Monique Spite and Roger. Cayrel and Vanessa Hill and Franccois Spite and P. François and Bertrand Plez and Piercarlo Bonifacio and Paolo Molaro and {\'E}ric Depagne and Johannes Andersen and Beatriz Barbuy and Timothy C. Beers and B. Nordstroem and Francesca Primas},
  journal={Astronomy and Astrophysics},
Context: .Extremely metal-poor (EMP) stars preserve a fossil record of the composition of the ISM when the Galaxy formed. It is crucial, however, to verify whether internal mixing has modified their surface composition, especially in the giants where most elements can be studied. Aims: .We aim to understand the CNO abundance variations found in some, but not all EMP field giants analysed earlier. Mixing beyond the first dredge-up of standard models is required, and its origin needs… 
First stars - XIII. Two extremely metal-poor RR Lyrae stars
Context. 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
High-resolution Spectroscopy of Extremely Metal-poor Stars from SDSS/SEGUE. III. Unevolved Stars with [Fe/H] ≲ −3.5
We present elemental abundances for eight unevolved extremely metal-poor stars with Teff > 5500K, among which seven have [Fe/H] < −3.5. The sample is selected from the Sloan Digital Sky Survey /
From detailed abundance analysis of >100 Hamburg/ESO candidate extremely metal-poor (EMP) stars we find 45 with [Fe/H] < –3.0 dex. We identify a heretofore unidentified group: Ca-deficient stars with
First stars X. The nature of three unevolved Carbon-Enhanced Metal-Poor stars ⋆
Context. On the order of 20% of the very metal-poor stars in the Galaxy exhibit large carbon enhancements. It is important to establish which astrophysical sites and processes are responsible for the
Abundances in the most metal-poor stars: nucleosynthesis in the early Milky Way
The detailed abundance patterns in extremely metal-poor (EMP) stars are examined, using the results of the First Stars ESO-VLT Large Program on large samples of dwarfs (located close to the main
The formation of the Milky Way halo and its dwarf satellites; a NLTE-1D abundance analysis. II. Early chemical enrichment
We present the non-local thermodynamic equilibrium (NLTE) abundances of up to 10 chemical species in a sample of 59 very metal-poor (VMP, -4 < [Fe/H] < -2) stars in seven dwarf spheroidal galaxies
First stars XII. Abundances in extremely metal-poor turnoff stars,and comparison with the giants
Context. The detailed chemical abundances of extremely metal-poor (EMP) stars are key guides to understanding the early chemical evolution of the Galaxy. Most existing data, however, treat giant
Are C-rich ultra iron-poor stars also He-rich?
Context. The three most iron-poor stars presently known ([Fe/H] equal to –5.96, –5.4 and –4.75) are carbon-rich, so they are called C-Rich Ultra-Metal Poor Stars (CRUMPS). The origin of their
New Extremely Metal-Poor Stars in the Galactic Halo*
We present a detailed abundance analysis based on high-resolution and high signal-to-noise spectra of eight extremely metal-poor (EMP) stars with [ Fe/H ] ≾ − 3.5 dex, four of which are new. Only
Observational Constraints on First-Star Nucleosynthesis. II. Spectroscopy of an Ultra Metal-Poor CEMP-no Star
We report on the first high-resolution spectroscopic analysis of HE0020-1741, a bright (V=12.9), ultra metal-poor ([Fe/H] = -4.1), carbon-enhanced ([C/Fe] = +1.7) star selected from the Hamburg/ESO


First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
We have investigated the poorly-understood origin of nitrogen in the early Galaxy by determining N abundances from the NH band at 336 nm in 35 extremely metal-poor halo giants, with carbon and oxygen
First Stars II. Elemental abundances in the extremely metal-poor star CS 22949-037 ? A diagnostic of early massive supernovae
CS 22949-037 is one of the most metal-poor giants known ((Fe=H) 4:0), and it exhibits large overabundances of carbon and nitrogen (Norris et al.). Using VLT-UVES spectra of unprecedented quality,
Abundances of 30 elements in 23 metal-poor stars
We report the abundances of 30 elements in 23 metal-poor ([Fe/H] < -1.7) giants. These are based on 7774 equivalent widths and spectral synthesis of 229 additional lines. Hyperfine splitting is taken
First stars. I. The extreme r-element rich, iron-poor halo giant CS 31082-001 - Implications for the r-process site(s) and radioactive cosmochronology
We present a high-resolution (R = 75 000, S/N 500) spectroscopic analysis of the bright (V = 11.7), extreme halo giant CS 31082-001 ((Fe/H) = 2.9), obtained in an ESO-VLT Large Programme dedicated to
First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
In the framework of the ESO Large Programme "First Stars", very high-quality spectra of some 70 very metal-poor dwarfs and giants were obtained with the ESO VLT and UVES spectrograph. These stars are
Abundances of RGB stars in NGC 6752
Abundances of O, Fe, Al, Mg, Na and Li determined from high-resolution and high signal{to{noise spectra of 21 red giant branch (RGB) stars in the globular cluster NGC 6752 are presented. We
Permitted Oxygen Abundances and the Temperature Scale of Metal-poor Turnoff Stars
We use high-quality VLT/UVES published data of the permitted O I triplet and Fe II lines to determine oxygen and iron abundances in unevolved (dwarfs, turnoff, subgiants) metal-poor halo stars. The
Evidence of Multiple r-Process Sites in the Early Galaxy: New Observations of CS 22892-052.
  • Sneden, Cowan, Lawler
  • Physics, Environmental Science
    The Astrophysical journal
  • 2000
The concordance of scaled solar r-process and CS 22892-052 abundances breaks down for the lighter neutron-capture elements, supporting previous suggestions that different r- process production sites are responsible for lighter and heavier neutron- capture elements.
Canonical Extra Mixing in Low-Mass Red Giants
We have used the latest observational data on the evolutionary variations of the surface chemical composition in low-mass metal-poor stars, both in the field and in globular clusters, to constrain
VLT/UVES constraints on the carbon isotope ratio 12C/13C at z=1.15 toward the quasar HE 0515-4414
We analyzed the CI lines associated with the damped Ly-alpha system observed at zabs = 1.15 in the spectrum of HE 0515-4414 to derive the 12C/13C ratio. The spectrum was obtained by means of the