Browsing Research publications by Author "Norris, J.E."
Now showing items 1-20 of 26
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Carbon enhanced metal-poor stars I : Chemical compositions of 26 stars
Aoki, W.; Beers, T.C.; Christlieb, N.; Norris, J.E.; Ryan, Sean G.; Tsangarides, S. (2007) -
Carbon-Enhanced Metal-Poor Stars. III : Main-Sequence Turn-Off Stars from the SDSS/SEGUE Sample
Aoki, W.; Beers, T.C.; Sivarani, T.; Marsteller, B.; Lee, Y.S.; Honda, S.; Norris, J.E.; Ryan, Sean G.; Carollo, D. (2008-05-10)The chemical compositions of seven CEMP turnoff stars are determined from high-resolution spectroscopy. Five are selected from the SDSS SEGUE sample of metal-poor stars. Another star chosen from the SDSS SEGUE sample has ... -
Carbon-enhanced metal-poor stars. Osmium and iridium abundances in the neutron-capture-enhanced subgiants CS31062-050 and LP625-44
Aoki, W.; Bisterzo, S.; Gallino, R.; Beers, T.C.; Norris, J.E.; Ryan, Sean G.; Tsangarides, S. (2006) -
Chemical Composition fo the Carbon-rich, Extremely Metal Poor Star CS 29498-043
Aoki, W.; Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Ando, H. (2002-09) -
The Chemical Composition of Carbon-rich, very Metal Poor Stars : A New Class of Mildly Carbon Rich Objects without Excess of Neutron-Capture Elements
Aoki, W.; Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Ando, H. (2002-03) -
A Critique of the Spite Plateau, and the Astration of Primordial Lithium
Norris, J.E.; Yong, David; Frebel, Anna; Ryan, Sean (2023-03-30)We investigate the distribution of the lithium abundances, A(Li), of metal-poor dwarf and subgiant stars within the limits 5500 K< eff < 6700 K, –6.0 < [Fe/H] < –1.5, and log >∼3.5 (a superset of parameters first adopted ... -
Estimation of Stellar Metal Abundance. II : A Recalibration of the Ca II K Technique, and the Autocorrelation Function Method
Beers, T.C.; Rossi, S.; Norris, J.E.; Ryan, Sean G.; Shefler, T. (1999)We have recalibrated a method for the estimation of stellar metal abundance, parameterized as [Fe/H], based on medium-resolution (1–2 Å) optical spectra (the majority of which cover the wavelength range 3700–4500 Å). The ... -
Europium Isotope Ratios in s-Process Element-enhanced Metal-poor Stars : A New probe of the 151Sm Branching
Aoki, W.; Ryan, Sean G.; Iwamoto, N.; Beers, T.C.; Norris, J.E.; Ando, H.; Kajino, T.; Mathews, G.J.; Fujimoto, M.Y. (2003-08) -
Extremely Metal-poor Stars : IX CS 22949-037 and the Role of Hypernovae
Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Ando, H.; Aoki, W. (2002-04) -
Extremely Metal-Poor Stars. VIII. High-Resolution, HighSignal-to-Noise Ratio Analysis of Five Stars with [Fe/H][[3.5
Norris, J.E.; Ryan, Sean G.; Beers, T.C. (2001-11) -
A high-resolution spectral analysis of three carbon-enhanced metal-poor stars
Goswami, A.; Aoki, W.; Beers, T.C.; Christlieb, N.; Norris, J.E.; Ryan, Sean G.; Tsangarides, S. (2006) -
Lithium abundances of extremely metal-poor turnoff stars
Aoki, W.; Barklem, P.S.; Beers, T.C.; Christlieb, N.; Inoue, S.; Garcia Perez, A.E.; Norris, J.E.; Carollo, D. (2009)We have determined Li abundances for eleven metal-poor turnoff stars, among which eight have [Fe/H] <–3, based on LTE analyses of high-resolution spectra obtained with the High Dispersion Spectrograph on the Subaru Telescope. ... -
Lithium abundances of halo dwarfs based on excitation temperature I : Local thermodynamic equilibrium
Hosford, A.; Ryan, Sean G.; Garcia Perez, A.E.; Norris, J.E.; Olive, K.A. (2009-01) -
Lithium abundances of halo dwarfs based on excitation temperatures. II : Non-local thermodynamic equilibrium
Hosford, A.; Perez, A.E.G.; Collet, R.; Ryan, Sean G.; Norris, J.E.; Olive, K.A. (2010)Context. The plateau in the abundance of 7Li in metal-poor stars was initially interpreted as an observational indicator of the primordial lithium abundance. However, this observational value is in disagreement with that ... -
Mg abundances in metal-poor halo stars as a tracer of early Galactic mixing
Arnone, E.; Ryan, Sean G.; Argast, D.; Norris, J.E.; Beers, T.C. (2005-02) -
Neutron Capture Elements in s-Process-Rich, Very Metal-Poor Stars
Aoki, W.; Ryan, Sean G.; Norris, J.E.; Beers, T.C.; Ando, H.; Iwamoto, N.; Kajino, T.; Mathews, G.J.; Fujimoto, M.Y. (2001-11) -
The new record holder for the most iron-poor star: HE 1327−2326, a dwarf or subgiant with [Fe/H] = −5.4
Frebel, A.; Aoki, W.; Christlieb, N.; Ando, H.; Asplund, M.; Barklem, P.S.; Beers, T.C.; Eriksson, K.; Fechner, C.; Fujimoto, M.Y.; Honda, S.; Kajino, T.; Minezaki, T.; Nomoto, K.; Norris, J.E.; Ryan, Sean G.; Takada-Hidai, M.; Tsangarides, S.; Yoshii, Y. (2005)We describe the discovery of HE 1327−2326, a dwarf or subgiant with [Fe/H] = −5.4. The star was found in a sample of bright metal-poor stars selected from the Hamburg/ESO survey. Its abundance pattern is characterized by ... -
A new sample of extremely/ultra metal-poor stars
Perez, A. E. Garcia; Christlieb, N.; Ryan, Sean G.; Beers, T.C.; Aoki, W.; Asplund, M.; Barklem, P.S.; Bessell, M.S.; Eriksson, K.; Frebel, A.; Gustafsson, B.; Korn, A.J.; Nordstrom, B.; Norris, J.E. (2008-12)A sample of 30 very metal-poor stars from the Hamburg-European Southern Observatory (ESO) objective-prism survey have been observed at high spectral resolution at the Very Large Telescope (VLT) using the Ultraviolet and ... -
Nucleosynthetic signatures of the first stars
Frebel, A.; Aoki, W.; Christlieb, N.; Ando, H.; Asplund, M.; Barklem, P.S.; Beers, T.C.; Eriksson, K.; Fechner, C.; Fujimoto, M.Y.; Honda, S.; Kajino, T.; Minezaki, T.; Nomoto, K.; Norris, J.E.; Ryan, Sean G.; Takada-Hidai, M.; Tsangarides, S.; Yoshii, Y. (2005-04) -
Oxygen Overabundance in the Extremely Iron-poor Star CS 29498-043
Aoki, W.; Norris, J.E.; Ryan, Sean G.; Beers, T.C.; Christlieb, N.; Tsangarides, S.; Ando, H. (2004-06)